Clutch won't disengage, SBC H55

Tidying up my H55 conversion before sending it to the exhaust shop and I'm having a few issues with the clutch.

I can't shift with the pedal depressed. If I start it up with it in gear the rig moves even with the clutch depressed. Obviously it's not disengaging.

73 FJ40...

SBC, H55, Downey bell housing, low profile 11" Centerforce clutch, 4 speed TO bearing, 4 speed fork, Stock 3 speed slave (from previous SBC and 3 Speed conversion), Stock 3 speed master.

I'm 95% certain the disc is facing the correct way. And that's the last thing I want to have to do, remove the Tranny. Other than that the pedal height is correct, the freeplay at the pedal is correct, and the slave is adjusted correctly. The system has been bled 3 times and there's no air in it (pedal feels "right"). The clutch fork throw measures only 1 1/8" when the pedal is depressed. I haven't measured the length of the slave pushrod but it's adjusted correctly so it shouldn't matter, right?

Any suggestions before I drop the tranny?

Thanks.

1 1/8th" throw seems a little low to me, I had the same problem with my old manual which was what finally got me to switch to an auto. I'm sure someone on here will know more than me but it sounds like a hydraulic problem to me.

Good luck,

Kevin

Dom, judging by your TLCA#, you know a lot more than I do, but did you disconnect the return spring on the slave before adjusting it? I would try to extend the acorn nut on the slave rod a little. I read your thread on the H55 conversion

Pilot bearing? I know it is new, but........

GL

Ed

Unfortunately, I had a similar problem on my earlier SBC conversion. Had to resort to a different throw out bearing, after turning out the acorn nut as far as I dared. PITA!

Can you get any more throw by altering your custom slave cylinder bracket? Problem is you may approach pseudo "riding the clutch".

How about a "new" cylinder in the slave barrel?

Good luck!

I'm down to San Diego for ten days starting Tuesday nite. I'd sure like to cross paths with you this time. If you need an assist, I don't mind getting my hands (shirt and pants too!) dirty!

Jim Seal(208) 559-1661 cell

most times with a sbc swap using the stock slave and master cylinder , the master does not flow enough voulume of fluid to disengage the clutch. . what i did was use a willwood master with a 1" bore and a longer stroke , it only requires me to push the pedal only a 1/4 way to the floor now. more volume of fluid to the slave is what you need.if you use a master and slave from a 66 it used a larger bore master and it has a larger line to the slave this could also cure your problem.

Thanks for the ideas guys.

Kevin- 1 1/8" seemed short to me as well. I think the simple answer is I need more "throw".

Ed- Return spring was removed. Thanks for the thought, I read a TON of posts w/o success for my issue bit they did remind me of the correct way to adjust. Pilot bearing is not outta the question either, but I did emory cloth it and assured it slid smoothly prior to install. I remember reading a post from Woody or Poser about trying to break one free while still installed. Maybe drop the clutch hard? I'll have to look at that again.

Jim- The TO bearing may be a start, I just hate to drop the damn thing! As far as the slave bracket goes it shouldn't make a difference right? The way I'm thinking if the slave pushrod is adjusted correctly it doesn't matter where it's mounted, there's only so much "throw" from the cylinder. It could be 3 feet back with a 3 foot pushrod and nothing would change. Or am I way off here? I've run the nut out a ton and no change. Again I'm thinking it wouldn't make a difference to have a longer rod if it's already adjusted tightly against the fork. Glad you're coming to SD again. I'm around so we'll connect. Dropping off the driveshafts tomorrow and towing it to the exhaust shop Tuesday.

LC- I used this hydraulic setup on my rig with a 3 speed w/o trouble, but I know I had a Chevy fork and now I've got 4 speed stuff. The Master may be the change I need, this sounds like it will increase the "throw" that I need.

Speaking of hydraulic lines... I did add a LONG ASS hydraulic line to move the fork to the other side.... hmmmm.... maybe the inside diameter is not as big as my old line? Giving me more pressure but less flow...

This looks promising LC...

05-09-05, 02:02 PM #14
Bennett
IH8MUD Regular



Join Date: Feb 2002
Posts: 285

I'm thinking that the clutch fork is giving my slave cylinder too much mechanical advantage and not enough throw. Thanks Chris[/QUOTE said:

You do not have enough throw on you slave... Been there done that for 6 months.

