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05-13-2008
i have a 1997 pontiac grand prix gtp that i recently put a 2001-2002 GTP transmission in, the problem is i have no reverse i have all other gears and they work flawless just no reverse. is this a valve body/solenoid issue or is my sun gear screwed, the transmission was fresh rebuild
thanks for your help
05-14-2008
No reverse can be a few problems, but since all of your other forward gears work fine then it rules out a handful of possibilities. Commonly no reverse is a seal problem on the reverse apply servo. It may have been installed incorrectly or an older short-style lip seal was used instead of an updated long-style lip seal. Also the reverse band may have broke which will give you no reverse.
05-14-2008
so basically i should be getting a new transmission
how hard is it to rebuild these things? lol
Last edited by GTX; 05-14-2008 at 08:01 AM.
05-14-2008
also my car has the thread in style transmission cooler lines, but the transmission itself was a quick release style, so i used an adapter fitting on the smaller hole and reused my style lines (threaded) could that be a problem?
05-14-2008
The mid 99 and newer cases had a larger fitting thread, the one that points straight down, to accept a fitting that has a checkball and spring and is larger in diameter than the early fittings. The function of this checkball and spring is to retain fluid in the torque converter when the vehicle is shut off, hence its name an anit-drainback ball. The earlier models had this inside the transmission, mid 99 to jan 04 had it in the fitting, then jan 04 to present has it inside the trans again. You may experience a long delayed engagement on cold startup but otherwise shouldnt case any major problems, however this really does need to be in the loop. There were thread in style fittings with this that were used in late 99 before they switched to the quick connect lines.
05-14-2008
so basically this transmission is junk for my application. whats your recommendation. once upon a time i was GM technician could do most any work thrown my way but never had the opportunity to learn how to rebuild these trannys even though i really want to learn them, and now i work on british cars ( land rover, and jaguars, aston martins etc.) primarily, still love GM and grand prix's, ive had 3 GP's now, 2002 gtp coupe, 2000 gtx sedan (black as seen in pic) and my 1997 gtx sedan ( as currently out of commission in my driveway with a a brand spankin new 3.8 and SC just needs a tranny now ..... again lol
Last edited by GTX; 05-14-2008 at 08:12 PM.
05-15-2008
do you think it would be wise to at least check the reverse servo, to see if anythings missing or has a bad seal? who knows it may be something that simple and after that IF it works i'll fix my cooler lines
thanks
05-16-2008
Is the no reverse problem on your original trans or in the newer one you mention? Sorry I guess I took your original post as you installed a newer trans and it has no reverse. If its your original trans did it show any signs of slippage? Does it make any attempt at all hot or cold? It is worth checking out the seal but if the band is broken you wont know without taking the trans apart.
05-16-2008
Originally Posted by Trannyman95
i installed a new transmission, and right out the box it has no reverse, when you put the transmission in reverse the engine/trans slightly (very softly) shift but no movement with acceleration
05-17-2008
Gotcha, I would check out the seal on the reverse apply servo-piston but you may also have a broken band.
05-19-2008
what should i be looking for inside the reverse servo? how will i know if anything looks bad?
05-19-2008
There is a rubber lip seal on the piston. There is an updated one that is a longer design than the stock seal which can cause a no reverse condition. Check this seal to see if it is rolled out of the groove it sits in or ripped or damaged in any way.
05-20-2008
Trannyman, was this seal ever updated from the factory or do all 4T65Es come with this defect still?
05-20-2008
The newest 4T65E that I have been into was an 06 and it still had the short seal. This was an aftermarket only upgrade to my knowledge. It is not a common problem but does occur now and then and was enough of a concern a number of years back that the aftermarket kits started to come with the long style lip seal. The Transgo shift kits also include this seal.
05-20-2008
Eh, just wondering to pass along some info if it ever proves useful. All the more reason to make it to you for a rebuild someday.
05-20-2008
with it being such an issue you would think there would be a TSB on it at minimum
05-25-2008
when you say new out of the box, was this built by someone else or you purchased this from gm?
I would def check the reverse servo before pulling the trans out. this can be done by removing the Air filter tube and TB out the way, remove you crossover pipe, and the reverse servo is right there.
I had this same problem. The servo was down to far allowing fluid past the seal.
05-28-2008
fresh from a local rebuilder and im thinking of just taking the damn thing out and refunding it so i can get a one of trannyman's transaxles
you forgot to include the rear exhaust manifold in the removal sequence
just received my ATSG 4t65e manual today, they make the rebuild look so easy... wonder if i can do it, other than TH350's,400, and 700's ive never messed with much in FWD transaxles other than drop the pan and service and adding shift kits to mine and friends vehicles
06-03-2008
**UPDATE**
i had a horribly slow day at work today so i left at noon, went home yanked the transaxle out, decided to check the reverse servo for ****s and grins, the seals were fine, however when i removed the springs and that giant pin i noticed on the side bottom there were some nice sized chunks of aluminum inside the servo housing..... i'd say that was my reverse problem
06-03-2008
Ouch! hopefully the shop takes care of you on the return!
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