Making a Panther Platform Vehicle Handle ... Crown
Victoria, Grand Marquis, and Town Car
The
following article is aimed at making a Panther Platform vehicle handle better.
Who is X Racer (Author)?
X
Racer has raced, wrecked, broken parts & bones till he is now "X"
Racer. X Racer may not be the one to
listen too on much more than how to break something or wreck it. But since you are, X Racer is me. My father even took my first wheelchair away
from me because he thought I would kill myself in it. It could have been the ramp to ramp jumps or it could have been
doing wheelies down the road at 25 mph.
I did not mind as I had worn the tires off it in about 2 months. Wheelchairs were never engineered to carry
that much plaster of paris. Anyway,
the devil lured me into wanting to go fast.
So I raced MotorCross, Hairscrambles, Enduros, Trials, AutoX and some
flying competition. We want even talk
about the fast women. If I was not
racing, I was playing Football, Wrestling or Boxing. I have been kicked out of every Go-Kart track in Panama
City. I have also been kicked out of
half the Water Parks I go to for going to fast. Along the way I learned a bit about racing and Orthopedic
Doctors. Between all these mechanical
toys, I learned how to repair them, weld them, modify them, and then break them
again. Now that I am older, more
mature, and laid back, I bought a 92 Crown Victoria and now my current 99 Grand
Marquis. These cars should carry me
well threw my slower years. During my
first AutoX race in the Grand Marquis, I blew away 1/3 the participants in a
nearly stock, full treaded tir,e land yacht after waiting nearly 15 years since
the last AutoX. Don't even ask me what
happened at the last Auto X. You are
supposed to do better each time.
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Handling and what is it. So
you want to make your Crown Victoria, Grand Marquis, or even Town Car handle
better. Good, it is not that
hard. But first what is handling? Smooth ride, quiet ride, high cornering
limits, good steering response, confidence inspiring, stop watch says its
fast, 0-60, 60-0, 1/4 mile times, low vibration, traction, and many other
words describe |
|
Hi! My name is Sarah. I am here to help X Racer
show you how to handle the curves and bumps.
Along the way, I hope to teach him how to spell and use proper
punctuation. |
handling. Racecar handling and a smooth quiet ride
tend to conflict. We are lucky with
modern cars because they give both better than ever. If you go to modifying your car, you are shifting the compromise
that the engineers picked. Engineers
are not wrong or right with the settings they chose. There is nothing wrong with shifting the compromise to satisfy
your taste. Just remember, you rarely
get something for nothing. I will try
to let you know the pros and cons of each modification. It is a lot like an old radio with a
treble/bass knob. No one can walk up,
set it and say, "This is the only correct position". It is personal. We are talking about a handling Vs ride. Sometimes you can get a lot of handling with
little trade off in ride. Some
modifications give very little handling and kill the ride. Many of the modifications listed do very
little to the ride by themselves, but start adding them all together and you
may be making big changes. Many of us
bought our CV/GMs for the smooth quiet ride.
Many for the safety, spacious interior, 6 seats, and more. Only you can decide how much handling Vs
ride you want. My wife says her car is
stock and it will stay that way. She
says I ruined my cars ride. I love my
car's modifications and most of us on Crownvic.net/.org do. I promise to do one thing here and that is
give you the Pros and the Cons so you can make an informed decision.
Tires:
The
tires are your only connection between the road and your vehicle. No one part of your car can influence
handling more than tires. First lets
put a hole in the old fiction tale that wide tires put more rubber on the
road. When you put 34 pounds of air in
a tire, you do not pull out a scale and weigh 34 pounds of air to pour into
your tire. It means 34 pounds per
square inch of pressure. No more and no
less. The front and rear of our CV/GMs
weigh about 2200lbs and 1800lbs respectfully.
That would be 1100lbs for each front tire and 900 lbs for each rear
tire. 1100lbs divided by 34psi would be
about 32 square inches. If your 225
width tire were about 8.7" wide, the contact patch would be about 3.7
inches long. 3.7" x 8.7" x
34psi = 1094lbs. Close for rounding
off. A wider tire, say 10", would
have a contact patch 3.4" long.
Obviously you would have to reduce the square inches of rubber in
contact with the road because of tread groves.
All this math means one thing and that is, wide tires only change the
contact patch shape. And yes, this does
affect handling.
There
are only three ways to increase rubber on the road. Lower your air pressure, increase the vehicle's weight, and go to
racing slicks so there is no tread cut out.
Tires have an ideal air pressure for peak performance. Lowering the tire pressure will only hurt
traction. Increasing the vehicle weight
is a BIG no no! That only leaves race slicks and that is illegal, dangerous,
and useless in the rain. You are now 0
for 0 on increasing the contact patch.
Well not really ... I left you an out with "ideal tire
pressure". We will come back to
this.
Many
of us have put wide tires on and noticed a big improvement. Was it the width, or was it the tire
compound, cord material and layout, and the profile?
Lets
go straight to the number one influence on tire traction since obviously it is
not tire width. Here it is...
"Tire Design". Tire companies
design their tires for a purpose. The
best dry weather paved road tires are classified as "Max Performance"
tires. Next are "Ultra
Performance" tires and last are "Performance" tires. Please reread all the conditions. That was dry weather & paved roads. Not rain, snow, or off road. "Max Performance" tires have
nicknames such as gumballs, Auto-X tires, DOT race tires, and such. They are purpose built for racing. They ride rough, they are noisy, expensive,
dangerous in the rain, and have very very short life spans. A highway tire typically is rated around 600
to 700 on wear. These tires typically
run around 50! That is 1/12th to 1/14th
the time! Like I said they are for
racing only or for the rich on sunny days.
They also need a special break in to work their best.
Ultra Performance Tires:
Now,
that 99.9% of us were just talked out of "Max Performance" tires,
lets go to the next category.
"Ultra Performance" tires are full treaded and normally
perform very well in the rain. The tread
wear ratings run about 180 to 280. Not
great on wear but that is the price you have to pay for performance. Also some of them ride rough and are
noisy. www.tirerack.com
has excellent write ups and comparisons.
