Make payments with PayPal - it's fast, free and secure! registry | CVN on Facebook | tech | news | email login Make payments with PayPal - it's fast, free and secure!


Welcome to CVN - Your Panther platform headquarters!


Custom Search


Page 1 of 3 1 2 3 >
Topic Options
#2183128 - 11/16/10 11:45 PM Rear-end change from 3.55 to 2.73-Couple Questions
ferg Offline
Climber

Registered: 11/05/09
Posts: 899
Loc: SE Michigan
I want to swap my rear end for a 2.73 rear end. 90% of my driving is highway and I want the better gas mileage and less engine wear (lower rpms).

Probably going to just change the whole rear end instead of just doing the ring and pinion (so I can do all the work myself).

I understand the speedometer and odometer will be off until I can get it programmed for the new gear, but will it be driveable until the program?

I can still use my p71 driveshaft right (for an '04 mgm rear end)?

How will the trans shift with the 2.73 w/o programming? Will it shift really early or really late?

What kind of programer/tuner can I use to make the necessary changes?

Thanks for any input!
Jeremy
_________________________
2006 P71 (current), white, bumper tuck, 5% tint all around, code alarm/remote start, cruise wheel, MGM carpet, rampage center console, bullet mufflers dumped at the axle, marauder spoiler, staggered 2015 mustang wheels. 141k and counting....

1998 Camaro SS, black, 6sp, turbo, c6 rims, 600hp
2018 Chrysler Pacifica (family truckster)
2009 Mustang GT/CS, vista blue, vert, 5sp.

Top
Links
#2183133 - 11/16/10 11:54 PM Re: Rear-end change from 3.55 to 2.73-Couple Questions [Re: ferg]
BigMerc96 Offline

I know nothing
Posting Addict

Registered: 06/05/10
Posts: 19868
Loc: I can see Detroit from here!
It'll shift really strange, but it should be drivable. As for the drive shaft, that will work just fine, the difference between the Civi and PI is in the length of the tail-shaft on the trans so reuse the PI drive shaft.

Not sure on an '04 if you actually need a tune to correct the speedo and shift points or not. You might be able to just change the gear in the Vehicle Speed Sensor, cant remember if that changed for '04 or '05.
_________________________
-Steve

2006 Audi A6 ~132k miles, stock.
1998 Mercury Grand Marquis LS HPP ~100k miles, slowly acquiring modifications.
1997 Town Car Cartier ~145k miles, Ported Plenum, Gutted Airbox, Contour E-fan Retrofit, Dual exhaust with Magnaflows, cats deleted, MSD Ignition, KYB Gas-A-Justs, P71 front bar, air ride reinstated, Projector retrofit, Caddy 4-note horn retrofit, Wood rim steering wheel retrofit, holistic weight reduction as the parts fall off..
1996 Mercury Grand Marquis GS 117,485mi. R.I.P. 7/14/12 frown

Top
#2183135 - 11/17/10 12:01 AM Re: Rear-end change from 3.55 to 2.73-Couple Questions [Re: BigMerc96]
ImpulseRocket89 Offline
Over the Hill

Registered: 08/23/09
Posts: 1799
Loc: Omaha, NE USA
Why not drop down to a 3.27 and maybe run a taller diameter tire because no matter what you are going to have to correct the speedo. Take it from me, the 2.73's are a dog. I hate mine and would love to swap up to a 3.27 or 3.55 gear set.
_________________________
2005 Crown Vic LX: Eaton 1.5" P71 drop springs & KYB Gas-A-Just P71 shocks. Heinous Control arms. Addco sway bars. 18x8.5 Fanblades. Mini D2S Projector retrofit - 50W w/ 5000k. Mach 1 Chin Spoiler, Kenwood head unit, upgraded speakers, Infinity Bass-link. Cryostop Rotors, and Porterfield R4S Pads. Trickflow Upper plenum, AFe Stage 2 intake, Steeda UD Pulleys, Catco high flow cats, Factory Duals w/magnaflow 11224's, MMC Driveshaft w/ Fabtech spacer, BOC Tune.
1988 Isuzu Impulse Turbo: Torn to bits, being built and collecting dust. (2.6L engine, 7670 EFR, MUA-5 trans etc. etc.)

