clutch release fork problems, more DAPO issues Options

[mightyohm]

Hey guys, I need some help with a release fork/pivot shim issue I have run into.

I am working on reinstalling my transmission after my lost driveshaft incident.

I have a new clutch release fork that I installed, and I noticed that when I stuck the transmission back on the engine, the fork doesn't have more than a few mm of free play before it hits the transmission housing. So I think hmmm and I pull it back apart.

Then I think back to the last time I did this, I put in a new cup in the old throwout arm. At that time I noticed the ball cup stuck way out of the fork and I had to actually trim it down to fit. I thought it was weird but blamed Brad on giving me crap parts (just kidding Brad). I even took a picture, shown below.

[mightyohm]

Keeping that in mind, I thought hmmmmmm maybe that has something to do with my problem. I got out the old clutch fork and pulled the cup out of it. Then I noticed something. The height of the cup in the fork was different between the old fork and the new one! Inside the fork there was a bunch of JB weld, and under the JB weld was a stack of washers!!!

Here is what I saw (f'ing DAPO!!!):

[mightyohm]

In addition to this there were 2 thin washers under the pivot ball on the transmission. I guess the flywheel has been resurfaced enough times that the DAPO decided to raise the cup height on the fork to take up the slack. The new clutch fork doesn't have the raised cup so now I have to add more washers under the pivot.

The problem is, I added a bunch of washers, and I am running out of thread. There still isn't the suggested 20mm of clearance between the fork and the transmission housing when I install the transmission!

[mightyohm]

I need to add MORE washers to get the 20mm (0.78in) of clearance on the fork with the tranny installed.

Another issue is that now the TO bearing is getting pretty close to the edge of the sleeve it rides on when I pull the fork all the way to the back of the transmission. With the transmission off the car, it even gets a little bit "stuck" on the lip inside of the TO bearing, and I have to jiggle it to get it to retract again! This can't be good but it must have been like this before also.

This pic shows the lip inside the TO bearing that is catching on the edge of the retainer sleeve on the transmission.

[mightyohm]

So my question is - what do I do?

Can I get by with less than 20mm clearance between the release fork and the transmission?

Is it ok for the TO bearing to be riding so far out on the retainer sleeve?

Can I add more shims to the pivot ball? It's getting ridiculous...

Maybe I should have bought a new flywheel instead of resurfacing the one I had... Obviously it has been resurfaced more than once before, but the flywheel bolts were not shaved... I know people go pretty far sometimes.

[mightyohm]

(IMG:style_emoticons/default/icon_bump.gif)

[SirAndy]

So my question is - what do I do?

get yerself a new flywheel with enough beef ...

(IMG:style_emoticons/default/wink.gif) Andy

[bondo]

I have a stack of used flywheels, if you come to the brunch this sunday you can take your pick (IMG:style_emoticons/default/smile.gif)

[mightyohm]

Andy,

Yes, that is the ideal solution. But I would prefer not to invest in a new flywheel for this engine, instead saving it for the new engine I am building. If I can get away with what I have I would really prefer to do that. What I want to know is, can I get by with less than 20mm travel of the clutch fork? Has anyone measured the clutch travel at the fork from pedal up to pedal against the floor?

Also what are those guys doing who resurface the flywheel so many times they have to take material off the flywheel bolts?? They must be shimming the heck out of the pivot ball.

bondo, that is an option... Maybe I will have to come now. (IMG:style_emoticons/default/biggrin.gif)

[bondo]

You can get by with 1 mm... but as the clutch wears down it will shrink to zero and then you have a problem. 20 mm is probably the number that gets it to zero by the time the clutch is toast. Let me know if you want me to measure flywheels to see if any of mine are better.

[bondo]

er, when I say 1 mm, I mean the free play of the fork, before any disengagement of the clutch starts. (How much it wiggles when you have no cable attached) I have no idea how much travel you need.

[SirAndy]

What I want to know is, can I get by with less than 20mm travel of the clutch fork?

ok, here's what you have to do. this might sound strange, but it has been done and works.
just don't tell anyone that i told you. (IMG:style_emoticons/default/wink.gif)

take the clutch-fork, put it in the vise and use a BFH and bend it.
make sure you bend it about 1" or so *after* the cup part, on the thin part of the arm.
that will give you more clearance on the tranny case and you'll get enough throw at the fork.

trust me, it'll work!
(IMG:style_emoticons/default/smash.gif) Andy

[mightyohm]

It wiggles a lot. At least 15-20 mm. That is the problem. The amount of throw left to disengage the clutch before the fork hits the housing is smaller than the spec of 20mm. Think of it as being just behind the middle of the opening. As I shim the fork it moves it closer to the front of the housing, giving me more throw - but then I run into problems with shimming the pivot too far and running off the end of the TO bearing guide sleeve.

[SirAndy]

bend here, towards the engine (away from the tranny) ...

[SirAndy]

but then I run into problems with shimming the pivot too far and running off the end of the TO bearing guide sleeve.

yes, be very careful with too many shims, it'll leak!
bend the fork and use *less* shims, get enough thread on the pivot, then bend fork accordinly until you have enough throw ...

(IMG:style_emoticons/default/smash.gif) Andy

[mightyohm]

are you serious? Andy, you're scaring me.

And this is my nice new release fork that bondo gave to me!
(IMG:style_emoticons/default/sad.gif)

I know what you are suggesting though.

If I knew how much movement I NEED I could make a call about putting it together with 10mm or 15mm or free play and saying good enuff... Maybe we can measure your car this weekend Royce.

[bondo]

Ahh, ok, I misunderstood the problem. Bend that sucker! (IMG:style_emoticons/default/smile.gif) Just don't bend it so much that it hits the other side of things once the clutch wears a bit. If you want to do an experiment to add to this board's wealth of info, put a badly worn clutch disk in there and see where the clutch fork ends up. That'll tell you how much free play you need in order to be able to use the clutch for its entire life.

[SirAndy]

are you serious?

yes, i am serious. i have seen it done twice upclose and it works like a charm.

even took a few (IMG:style_emoticons/default/smash.gif) at it myself at the shop of the guy who's not our leader anymore ...
(IMG:style_emoticons/default/wink.gif) Andy

[bondo]

And this is my nice new release fork that bondo gave to me!
(IMG:style_emoticons/default/sad.gif)

I have plenty more (IMG:style_emoticons/default/smile.gif) I swear I could go into the 901 parts business.. I now have 5, and an early 912 trans on the way ("H" gear.. yeah baby!)

[mightyohm]

Ok. So that solves the problem of the fork hitting the housing. What about the TO bearing running off the edge of the sleeve it rides on? When I fully extend the TO bearing it gets caught by the edge of the sleeve and does not want to retract without a little nudge. Ever seen that problem before? Maybe it is a non issue if the clutch disc holds it in place during normal operation, but if it goes crooked it may not slide back to the retracted position again.