Spend some time at this great web site when it is tire time. High performance tires tend to handle
better, have better steering response, more neutral handling, more forgiving,
more confidence inspiring, better rain performance, brake better, accelerate
better, and flat out corner harder. You
buy a lot with your money here! This is
the first spot to not be skimpy with your money if you want good handling.
|
Plus
sizing has been proven to help handling while maintaining the stock gearing, ride
height, speedometer accuracy, and overall handling characteristics. The lower profile tires used in plus
sizing helps reduce slip angles, improves steering response, and they corner
harder on smooth roads. Using the stock wheels and low profile tires, will
lower the car, drop your gearing, improve steering, improve cornering power,
reduce wheel weight and rotating inertia, |
Rocket Couch ++sizing
|
and
throw the speedometer accuracy off. My
old 245x50x16 tires dropped the gearing the equivalent of going from the stock
rear end ratio of 3.55 to a 3.70. The
speedometer was off about 3 mph by the time I am running about 70 mph till
corrected with a performance chip.
When
it comes to ride, anything that firms up the tires will also hurt the
ride. That includes performance level,
plus sizing, profile, rim width, etc...
As
you firm up the sidewall with wide rims and/or the short sidewalls used in low
profile tires, the tires ability to grip on rough roads may be reduced instead
of improved. Our solid rear axles tend
to aggravate this problem. The vast
majority of pavement is not that rough.
Just be ready the first time you see ripples in the asphalt. That means slow down. Good shocks help offset this.
Next:
For
the next step in making your car handle, you need to decide what part of
handling is important to you. For most
of us, it would be confidence inspiring and fun cornering. Sway bars normally win with no contest. But the stock swaybars are not too bad on
the HHP cars and our stock shocks are soooo soft. Do shocks first if you have HHP bars and then swaybars or flip a
coin. It is close.
Shocks:
Bilstein
HD shocks are the only reasonably priced shocks that work on CV/GM cars. There are many shocks that do wonders for
other cars. They just don't work on
ours. The part numbers are:
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Bilstein
HD front P/N B46-1495 Bilstein
HD rear P/N B46-1496 They
run about $65 a piece. Better shocks
will help braking power and acceleration off the line on even smooth
roads. It will also help cornering
power and tire wear. Don't expect
night and day changes on these improvements.
Expect night and day on these:
no more float, confidence on rough roads is way up, much better
bottoming resistance, much tougher to
|
|
I
like a firm ride ! Let
me hold those big shocks while you tighten things down. |
belly
the car into the ground. Here is the
down side. Your passengers will not
sense the much improved handling that the driver will notice, but they will
notice the much firmer ride. The stiffer
ride opinions have varied widely amongst CV/GM owners. Bilstein shocks may not be consistent on
their dampening. This may be an area
where people vary a bit with seat of the pants judgement. Even though there is
no consensus on how Bilstein shocks affect the smooth stock ride, we all agree
it was worth the money. You definitely
get used to it. I have one advantage
over others and that is my wife also has a 99 Grand Marquis HHP. I can do back to back comparisons to a stock
GM. That way my slipping memory does
not get off base.
Here
are the specifications on dampening rates in lbs. for both standard Bilstein
shocks that are virtually the same as stock and HD Bilstein shocks:
B46-1497 Comfort, Front 1240 compression, 1040 rebound (Close to stock)
B46-1498 Comfort, Rear 1000 compression,
470 rebound (Close to stock)
B46-1495 HD, Front 3090 compression,
2000 rebound
B46-1496 HD, Rear 1750 compression, 850
rebound
So
you say you want Max Performance from your Bilstein shocks. Call up Energy Suspension and order
polyurethane shock mount bushings. This
will help tie the wheels down even better.
Notice how all real race shocks use spherical bearings. Polyurethane give near metal to metal
results with less vibration and noise and unless there is rotation in the
joint, it will not need lubrication.
Two people have done this. One
said the ride was much rougher and the other could not tell a change. I'm sure that helped you.
Very
often people ask what other shocks do better (stiffer) than stock for less
money than Bilstein. Years of knowledge
from the hundreds of CV & GM enthusiast has lead to the following list:
Gabriel LT (1 driver) $18-$20
Edelbrock IAS (There is very positive feedback on
the newest models and all say they are not harsh) $??
Ford PI (1 driver felt it got most of the float out)
$22
End
of list.
Don’t
ask about Marauder shocks. They will
not fit. Marauder shocks should have
the perfect blend of ride and control.
They rear shock mounting points have moved to the outside of the frame.
Ok, for more money what is
there. You are now stepping into new
territory. The only place left to go
are separate rebound/compression, low speed adjustable & reshimable shocks. No one has gone there to our knowledge with
CV/GMs. There is only potential for
improvement and I believe it is there in transit steering response. Long ago, experts believed shocks had little
control on cornering. Wrong. Around 91 or 92 Indy race cars learned about
the shocks offroaders have used for centuries.
In recent years Auto-X racers have adopted this technology too. We are talking about separate low/med/high
speed dampening, one way shim stack dampener and other spy stuff. You may also need someone with a shock dyno
that knows how to use it and knows how to tweak all those springs, washers,
orifices, and whatever. When you turn
the wheel hard the car leans, weight shifts, tires take a set in slip angle,
and more. The inside turn shocks must
extend while the outside shocks compress.
This takes time and there forth we call this transit cornering. It also gives the shocks time to work. If we set the shocks with different rebound
and compression settings, we can momentarily shift weight to wheels different
than what the springs and swaybars would do.
With our big cars the front tries to push with a quick jerk of the
wheel. With shock tuning we could get
the right tires working harder and faster.
Unless you are rich, an Auto-X racer, or just want an all out handling
CV/GM, then you would most likely find the extra work, money, and possibly ride
harshness a disappointment for what you get back. If you are still with us, then go to Koni shocks web site. Just remember that you want dual adjustment
for both rebound and compression. There
are also other shock manufacturers.