Top
#2183157 - 11/17/10 12:39 AM Re: Rear-end change from 3.55 to 2.73-Couple Questions [Re: ImpulseRocket89]
ferg Offline
Climber

Registered: 11/05/09
Posts: 899
Loc: SE Michigan
BigMerc - Thanks for the input. It would be really nice if it was just a vss gear change as opposed to the programming. P.S. I can see Detroit from here too (e.p.)!

Impusle - If you are planning any trips to the Detroit area I would love to get you into a 3.55! Honestly, in the last year or so I've started driving like an old lady and accelerate soooo sloooow. I came across this chart the other night:

https://crownvic.net/ubbthreads/ubbthreads.php?ubb=showflat&Number=1951962

...and can't believe how high my rpm's are on the highway!! Ofcourse, if I had a tach I would've made the change sooner.

Another member said he might be interested in trading some 3.27's for my 3.55's but I'm not sure that's going to be a big enough difference....
_________________________
2006 P71 (current), white, bumper tuck, 5% tint all around, code alarm/remote start, cruise wheel, MGM carpet, rampage center console, bullet mufflers dumped at the axle, marauder spoiler, staggered 2015 mustang wheels. 141k and counting....

1998 Camaro SS, black, 6sp, turbo, c6 rims, 600hp
2018 Chrysler Pacifica (family truckster)
2009 Mustang GT/CS, vista blue, vert, 5sp.

Top
#2183166 - 11/17/10 12:55 AM Re: Rear-end change from 3.55 to 2.73-Couple Questions [Re: ferg]
ImpulseRocket89 Offline
Over the Hill

Registered: 08/23/09
Posts: 1799
Loc: Omaha, NE USA
yea, its a shame we dont live reasonably close lol. just park back to back and swap em around.

I only suggest the 3.27's because I recently got to drive an 05 Sport, and although I know they have a bit more power I know its not enough to make THAT big of a difference in how well the car gets going from a stop. Its night and day compared to my 2.73s (to me it was at least) and the fuel economy on said sport was more or less the same as my LX gets with the granny gears.
_________________________
2005 Crown Vic LX: Eaton 1.5" P71 drop springs & KYB Gas-A-Just P71 shocks. Heinous Control arms. Addco sway bars. 18x8.5 Fanblades. Mini D2S Projector retrofit - 50W w/ 5000k. Mach 1 Chin Spoiler, Kenwood head unit, upgraded speakers, Infinity Bass-link. Cryostop Rotors, and Porterfield R4S Pads. Trickflow Upper plenum, AFe Stage 2 intake, Steeda UD Pulleys, Catco high flow cats, Factory Duals w/magnaflow 11224's, MMC Driveshaft w/ Fabtech spacer, BOC Tune.
1988 Isuzu Impulse Turbo: Torn to bits, being built and collecting dust. (2.6L engine, 7670 EFR, MUA-5 trans etc. etc.)

Top
#2183167 - 11/17/10 01:02 AM Re: Rear-end change from 3.55 to 2.73-Couple Questions [Re: ImpulseRocket89]
mustang_zulu Offline
I am not
Over the Hill

Registered: 04/16/08
Posts: 1899
Loc: Garland, TX
hey on the highway i "can" get 26-28 mpg with my 3.27's... perhaps ur driving style is the issue??? difference between 3.55 and 3.27 is not noticeable.....
_________________________

http://www.supermotors.net/vehicles/registry/19076
http://www.kiaboard.com/1998CVHPP/phpslideshow.php
1998 CVHPP P74, 130k Orginal Miles, Flow Master Delta 40's/ CAI/ P71 PCM, P&P Inc. plenum & 75mm TB/ PI Intake & Cams/ 24 lb Injectors/ Steeda UD's

Vortech S/C Vic under construction **stay tuned**

Top
#2183197 - 11/17/10 04:19 AM Re: Rear-end change from 3.55 to 2.73-Couple Questions [Re: mustang_zulu]
ferg Offline
Climber

Registered: 11/05/09
Posts: 899
Loc: SE Michigan
 Originally Posted By: mustang_zulu
hey on the highway i "can" get 26-28 mpg with my 3.27's... perhaps ur driving style is the issue??? difference between 3.55 and 3.27 is not noticeable.....


