6T75 Rebuild Tips

[@nickyponz4475]

Gary last time I said I was experiencing a lag and weird shifts on my 17 traverse with a 6t75 unit, when I went in for service the tech saw my front mount was bad and they changed it, after they changed the mount my shifts were improved and no longer experience the lags or rpm changes. Jus wanted to share this incase anyone had similar problems. Once again thanks for all your valuable info and great videos.

[@GaryFerraro]

Wow, thanks for sharing, were there any codes present?

[@nickyponz4475]

No there weren't any codes, I told them what I was experiencing also a slight klunk when I put in gear. Im just glad that minor fix improved the performance and im even more happy that it was covered under drivetrain warranty.

[@GaryFerraro]

@@nickyponz4475 So the engagement was the problem?

[@nickyponz4475]

@@GaryFerraro probably so Gary I cant explain

[@mastertech8112]

Hi Gary, I asked you about a 4th gear neutral on this board a few months ago. Just got back into it and it seems I cut a teflon seal at the back of the case. Burned up 4th. Now I am going to go back through it. Just wanted to let you know what I found. Thank you

[@lukestrasser]

Bummer that the valve body and TECHM didn't fix the unit Gary. This unit will be in top shape for a long time to come now! Great work and great tips!

[@GaryFerraro]

Thanks for stopping by Luke

[@ramonkjhjjkjkkiy6541]

Than you for you information good explanation 🎉

[@bo-boboski4118]

Hey gary. I just rebuilt a 6T75 for a gmc arcadia. Put in a new techm and it slips in 2nd Any advice?

[@GaryFerraro]

@@bo-boboski4118 what was original problem

[@jeremyhelm2833]

@Gary... this video is a godsend. You mention "chatter" at 10:45 kzbin.info/www/bejne/iqHXaZyqfJiBeJo Wife's 2015 Acadia has a bad stutter/chatter on acceleration. Have you seen this issue as late as 2015 model year? Is it primarily the converter or that seal/bushing? Nobody up here near philly seems to have any idea what I'm talking about. Been to 2 shops. They just changed fluid but offered zero real insight. I've hear "flex plate" thrown around as possible reason but no real wisdom. Thanks !

[@benjaminacevedo3616]

gracias gary.. exelente explicacion

[@GaryFerraro]

Thank you

[@kawabuggy3842]

I have one out, on my bench, now for the 4th time.. CANNOT get it to work properly. Flares on the 2-3 shift.. has no 4th at all.. just LOTS of problems.. I've tried multiple different valve bodies, 3 different TEHCMS (that we programmed using the AC Delco TDS web site) and this unit REFUSES to work right... All bonded pistons have been replaced-EVERYTHING air checks correctly! It all locks up quickly and holds well with as low as 35 PSI of pressure. The one odd thing I find that I can't figure out is... If I put the 3-5-r/4-5-6 drum on the end cover and attempt to air check the 3-5-R clutches and then the 4-5-6 clutches-there is TONS of air leaking between the two pistons in that drum. If I'm trying to test the 3-5-R clutch stack and I apply enough air pressure the 4-5-6 will actually apply!!!!!! I've tried 3 different end covers... all new sealing rings... I've tried so many different things but I cannot prevent or stop an air leak between those 2 pistons in the drum.. UNLESS... I say UNLESS they are both supposed to be applying simultaneously when you apply air pressure to either of them separately? There is NOTHING in the ATSG book about testing this drum while it is on the end cover.. NO DATA anywhere that I can find.. Just does not seem right to me that one set of clutches is being applied by air pressure you are sending to the other clutch stack. Can you PLEASE do a video where you air-check the 3-5-r/4-5-6 drum while it is sitting on the end cover!!!!!?????? PLEASE??!!??!?!?! I'm losing my mind trying to figure out what the heck is happening with the cross-leak in that end cover.. For the record, you CAN take your pump assembly apart! It's not that big a deal.. Just remove the one-time-use installed at factory screws... Then use the correct tap (6MM I think) to clean out the holes before you put them back together.. No big deal.

[@GaryFerraro]

Send me an e-mail [e-mail], i can send some info on air checking. Are there any codes?

[@danielmichaelcherrier]

will the pressures switchs cause it to chatter?

[@GaryFerraro]

It really shouldn't but I have had some driveability issues that once I did do the switches it drove ok. When do you feel it chatter?

[@juanolea1611]

Do you have an actual fix for tcc shudder? Does problem might come due to valvebody? Maybe a leak from tcc valve? Or techm?

[@theicee1]

My 2013 traverse (6T75) had shudder, and delayed shifting issues. Should I change the clutch pack Pistons? My 1-2-3-4 frictions were alittle torn up. I am changing torque converter, filter, 3-5r wavy, 1-2-3-4 frictions. Also, my 4-5-6 housing was alittle brown, but frictions looked fine. Am I missing something?

[@oscarespinoza1163]

Is a 2008 buick enclave 2wd

[@isais7733]

I opened my transmission acadia 08. It had shatter in 3-5 gears and it went into limp mode. I put a rebuild tehcm, got it programed. I cleaned the valve body, changed some clothes, the wavy plate was broken, changed the oil filter, the torque converter another used one. It worked better but reverse shift hard and 1 gear takes time or have to press the gas to kick in. Can you give me some insight on what can be the fix so i can check. Thank you

[@GaryFerraro]

did you open the valvebody

[@isais7733]

@@GaryFerraro yes i did part of it. Not the part wirh the plastic pins. I cleaned all the pistons and checked tje little ball not to be stuck. Some of the pistons had some scratches. They have like paint on them and the scratch took the paint off. I didn't change anything no seals or anything.