I tried a number of suggestions with no success until I mounted a pre 69 brake master instead of the stock clutch master.
Mark Whatley from LCML told me to try it.
It works awsome..
The pre 69 brake master is 1" bore and the slave is under that ( 3/4" IIRC)..... thus more movement by nealy 5/8" for me or 25% more. The pedal is a *little* stiffer but works absolutely perfect.
I actually had too much movement and needed to adjust my slutch slave rod down The Master bolts right on in 2 miuntes ... hooked up and bled and shazam.. great clutch movement.

By the way.. in plantex pic he has his slave mounted upside down.. hard to bleed with the bleeder down.. I'd make sure yours is on top.

my similar troubles..https://forum.ih8mud.com/showthread.php?t=24851
Last edited by Bennett : 05-09-05 at 02:08 PM.

Click to expand...

Pics of the clutch disc installed...


and uninstalled....

UPDATE: What the...!!???

Ok, so this gets a little more strange...

Ordered up the '69 Brake master to use as a clutch master to improve the throw in the fork. Should arrive tomorrow, BUT...

While backing the rig off the trailer at the exhaust shop I found something very interesting. With the engine on and the pedal to the floor it is difficult to shift and the rig moves in whichever gear I'm in, but if I let the pedal up 1/4 of the way it disengages, stops moving and is easy to shift. Then let it up the last 3/4 and it engages and drives like normal (except for the fact that there's nothing more than manifolds on it).

So... I must have too much throw and not too little? Anyone heard of the clutch engaged at the floor, disengaged on the way up and engaged again at the top?

The pedal height and master pushrod are adjusted per FSM but I'm thinking that's the only place I can make up for too much throw without having a sloopy slave pushrod.

Any suggestions? Am I on track here?

Too much throw might push the disc up against the flywheel enough to transmit enough power to make it hard to shift and even spin the input on the transmission. Try backing off the slave acorn and see what happens. Sounds like you have too much throw on the clutch fork.
Just a guess.

You could also reduce the throw with the pedal itself, I guess.

Ed

Thanks Ed. When I get the rig back I'm going to try some adjustments. The only problem I see with the acorn nut is I'm just going to create slop at the slave. I'll gain maybe a bit there, but was thinking the pedal might be a better spot. I am in uncharted territory for me on this one.

I could drive it just fine only putting the clutch in 3/4 of the way, but I want it right and I let quite a few friends drive this thing too and have to idiot proof it. hmmmm... that makes it sound like I let idiots drive it... maybe I should re-evaluate my position...

Are you sure the clutch fork is seated on the pivot?

Dave-

I'll double check that too when she gets home. It seems to me that with only 1 1/8" of throw at the fork end it's hard to believe I have so much throw to flex the clutch back into the flywheel.

I'm not sure with your bellhousing, but I just take off the clutch cover and watch the clutch fork move as someone else operates the pedal. You can then visually look to see how much free play you have and a workable adjustment is obvious. I'm thinking you are probably OK.

First adjust the free play of the pedal to the master-you want full disengagement but minimal free pedal travel.

Then adjust the length of the slave rod.

On FJ60s anyway, the 84 and down slave rod is adjustable, the 85 and up it is not adjustable. The pivot and fork are slightly different as well. You may need to search for that magic combo to get it to work properly.

I'm not sure with your bellhousing, but I just take off the clutch cover and watch the clutch fork move as someone else operates the pedal. You can then visually look to see how much free play you have and a workable adjustment is obvious. I'm thinking you are probably OK.

I assume you bled the air out of the clutch hydraulics. They are pretty darn simple-this should be easy to figure out!

First adjust the free play of the pedal to the master-you want full disengagement but minimal free pedal travel.

Then adjust the length of the slave rod.

On FJ60s anyway, the 84 and down slave rod is adjustable, the 85 and up it is not adjustable. The pivot and fork are slightly different as well. You may need to search for that magic combo to get it to work properly.

Well now that it's all back together a few things have changed. Before replacing the clutch master I decided to drive around a bit to see what happened.

1. After driving a little I seemed to have unintentionally corrected the problem of re-engagement. So maybe the pivot ball was not seated correctly?

2. I bled the clutch again after being on the road and got a little more air out.

3. Then I started experiencing drop in pressure while slightly holding down the clutch. It seemed like the master/slave was leaking by without any real fluid loss. So I ordered up new master and slave. The day before I was going to install it and after a nice cruise up to Santa Barbara, it went away. I cannot get it to reproduce the pressure loss no matter how hard I try.

4. Now it's almost perfect. I get a little chatter when the clutch is pushed all the way to the floor but it shifts cleanly, right about where it should.

I think I'm going to bleed one more time, adjust the slave, and back out the master pushrod to see what I get.