...going down hill with the wind at your back, maybe.....
j/k that surprises me with 3.27's. I'm only getting 20 on the highway (with winter mix gas), with a steady foot and 65mph. Aside from the gas mileage issue, I don't like turning these high rpm's with the 3.55.
_________________________
2006 P71 (current), white, bumper tuck, 5% tint all around, code alarm/remote start, cruise wheel, MGM carpet, rampage center console, bullet mufflers dumped at the axle, marauder spoiler, staggered 2015 mustang wheels. 141k and counting....

1998 Camaro SS, black, 6sp, turbo, c6 rims, 600hp
2018 Chrysler Pacifica (family truckster)
2009 Mustang GT/CS, vista blue, vert, 5sp.

Top
#2183209 - 11/17/10 06:48 AM Re: Rear-end change from 3.55 to 2.73-Couple Questions [Re: BigMerc96]
2004_p71 Offline

no replacement for displacement
Posting Addict

Registered: 09/04/03
Posts: 15710
Loc: Quebec Canada
 Originally Posted By: BigMerc96


Not sure on an '04 if you actually need a tune to correct the speedo and shift points or not. You might be able to just change the gear in the Vehicle Speed Sensor, cant remember if that changed for '04 or '05.


any 03+ car will require a tune for proper speedo calibration and shifts point because of theses two reasons:

1-there is no more plastic gear to switch in the trans like it used to be for the 92/02 cars
2-you are above the two step gear change..meaning that if you would have went down to 3.08 you would have been ok but 3.55 to 2.73 is 3 step.
_________________________


new best time 13.079 @ 105 1.8 60'

Top
#2183228 - 11/17/10 08:11 AM Re: Rear-end change from 3.55 to 2.73-Couple Questions [Re: ImpulseRocket89]
98VicP71 Offline
[email protected]
Grand Poobah

Registered: 03/28/06
Posts: 12731
Loc: ATL
 Originally Posted By: ImpulseRocket89
Why not drop down to a 3.27 and maybe run a taller diameter tire because no matter what you are going to have to correct the speedo. Take it from me, the 2.73's are a dog. I hate mine and would love to swap up to a 3.27 or 3.55 gear set.



Well sounds to me like you two should get together and swap rear ends with eachother.. Then you both would get what you want.
_________________________
1993 Lincoln Town Car 150k+ - RIP 5/10/2011
1998 Ford Crown Victoria P71 - RIP 12/25/2006
2001 Ford Crown Victoria P71(Count blackula) 297k+ - Ummmmmm evil

Top
#2183271 - 11/17/10 09:57 AM Re: Rear-end change from 3.55 to 2.73-Couple Questions [Re: ferg]
GrandMarq9807 Offline
Over the Hill

Registered: 05/10/10
Posts: 4420
Loc: Virginia
 Originally Posted By: ferg
...and can't believe how high my rpm's are on the highway!! Ofcourse, if I had a tach I would've made the change sooner.

Another member said he might be interested in trading some 3.27's for my 3.55's but I'm not sure that's going to be a big enough difference....

You guys don't know what high RPMs are, try running 4.10-4.30 gears WITHOUT O/D like we did in in the old days...

For a good all round gear I'd recommend 3.08s, my older Panthers all had them and were great... My '98 is a dog with the 2.73s, always feels like it's in a strain below 50 MPH and only gets 13-14 MPG in town(where it's driven 90% of the time), but will knock off 26+ on the highway... The '07 seems to handle the 2.73s much better, doesn't have the "well if you insist" feeling when accelerating like the '98...


