3 Finger Clutch + OE Hydro - WHO'S DONE IT???

[nvrenuf]

Disclaimer: I tried this before but didn't find much info, I figured I'd try again.

Has anyone used a 3 finger type pressure plate on an OE hydro bellhousing set up?

SweetK30 made this post where he had problems - http://coloradok5.com/forums/showthread.php?t=193238&highlight=HYDRO+CLUTCH+FINGER

I'm looking to see if maybe someone out there successfully did this (possibly by combining mech / hydro parts). It was suggested to me that using a mech fork and pivot ball inside the hydro bell might work but it's just a theory and I'd rather not find out the hard way that I need to pull my Doubler back out.

 

[dyeager535]

Has anyone looked at a service or parts manual to see what GM offered?

I'd be somewhat surprised to find that a heavy duty 1 ton in 1985 came with a diaphram clutch. But then we may get into differences in the clutches, and what I assume you are trying to do is get an older mechanical clutch/pressure plate to work with hydraulic stuff?

I've got my '91 manuals at home, I can see if they reference specific types of clutches tonight.

 

[bp71k5]

You'll need to find a fork and throwout bearing combination that doesn't crash into the pressure plate or the tranny when it moves through it's range of travel. They make different height bearings and forks for different applications but it is a pain. I had similar trouble when I did mine.

That might be tough since I thought the 3-finger style was done by the time you're combo was being built. Why not stick with the diaphram style?

 

[nvrenuf]

Yeah, I've got a McLeod dual disc set up from my old mech application that I want to use on my current project. I agree that it would seem crazy for the clutches to be so different they wont interchange.

 

[bp71k5]

If you do find a longer bearing that works, they make adjustable fork pivots that can be used to tweak the throw on the fork a bit. I tried one but it didn't fit my bellhousing combo. If you have a later model bellhousing it might have a better chance.

 

[nvrenuf]

My bellhousing is out of a 90 Sub.

How did you figure out what you needed? Any way to check without assembling the entire set up.

 

[bp71k5]

An easy way to check most of it is to assemble the bellhousing onto the engine (separate from the tranny).

Just doing that, you can:

1. Check that the bearing can back away from the pressure plate enough to give you enough pedal freeplay. (The bearing will burn up if it constantly touches the plate fingers.)

2. You can also check the position of the fork when it does contact the bearing. If the fork is too far into its travel, you might not be able to get enough force on the pressure plate to release the clutch. (I had this problem)

If I had to guess, you probably need a shorter throwout bearing to accomodate the taller pressure plate. If you can get a shorter bearing in there without the fork hitting the plate or the bearing getting squished between the pressure plate and the transmission input retainer, you are probably ok. If you can measure the height difference in the pressure plates, you can estimate how much shorter the bearing needs to be.

On mine, I did end up having to remove the tranny (with doubler still attached) because the clutch wouldn't fully disengage. I ended up having to use a custom clutch fork pivot ball that I had made to get it to work right, but I was using a modern clutch with an old 71 fork.

 

[nvrenuf]

Good info Brian, thanks! I'll spend a little time under the truck mocking it all up.

 

[bp71k5]

no problem. When\if you get to the point where it looks like it'll work, one of those ATV jacks from the auto parts store makes it tons easier to mate the tranny\x-case combo and take it back off a few times in one night. You can bolt it in with a couple bolts and actually try the clutch to see if it disengages all the way.

 

[sweetk30]

Disclaimer: I tried this before but didn't find much info, I figured I'd try again.

Has anyone used a 3 finger type pressure plate on an OE hydro bellhousing set up?

SweetK30 made this post where he had problems - http://coloradok5.com/forums/showthread.php?t=193238&highlight=HYDRO+CLUTCH+FINGER

I'm looking to see if maybe someone out there successfully did this (possibly by combining mech / hydro parts). It was suggested to me that using a mech fork and pivot ball inside the hydro bell might work but it's just a theory and I'd rather not find out the hard way that I need to pull my Doubler back out.

nice to see somepeople read what i type on here and possibly learn from it.

good luck and keep us up to date.