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Manual trans swap

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Manual trans swap

mitchempat mitchempat
New User | Posts: 19 | Joined: 12/09
Posted: 12/11/09
12:03 PM

My girlfriend has a 99 Grand Prix GTP. She wants to swap a manual transmission into it. My questions are: 1 Is this swap possible? 2 Where can I get a transmission that will fit in her car? 3 Any ideas on how much it will cost? 4 Am I getting over my head? 5 Is this swap worth it? Any advice/suggestions/ideas you guys can provide will be greatly appreciated.  

mitchempat mitchempat
New User | Posts: 19 | Joined: 12/09
Posted: 12/26/09
06:19 PM

Can anybody help or is this just not possible?  

idrivejunk idrivejunk
Addict | Posts: 5162 | Joined: 12/09
Posted: 12/26/09
11:14 PM

I was waiting to see if anybody else would take a stab... sorry you had to wait.

I own a 99 GT.

You gotta love a gf who wants that. Unfortunately, she's out of luck. And as a matter of fact, the shifter is altogether useless and unexciting except for the PRND range. It should at least have a "performance shift" button on a GTP. The car will shift as it is programmed regardless of what funny ideas you input via the stick.

What the deal is.... is that GM didn't offer a manual behind that engine. Too much power. If they made one it might be too big for a FWD application. Four cylinder cars can use a manual transaxle because the torque is low and parts are small. Swapping one of those in should not be considered, you could get hurt! Not to say that it can't or hasn't been done.

For what its worth I just had my trans rebuilt. Its a 4T65E. Her GTP will have the 4T65HD. I can tell you that the final drive, or differential gears look like lawn tractor parts, just a few inches across. A mild V8 with about the same power needs at least an 8" diameter ring gear and these are half that size. Its a "size matters" issue. If you put sticky slicks on the front, I bet you could break the trans right then and there if you tried. They are juuuuuust strong enough stock. These cars can be modified to achieve some truly hair-haising performance numbers, but you won't see anybody stirring a stick shift.

What she might consider is a shift kit for the trans, or a reprogrammed PCM.

Check out 3800performance dot com...  

barneyformula barneyformula
Addict | Posts: 3306 | Joined: 01/07
Posted: 12/27/09
06:18 AM

I read this post earlier but didn't really have a good answer either. As far as improving what you have, there was an article a few years back in HPP about installing the "performance shift button" feature on later GTP's (the early GTP's, 97 and maybe 98 came with it). I don't recall the particulars, but a search thru the tech articles on the main HPP page might find the article for you. I believe it was written by Chris White.
A little help... 'cause we don't all have to learn the hard way!

mitchempat mitchempat
New User | Posts: 19 | Joined: 12/09
Posted: 12/28/09
11:36 AM

Thanks for the info guys. I'll have to break the bad news to her, not looking forward to that. Her's does have the performance shift feature built in so all is not lost if she'll learn how to use it. Guess she'll just have to be content with an automatic since the only other option is to swap to rear drive and take the car off the road. Thanks again. It will still be fun making a front wheel drive screamer out of it.