trans replacement.. [Archive] - GrandAmGT.com Forum

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350rs
01-05-2010, 08:34 PM
im getting to the point where i fear the tranny may decide to no longer work.. Im wondering what the model is for the auto in a GT, and other possible doner cars. I cant find any GAs here in local salvage yards. So it may be something that i have to grab from another car. OR have the current one rebuilt. We have a very reputable shop down the street, but i havent priced it. Any ideas on cost to rebuild the current unit?

Its not that its acting weird really, other than the strange "hopping" around that i have a video of. But thats gotta play hell on various parts, not to mention my pride. ( what little is left with this car. lol)

Tonyyank
01-05-2010, 08:39 PM
4T40E is what it is i think

Grandamgtblk99
01-05-2010, 10:06 PM
4t45e in the GT

350rs
01-06-2010, 03:23 PM
right on, thanks.

GrandAmMe
01-06-2010, 03:32 PM
right on, thanks.

The guy who is parting out like 10 GA's in the stuff for sale section is selling a tranny for $100!

hahano404
01-06-2010, 03:32 PM
40 is in 4 bangers.

hahano404
01-06-2010, 03:33 PM
nice good deal. replace convertor while your at it.

hahano404
01-06-2010, 03:37 PM
check if it is out of a gt. all other 4t45e's have different final ratios. that may upset the computer a lil

GrandAmGTTT
01-06-2010, 04:09 PM
check if it is out of a gt. all other 4t45e's have different final ratios. that may upset the computer a lil

ya the tranny out of the SE has a slightly smaller gear ratio, but i'm not sure what you would need to do in order to make it run correctly

350rs
01-06-2010, 06:35 PM
The guy who is parting out like 10 GA's in the stuff for sale section is selling a tranny for $100!

oh yea?! well ill have to have a look see

MIgrandamguy
01-08-2010, 04:02 PM
as long as your get the tranny off the same motor, you should be fine as far as gear ratios go, i would assume.

See if you can find any Aleros in your local junkyard with your motor.

AaronGTR
01-08-2010, 06:48 PM
as long as your get the tranny off the same motor, you should be fine as far as gear ratios go, i would assume.

See if you can find any Aleros in your local junkyard with your motor.


Nope, the SE with the 3400 v6 has a 4T45E trans with a 3.05 final drive ratio and the GT with the 3400 v6 has a 4T45E has a 3.29 final drive ratio. Exact same engine and transmission, but different final drives.


If you buy a used trans from someplace, make sure they check the RPO codes on the car it came out of. If it has MN5 and FR9 in there, it's the right one. MN5 is for the 4T45E transmission and FR9 is the 3.29 final drive ratio.

lightningGA
01-08-2010, 08:50 PM
just curious....what would have to be changed in the PCM to make it work SE -> GT or GT -> SE final drive ratio. Or is this something that can't be done with a Powrtuner?

350rs
01-08-2010, 10:49 PM
going to check price on rebuild if i just drop off the car tomorrow. Ive asked this guy that same question about a few cars. Only a hour or two of labor. Only another 100 or 200 bucks? Ill spend that on the "new" tranny. So if thats the case ill just bring the whole car.

I think ive got a main seal leak which i can fix while the motor is out anyway.

burgett2103
01-08-2010, 10:53 PM
ok quick question i figured i'd throw in here.. does a 3800 supercharged gtp tranny fit up to our 3400 v6's?

350rs
01-09-2010, 08:36 AM
i would imagine no. i think those have the same transbolt pattern as a standard SBC

AaronGTR
01-09-2010, 09:11 AM
just curious....what would have to be changed in the PCM to make it work SE -> GT or GT -> SE final drive ratio. Or is this something that can't be done with a Powrtuner?

I haven't tried it myself, but I've looked into it because others have asked before. I know it can definitely be done. I'm just not sure exactly what has to be done. It basically depends on the speed output sensor. I don't know if the sensor ring has the same number of teeth for both transmissions or not. iirc it's on the output shaft right next to or on the differential. It's been a while since I looked at it. If they were a different number of teeth, you might have to switch it over to the new differential. If they are the same, which I think they are, then it would all be programming. Or it's possible that even if they are different, you might be able to simply make programming changes in the pcm and it would work just fine. I'm inclined to believe the later. The pcm uses the pulses from that sensor to run the speedometer, odometer, and for shifting under 100% throttle because shifting is done on a gradient based on throttle position and MPH. All that may be required is changing some of the shift tables for the trans and the pulses per mile table... or maybe just flashing the pcm with a complete program for the SE or GT depending on which trans you are using.

Basically though it shouldn't be as complicated as it sounds. ;)

ok quick question i figured i'd throw in here.. does a 3800 supercharged gtp tranny fit up to our 3400 v6's?

i would imagine no. i think those have the same transbolt pattern as a standard SBC

Actually, yes it will bolt to our block. The 3100/3400 block and 3800 block share the same bolt pattern. Both engine families have been bolted to 4T40/4T45 transmissions and 4T60/4T65 transmissions. The previous model grand am has a 3100 v6 bolted to a 4T60E. ;) Bolting a 4T65E-HD up to a 3400 is actually easy. It's making the custom mounts and axles and figuring out the electronics that is hard... but it can and has been done.

350rs
01-09-2010, 11:32 AM
really? hm, maybe its the 4.3 thats got the SBC pattern then. i cant remember.

oldschoolguy
01-09-2010, 11:34 AM
@AaronGTR you should write a book with everything you know about grand ams. lol Seems like no technical question gets past you

AaronGTR
01-09-2010, 09:28 PM
lol most of it comes out of a factory service manual, or just from trolling these forums for years and years. There are certain topics I don't answer though, mostly because I either haven't looked up that particular thing, or it's one that has been beat to death and I don't feel like helping out someone who doesn't bother to search.


Tom, it probably was the 4.3 vortech V6. That engine was based on the chevy v8. It's basically a sbc with two cylinders chopped off.

350rs
01-09-2010, 11:35 PM
Tom, it probably was the 4.3 vortech V6. That engine was based on the chevy v8. It's basically a sbc with two cylinders chopped off.

thats what i hear, i guess thats where i get the idea.

Gotcha95
06-09-2010, 12:50 AM
i had mine trans swapped out with two different transmission. i also question if by chance it came out of a SE V6. would the SE transmission in a gt cause it to shift hard? Both trannys shifted hard in all gears. someone also said it could be my torque converter. should a flash the pcm to a SE?