I have a Ram 10.5 twin disc clutch. The clutch was installed by a mechanic (and I use that term loosely) that I know. I'm in the process of rebuilding the entire car and am at the stage where I'm putting the transmission back on the engine. I had some problems when the clutch was first installed and didn't really know why. I think I'm beginning to understand now. The bellhousing is a Quicktime blowproof bell housing. Since the clutch was installed initially, I always heated the floor bad. Then last summer (2010) I had the trans faceplated by Liberty Gears. Go to put the trans back on with a new clutch slave and after bleeding the slave, everything appears fine. Next morning I have no peddle and the mechanic pulled the trans back off and the throw out bearing had come off and spewed the clutch fluid all inside. Put the original clutch slave back on and he decided to put a shim in. Everything appears fine until the floors start getting really really hot and it gets to the point I can't get it in reverse. Let it cool down, and it would go into reverse, get hot, no reverse. Now to the present. I'm putting everything back together and think, do I really need a shim. So I get you diagram that shows how to calculate all of the dimensions. This is what I do. Here are the dimensions.

A - .504"
B - 3.577"
C - 3.2075"
D - 2.681"

Here is the diagram Ram uses to determine preload.

http://ramclutches.com/Instructions/...SITION1010.pdf

If you go through all the calculations that you have on that diagram, the space available is 2.893", the setup height is 3.2075". Right there the minimum space requirement is .3145" bigger than the space available. This appears to be a problem in and of itself. Now for preload, the installed bearing preload appears to be 1.0605". Is this right? This is saying I am supposed to have no less than .500" of preload and I have 1.0605" of preload. If that is the case, then with that much preload would that make the clutch be hot and would that have a bearing on me not being able to get it in reverse? This also means I don't need to shim the slave which goes back to my comment on the installer of the original clutch system. Is this much preload ok?

 

Thats a bit different then I measure them but the final measurement would be the same. Many here measure from the surface of the trans to bellhousing surface instead of block to bell.
First, your B and D measurements seem normal since .800 + of travel on the slave is the norm.
3.577 -2.681= .896
Your A plus C measurement puts the clutch finger height at 3.711 from the surface of the front bellhousing

With the clutch slave fully depressed, you have a distance of only B=3.577 which means that the throwout bearing is depressing the clutch fingers .134

In everything I've ever installed, I shoot for about .130 GAP between the FULLY depressed slave and the clutch plate fingers. As I read your measurements, you are nearly +.260 from that. Are you measuring with a shim in it right now? Most common shims are between .110 and .170. If you have a .170 shim behind the slave and take it out, your air gap will be about .40. Still smaller then I like since the fingers close the gap when the disks wear. If your shim is only .110, I'd check the thickness of the disks and call the mfg. of the clutch to see if they need new friction surfaces.

 

Nope, there are no shims on at all.

 

I'd call the clutch mfg. next. Make sure you have a measurement of the thicknesses of the disks when you do.