Research it. Don't expect big
changes, just the ability to fine tune.
Notes
for installation on all shocks: Take it
easy on the lower front shock bolts.
There are no nuts ... just the thin soft stamped sheet metal lower control
arm. I learned the hard way. The top nuts use a 9/16" wrench or
socket. The top of the shock can be
held with a #9 spoke wrench or a ?/?" wrench. To speed up removal, you can cut the plastic guards, slide them
down, and vise grip the shaft so you can remove the nut. If you take this short cut, the old shocks
are history. Also use penetration oil a
few days before work. You will cuss the
access to the rear shocks upper nut. It
requires a long wrench and you can turn it very little. This will require a lot of patience (beer).
Swaybars:
Next
are swaybars and Addco is the only one there for us. The part numbers are:
Addco
front swaybar #509 1 1/4", about
$90
Addco
rear swaybar #650 1", about $90
Energy
Suspension ENS-9-5165G 1 1/4" "C" clamp w/grease, $13.95
Energy
Suspension ENS-9-5161G 1" "C" clamp w/grease, $13.95
New
front end link - ENS-9-8124G x2, 3 9/16"
$13.95
Addco/Energy
Suspension endlink bushings for rear - Package of 8, $7.95
98
Stock rear bar ?" next to Addco's 1"
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|
I
can help you stiffen the ride. |
"crownvic96"
Without Addco Swaybars. Not to bad, but
room for improvement. 
Addco
quality is satisfactory and the results are always very worthwhile. Everyone has been glad they did this
upgrade. They are very modestly priced.
Addco increases the front bar roll resistance about 52% and 71% for the
rear over the 98+ HHP bars and more on the rest. This is done with a 1.25" front bar and a 1" rear
bar. So far 100% of us have mounted our
bars on urethane or polyurethane bushings.
The ride will noticeably tighten up.
This is more noticeable on rough roads.
You can always substitute some of your old rubber endlink bushings with
the urethane/polyurethane bushings till you get the ride you want. I have never heard of a person complaining
about the ride with 100% rubber. You
can still get about 75% of the improvement with all rubber. Nothing does more to make hard cornering fun
than swaybars. The tire wear improves,
tire squeal changes to a growl, and the car stays much flatter in the
turns. You do get some improvement in
cornering power. This is the one
handling modification that puts more smiles per turn than anything else.
The
stock 98+ HHP bars are not too bad with stock tires. Just replacing the stock bushings with urethane/polyurethane
helps some and does not change the ride.
This is very cheep with a modest improvement. Cost is about $37 if you hunt around.
Mounting
is done with either Energy Suspension polyurethane bushings or Addco urethane
bushings. With either you only want the
"C" clamp bushings with grease fittings. Only Energy Suspension comes with them, but they also have them
without so be careful which ones you order.
With Addco, you will have to drill, tap, and cut a grove. If you do not have grease fittings, you will
soon hear the dreaded dry bushing squeak.
Addco tends to be over priced with their mounting hardware. They do have a good deal on the endlink
bushings. These can be bought at
Advanced Auto Parts and other parts shops.
Do note that Ford's rear "C" clamp is not a conventional two
bolt set up. Some people have drilled
and tapped for a second bolt. Some have
inserted a 3/8" spacer under the urethane/polyurethane bushing and reused
the stock "C" clamp. 
This
requires that a grease fitting mount be drilled and tapped. Also the grease fitting will need to be long
threaded as the Ford's "C" clamp has a reinforcing ridge running down
the middle creating a gap. Energy
Systems rear "C" clamp will not bolt up without modifications. Addoc's will bolt up but it does not have
grease fittings. We have one known
failure with this "C" clamp.
No matter what the rear will require some work or risk the dreaded dry
urethane squeak from lack of lubrication.
Suspension friction = poor ride and handling.
Addco
has in the past forgotten to add all the instructions. They have had fatigue problems with the
stock front endlinks. They now have a
new front endlink that bolts to the lower "A" arm. There is an existing unused hole in the
arm. The hole is punched so the edge is
very sharp for the plastic bushings. I
would recommend grinding the ridge down and adding a small radius to the
hole. The link is ?" long.
There
is a down side to Addco's endlink replacement.
The following is a quote from a Ford engineer on their ball jointed link
directly connecting to the spindle:
” We attach with
a ball link directly to the spindle since 1991 Town Car. We call this a 1-1
stabilizer bar attachment. It is much much more efficient than attaching to the
lower arm with rubber insulators, like some do, and we did for years. Of course
the ball attachment is more expensive, but the effects on steering response and
transient roll control are dramatic."
The
Ford engineer was very confident on the durability of their endlinks. Still, safety comes first.
Because
of the data making the stock endlink desirable, a letter was sent to Addco to
verify the problem. Here is the reply:
Dana,
I have not heard
of any problems we have had with endlink failure. I have asked around the
office and no one seems to have heard anything either. I'm not sure who sent
you information indicating there was a problem but as far as I know there isn't
one.
Let me know of
any further information you can get me and I will do the same.
Dan Osborne /
Vice President of OEM Operations
ADDCO Mfg. Inc.
1596 Linville Falls Hwy.
Linville, NC. 28646
Phone: 800/621/8916
Fax: 828/733/1562
e-mail: dosborne@addco.net
A
second E-mail was sent with the original installation sheet. With no reply, I spoke to Dan Osborne on the
phone.3-26-02. Dan is now saying not to
use the stock front end links. He could
not expand on the change in his response.
Don't
ask me what to do. This has left me a
bit confused too. These are the facts
as they are.
The
PI CVs have clearance problems with the front Addco bar because of the oil
cooling lines. I have not looked at the PI models to see what the problem
is. If the stock 1 1/8" bar
clears, why would Addco's 1 1/4" not?
