What is involved on the software side of things? I suspect that 2.73 would make me sad, which is what most Marquis would have. So I am curious, apart from the regular mechanical stuff, what would be involved. Not interested in buying a Vic, but rather a low jane Marquis GS--well, if interested at all.
Panther rear end swap
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What year? When I put 3.73 in my '94 CVLX/HPP all I did was swap the speedo driven gear to a 23 tooth. Wasn't exactly dead on, ut close enough for anybody to drive. In fact, same thing with my '96 Mustang. Not sure which year switched to requiring a tune or speedcal. Which, BTW, Speedcal is/was a little box that wires into the harness between the VSS and PCM to adjust the signal as necessary for your gears/tires. It was MUCH cheaper than a tune but IIRC was still about $100 a few years back. Some people like to tune at this time anyway to tighten up shifts and raise limiters. I've heard reports of issues hitting the limiter due to soft shifts but didn't have that propblem on my 94. The Mustang is a stick so can't comment there.
Edit: Remember with the longer driveshaft length on the panther platform, most people going to 3.55 or numerically higher gears swap in an aluminum driveshaft and extended tailshaft housing- these are readily available from junkyard P71 vehicles. If you want to go 3.73 or higher its highly recommended to do the forced lube tailshaft bearing mod- very easy but its been years so I'd have to look up the details anymore.
Edit: Remember with the longer driveshaft length on the panther platform, most people going to 3.55 or numerically higher gears swap in an aluminum driveshaft and extended tailshaft housing- these are readily available from junkyard P71 vehicles. If you want to go 3.73 or higher its highly recommended to do the forced lube tailshaft bearing mod- very easy but its been years so I'd have to look up the details anymore.
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Easy peasy: find a junked P71. They had the special driveshaft (which is stamped "POLICE") and at least 3.27 gears. Many (including mine) had 3.55 gears. I THINK all with 3.55s also had a limited slip. I recall that most Town Car limos also got the 3.55 gears.
I suspect simply using the ECM from a 3.55-geared P71 might deal with the speedo calibration, also.
crownvic.net has any Panther info you might want.
I suspect simply using the ECM from a 3.55-geared P71 might deal with the speedo calibration, also.
crownvic.net has any Panther info you might want.
supton, a GS will likely have 2.73s and single exhaust, as you suspect. Look for a Grand Marquis with the HPP- Handling and Performance Package. It will have a rear sway bar, dual exhaust and a 3.27 RAR.
I'm not sure how Crown Vics are set up, but IF they use the speed sensor/ABS sensor on top of the rear diff like the Ford trucks do, then you don't need to recalibrate anything for a gear change. The ring gear inside the diff spins the same speed as the wheels, regardless of gear ratio. The only thing that would throw the speedo off is changing tire size.
If they use a speed sensor on the transmission, then disregard everything I said above.
If they use a speed sensor on the transmission, then disregard everything I said above.
They use a speed sensor on the transmission.
Originally Posted By: RF Overlord
They use a speed sensor on the transmission.
Even if they just used the abs sensors, the ecu might toss a code for excessive slip, or otherwise not be happy. Saturn and VW cars, one of the mods was to change fifth gear for lower cruise rpm. That would often kill cruise control, as the ecu thought something was broken.
They use a speed sensor on the transmission.
Even if they just used the abs sensors, the ecu might toss a code for excessive slip, or otherwise not be happy. Saturn and VW cars, one of the mods was to change fifth gear for lower cruise rpm. That would often kill cruise control, as the ecu thought something was broken.
Nick1994
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What's wrong with 2.73? If you up the gears the mpg will likely suffer. They've got a V8, there shouldn't be any power issues.
Originally Posted By: Nick1994
What's wrong with 2.73? If you up the gears the mpg will likely suffer. They've got a V8, there shouldn't be any power issues.
Modular motors are not torque monsters. They need to rev to move.
BTDT too many times.
What's wrong with 2.73? If you up the gears the mpg will likely suffer. They've got a V8, there shouldn't be any power issues.
