Put 4:10's in my 94 gt auto, now my car wont shift right please help!!!

[npwrestler]

hi all,
i put 4:10's in my 94' mustang gt automatic and now my car seems to bounce off the rev limiter, i need some advice on how to fix this if someone knows, also i put the new speedo in and seems to work ok planning on testing tommorow.... thanx all

[Capri306]

Before I move this post to Windsor Power, I'll throw in my 2 cents: I think mebbe when you replaced the speedometer drive gear, the VSS (vehicle speed sensor) signal might not be getting back to the EEC-IV. Chances are that the sensor itself was damaged, the wires aren't plugged in right, or something related to it. Correct me if I'm wrong, but the 94 GT's had the AOD-E, right? AFAIK, the VSS signals the computer as to how fast the driveshaft is rotating, and the EEC uses this and load (TPS and MAF) to determine shiftpoints. If the computer has no idea how fast the vehicle is going, it's never going to shift correctly. Does it make a significant difference how fast you're going or how far open the throttle is as to the relative shift point? Does it consistently shift at a certain RPM?

[npwrestler]

thanx for the input, it only seems to happen when it shifts from 1st to 2nd gear, i just put the new speedo in yesterday and it still does it, do i have to reprogram anything? if so please let me know.
thanx's again any input is appericated

[moosejaw]

A simple test for the VSS would be the cruise control. Cruise won't function without the VSS. Let us know the results and we can go from there.

Mike

[npwrestler]

i tryed the crusie out and it works fine.... also when i changed the rearend and it threw the speedometer off i changed the speedo gear and it helped a little but did not fix the problem so i dont know what to do now.... but it still shifts funny and the cruise works!

[moosejaw]

So the VSS works ok. Next up is it the right speedo gear. You didn't mention which speedo gear you put in. You need a 23 tooth gear to get it close.

Which gear did you use?

If that doesn't fix it then a chip would help correct it. You can adjust the AODE shift points on a chip.

Mike

[FivepointOH]

Correct me if i'm wrong but don't you need a chip to put bigger than 3:73's in an aode?

[andy669]

The reason why your car is bouncing off the rev limiter between the 1-2 shift is because of the sloppy shifting trans. The problem has always been there with your trans, but putting the 4:10's in magnified it due to the quicker acceleration. A good shift kit will take care of that.

As for speedo calibration, the 94-95's are still an EEC-IV and dont require electronic programming. All recals are done mechanically via changing the drive and driven gears. The problem is the drive gear is machined in to the output shaft of the trans, and its 8 tooth. There is no such driven gear to compensate for 4:10's with an 8t drive gear. The closest you can get is a 23 (which is close for 3:73's) and the teeth on that thing are paper thin. I had mine rebuilt with a 7 tooth output shaft.

IMO 4:10's are too much for your car. With the 5500 rpm rev limiter and the stock size tire, your car is going to max out about 95-98 mph in drive.

Good Luck

Andy

[npwrestler]

as far as the gear i went to the local ford dealer and they sold me that a orange 20tooth gear it helped a little but perfect... if i move to a 23 will it help more or less?as far as a shift kit what should i get and how difficult will it be to put it in? im also looking for a stall for my aode any suggestions? whats the price range and a good spot to find them?

thanks for all suggestions






94 gt: 4:10's, k&n, off road xpipe, 40 series flowmaster, and that funny jucie (not used yet ) ET:14.43@94mph

[andy669]

The best thing you could do for your car is call Johnson Motorsports and get a chip burnt for it. The right chip will bump the line pressure up resulting in firmer shifts. It will also get the rev limiter up out of the way, and add timing. The hp/dollars ratio of a chip for your car rivals a basic nitrous kit.

If the trans still shifts a little sloppy after a chip and after a fluid flush, then look in to a valve body kit for it. I recommend a Trans-Go kit. A good torque convertor will cost around $800-$900. There are cheaper ones available, but you wont get the same performance. I'd call Harvey at Performance Automatic.

Andy