Well the word back to me is the arms have a different bend. Energy Suspension does make tall mounts as
well as standard. Also the endlink
height could be adjusted some. Maybe
between the two, it can be done. I would think that the oil lines could be
rerouted. I don't have a PI so I don't
know. Do NOT mount just the Addco rear
bar alone! That would make the car tend
to spin. This is especially true in the
rain. This is not theory as several
people have reported their cars handling dangerously with only a heavy duty
rear bar. Addco says this too and so
will I.
See
Bada Bing's web page on installation with some great pictures. Thanks big guy!
http://home.swbell.net/jorem/addco_sway_bars.htm
Some
people have reported that Addco uses a poor grade of steel. This may be true and would help explain
their low prices. However all steels
have the SAME spring rate. Using a
lower quality steel would only be a problem if you twist the bar to its yield point
or close. If Addco's bars were reaching
the yield point, I would think it would be only a short time till they
break. You just can not bend steel back
and forth with out it very shortly breaking.
I just don't think our cars have enough suspension travel to twist the
bars to their yield point. Besides,
Addco are the only ones there for us and we have never had a problem.
Rim widths:
This
comes second to tires on pure cornering power.
Radial tires are sensitive to rim widths and they DO respond to it. Wide rims speed up the steering response
noticeably! A wide rim is a great
foundation for the tire. This is
especially true with heavy cars. I believe it also lowers the optimum tire
pressure. Lower tire pressure means
more rubber on the road. You should
also get better tire wear. If you
research the tire you are buying, you should have found the approved rim
widths. Sometimes you will see wording
like, "Recommended rim width".
This may be true, but is only true when keeping it conservative on
ride. It really should say rim width
used for tire measurement and many do this.
For maximum cornering power, reduced slip angles, best steering
response, pick the widest rim width.
The ride will degrade noticeably.
This happens mainly on sharp edged bumps. You should notice very little with normal road bumps. For most 245 x 50 x 16 tires the max rim
width would be 8.5" and for 245 x 45 x 17 tires this would be
9". This is an additional
1.5" to 2" over the stock 7" rims. Where are you going to put it?
On the inside you have an upper ball joint that hits first and in the
turns it is the front swaybar. It only gets worse with 255 tires. The rule of thumb says overall width goes up
.4" for every additional 1" of rim width. If I wanted performance over looks, I would go with 225 tires
over 245 or 255 if it meant loosing rim width.
It helps that much. You ask how
wide it best for cornering power? The
width of the tread is a good rule of thumb for the width of the rim for max
performance.
There
are two down sides to a wheel too wide (exceed recommended rim width). First the cornering power will start to
diminish. Second the flexing of the
sidewall will move down closer to the bead.
The bead area is thicker and will not tolerate this well. Heat will build up and the tire may
fail! At the same time if the rim is
too narrow, the flexing will move up to the tread area. Again the rubber is getting thick and heat
will be generated. Excess heat can
cause tire failure. The manufacturer's
guide lines for approved rim widths should work fine. Use the recommended rim widths and everything will be fine. That
also means that even the widest recommended width should not be too wide for
maximum cornering power. Maximum
cornering power hits typically when the rim width matches the tread width.
The
heavier a vehicle is, the more important it is to have a good foundation for
the tires. Our cars are very heavy
compared to sports cars.
On
the down side, rim width has a direct affect on the ride. Also the rims will be moving out from the
protection of the tire. It will be
easier to scrape a rim on a curb. If
you have scuffmarks on your rims now, then this may not be a good idea. My mom's car is a great example for not
needing wider rims. Lol! That is something to think about before
loaning out your car.
Here
are some Tire Manufacturer links on this subject.
Dunlop:
http://www.dunloptire.com/tiretech/?article=tire_width.txt
If
all those tire size numbers did not register, click here for tire numbers 101.
http://www.howstuffworks.com/tire2.htm

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Scrub radius: |
|
X Racer, you got me all
dirty ... Now you have to scrub me too! |
This
is also called Kingpin offset and Pivot Radius. This is simply the distance from an imaginary line drawn through
the ball joints till it hits the ground and the center of the tire.
|
|
This
imaginary line is what the tire pivots around when you turn the wheel. Most of the time it is 1" to
1.5" inches on rear wheel drive cars.
It is also the leverage the wheel has against the wheel in your
hands. Think of it as a wrench
1" to 1.5" long trying to fight you when driving. The good thing is
you should have a second wheel on the front of your car balancing things
out. Every time one wheel hits a deep
water puddle and pulls on the wheel, this is the lever pulling against
you. Same thing for brakes that pull.
It is also what gives you much of the "road feel" sensation when
driving. Why are you telling me all of this? Because on most cars all the added rim width will have to go to
the outside. Going to a 17" x 9" rim may add at most 1" to the
scrub radius. This is a 100% to 67%
increase. The wrench just got longer. Every water puddle will pull twice as
hard. |
That
brake job that was over due will be twice as bad. Our cars appear to have good room on both sides. CV/GM cars have
some of the poorest road feel and the strongest power steering units around. I
don't think we have too much worry about.
The only time I was mildly disappointed in the scrub radius change was
when I jumped from a 5" wheel to an 8" wheel with manual steering.
You should be able to add 1" more rim on both sides keeping the scrub
radius the same if you use nearly the same offset. Where do you get the data to mount wider wheels? All any tire shop will do is add all the
width to the outside and it is your problem if it hits the fenders. Most front ends are tight on the inside
anyway so their brainless method is right most of the time. Can
you tell me what clearance you need? Sure,
here is the formula. Just factor in the
tire coefficient of friction that generates the cornering forces that compress
the rubber "A" arm bushings, bows the spindle, twist the frame,
flexes your wheels, and off sets the tire on the rim that air pressure and rim
width also affects. It's just that simple! Ok, it is too complicated with to many variables. Adding it all to the outside is safe except
for the fenders. 8" rims appear to
be very safe on our cars. With a nearly
stock offset, 9" rims should work with 245 tires. Most likely 255 tires will squeeze by. Several people have used up to 275 tires on
the rear. I am not sure what rim width
they used. Wider rims do affect the
overall tire width. Obviously it has no
affect on tread width. If you want to
go wider, ask yourself, "am I ready to flare my fenders to make the tires
and wheels fit if there is a problem?"
