turbotuner20v

So I've lost 2 stock slave cylinders in the past ~2k miles. Both ~1k miles each after I completed my build using a McLeod RXT clutch. I have the RXT, aluminum flywheel, stock crank, stock bell housing and stock torque tube. From everything I've read and been told by McLeod this should work (and is working for many others).

While I replace this slave cyl, I took some measurements and found that the slave cylinder appears to be preloaded against the clutch pressure plate.

Melt down pic:



Measurement instructions:



My 'A' - 3.1875"


My 'B' - 3.25" (compressed)


A - B = -.0625

This measurement should not be negative (preload). The recommended distance is .125" to .200"

Has anyone else had issues like this with either a McLeod clutch or other?

Is it ok to try a temporary fix of shimming the torque tube using .1875" to .2625" washers to get my clearance? Or will this weaken the connection between the torque tube and bell housing since the full surface area is not sitting flush?

Blackonblacksls

You could try a zr1 slave and shim it up. They are much shorter. I have a brand new one at shop if you need it. Strait from gm. I'll probably never use it.

On my 5th gen camaro when I did a twin disk I had first used washers between bell housing and block. To get desired height.

But eventually had a motor plate made with the ears cut off. Then had it milled locally to my required thickness.

jon6.0

Weird. It's like your car has some sort of wrong build tolerance. What about maching some off the back side of the slave so it sits farther down? If a ZR1 slave won't work like previously mentioned.

turbotuner20v

Would you mind taking a measurement for me on the ZR1 slave? From bearing to base both compressed and non-compressed?

Like this:



I picked up 10 washers (2 for each torque tube/bell housing bolt to make up 5mm). I'm concerned about how the load will be spread over those 5 circles now though vs. spread evenly over the mating surface.

turbotuner20v

I would think it has more to do with McLeod than GM since my original slave cyl worked for 14k miles before the McLeod killed it in 1k miles after finishing the build and reusing it.

There's not enough material there to machine down 5mm

My options will either be to pick up the LS9 slave and shim it (waiting to see how much based on the measurements above).

Or buy an aftermarket slave cylinder to the specifications of my measurements.

Blackonblacksls

3.5 and 2.6 area from what I can find looking it up on google. Someone else had posted Thier measurements. I'd have to grab it from shop to get my own.

So a 3/8 spacer would put it right where you need to be?

jon6.0

I wouldn't do washers on the torque tube. I would have a machine shop make you single spacers of an exact thickness once you for sure know what you need. Best would be a one piece spacer that would go between the bell housing and torque tube. If it's the McLeod, have you tried contacting them to see if the unit they sent you is out of tolerance somewhere? Maybe see if they will send you the print with all the dimensions for everything. Flywheel too thick maybe? I'm just spit balling here. I'm now a little worried as I have an RXT with a steel flywheel waiting to go on when my LS7 clutch gives up the ghost.

turbotuner20v

3 7/16" (3.4375") is the height of the ls3/ls7 compressed.

I need it to be .1875" to .2625" shorter.

So my final compressed height (with shim) on the ls9 slave cylinder would need to be 3.25" to 3.175".

Depending on the exact compressed height of the ls9 slave I can determine the shim size I need.

turbotuner20v

Yea, I scrapped the washer plan. Unfortunately I need it for an upcoming event, so it's going back together with the same preload

I'll definitely be contacting McLeod since this has been very tiring and cost me 2 slave cylinders.

The next repair will use an ls9 with the appropriate shim, I'd rather work it from that angle.

Blackonblacksls

Washers worked fine for a long time in my camaro. I think I had 3 per bolt? Shooting for 3/16s of an inch. And that was a 4100lb car on drag radials with a 560rwhp motor and a bunch of nitrous.

Cordes Performance Racing

jon don't be worried, look at how many rst/rxt's i have out there.

gotjuice?

Be careful using washers as they are always different thickness. With the Quicktime bellhousing, You can measure with it all bolted up. There is a hole in the bottom of the housing. Maybe you can try one washer to help with more clearance. I would of thought with that much preload you would of burnt up the clutch disc. Hopefully you get it all figured out, It's a pain to keep removing the torque tube assy.

Blackonblacksls

This is true but it didn't cause any issues that I noticed.

The extra preload on my car caused my clutch to not hold. That's what first made me aware of an issue.

turbotuner20v

Yea, it was hard to find the same thickness. Plus I don't want to tweak anything else to make a relatively cheap part I'd need to replace either way work.

It is weird that the clutch grabs fine preloaded like this, that's one of the things I'll be asking McLeod about, I want to make sure my clutch life hasn't been shortened.

jon6.0

Lol. I already bought the damn thing. It's going in.

turbotuner20v

I'd just recommend checking the measurements, it doesn't take much more time and I wish I'd done it on my initial install now vs. just assuming everything would bolt together.

turbotuner20v

Of course the one measurement I didn't grab was from flywheel surface to fingers. McLeod says that this should be 2.1".

I guess when it's apart next I'll check that measurement.

They didn't have any ideas on why I was having this issue, but told me that if I shipped it to them, they could look at it and get back to me in ~5 days.

Hopefully the ~1.6mm of preload gives me another ~1,000 miles and it'll be a winter project to see whats up and take the corrective action w/ a LS9 slave + shim.

turbotuner20v

So this is a picture of an LS9 vs. LS3/LS7 slave cylinder. No measurements unfortunately, but based on my picture above and the only difference appearing to be that cast spacer, I'd guess it's ~1" shorter.

This would place the compressed height of the LS9 at ~2.4375". I need it to be ~3.25" to 3.175", so I would need a .8125" to .7375" shim.

That's huge and there's no way it would work.

I guess that blows the shimmed LS9 idea away.

http://www.vetteweb.com/tech/vemp_10.../photo_16.html

turbotuner20v

Looks like Quarter Master tri-lite 2 is going to be the ticket...

They have 3 sizes (waiting to confirm they're measured base to bearing surface using the OEM style flat bearing). The sizes are 3.150, 3.200, and 3.300.

So I should be able to order their 3.200 size and be set. It comes with the total assembly + bleed line + line to connect to the oem master cylinder quick connect.

jon6.0

It's also half the cost of an RXT. But if that's what it takes, then it needs to be done.