Modular motors are not torque monsters. They need to rev to move.
BTDT too many times.
MPG could actually go up, depending upon the area being driven in. If I stuck to the back roads with their rolling hills, it definitely would go up. Highway, sure, 2.73 would be best; but toss in normal city/town driving, and overall it's likely to be better mpg with a few steps down.
Pretty much every review I've read, online, has indicated much happier owners with 3.27 or 3.55; and a number indicated no mpg loss, in particular with the 3.27's.
Pretty much every review I've read, online, has indicated much happier owners with 3.27 or 3.55; and a number indicated no mpg loss, in particular with the 3.27's.
2.73 on my MGM gives me a consistent 22.2 MPG with about 35/75 city hiway. They aren't really going to snap any necks, but aren't underpowered. Its similar in power to an average mid range V6 sedan today. V8s always have more torque. The T-bird has 3.08, and is in the same weight range, and has the older style intake with supposedly a bit less power. The car feels noticeably more powerful off the line.
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After moving to a P71 with 3.27s from my 2.73 gear CVLX, I can say I will never buy another one with the 2.73s. They move off the line like a Econoline van up to about 20-25mph.
Here's my 2004 CVLX going WOT to 55mph. This was only a month after I bought it, so I hadnt yet done any mods. Had the factory Michelin Energy tires still.
https://www.youtube.com/watch?v=e-i3mkyEBI4
(The Youtube embed is not working for some reason)
On the software side, if its a 2002 or older all you will have to do is change the gear on the speed sensor of the transmission. Thats it. Its not enough of a difference to screw with the programming of the PCM.
If it was a large jump, like to 3.55s, what can happen is the PCM commands a shift at WOT based on RPM, then after it shifts the MPH is low enough to want it to go back into the prior gear and it redlines the engine.
On 2003+, the speed sensor was eliminated and the PCM generates the speed signal from the Output Shaft Sensor on the trans, so the only way to correct it is to change the programming.
I would look for a HPP car, like above. They have factory dual exhaust and a rear swaybar on the axle. A lot of places don't know these cars are anything special and price them like the plain jane cars just with alloy 16" wheels. Its the Sport and LSE models with the 17" wheels and center console shifter that get the increased price.
I almost bought a CVLX HPP after I wrecked my old one, but when I called, they had sold it. It was a good price too.
Here's my 2004 CVLX going WOT to 55mph. This was only a month after I bought it, so I hadnt yet done any mods. Had the factory Michelin Energy tires still.
https://www.youtube.com/watch?v=e-i3mkyEBI4
(The Youtube embed is not working for some reason)
On the software side, if its a 2002 or older all you will have to do is change the gear on the speed sensor of the transmission. Thats it. Its not enough of a difference to screw with the programming of the PCM.
If it was a large jump, like to 3.55s, what can happen is the PCM commands a shift at WOT based on RPM, then after it shifts the MPH is low enough to want it to go back into the prior gear and it redlines the engine.
On 2003+, the speed sensor was eliminated and the PCM generates the speed signal from the Output Shaft Sensor on the trans, so the only way to correct it is to change the programming.
I would look for a HPP car, like above. They have factory dual exhaust and a rear swaybar on the axle. A lot of places don't know these cars are anything special and price them like the plain jane cars just with alloy 16" wheels. Its the Sport and LSE models with the 17" wheels and center console shifter that get the increased price.
I almost bought a CVLX HPP after I wrecked my old one, but when I called, they had sold it. It was a good price too.
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A friend of mine just got his 2005 P71 back on the road after having a pinion bearing let go. His had the factory 31 spline axles so he ordered the FRPP Trak-loc with carbon clutches and F-150 S-spring. The gears were damaged so he swapped in a set of 3.55s from another 8.8 he had laying around. Going to try and get one of the techs at work to reprogram the as-built data with an IDS to correct the speedo and get rid of the ding at 75mph.
