Hydraulic TO bearing woes - HELP

I've done a search and didn't come up with any solution so seeking help here.
Here's the situation: I ran a McLeod hyd. throw out bearing (1300) for almost 20 years with success until recently. I swapped my engine (SBC to another SBC) plus changed to an aluminum flywheel from a steel. Now the unit don't disengage the clutch - WTF? I replaced the TO bearing with a updated model ($150 + core) being it was old but nada. I then thought my master may be going out so replaced it with a Wilwood 3/4" but still nada! I noticed the piston was only traveling about 3/8", not enough to disengage the clutch. I extended the pushrod to give master more travel but still not enough. At this point, I'm at wits end and still can't figure out why the piston's not getting the travel it needs. I've bled the unit several times and even ****ed fluid out the bleeder. Did I overlook something simple? Remember this unit was working until engine swap. Thanks for your thoughts and suggestions.

 

did you compare the flywheels before you installed the aluminum one... They may not be the same thickness and the throwout bearing may need to be shimmed. Did you change the clutch plate and pressure plate?

 

No I did not compare the flywheel thickness but began to wonder about that. If I shim the bearing, problem is it'll be riding on the fingers constantly with some pressure on it. As is now, it don't have the required clearance required. I did change the disk but not the pressure plate so that shouldn't make a difference. I'm almost thinking I should pull the Lakewood bell housing and compare the flywheel... damn hate pulling the trans again - back and shoulders hurting, rough on a 68 year old!

 

If the clutch disk is the wrong thickness for the pressure plate you have that could cause problems too. if you only changed those 2 things one of them is the problem

 

I replaced a clutch disc and pressure plate on an O/T truck. It looked the same as the unit that came out, but the disc itself was thicker (must have been the wrong part number or manufactured wrong). I pulled the trans 3 times thinking it may have been something I did wrong. My lesson learnt on that one (I"ll supply the parts at a slight mark up to cover those problems!)

 

Thanks guys but what it looks to me is a hydraulic problem - piston is not traveling far enough to disengage the clutch. Maybe I'm overlooking something simple? I'll go and try bleed the unit again and see what happens. There's good pedal pressure but just not enough travel... more .

 

As you already stated, I would bleed the system out again. Some of the can be really tricky to get all the air out. And this may seem like a dumb question, but is the pressure plate new? And if so did you take out the wood blocks that are sometimes in them from the factory.....that'd definitely limit how far the fingers allow release.

 

You may need a longer cylinder to get more travel. Was there space between the to bearing and the clutch fingers with the bearing fully compressed?
Mcleod has different length cylinders available.

 

True. There is a specific clearance measurement you can get from McLeod and you will need to swap pistons to get yourself into the correct zone. They have different length pistons for this, you do not use shims.

If you over extend the travel at the pedal or master cylinder you may risk pushing the existing clutch piston out past its seal, and that is not good.

 

No, the pressure plate is the one I was using, a diaphram unit.

The piston is the same length that was in use (which worked previously). There're shims (spacer rings) on the upgraded unit for adjustment which my old unit didn't have. But by adding these shims, it'll push the piston up against the fingers and not allow for clearance needed. The clearance needed is allowance for clutch wear which raises the fingers closer to the TO bearing.

I'm still thinking it's a hydraulic problem...

 

Does this unit replace the trans bearing retainer? Just wondering where these shims go you are talking about. Sort of sounds like a 1400 series.

Did you make the measurements they describe in this link?


http://www.mcleodracing.com/products/default.asp?id=5204&v=more

A call to Mcleod tech would be my first call.

 

That's the information Tudor.

 

The 1300 is the bolt on bearing if you have changed the flywheel you need to check the measurements and you might need to change the piston in the bearing. I don't know what the shims are for I have never used them with this bearing it is a bolt on correct

 

Have you checked to see if the disc is in backwards?

Not throwing stones, a friend of mine had that issue on a mechanical clutch after an engine swap.

Turned out the "thick" side of the clutch hub was towards the crank, and it was hung up on the flywheel bolt heads.

I know it ****s to pull the trans, but it sounds like you need to do that to at least check the flywheel thickness, seems an oportune time to check everything.

I've also seen people have an issue with aftermarket flywheels having problems with the bolt heads hanging up on the hub when it is installed right.

Neither of these may be your issue, but are worth checking while you have it open.

Best of luck.

 

I was down at McLeod and spoke to the tech there. The clearance they recommend I cannot acheive unless I add two washers to space the trans back away from the clutch which only worsens what's happening. The shims go between the piston/bearing and the stationary housing of the unit spacing the piston forward into the fingers whereby applying some premature contact. I could do that but there'll be constant pressure with bearing on to fingers and bearing will wear out prematurely fast.

