Auto Transmission Swap 3 spd to 4spd

Fr0z3nMechanix · Post by **Fr0z3nMechanix** » Wed May 20, 2009 12:10 am

Ok... So I've got some transmission problems goin on w/ my 3 speed Auto (Pretty sure it's got a gear that's missing teeth or something cuz if I punch it or let it shift at the wrong rpms it makes the whole front end of my car shake somethin fierce)... Anywhoo... I was wondering how much trouble it would be to upgrade to a 4 speed while I was at it... I did a tiny amount of research and I think I can pretty much rip one out of a newer neon, stratus, sebring, etc. Any kind of input would be extremely helpful.

As a note... the whole issue is probably my fault anyways for beating the heck out of my transmission... but I'd like to replace it w/ something that can take a beating... I don't shift it like a straight or anything... it's just that i've gotten to where I can force it to drop gears w/ the pedal and i think I overdid it on a rainy day doing a small burnout (if you can even call it that haha)... either that or it was the wreck i got into that smashed my radiator and computer into tiny bits... either way... these are the facts... I'd like to have input from people rather than just doing some site research and going out and buying something that may or may not work.

Thanks

fearingdark · Post by **fearingdark** » Wed May 20, 2009 12:15 am

if i remember correctly the 3 spd is the one that can be made to be just about bulletproof. i think there is someone building a 3spd to put into their srt.

might want to look into building the tranny you have

Fr0z3nMechanix · Post by **Fr0z3nMechanix** » Wed May 20, 2009 12:31 am

Then if it's good why do i have to baby it to keep it from slipping?

fearingdark · Post by **fearingdark** » Wed May 20, 2009 12:36 am

i think that the tranny in stock form is just like every other tranny. once its a little f'ed up it goes downhill.

check this thread out viewtopic.php?t=41904

Fr0z3nMechanix · Post by **Fr0z3nMechanix** » Wed May 20, 2009 12:44 am

Yeah like my dad says it's probably the transmission slipping gears when I start off... like... if I start off by flooring it... it shakes really bad like i just ran over the world's bumpiest road... or if i hit 20mph at the wrong RPM it's like i ran over a small speed bump... is it the tranny? something else? or a combination of things?

Post by **racer12306** » Wed May 20, 2009 10:55 am

one thing to think about:

3 speed: hydraulic control

4 speed: electronic control

I don't know if you can use a 02 computer in your 00, but if you can then that should fix that problem.

Post by **occasional demons** » Wed May 20, 2009 12:17 pm

IIRC the TCM is seperate from the PCM on '01 and '02 41te's
('01 being export)
If you really want to pursue the 4 speed you will need the '02 pcm to comunicate with the TCM, and an '01 up IAC valve/TB so the PCM can run it. I think the '00 PCM can run a newer IAC with some wiring mods but not the other way around. '00 is a stepper motor, '01-'05 is a linear solenoid.
I don't think an '01 (domestic) or '00 pcm will have the software? to sync with the seperate TCM unit. And No one makes a stand alone for the 41te. I imagine if you have the inputs needed for the TM to work, you might be able to hack the '00 and '01 to comunicate as far as what the TCM needs.

Edit: And you will prolly need the halfshafts too.

You would also need the '02 wiring harness.

And for reference, if the 3 speed is like the old TF's, manually shifting while accelerating is better. Using the kickdown only engages the band. Manually downshifting/holding that gear, uses a clutch pack, and the band.

Fr0z3nMechanix · Post by **Fr0z3nMechanix** » Wed May 20, 2009 4:30 pm

So... are yall saying maybe it's the computer that's screwing up? The computer I replaced my old one w/ was used (didn't have the money for a new one)...

Post by **occasional demons** » Wed May 20, 2009 4:51 pm

Fr0z3nMechanix wrote:So... are yall saying maybe it's the computer that's screwing up? The computer I replaced my old one w/ was used (didn't have the money for a new one)...

No, it has nothing to do with your PCM.

To run a 4 speed (41te or 40te) you would have to add the TCM to control it.

The 3 speed (A413/31th) does not have any electronic controls, except the torque converter clutch, possibly. Which might be the whole problem. If the lock-up clutch is malfunctioning, or the wrong ATF is in the trans, it can cause some wicked TC shudder.