C6 Help with slipping
Thread Starter
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Tuned
Joined: Apr 2018
Posts: 286
Likes: 40
C6 Help with slipping
Looking for help on where to start.
460 with C6 which was rebuilt by previous owner in 2018 and had 500 miles on the rebuild when I purchased the truck. Truck now has 2,000 miles and the transmission slips just about every time from 2nd gear to 3rd gear right at 28mph - 30mph. You have to barely have any gas for it to shift or it slips and over revs until you let off the gas. Slow driving to normal driving it works ok but any acceleration and it slips bad.
So where do I start for diagnostics? Fluid level is fine. Not sure if changing fluid would help with the slipping? My previous thread I started on That topic did not give me any clarification. So I am looking for help on what I should do stone fix the slippage. Thanks in advance
460 with C6 which was rebuilt by previous owner in 2018 and had 500 miles on the rebuild when I purchased the truck. Truck now has 2,000 miles and the transmission slips just about every time from 2nd gear to 3rd gear right at 28mph - 30mph. You have to barely have any gas for it to shift or it slips and over revs until you let off the gas. Slow driving to normal driving it works ok but any acceleration and it slips bad.
So where do I start for diagnostics? Fluid level is fine. Not sure if changing fluid would help with the slipping? My previous thread I started on That topic did not give me any clarification. So I am looking for help on what I should do stone fix the slippage. Thanks in advance
Laughing Gas
Joined: Feb 2011
Posts: 995
Likes: 317
Have you checked the vacuum source to modulator?
Myriad of other possible issues especially depending what was done/changed when it was rebuilt. If you google "C6 slipping 2nd to 3rd" or some similar combination of key words, you'll get a number of hits to follow up on.
Myriad of other possible issues especially depending what was done/changed when it was rebuilt. If you google "C6 slipping 2nd to 3rd" or some similar combination of key words, you'll get a number of hits to follow up on.
Thread Starter
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Tuned
Joined: Apr 2018
Posts: 286
Likes: 40
Have you checked the vacuum source to modulator?
Myriad of other possible issues especially depending what was done/changed when it was rebuilt. If you google "C6 slipping 2nd to 3rd" or some similar combination of key words, you'll get a number of hits to follow up on.
Myriad of other possible issues especially depending what was done/changed when it was rebuilt. If you google "C6 slipping 2nd to 3rd" or some similar combination of key words, you'll get a number of hits to follow up on.
Cargo Master
Joined: Nov 2009
Posts: 2,364
Likes: 117
From: starship enterprise
So a c6 has a band (2nd gear) a direct drum (inputshaft from engine and torque converter engages) A reverse/low clutch pack a forward clutch pack. I would suggest starting by pressure checking the control pressures and if that is not an available option then remove the pan, oil and valve body and air check the circuits.
Thread Starter
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Tuned
Joined: Apr 2018
Posts: 286
Likes: 40
Still looking for help with this. I can drive the truck as long as I baby it around the 2-3 shift speed. If I get on it, it slips and over revs like crazy.
Anything else I can look at or try to self diagnose or repair before I take it to a transmission shop?
Anything else I can look at or try to self diagnose or repair before I take it to a transmission shop?
Hotshot
Joined: Feb 2004
Posts: 10,759
Likes: 2,589
From: The Shenandoah Valley
As I recall being told once, a too tight 2nd band will force a slipping 3rd clutch as they overlap at shift. If this was a change from how it was just 1500 miles ago, I'd befriend an auto trans guy of some experience.
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Hotshot
Joined: Dec 2005
Posts: 14,375
Likes: 604
From: evansville in
You could have a band adj issue but from the sound of it this unit needs to come out. Likely the direct clutch pack is smoked. It could have stator support seal rings bad,bushings bad ,piston seals bad. No matter what there is nothing in the vehicle than can be done.
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Tuned
Joined: Jun 2018
Posts: 458
Likes: 123
From: Arkansas
Have you checked the vacuum source to modulator?
Myriad of other possible issues especially depending what was done/changed when it was rebuilt. If you google "C6 slipping 2nd to 3rd" or some similar combination of key words, you'll get a number of hits to follow up on.
Myriad of other possible issues especially depending what was done/changed when it was rebuilt. If you google "C6 slipping 2nd to 3rd" or some similar combination of key words, you'll get a number of hits to follow up on.
Thread Starter
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Tuned
Joined: Apr 2018
Posts: 286
Likes: 40
I spoke to the shop that did the transmission rebuild. They are about 2,950 miles away from me so no way to have them fix it. They rebuilt it 6 years ago and the PO put about 400 miles on it over 6 years and within the last 4 months we put 1,000+ miles on it. The mechanic thinks its something with the bands being loose or loosening over time from the vehicle sitting. They did an extensive amount of work including a B&M shift kit, torque convertor, HD band, Bearings, etc. I have copies of the invoices showing everything done.
Also they used type F fluid. Being it’s 6 years old should I flush and replace it or would it still be ok?
I guess this is all good to know when I bring it the the mechanic.
Also they used type F fluid. Being it’s 6 years old should I flush and replace it or would it still be ok?
I guess this is all good to know when I bring it the the mechanic.
Hotshot
Joined: Feb 2004
Posts: 10,759
Likes: 2,589
From: The Shenandoah Valley
I checked it as in no fluid leaking from it so the modulator is ok. Not sure about the vacuum or how to check if there is vacuum on the line. Ive googled it before as well as a search on this page but can't get any definitive help or a list of things to check. I was kind of hoping someone had the same issue and fixed it and would advise. No luck yet.
Cargo Master
Joined: Nov 2009
Posts: 2,364
Likes: 117
From: starship enterprise
this sounds like basic in frame trouble shooting is out of ball park for this particular situation. maybe he does not even need an old vehicle since the shop rate repair will kill it entirely, If basic checks are out of the question then not much hope. From the sounds here he might not even have fluid in the unit, has anyone checked that? It doesn't go into the window wash opening; it does not go into the power steering fluid opening; does not go into the brake fluid opening; is there fluid and if there is then is the dipstick being checked correctly? fluid level is "fine" I love it. Exactly how was the fluid check performed in order to determine this final outcome of FINE?