The bearing unit replaces the stock input shaft bearing retainer - unbolt the retainer and bolt on the TO brng. unit. Shims are for as described above. The piston/bearing length is as prescribed by McLeod - the shortest one as they have three lengths.

Thanks but I'm 99.9% sure of the disc direction - I know what you're saying though...

Thanks everyone for your thoughts and ideas!

 

Did you ask the Mcleod Tech about changing the bore of your master to get more travel? Sorry you're having a problem. It's a ***** I know. That hydraulic circuit is super small and should be straight forward. What about your pedal travel? Can you adjust where the rod attaches and get more stroke?

 

Thanks for your ideas and thoughts... anyone else?

 

You are very welcome. I'm not sure you understood one of my comments though.

You said you lengthened or extended the push rod that went into the master for more travel. That is more or less just taking the slop out of the rod pedal set up. I was suggesting changing the pedal ratio by Changing the length on the pivot. Also, with the different size bore the added pedal pressure may not be so bad if you get e travel you need. I'm not sure I'd write that off so quickly. Good luck. I won't bother you anymore. Thanks.

 

Is your master a 3/4 bore

 

Thanks Tudor for your concerns and ideas, you're not bothering me at all! All suggestions are taken into consideration if not already done.

 

Yes it is. Thanks everyone - I'm going to go and shoot myself now...

 

This may sound 'bonehead', but a customer of mine had the same type problem after replacing his flywheel (steel) with an aluminum one.

My apprentice found the problem: The pressure plate was approx. .150" off the flywheel surface. When we removed the trans, bellhousing, and pressure plate, I discovered the flywheel, while tapped 3/8" std. for the p.plate, the holes hadn't been counter bored, only allowing the bolts to go down to their threaded length.
The centering shanks stopped the pressure plate from going down to its specified 'height'.
Counter bored all the P.plate holes, cleaned up with 3/8" tap, and all was well.

 

I helped a friend bleed his Fiero a while back. It had the same issue yours does, it didn't have enough travel. We bled the system and no improvement, then we bled it again, but we pumped much faster while bleeding it and then got a longer travel. Don't ask me why, but it did work for us.

 

I did not see any mention of wether you opened the hyd.system. if you did it is probably just a bleeding issue. hyd. clutches can be a pain to bleed there not the same as brake systems. I cant see that you changed enough to efect travel in the slave .

 

If you did have the system open for any time could there be moisture in the system. Have you flushed it and used new fluid?

 

subscribe!!!!!!!!

 

BTDT.Hydraulic clutches can drive a person WAYYYYYYYYYYYYY round the bend.
Good luck.Have fun.Be safe.
Leo

 

I had an oil leak at the back of the engine and it was driving me nuts being it's a new engine. I figured it was the rear main seal so decided to pull everything off so I could see what was going on and check to make sure everything was installed correctly... when I pulled the trans, WHAMO, it stared me square in the face! I wish I could say the problem was an exotic one but I'll have to bone up, eat crow and admit I f_ _ ked up royal and couldn't believe I did that! I owe it to all you guys who gave me feedback to tell you the findings - the disc was installed backwards! Okay before you say it, I'll admit I'm a DUMB ****! Must've been spacing out when I installed it - only been changing clutches since the 60's... I guess even "monkeys fall off trees sometimes"... Found the oil leak not from the seal but the rear cam plug installed (****ed) by the machine shop - honest, not me! So changed the freeze plug and reinstalled everything (with disc in right direction) but still can't get the clearance McLeod recommends. I can now spin the driveshaft with clutch depressed in gear - will give it a test drive tomorrow. Something I learned from this is not to overlook the basics and PAY ATTENTION! Thanks for all your input and ideas guys, I'm humbled by your responses! PS. the aluminum & steel flywheels are the same dimensions.

 

Glad to hear you got it worked out sometimes the simplest things bite us in the a**

 

You aren't the first to do it and you won't be the last. I've seen mechanics who install clutches every day do it. I once got into a heated argument with a co-worker about which way the disc goes in a multi disc clutch in a semi tractor. I was right but he almost got me to agree with him. I've seen them install a throw out bearing backwards too. I've seen a man who ***embles engines every day put pop up pistons in backwards. He even had an argument with his shop helper about it and he was certain he was installing them correctly until he tried to turn it over after the heads were on. I've seen heads installed without gaskets. Sometimes we get ahead of ourselves and are too confident to stop and think about it. Most of us have left a bolt loose or forgot to put a nut on. It happens and you have to be able to admit that you might have made a mistake.