I am not talking about 5" fiberglass flaring like some road racer
with tires 12" or wider. I am only
talking about folding the inner lip and then maybe a body man massaging and
extra inch or so into the metal, if anything is even needed. I have done this before and it is no big
deal. You will also be widening the
track width and this tends to help cornering power. "If" you feel the increase in the scrub radius
adversely affected the handling, then you can tighten things up. Many wheels companies machine the center
section of the wheel down for different offsets. Check to see just how much they approve. Second, place some clay on the tight fitting
areas. This would again be the upper
ball joint and the swaybar. The swaybar
only hits in full lock turns and is not sharp.
This should do little harm if they bump from time to time. Just don't crank the wheel with a lot of
pressure at full lock. When it stops
turning that is it and let up. The ball
joint is the key, but don't trust me.
Get in there and look around. It
could be the brake calipers. Anyway
pile the clay on and go for a drive.
Hit the roughest and hardest turns you know of. When you are done, measure how thick the
clay is. You could do this with the
stock wheels to see just how much room you have with the fenders. Just remember that the tire only moves over
half the rim width you are adding and the center bulge only moves .4" for
every 1" of rim width over the wheel used to make the tires
measurements. This is listed with the
approved rim widths. This peak bulge is
not at the edge of the tread. It is
even further away from the fender. Also
do not eye ball the fender clearance.
The top of the tire is pulled in by the shorter top "A" arm
giving even more clearance. Adding say
1 degree or more negative camber will also add fender clearance. Clean the parts and with a little luck the
clay will stick. Once you know exactly
how much room you have, take the wheels to a machine shop and machine the
mounting flange down to your new specification. Keep the changes small or go buy a new wheel with a different
offset. Spacers are frowned at, but up
to a 1/4" is safe with longer studs.
Don't forget, if you are testing with a tire with a lower performance
level than you plan to use in the future, deflections may be less. The "Watts Link" used on 98+ CV/GM
cars does a better job of locating the axle laterally. Obviously this means on pre 98 vehicles you
will have to have more clearance or replace the control arm bushings with
polyurethane to firm things up.
Ok, is there anything you do
know for sure? Yes, on stock 15" x 7" 10mm offset
wheels (pre98s), 255/50/15 tires will fit with some slight dragging on the
swaybar and the plastic by the footwell, but only at full lock. With 255/50/16 tires with stock 7"
wheels (98+), other owners say they clear.
My 245/50/16 tires on stock 16x7 10mm offset wheels cleared until the
Addco front sway bar was installed. It
took awhile, but plating is wearing a tad.
Again this is only at full lock.
We have a few members who have used the 17"x8", 25mm offset
Mustang Cobra wheels with 1/4" spacers.
Mustang wheels normally do not fit without spacers. Cobra wheels are
17" in diameter and 8" and 9" in width. With stock 16" wheels, it looks like we
have 1.75" of clearance on suspension parts. You should not have any problems with 8" width wheels, 9" may be tight and I highly recommend
17" wheels on any car with 98+ brakes.
I have yet to find a 16"x9" wheel that will fit. Currently I am running Ford Cobra 17x9
wheels with 1/4" spacers. More on
this four paragraphs down.
The
Tire Rack (www.tirerack.com)
has a 16x8 wheel for our cars. Cheap, easy,
and you know it fits.
The
stock wheels use a 10mm offset and the new appearance package Crown Victoria's
use a 12mm offset. The max backspacing
appears to be 5.5" that will fit.
If
this is not complicated enough, a college did a study on the affect of scrub
radius on cornering power. They
designed a custom adjustable spindle so that they could play with the scrub
radius and not affect any other measurements.
They took it all the way to a negative scrub radius. Their test showed that the cornering power
went up a full 0.1G with a negative scrub radius over about a 1.5" scrub
radius. Remember they adjusted the
scrub radius without changing the track width.
Adding track width normally improves the cornering power. I noticed that the skid pad was very very
tight. I would guess near full lock on
steering. Also the test were done with
a SUV. Still 0.1G is a big jump. They said nothing about the stability on the
highway. The old school of thought is that wheels that widen the track help
cornering. This makes you think about
it twice. Once again, this data does
not lead to a clear answer. I never
said I knew everything and if someone claims to; RUN!
Ford Cobra 17" x
9" wheels and Kumho ECSTA Supra 712 245/45/17 tires:
As
of June 2002 I have not found a wheel under $1000 each that is 9" or more
and will fit our cars. That does not
mean it does not exist, but I searched for months. I did find a 16x9 wheel with a near perfect offset that would
work on any pre 98 car. Even though it
will mount a 16" tire just like a stock98+ CV/GM stock wheel, the inside
wheel diameter will not clear the 98+ brakes.
The only thing I have found is 17x9 Cobra wheels with 1/4" spacers. I would think twice about using replica
Cobra wheels. They tend to weigh more
and if you ever dent/damage a wheel, you have no guaranty the company will be
around for a match. Ford will be here
tomorrow. Also the best price on each
is very close. Tire Rack had the best
deal at the time of my purchase. The
Cobra 17x9 wheel and tire added 5lbs per wheel over the 16x9 wheels I
found. Even these were about 9 to 10lbs
over the 16x7 HHP wheels with near bald tires.
Obviously, this is no way to improve your 1/4 mile times. Also the extra weight is toward the outside
of the rim. This is a modification for
handling and not for acceleration. Even
with 1/4" spacers, the offset is a tad less than stock. Between new full treaded tires and less
offset, you can feel that the steering is lighter. It was light enough to begin with. I chose Kumho ECSTA Supra 712 245/45/17 tires. They are not the best Ultra performance
tire. But they are near the top. I did compromise a tad to gain better tire
wear, reduced noise, wet traction, and ride.
