Hydro Clutch Conversion Problems

[Mattman2010]

I converted my crew cab to a manual transmission and used a 76 SM465 with a 80's aluminum bell housing. I also converted this all to a hydro clutch.

Here is the bracket I made.


Now I am having trouble with the clutch engaging. I am getting about 1" of travel in the clutch, but I have about an 1/8 to 1/4 inch of free play in the throw out bearing (I think, cant remember for sure). From what I have read it takes about an 1" to get full engagement of the clutch, but I am not able to get that, I need at least 1 1/2" of movement to get the clutch to fully disengage. If I extend my push rod to try to utilize the 1" of movement then I have no free play left on the throw out bearing and will be replacing them all the time. Is there a problem with my hydro set up the way I have it? I have replaced the master and slave cylinder and I got the same results, the only thing I can think of now is that the clutch pressure plate is bad. I would like to try to figure this out before I go about tearing the transmission back out of the truck.

Thanks, Matt

[lilpoindexter]

Are your clutch and slave cylinder bores about the same size? or are they different?

[Mattman2010]

Not sure. I got the stock parts for an 85 Chevy truck from oriellys.
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[truckmannorth]

Mattman
If I remember corectly whith that style hydro system chevy ran a return spring. What I would do is adjust the push rod to bottom the slave cylinder and still have about an 1/8" free play at the clutch. then put a return spring on the clutch fork. it should work. we had this type of set up at UPS when I worked there as a mecanic. What are you using for a Master cylinder?
Dale

[Mattman2010]

I know that I should have a return spring, but I am not worried about getting the clutch to disengage. If The truck it set to exactly where you said it should be. All the way in with 1/8 of play, but the slave will not push the lever far enough to disengage the clutch. I am using a stock replacement master and slave cylinder.

[truckmannorth]

humm. 2 questions; are you getting a full stroke at the master cylinder? and do you have all the air out of the system? I know that some times thoes were hard to bleed. I would ussualy use a break fluid pump and push the fluid through the slave into the master cylinder. even with that I would have to pump the peddal several times to get full stroke out of the slave. pushing the peddal clear to the floor and then letting up and letting the return spring pull the slave all the way back and doing that for 15 to 20 times to let the system purge all the air.

[Mattman2010]

Yeah, Getting full stroke at the master. Ive got an 85 pedal setup so it is just like stock. And all the air is out.

[truckmannorth]

ok,
If you have full stroke at the master and the stock master and slave cyl. the only thing left is air in the system. Trust me hyd. clutch systems can be a pain to get bled. What I would do and have had good luck with in the past, is set the 1/8 clearence at the throughout bearing put a returnspring on to help pull the slave back and then get in and pump the clutch pedel. You will want to pump rather fast and use full strokes making sure that the pedel comes all the way up. Then after 10-15 pumps let up and let the system relax. wait a minute and then repete. what you will find is as you do this the pedel will get more resistence and the slave will be moving farther each time. on this style of system usualy 5 or 6 times of pumming the pedel up will clear the system and get your clutch working. The worst one I have had to do latley was on a newer Ford Took us over 4 hours to get the air out of that one at the shop. The way that one was set up just sucked!!
Dale

[Mattman2010]

I did something close to that when I bled mine. I think we bled it for an hour or more, we were having trouble with it for a while. I am almost certain that all I read that I need was 1 inch to 1 1/8 inch of travel in the slave cylinder, I am getting this much travel. But the clutch takes 1 1/2 to 2 inches of travel to disengage (going from free play to fully disengaged). This makes me to believe that something is wrong with the clutch disc or the pressure plate. Also I remember when I first got the truck running and the clutch was working (It was working because the stock stuff that I got with the clutch pedals was not bleeding off properly) my dad said that he thought that the clutch was locking up full when you let just a little bit of pressure off of the pedal. It was not slipping a little bit like it should be. So I am really starting to think it has something to do with the clutch disc or pressure plate, I need to fix a leak between the transmission and transfercase anyway so I am going to go ahead and look at it. I have been talking to some of my buddies and they are starting to think that it may be a clutch problem.

[Altec]

Is the length of the mechanical fork different then a hydro fork by any chance? Just a thought...

[Mattman2010]

Not by much if anything I would think. There have been plenty of people that have done this swap, but I am not sure what master and slave cylinders they have used.

[truckmannorth]

OK, I understand what your saying now. Sorry I just read your first post to quickly before. I have seen similer problems before. usualy what we find when we drop the clutch is that one of the damper springs is broken or displaced and cetching between the clutch disk and flywheel. I would also take a close look at the pilot bearing. if it is a neadle type they can get dry and start to hang up on the Trans input shaft. Good luck and let us know what you find.
Dale

[cheepin]

I bet your clutch arm ratio is messing with ya.I know the stock arms are differnent.

[hatzie]

I had an 85 C10 with the full factory hydraulic setup.

The fork is different on the hydro bellhousings. The incorrect geometry will screw with you.

The pressure plate is different for the hydro setups. If you're running a regular pressure plate this is part of your problem too.