_________________________
1998 Grand Marquis LS. 96K mi. .. Stock
2007 Grand Marquis GS. 90K mi. .. Stock
1996 F-150 XLT 196K mi Beater, Stock

----------My Toys---------(links are up)
1969 Fairlane Cobra 428CJ 4-Speed
1972 Comet GT Restomod 306, C4
1988 Turbo Coupe 331 AOD & 3.73 .. Pressurized ½ Motor is History

*****************NEW TOY!!!*********************
1969 Base Fairlane 302, C4, 45K mi(really!)

Now with P/S & PDB
Gonna wake it up with a Blue Print headed 347




Top
#2183279 - 11/17/10 10:28 AM Re: Rear-end change from 3.55 to 2.73-Couple Questions [Re: GrandMarq9807]
slipshod77 Offline
Member

Registered: 05/02/10
Posts: 224
Loc: Cincinnati
^^I thought 3.08s were verboten since they have weird driveline harmonics with the Panther wheelbase?

OP - I'd suggest driving a Panther with 2.73s (if you haven't already) to see if you could live with them before you do the swap. Lots of used Panthers in dealer lots with 2.73s you could test drive.
_________________________
2004 Mercury Grand Marquis LS HPP, 97K miles


Top
#2183294 - 11/17/10 11:03 AM Re: Rear-end change from 3.55 to 2.73-Couple Questions [Re: slipshod77]
BlueFusion Offline
Over the Hill

Registered: 05/24/09
Posts: 2819
Loc: /root
I have 2.73s and they are indeed dogs. But I do love them for my highway travelling. They pull hard as hell above 2,500RPMs. Harder than any of the other gears because there's more gear to go through before having to shift. I do the 1/4 mile without shifting to 3rd and get a trap speed of about 91MPH. On the highway I get about 26-28MPG at 70MPH, 30-31 at 60MPH.

If you don't get the full rear axle, I'll sell you my 2.73s once I get them pulled out by Insight's guy. I also have a set of 3.27s I was going to use, but decided they were too little of a jump. If you use that guy that will pull them out of mine he will know exactly how they should fit into your rear end for proper operation/wear/noise.

Top
#2183298 - 11/17/10 11:12 AM Re: Rear-end change from 3.55 to 2.73-Couple Questions [Re: ferg]
Big_Bad_Joe Offline

Poobah

Registered: 12/12/01
Posts: 8468
Loc: Rochester NY
 Originally Posted By: ferg
 Originally Posted By: mustang_zulu
hey on the highway i "can" get 26-28 mpg with my 3.27's... perhaps ur driving style is the issue??? difference between 3.55 and 3.27 is not noticeable.....


...going down hill with the wind at your back, maybe.....
j/k that surprises me with 3.27's. I'm only getting 20 on the highway (with winter mix gas), with a steady foot and 65mph. Aside from the gas mileage issue, I don't like turning these high rpm's with the 3.55.


You are not turning that high with overdrive... I get better mileage with the 2000 with 3.55 than that.... time for tune up and some fresh front O2 sensors.... clean maf etc... should do better than that...

i can squeeze 25-26 out of the 2006 but I have to drive like a wuss to do it.... we have a lot of elevation changes in NY and in western NY so mileage never is what the florida and southwest guys see.... thats a huge reason....
_________________________
2006 LX with HPPBlue, Light Camel Interior,Magnaflow Exhaust,PI Zip Tube
Underdrives from ADTR.net
Pioneer AVIC X930BT Nav system, JL xD400/4amp, JL Speakers, Audiovox backup camera
Given to DG in Ohio

2013 Ford Expedition Limited EL, Pearl White

2000 HPP RESURECTION RIP 8/17/2012 died in Dayton OH

Top
#2183309 - 11/17/10 11:55 AM Re: Rear-end change from 3.55 to 2.73-Couple Questions [Re: Big_Bad_Joe]
98VicP71 Offline
[email protected]
Grand Poobah

Registered: 03/28/06
Posts: 12731
Loc: ATL
 Originally Posted By: Big_Bad_Joe
 Originally Posted By: ferg
 Originally Posted By: mustang_zulu
hey on the highway i "can" get 26-28 mpg with my 3.27's... perhaps ur driving style is the issue??? difference between 3.55 and 3.27 is not noticeable.....