A 50 profile tire would keep the diameter closer to stock. The Cobra center hole is perfect for our
cars. The hub that fits into the hole
is rather short. I have concerns as to
if the two even touch with the 1/4" spacers. A 1/8" spacer may work.
I need to pile some clay in a few places and see just how much room I
have. I would highly recommend longer
studs any time you use a spacer. Summit
should have longer wheel studs.
That's a lot of details, but
how did it perform? The steering is noticeable
more tight and a tad lighter. Cornering
power is way up. The tires will not
squeal until clearly over the edge. It
is more of a whooshing sound in the turns.
The back and front end used to have different ideas on what they wanted
to do. Now the rear end follows the
front with absolute precision. It is now
boring to drive because it is so easy at normal speeds. You feel like you have less control on speed
as the car no longer responds to the throttle much. What I mean is if you take you foot off the gas when turning
hard, she will not slow down nearly as fast.
The scrub is greatly reduced.
This is free HP. Less scrub means that if you screw up and get to hot in
a turn, you are in real trouble. Plus
the speeds are way up. A public road
can no longer be used to the limit even when no one is around. The speed is just to fast. With the old set up, you only had to hold on
for a few seconds and the speed would scrub off fast. The ride is much rougher on sharp edged bumps. Rounded bumps are virtually the same. It is almost the same amount of ride change
as when the Bilstein shocks were installed.
If your butt meter likes it smooth, then stick with a 8" max width
rim and no lower than 50 on the profile of the tire. The ride is still very quiet.
Many people say some of the very best of the Ultra Performance tires
tend to be noisy. Tire Rack post
owner’s opinions good or bad. The ride Vs performance with this tire/wheel
combination is not as favorable as expected.
The body rubber mounted on the frame does a great job of reducing any
harshness that modification can cause.
Evidently, you can push this rubber too far. My butt meter is at its limit on harshness. Our cars will never be race cars so me
there is no reason to totally kill the ride.
But I am getting a little older.
Someone in there 20's may say, "What’s next?" But at the very beginning I said much of
this is personal and subjective.
I
have played with the tire pressure some.
Dropping the air pressure to34psi front and 32psi on the rear seems to be
helping and I feel both ends take a better set at the same time in a turn.
Alignment:
Camber: For peak cornering power, cars need negative
front camber. If you are wearing the
outside edge faster than the rest of the tread, then this is a win win improvement. With our cars, you most likely have a
suspension problem if you are wearing uneven.
Especially with a 98+ car. They
take abuse very well. While adding
negative camber helps cornering by keeping the tire flatter when the car leans,
it also increases the camber change when using the brakes hard. You may loose a tad in braking. For peak performance, most radial tires like
2 - 3 degrees of negative camber. Most
street cars run 1/2 - 1 degree as a reasonable compromise. If you are wearing the outside edge, then
keep cranking the camber in. Cornering
power will go up and uneven tire wear will go down. It also may be time for HD swaybars and/or "A" arm bushings
if you are wearing the outside edge badly.
98+ CV/GM cars handle hard cornering with even tire wear. Thank you Ford.
Even
the rear tires like camber. If you are
ready to go 100%, you can torch the top of the rear axle making it warp. This is how many NASCAR and other solid axle
race cars add about .75 degrees camber to the rear. Anything more and you have to modify the axle splines. Also bearing, axle, and differential wear
goes up. This would make this
modification rather drastic with little return. This would be cool for a dedicated Auto-X car and not much
else. That eliminates about 99% of us.
How much gain in cornering
power does 0.5 to 1.0 degrees camber give you? If you can find the data, then let me know. Experts only say it helps. Handling is part science and part art. Every vehicle and tire will be different.
Toe-in: Our cars are slow to initiate a turn. Setting less toe in will help. I have tried toe out before and the car (not
a CV/GM) was still fairly stable. Wide
tires tend to add stability too. Going
toe out is a trial and error method.
The car may become darty, and braking may be more unstable. Front end condition and tires can have an
affect. Experiment with caution is the only advice with toe.
Castor: Castor adds stability and helps with
straight line stability. It also
affects trail. Trail is the same as on
bicycles and motorcycles. Castor is
more like the fork angle. Just like
with two wheel vehicles, increased castor and trail increases stability. It also may slow down turning. With four wheel vehicles, it adds negative
camber to the outside tire as you turn the wheel. This can help keep the tire flat in the turns and or help add the
negative camber needed for maximum cornering power. Trail changes with castor changes. There are no separate adjustments except for casting/forging your
own spindles.
Tire loads Vs Traction:
This
makes all the difference in the world to cornering power! Lighter is better. If you take a tire and apply a 500lb vertical load, you would
likely find it could handle a 500lb side load.
That would be the same as turning 1G!
That would be great. Now if you
place a 1000lb load on the same identical tire you would hope to get the same
ratio and get a 1000lb side load.
Nope! It would be closer to
850lbs or about .85G. That is no where
close. Our tires are running about
1100lbs on the front and about 900lbs on the rear empty! Yes they are big cars! From hear it goes down hill.
Weight shifting:
Our
cars sit a tad high and we get a fair amount of weight transfer from the g
force of a turn. You could easily
transfer with good tires about 80% of the weight. Lets play with some numbers.
Take a 3950 lb Grand Marquis with 12 gals of fuel and a 200lb driver and
CV/GM's 55%&45% front to rear weight split. This would place about 1858 lbs on the outside front wheel and 1520
lbs on the rear! The inside tires would
be running about 464 lbs and 380 lbs.
Note the rear inside wheel weight of 380 lbs and then think of trying to
put power down threw an open differential.
Can you say wheel spin! This is
just an example and we do not have any real data to show real weight transfers
and which end of the car is doing the most roll resistance. This is controlled by the sway bars,
springs, track widths, and more, but then taken away by frame flex. Many front wheel drive vehicles lift the
inside rear wheel right off the ground in a turn. Porsche rear engine cars tend to lift the inside front wheel off
the ground. This shows how cars react
when the front to rear weight bias is way off 50/50. The best performance with a given tire is when all four tires
work evenly and at the same time.