Originally Posted By: bdcardinal
A friend of mine just got his 2005 P71 back on the road after having a pinion bearing let go. His had the factory 31 spline axles so he ordered the FRPP Trak-loc with carbon clutches and F-150 S-spring. The gears were damaged so he swapped in a set of 3.55s from another 8.8 he had laying around. Going to try and get one of the techs at work to reprogram the as-built data with an IDS to correct the speedo and get rid of the ding at 75mph.
Lemme know if he is able to do it with the IDS. I have a friend with a 2011 that wants to put 3.27s in his 2.73 car.
Im getting ready to put those carbon clutches and F150 spring in my P71. Hopefully that will keep me from getting stuck on ice with the standard clutches and s-spring.
Well, maybe Ill still get stuck but if it spins both tires and doesn't just become an open diff because theres no torque to latch the clutches, Ill be happy.
A friend of mine just got his 2005 P71 back on the road after having a pinion bearing let go. His had the factory 31 spline axles so he ordered the FRPP Trak-loc with carbon clutches and F-150 S-spring. The gears were damaged so he swapped in a set of 3.55s from another 8.8 he had laying around. Going to try and get one of the techs at work to reprogram the as-built data with an IDS to correct the speedo and get rid of the ding at 75mph.
Lemme know if he is able to do it with the IDS. I have a friend with a 2011 that wants to put 3.27s in his 2.73 car.
Im getting ready to put those carbon clutches and F150 spring in my P71. Hopefully that will keep me from getting stuck on ice with the standard clutches and s-spring.
Well, maybe Ill still get stuck but if it spins both tires and doesn't just become an open diff because theres no torque to latch the clutches, Ill be happy.
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Also, back to the OP, if all he is doing is going from 2.73s to 3.27s, I would leave the factory driveshaft in place. This is a factory configuration with the HPP cars. The steel shaft is good to 5000 RPM minus 10% for safety. Thats 107MPH with 3.27s.
The reason being is that the police shaft is an inch shorter and while you can just change the tailhousing on the trans, the output shaft of the transmission is still shorter by that inch. So it doesn't fully engage the splines.
I ran this configuration in my CVLX and I suspect thats why I broke the stubshaft in the original transmission. It was an oddball failure for a car that was basically stock. I think some stuff was moving around that should not have been and cracked it.
The reason being is that the police shaft is an inch shorter and while you can just change the tailhousing on the trans, the output shaft of the transmission is still shorter by that inch. So it doesn't fully engage the splines.
I ran this configuration in my CVLX and I suspect thats why I broke the stubshaft in the original transmission. It was an oddball failure for a car that was basically stock. I think some stuff was moving around that should not have been and cracked it.
My 94 CVLXHPP came with a 3.27 open and I always felt that car is pretty good for what it was. Eventually I rebuilt it with 3.73 and a trac-lok with the alternative clutch stack. HUGE improvement. Just massive.
My '96 Mustang just got 3.73's this year (up from factory 2.73). That was just what the car needed. Its pretty much full bolt ons plus PI cams/intake. No tune. Now, I won't say I'm running 12s but the car no longer feels like a total dog off the line. Its actually pretty snappy and just a hoot to drive.
My '96 Mustang just got 3.73's this year (up from factory 2.73). That was just what the car needed. Its pretty much full bolt ons plus PI cams/intake. No tune. Now, I won't say I'm running 12s but the car no longer feels like a total dog off the line. Its actually pretty snappy and just a hoot to drive.
It's all good info. Sounds like it's best to wait for a better deal--a GM GS with HPP and no other options (about how I'd like it to be). Too much work to swap parts around otherwise.
I might look at a wrong one tomorrow, just 'cuz. Never sat in one, much less driven one, so it might be interesting to try a 2.73:1 version to get a baseline. For all I know I might find other fault with the car.
I might look at a wrong one tomorrow, just 'cuz. Never sat in one, much less driven one, so it might be interesting to try a 2.73:1 version to get a baseline. For all I know I might find other fault with the car.
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