...going down hill with the wind at your back, maybe.....
j/k that surprises me with 3.27's. I'm only getting 20 on the highway (with winter mix gas), with a steady foot and 65mph. Aside from the gas mileage issue, I don't like turning these high rpm's with the 3.55.


You are not turning that high with overdrive... I get better mileage with the 2000 with 3.55 than that.... time for tune up and some fresh front O2 sensors.... clean maf etc... should do better than that...

i can squeeze 25-26 out of the 2006 but I have to drive like a wuss to do it.... we have a lot of elevation changes in NY and in western NY so mileage never is what the florida and southwest guys see.... thats a huge reason....


I agree the area where you live, driving style, and if where you live changes the fuel mixes for the seasons can have effects to your fuel mileage.

I am running 3:73's at 70mph I am turning 2400rpm. I get around 21-22mpg on the highway and like 17-19 in town. That was before my high stall converter I am sure it is down a little from that in town but couldn't tell you exactly as there has not been 1 tank of fuel I have run since I got the car back that I haven't been heavy footed with.

my TC has 3:08 gears and get like 16 in town and 28-29 hwy.
_________________________
1993 Lincoln Town Car 150k+ - RIP 5/10/2011
1998 Ford Crown Victoria P71 - RIP 12/25/2006
2001 Ford Crown Victoria P71(Count blackula) 297k+ - Ummmmmm evil

Top
#2183378 - 11/17/10 01:21 PM Re: Rear-end change from 3.55 to 2.73-Couple Questions [Re: GrandMarq9807]
Mileaway Offline
Posting Addict

Registered: 10/06/05
Posts: 16831
Loc: Sacto. Calif.
 Originally Posted By: GrandMarq9807
 Originally Posted By: ferg
...and can't believe how high my rpm's are on the highway!! Ofcourse, if I had a tach I would've made the change sooner.

Another member said he might be interested in trading some 3.27's for my 3.55's but I'm not sure that's going to be a big enough difference....

You guys don't know what high RPMs are, try running 4.10-4.30 gears WITHOUT O/D like we did in in the old days...

For a good all round gear I'd recommend 3.08s, my older Panthers all had them and were great... My '98 is a dog with the 2.73s, always feels like it's in a strain below 50 MPH and only gets 13-14 MPG in town(where it's driven 90% of the time), but will knock off 26+ on the highway... The '07 seems to handle the 2.73s much better, doesn't have the "well if you insist" feeling when accelerating like the '98...


yep, had an 84Vic with 2.73 I guess... must of been?.....wouldn't get up and go... seriously sucked vs.this 2000 setup!

Had a 79 Impala with that cool curved rear window at the ends
that would wind-out at 65+ so bad damn....
only had a 3 speed tranny
sigh

couldn't/wouldn't dare go beyond 75..might blowup from high revs!
_________________________
2000 P71 Interceptor orig. equip.near mint parchment int.& carpet 155,000 mi. 3.55 rear .











Top
Page 1 of 3 1 2 3 >

Who's Online
4 registered (PaulyPeligroso, LTC_Dave, VP71, TheCableGuy), 90 Guests and 287 Spiders online.
Key: Admin, Global Mod, Mod
Shout Box

Top Posters (30 Days)
bluejay_32 155
Old_Guy_Stu 97
a_d_a_m 94
Moby_Vic 55
DudeAbides 53
CrystalPistol 50
TheCableGuy 47
RF_Overlord 45
Rainbowpizza 39
Ponyguy 39
Member Spotlight
Member Since: 08/26/07
Posts: 4890





Copyright 2000-2015 by Crownvic.net and Steve Spaulding. All Rights Reserved.
The photographs, graphics and data contained in this Web site are the properties of the contributors, or Crownvic.net and may not be used without expressed written consent.
Crownvic.net is not affiliated with the Ford motor company.

Happily consuming the fuel saved by Prius owners!