However, racing has shown weight distribution close to 40% front and 60%
rear on rear wheel drive works best.
The fact that our inside tires are very lightly loaded and can withstand
higher G loads as shown above, does not make up for the highly loaded outside
tires that we know can not corner hard.
Not even close with say 20% of the weight in their corner. The poor performing 80% of the weight or
whatever will dominate.
Lets
see what we can do to balance the traction.
Try to imagine a car with only one large sway bar at one end and nothing
at the other. Most all the weight
transfer would be carried by the sway bar end and it would be massive or even
100% as in cars that lift a wheel. The
non sway bar end would have both inside and outside tires working together with
nearly the same load. Guess which end
will have the most traction. Yep, the
non swaybar end. This is how we tune
our cars. If one end of the car is
loosing traction before the other end, we can shift the traction. Our cars are heavy in the front and lighter
in the rear. About 55/45. They also come with a rather large front
swaybar. Our rear track width is about
65.3" Vs 63.4" on the front.
All of this tends to make the front push. Addco bars are 40% stiffer in the front and 70% in the rear. This will shift the traction from the rear
to the front so that all four tires are working more evenly. We call this a balanced car when both ends
work equally. The bars also keep the
tires flatter on the road by reducing body roll. This all adds up to more cornering power. The stiffer rear bar also transfers more
weight off the inside rear wheel making it tougher to accelerate out of a
turn. Our cars are not all that
powerful so the wheel spin is not much worse than the stock set up before
Addco. Our CV/GM cars have a big
problem with frame rigidity. The same
body on frame with rubber mounts that makes our cars so smooth and quiet also
lets everything flex. It is hard to
adjust a sway bar and get the chassy to respond because the frame flexes
instead shifting the weight like we wanted it to. Again, a Panther platform car will never be an ultimate sports
car. Just better if you want it to be.
So what if you go threw a
turn so hard that nothing is left to put power down threw an open differential? You are going so much faster than the other guy that he will
never catch up. The only real fix is a
limited slip of some sort.
Adjusting the cars balance
If
the car is pushing (to tight, understeering) to much, try the following:
More
front tire pressure
Less
rear tire pressure
Smaller
front swaybar
Softer
front swaybar mounts
Larger
rear swaybar
Stiffer
rear swaybar mounts
Wider
front tires
Wider
front rim widths
Shift
weight from the front to the rear
Use
softer front springs
Use
stiffer rear springs
Use
softer front shocks
Use
stiffer rear shocks
Widen
the front track
Narrow
the rear track
Use
a softer compound tire on the front.
Use
a harder compound tire on the rear
Reduce
the roll axis angle by lowering the rear center of roll (rear is normally
higher than front)
Reduce
toe in on the front (toe out may be unstable)
Add
more front camber
Reduce
scrub radius (may only work on tight turns)
Reduce
kingpin angle without increasing the scrub radius (only works on tight turns)
If
the car is oversteering (loose, trying to spin) too much, try the following:
Do
everything the opposite as shown for understeering. If that does not work, lift your right foot a tad off the right
pedal.
Reducing weight shift in the
turns, Ride Height, Springs:
Obviously
we have learned so far, that anything that reduces weight transfer in a turn
and helps all four tires work together in a turn will also help cornering
power. The easiest way to reduce weight transfer in a turn is to lower the
car. The air ride rear suspension cars
are easy. Just loosen the ride height
sensor, slide it over away from the differential, and retighten. Done.
This is only on the rear on some of our cars. They all have coil springs on the front.
With
springs there are two ways that are cheap.
The easiest is to cut the spring down.
The problem is it will also make the spring stiffer. If you cut 1" worth of spring you may
only get 3/4" lower. 1/2 to 1 coil
is about all you can get away with on our cars. This is a bit of trial and error. Just go slow because you can not add back what you cut. One
member reported about a 2" reduction in ride height with 1 coil cut. He also felt the ride was noticeably stiffer. He strongly recommended starting at 1/2 a
coil to start with. He said that the
camber adjustment was maxed out during the realignment.
The
second method is to use the same spring compressor that you used to remove the spring.
Compress the spring as far as you can.
Then place it in your oven at 450 degrees for say about 10 minutes. Remove and recheck the length. You did measure it before baking it? Keep increasing the time till you get the
desired results. There is no data on
baking time. So go slow or risk messing
up a spring. This is a great way
because the spring rate does not change.
It is also a trial and error method.
Again, go slow. The toughest
part is getting the left and right the same.
Just make sure you compress the left and right springs the same and use
the same oven time. They should come
out the same. If not just cook a tad
more on the long spring. The low 450
degree temperature will not alter the heat treatment. Some people use a torch directly on the springs while on the
car. This is a BIG NO NO. It also gives the oven method a bad
rap. Jumping from 450 degrees to about
1500 degrees or more will mess up the metal grain structure, temper, heat
treatment, or whatever you want to call it.
The oven method will not change the spring stiffness and there forth no
ride change.
The
third method is to spend your hard earned money on after market springs. Most after market springs are stiffer. Same or close to a cut stock spring. Increasing the spring stiffness is one of
those modifications where the handling increases very little, but the ride
takes a big dive. Remember that stiffer
springs work similarly to stiffer swaybars.
It can change the balance of understeer and oversteer.
I
would NOT lower a CV/GM without much better shocks and HD swaybars. Car lean and weak shocks can use up most of
the suspension travel leaving you little for the bumps in a turn. You do NOT want to ride your bump stops in a
turn! This will kill your car's handling. Some people try stiffer springs to stop
bottoming and dragging the car.
Offroaders use compression dampening in the shocks as the primary method
for bottoming control. This is catching
on with street vehicles. Both stiffer
springs and stiffer shocks reduce bottoming.
But stiffer shocks hurt the ride less.
Stiffer springs will kill the ride.
