T56 Slave shims and centering of teh slave after install?

[jorgezee1]

Hi,

I recently restarted my build project and I am moving onto the clutch/transmission checking and installing. I have a few question or concerns and would like to know if anyone else ran into this issue and how they addressed it.

Build is a LS3 with a T56 Magnum, Tremec F body Bell housing (1386-212-005), Monster Stg 2 Clutch, LuK LSC265B 98-02 Camaro Slave.
Air Gap Measurements with this setup are;
Clutch Fingers to back of Bell housing
A=2.32
Slave with removed spring and resting at the back of the housing to face of the transmission
B=1.93
It appears I have a .39 gap. I need to get to a .100-.200 (Monster recommend .100 to me via email)
Purchased the Holley shim kit: 319-204
Shims included: 0.059 in., 0.119 in. and 0.197

Issue:
It seems I can stack the .197 and .059 to get me within spec, but the issue I see is the slave would normally index to the transmission without shims. How did you guys center it and are there any concerns with shifting side to side since it no longer register on the trans?

I also received some conflicting information about if a shim is really needed since the TOB has a spring to self adjust to the clutch and using GM parts should not be needed.

I will shim the TOB but just trying to get any feedback, or if I am overthinking adding the shims.

[andrewb70]

I have never used a shim, mostly because I use a stock LS7 clutch, but you have a valid concern regarding the indexing issue.

Andrew

[jorgezee1]

Andrew, thanks for the input.

Did you measure the air gap or did you feel comfortable with just running the slave as is with a LS7 clutch?

[andrewb70]

Andrew, thanks for the input.

Did you measure the air gap or did you feel comfortable with just running the slave as is with a LS7 clutch?

I didn't measure. The LS7 clutch is well documented with the f body style slave. I've got 25k miles on it without issues.

Andrew

[jorgezee1]

Thought I should update what I found.

So far I do not really have an answer for the indexing concern, but this seems to be a common setup so I assume it will be fine to center it as best I can and call it a day.

As for the whether to shim a GM slave or not I found a great thread on LS1tech.

link:
https://ls1tech.com/forums/manual-tr...hes-shims.html


What I learned from this article and a few others is shimming just helps you keep the slave in the safe zone of it's travel or within spec of it travel. Disengagement of the clutch will be the same regardless of starting point unless you have a negative start. The GM slave has about .95 of travel and if you have a huge gap to start, you could potentially over extend the slave if all other variable stack up with to much air gap. Accounting for the slave start position; A + B = C, plus the amount of travel that it will require to disengage the clutch (depending on Clutch Manufacture) and how much will the master push the slave. It seems there is a good margin for error with the GM Slave, but to be safe just measure it.


In my case.

The LuK LSC265B 98-02 Camaro Slave I measured to have .91 of travel from the base of the retaining plate (measure with spring removed) to fully extended on the stop. I would not call it really a stop but it the furthest it can extends before the inner lip of the plastic housing the bearing stops against the housing or What holds the two pieces together with the spring installed.

Monster Stage 2 Clutch: Per the link; the Monster PP disengages @ .250" and at anything more than .400" can damage the PP. I would need to ask Monster if this is correct.

My specific measurements:

T56 Magnum, Tremec F body Bell housing (1386-212-005), with LuK LSC265B Slave

Tremec F body Bell housing (1386-212-005) to Monster Clutch Fingers = 2.32

LuK LSC265B 98-02 Camaro Slave to mounting face of T56 Magnum = 1.93

My starting point is .39

If I install the slave without any shim I would be .91 slave travel for my setup - .39 air gap = .52 start on the slave. Basically I will loose over half the travel to start.

If I take my start and add what it takes to move the clutch to disengage that would be .52 slave start + .25 ( min ) Monster pressure plate disengagement = .77.

This leaves me with .2 margin before the slave possibly pops out and I destroy something and assuming it will really only take .25 to disengage the pressure plate.

I have a 3/4" Tilton Master with 1" of travel, I have not added this to the equation, but assuming I did not shim, I would just adjust it to only travel .4 max.

I will shim this slave but I just wanted to work it out to better understand what shimming does and if it really is needed on a a stock GM slave that has constant pressure on the clutch fingers and self adjusts for wear.

I am not sure if this is all correct, but it is so far how I understand it. It would be great to have someone correct me or add to this.

[andrewb70]

I'd say a typical diaphragm style spring will take about .3-.4" of travel to achieve clean release.

Andrew

[jorgezee1]

Thanks for chiming in Andrew!

Emailed Monster on the Clutch engagement and max travel and I received the following response:

"You don't want to see more than 0.600" of travel, the clutch will start to release at 0.245" of travel."

Hope this helps someone if they search for it here.

Thanks,
Jorge

Here are a few pics for reference.