Quick trans Overhaul

[JJ91284]

This trans had roughly 10k miles on it as I rebuilt last summer with a transtar overhaul kit with borgwarner frictions and z-pack for 3rd. I took the trans out and cracked it open because I never had a nice 3-1 downshift. It always seemed like it was slipping at first, and then it would slingshot you forward. From a dig, the car always pulled well, it just didn't like the 3-1 downshift at 42 mph.

These are some horrid pics of the input clutch (bottom set), while the raybests z-pack is up top and I'm reusing it because it looks great. All the rest of the frictions with be getting Raybestos performance stage 1 frictions. I also installed another friction in 1st, and ran thinner steels for the input clutch (final clearance is .058). The z-pack has roughly .055 clearance in that set. I was going to install the 2nd frictions when I noticed (after I soaked them), transtar sent me input frictions for 03+ for my 2nd clutch. Need to call them first thing and see about these getting shipped ASAP to me.

Forward HE band is toast, everything else looks pretty good so far. I'm going to inspect the torsen diff tomorrow, but the thrust washers looked good on it.

So what should have been a quick overhaul (open up trans, replace frictions, sprag assembly input/3rd and 1-2 roller, sealing rings, and basic seals), did not go as planned. Then again how often do things go as planned. Bottom case torx bit damage 2 of my craftsman torx t40 (or t50), and of course it strips. So I dremeled a slot in it to put an 1/8 steel bar in to try and twist it out, ended up twisting the steel. Got it out with 1/4 steel, I might have to add that to my toolbox.

BUT THE MAIN REASON was to change my 7/8 2.93 gears from trannyman to the new 7/8 3.29 gears from him

After looking at my input frictions, I'm kind of puzzled on how they became so burned up and even coned like the typical 3rd frictions normally look like. I have a feeling I might have flipped the bottom backing plate with the step up and that made the pack an extra .070 tighter. Unfortunately I don't know as I dumped all the steels out and wasn't paying attenting when I put them aside as far as orientations is concerned.













Here was my original build thread last year

http://www.grandprixforums.net/f21/official-4t65e-hd-rebuild-4715.html

 

[Iron Indian]

how do you like that Torsen Diff?

 

[JJ91284]

how do you like that Torsen Diff?

Its great when the weather is crappy. I really enjoy the added traction it gives when crossing traffic to merge lane with traffic. I cross a very busy rd then have to merge with traffic on a daily basis. This intersection was ranked as the 3rd worse in the country years back for most accidents. I use to get the constant 1 tire peel, where now it hooks and hauls ass while turning to merge with traffic.

 

[Trannyman95]

Wow those input frictions are pretty beat! I dont think I have ever seen them that bad from one of these transmissions so something had to be off. Did you air-check everything when you put it back together last time? Did you replace the teflon sealing rings on the input clutch drum? IF you did put the input clutch apply plate upside down the input piston would had to have traveled a lot more than it should have and could have caused poor clamping force and on a 3-1 kickdown it would have had a lot of clearance on the bottom and top side of the apply plate before the clutch would apply and this definately would have caused your clutches to burn up like they do. This also could have caused your forward band to burn, but low pressure somewhere or a leak in the system could have caused this also so make sure you look over all of the seals and also make sure you check the flatness of the accumulator body and cover and replace that gasket as that can be a leak point for the forward band apply feed. I would definately replace the pressure control solenoid even if it was new last time you were in the trans.

 

[JJ91284]

Wow those input frictions are pretty beat! I dont think I have ever seen them that bad from one of these transmissions so something had to be off. Did you air-check everything when you put it back together last time? Did you replace the teflon sealing rings on the input clutch drum? IF you did put the input clutch apply plate upside down the input piston would had to have traveled a lot more than it should have and could have caused poor clamping force and on a 3-1 kickdown it would have had a lot of clearance on the bottom and top side of the apply plate before the clutch would apply and this definately would have caused your clutches to burn up like they do. This also could have caused your forward band to burn, but low pressure somewhere or a leak in the system could have caused this also so make sure you look over all of the seals and also make sure you check the flatness of the accumulator body and cover and replace that gasket as that can be a leak point for the forward band apply feed. I would definately replace the pressure control solenoid even if it was new last time you were in the trans.

I think the input clutch assembly would be much tighter since the bottom of the input clutch apply plate has the machined groove in it for the 3rd clutch snap ring. Since the groove was probably on the other side, the input clutch apply plate was then resting on the 3rd clutch snap ring which should have tightened the clutch pack quite a bit which is what I think burned it up. As far as air checking the assembly, I'm pretty sure I air checked it. I know I did it for the zpack for sure, but don't quite remember if I did the input clutch drum. I have all the J-tools for all the input clutch seals as well as all the teflon seal resizers.

As far as the Forward band being burned, that would be caused by the input frictions slipping right? All the other clutch frictions look great. The PCS sensor was replaced last year with a new borg warner so I'm not sure if I want to spend another $50 on the solenoid but I probably should. The only other potential issue that I think could have caused this is if the trans shop that did all my valve body plate/channel plate reaming didn't do a great job. I had them ream the AFL valve and forward and reverse boost valves so I could install the rest of the Sonnax Sure Cure Kit.

When I reinstall the trans, I'll make sure to check the line pressure with my matco trans pressure gauge

On a side note, why would GM use torx bolts on the bottom of the trans. I think I'm replacing those all with bolts.

 

[BillBoost37]

The torx are probably to clear the subframe in one of the models.