For maximum traction, you always use the softest spring you can
use. Again, Bilstein shocks do a great
job at this and they are matched to the stock springs. Stiffer springs may throw off the rebound
setting Bilstein designed. Just don’t
know. Here comes the down side again. When you lower a car using the springs, you
change the "A" arm geometry.
This may hurt the handling more than you helped it. Not often, but it can. Also you are loosing some of your
compression travel. Hopefully, better
shocks and swaybars will keep this in check.
It has on mine and other CV/GM drivers.
There
is a forth way to lower your car. Just
buy low profile tires with the stock diameter wheels. This will lower your car, gear her down for better out of the
hole power, increase braking power, improve the sprung to unsprung ratio, the
tire profile is lower, the steering response is better, the control arm
geometry is unchanged taking the risk out there, the rotating inertia is
reduced, and you will still have full compression travel in the
suspension. Wow! For the down side, smaller diameter tires
will lower your gas mileage just the same as if you changed your rear end ratio. The same thing happens to the
speedometer. And just the same, you can
buy a new speedometer gear and/or burn a chip to bring the accuracy back in
line. Also anytime you use low profile
tires, the rim is closer to the ground.
This will degrade curb and pothole damage resistance. Last, the car will be lower when the bump
stops are reached.
And
you thought we were out of methods.
Lol! Here comes #5. Another trick is to replace the frame to
body rubber mounts with a stiffer and lower mount. This will hurt the CV/GMs great ride. This method also ties the body and frame together adding
rigidity. This helps a lot when it is
time to use sway bars and shocks to tune the car's balance. This is rather extreme for most of us. This method keeps your ground clearance and
suspension geometry the same. Note: The
gas lines pass between the frame and body by the drivers side rear wheel. Check for wiring, engine, transmission, etc...
clearance and interference problems first.
You could say forget the bushings all together and bolt the two
solid. I have noticed that all large
trucks lay a piece of wood between the frame and body. I would think this was to keep from rubbing
metal on metal. Also welding lumps and
such could be imprinted into the wood Vs steel that is not so good at it. Kind of like a gasket making up for
irregularities. 95-97 Impala owners
have gotten great results in handling by messing with the body to frame bushings. No, CV/GM owners have messed with these
mounts to date. This would be new
ground to break for us.
If
you do lower your car using the springs, expect the alignment to change. You should find more negative camber. That will help cornering and most likely
cause uneven tire wear.
The
track width also plays an important part of the weight transfer. Making the car wider helps. The only real option is with wheel offset
and width. The down side on scrub radius
is covered under wheel widths. The only other way is custom control arms and
spindles. Can you say $$.
Anything
to get weight off the front will help.
Remember that the more even the tire weights, the better their
performance. More rear weight also
helps acceleration off the line and braking potential if you readjust the
bias. Moving the battery to the trunk
will shift a little under 1% of the weight and lower it and get it out of the
heat so it will last longer. Pre 98
cars have aluminum bumpers that may weigh less. We have not compared to know.
Exhaust systems have been upgraded to improve power and they tend to be
much lighter. Trailer hitches add
weight. But, I have things to tow and
that adds 40+or- lbs to a bad spot. A
mini spare can knock off 15 to 20 lbs.
Mustang Cobras use a light weight mini spare that may work on our cars.
Spring
and ride height data from Ray Bones.
Great work Ray!
From Ray Bones:
The spring rate is different (HPP = 102
lb/in, base air spring is 89 or 75 depending on year). They are a direct plug
in for each other, ie no vehicle modifications required. HPP springs have a
firmer ride and are harsher. Handling will be a little different.
--------------------------------------
Spring rates for the
pre-03 non-HPP CV (P73/74) - Front=440 Rear=130
Spring rates for the pre-03 CV PI (P71)
- Front=700 Rear=160
Spring rate for the pre-03 HPP - Front=560 Rear=Air 102
---------------------------------------
Base air springs EN & FN 1990 -1997
(75 lbs/in) Cream piston and cream cap, HPP air springs all years (102 lbs/in) -
black piston and cream cap, Base air springs 1998-present (89 lbs/in) cream
piston and black cap.
--------------------------
Aprox. rear metal to metal travels at
curb.
Jounce Rebound
Base = 5.5 3.9
HPP = 5.1 4.3
Police = 6.3 3.1
-------------------------------------------
Mercury Marauder uses the HPP rear air
springs. Front springs are 325 lbs/in (do not compare directly to older cars
spring rates due to different motion ratios). Shocks have much more effective
damping than the older car you are talking about. Also Mercury Marauders have
less suspension travel in order to protect package space for the larger
tire/tire package.
Slip angle:
When
we turn the wheel we assume the tire contact patch turns with it. However our tires are very flexible with the
massive weight they have to support.
When we corner, the contact patch is turning a different direction than
the wheel. We call this the slip angle. It does not mean we are sliding on the
pavement. This is easy to see in a
parking lot. With the engine running, stand outside your open window. Apply pressure to the steering wheel till
you can see the wheel turn. Then
release. The steering wheel and rim
will spring back in place. Keep doing
this till the tire contact patch slips.
If the tire slips, the steering wheel will not return to its original
position. This is the maximum slip
angle for your car. At least in the
parking lot with no weight transfer.
Anouther way is to go to a large empty parking lot. Turn the wheel to lock. Now make a slow turn. Keep speeding up and note that the car keeps
making larger turns. You have not moved
the steering wheel, and the tires are not sliding. Yet the side loads are reducing the effective steering angle
making for a bigger turn. Just say slip
angle.
Engineers make sure the front lets go first for safety reasons. That also means that the front slip angles are much greater than the rear. When we add Addco swaybars, the slip angles are much more even. We get a slip angle on the front tires by turning the wheels. So how does this work in the rear? The whole car must turn side ways to get a slip angle. When Addco added about 70% more roll stiffness to the rear bar Vs 40% for the front, they induced more slip angle on our rear tires. This does mean you will go threw a turn more sideways. Lets say it was 5 degrees before we upgraded the bars.