Any Transmission guys here?

I am rebuilding a Th 400 transmission but i can't find the clearance between the clutchplates in the manual.
I did put in new plates in the direct clutch, but the clearance became 0 so i could'nt turn it around.
I made some adjustments on the piston so i've got at least 0,018" of clerance, is that enough? or should it be more.
How much should the clearance be?
Do i get any advantage of removing some of the clutch release springs, like faster/harder upshifts etc.

 

Did you use the same thickness steel plates that were in it before?

 

Hmm! Probably.
Using those who were in the package.
The old ones were burnt and warped.

 

If you didn't throw the old ones out yet clean them the best you can and stack them up to get an overall total. Match this within close tolerance of the new ones and you should have it. Also if the new ones stack a little higher it's due to wear, also soak the whole mess really good in ATF before assembly.


Tim

 

No one knows the clearance?
Using the old steel plates is not a option. they are badly burnt, and heavily varped.

 

Check out these guys setups...

https://www.700r4l60e.com/store/home.php?cat=17

 

No one knows?
Is HAMB going to fail on technical question.
Help me now! PLEASE.
I've got to get the car running til this weekend.
It's going to be used in a marriage. (Not Mine!)

 

What I meant was to measure the thickness of the old plates, and make sure the new ones are the same (better yet, make sure they're the correct ones for that clutch).

I think there are 4 different steel plate thicknesses available for the 400, you need to make sure you have the right parts for that clutch pack.

GM does not specify clutch clearance numbers on that trans.

 

The problem is that the transmission is rebuilt before about three years ago. ( Not by me )
And the pack has burned again, so if the pack has been incorrectly adjusted by previous mechanic.
And how do i know i've got the correct one since nobody seems to know the clearance.

 

I just did my TH400 in the spring. I've got the HPBooks manual at a friends house right now with all of the specs. I built my '73 Buick TH400 with the specs that were in it, and it shifts great. I'll get back to you later if no one chimes in.

 

.018" clearance will probably be enough.

How do all the other parts look? which clutch pack is it that burned? what vehicle is it in, what engine, how much hp? If there are some other parts worn out then you need to fix them too. Usually a burned clutch pack is a symptom of some other problem.

 

Got a Turbo 4 book at home, will check tonight and get back with you.

 

Are you using the wave plate in the direct clutch? If you are, try to get it close to.030 clearance. W/ no wave plate, best rule of thumb is .010 per friction plate. Fwd clutch NEEDS the wave plate for garage feel when when applied. (No wave plate=Very harsh apply) Same rule apply, as direct clutch w/ wave plate. You must have clearance or the clutch pack wont cool & burn up. DAVE

 

PS, We make step by step videos for this trans if you need to use one. DAVE

 

Thanks for the info about the clearence, that was the thing i needed to know right now.
I'm not using any waweplate because there are no one avaliable right now.
The handbook that is used is GM service manual for -70 Cadillac.
But the car is a HAMB unfriendly -71 Buick Skylark Convertible, with a lightly modified 350 engine.

And i think i have found a couple of reasons of the breakdown.
1. Transmission vaccum was connected to distributor vaccum inlet, And the distributor vaccum connected to transmission vaccum under carburator.( explains the waving idle)
2. Direct clutch piston and forward clutch piston was mixed up, the direct clutch should have a check ball. According to service manual.
3. They were towing a caravan.