[@isais7733]

It has a code selenoid B stuck off. P0756

[@GaryFerraro]

@@isais7733 That is a mechanical code

[@isais7733]

@@GaryFerraro so it could be maybe a piston on valve body or a piston that pushes the clutches?

[@JosePerez-fw1zj]

Thank You Gary

[@chatolopez4268]

Where can I get a 2Gen 6t75 rebuild kit is for a 2016 gmc acadia?

[@GaryFerraro]

Where are you located?

[@chatolopez4268]

Here in Minnesota, trying to find a supplier but I haven't got any luck. Only 1Gen. Can you recommend me a supplier.

[@GaryFerraro]

@@chatolopez4268 I know these Gen2 parts are hard to get, i will make a few phone calls and let you know

[@chatolopez4268]

@@GaryFerraro Thank you very much.

[@GaryFerraro]

@@chatolopez4268 I spoke with my rep, i can get a Banner kit for a Gen2 Banner kit is, overhaul kit all molded pistons all clutches

[@javilsx363]

What did you program the tcm with?

[@GaryFerraro]

My Laptop and pass thru connector, i purchase time on GM's website to program

[@nickyponz4475]

I have a 2017 traverse with 25000 miles on it and while going up hills I see a change in rpm and while running sometimes I get a tiny lag, any tips on fluid change intervals?

[@ianhylton1974]

Hey Gary how you doing do you have any tips or can you make a video on how to to productively rebuild a GM 4T40-E 4 speed transmission for a 1999 Chevy Malibu with a 3.1 V6 if you can thanks

[@GaryFerraro]

Are you currently working on it? What is the problem with the trans?

[@ianhylton1974]

@@GaryFerraro when I put the car in Drive there's a really heavy thump and then when I go to drive it feels like the car is something is grinding you know a little bit of time and it's like moving forward if it's it's like struggling it's grinding when the car gets at the operating temperature it stops I did have my driver side axle replaced I haven't touched the car yet and I'm thinking about taking it to a repair shop give me your thoughts on what you think it might be the problem thanks

[@johnbills1596]

Gary, I just rebuilt a 6T75 with all new parts however, now when come to a stop I get a whining sound as if it is down shifting too soon. If I come to a stop with the trans in neutral then I get no whining. Is this a sign that my converter is bad? Do you have any advise or does anyone have some suggestions? Thanks

[@GaryFerraro]

with the car in drive standing still is there a noise in drive and goes away in neutral?

[@johnbills1596]

There is no sound while in drive or neutral only when moving and coming to a stop in drive.

[@johnbills1596]

Also it is a 2007 GMC Acadia

[@GaryFerraro]

@@johnbills1596 Any hard parts changed, also any bad mounts?

[@johnbills1596]

@@GaryFerraro well the trans has all new parts in the inside except the large gears. So, all the steels and friction plates, along with all seals. We added a 3,5,rev wave plate protection kit from Sonnax as well as a shift kit for the valve body. But I have not changed any mounts.

[@oscarespinoza1163]

Hi I have a question I just rebuilt my 6t75 transmission because before shaking on 3-5 but after rebuilt still have the same problem any body have any idea what i doing wrong thank you

[@GaryFerraro]

Did you reset shift adapts?

[@oscarespinoza1163]

No I didn't

[@isais7733]

@@GaryFerraro how do you reset shift adapts? Mr. Gary

[@GaryFerraro]

@@isais7733 need a scan tool like a snap-on or autel

[@09corvettezr1]

Thanks for the videos Gary, I have a few questions regarding 6t40’s and 6t70’s and to a lesser extent the Ford versions of these transmissions. I work at an auto recycling yard in central Canada and I work with drivetrain parts all the time. I often find the trans fluid is very dark in the 6t40’s and to a lesser extent the 70’s, even with relatively low mileage, is this your experience and if so do you know why this is? I was also wondering if your shop finds that the snout of the torque converter getting stuck in the back of the crankshaft when separating the trans from the engine.(even with all the torque converter bolts removed.) I have to be very careful to separate the engine and trans without destroying the bushing inside the converter on the stator support and the input shaft. Is this your experience and if so do you just replace the bushing, or do your guys have any tricks to do it without the bushing. I am lucky at a wrecking yard and am doing this on the floor, I can’t imagine doing this in the car without damaging the bushing. Thanks for the answers and stay safe.

[@daveyio87]

GM states the fluid is dark due to an additive they use from the factory, from my limited ford experince the fluid they use is purplish. same transmission... as for the torque converter i found what helps with the converter sticking is spin it over a few times after its unbolted and push away from flex plate and they usually pop right out.

[@68-And-I-Owe-You-NONE]

Did you ever find out if the bushing/seal in the converter can be replaced or did you have any issue when reinstalling the converter? I’m doing an engine replacement on jack stands in my garage, when I separated the engine from trans the converter stayed with the flywheel same as you mentioned. I’m concerned now about reinstalling the converter. Any advice ?

[@09corvettezr1]

@@68-And-I-Owe-You-NONE from what I've gathered from transmission shops near me if you can install the converter and spin it freely, the bushing is still ok. I just would hate to reassemble something and then end up with TCC codes because the bushing can't hold the TCC charge oil in the converter. Since posting my original comment I bought some good prybars and am much more careful about making sure the converter stays in the trans. May I ask what kind of vehicle/engine/trans you are working on?