GregBBRD

Stick to Dot 3, like Tilton suggests. We're pretty sure that the Tilton T/O bearing on Jim Corenman's car caused the thrust bearing damage. The internal seal swelled up and would not allow the T/O bearing to return. There was 70 lbs of constant pressure on the old clutch, from the T/O bearing.

GM makes what appears to be a pretty good Dot 3 fluid (working fantastic in testing) under part number 10-4110 or 19353126. (I have not tried to "boil" it with the brakes, yet.)

GregBBRD

There's still one clutch (from the first batch) available, at the special price.

Somehow we lost one of the custom short clutch shafts and could not ship this one....but I just got in another run of short shafts, today.

It takes an amazing amount of time to make trick parts.....4 months, to the day, to make the second run!

olmann

Thanks, Greg! I appreciate the feedback. I will look into the GM stuff.

Bigfoot928

The Tilton sheet states DOT 3 or 4. So the ATE Type 200 isn't acceptable?

GregBBRD

Tilton really has no idea and no input, because up to this point in time, they have been building racing clutches (which get the T/O bearing changed often.) They have probably seen issues (since they print instructions about it), but they are not specific about what brands/types of fluid to use/not use. And frankly, the "temperature" distinction they make is pretty vague.
Unfortunately, since I don't make the T/O bearing, I do not have enough data to know, either. (If I made it, I'd know exactly what the rubber seal was made from and what affected it.)

However, I believe that Jim's old T/O bearing (which had seal swelling) had run on ATE Blue and ATE Type 200, it's entire life. Worth noting, however, is that the carbon/carbon clutch needed to be slipped a bit and there was considerable heat added into the equation. This new clutch is so "positive" and "smooth" that there is no need to slip the clutch, so heat build-up is/will be significantly reduced. (At 2,000 miles, Jim removed his clutch, just to look at it and make some measurements. There was no sign of any hot spots, whatsoever. The discs were not completely seated in, at this point in time. The clutch appeared like it had been driven around the block a couple of times. This is an amazing piece of work!

Beyond that, one of the good things about how I made this clutch is that is is really easy to feel the "take-up" travel of the T/O bearing (the travel of the T/O bearing from rest to where it contacts the pressure plate.) If the T/O bearing internal seal swells, the T/O bearing will not return to rest, which should be instantly obvious to whoever has been driving the car. (It will feel like the freeplay is gone.)

For the "stockish" power output application, we will be using a completely different T/O bearing (sourced from a mass produced vehicle), so that will eliminate any/all concerns about fluid compatibility.

Bigfoot928

Intereting. I got an email response from Tilton that the ATE Type 200 would be fine for the 6100 TO bearing. If the TO bearing has to be replaced "often" for me that is a downer as the 6 speed cannot move back far enough, and the whole rear suspension has to come down and out.

I may just order a seal and soak it in some of the ATE fluid to see how it responds.

GregBBRD

I do not anticipate this being an issue, whatsoever. Jim's was installed for several years and, as I said, was subjected to extreme amounts of heat.
You got way more out of Tilton that we did. The person we talked to at Tilton would not comment on any brand or type fluid. Perhaps they have checked into it, after we pointed out that this ST-246 clutch wasn't going to require a T/O bearing very often....

Bigfoot928

this is the word I got from Tilton.

They initially replied that the ATE Type 200 was ok but I asked about the "recommended" fluid.

olmann

I’m going to give the GM stuff a try. Worst case is I don’t like it for my brakes and then I will install a separate clutch reservoir and flush out and replace the fluid for the brakes. I don’t really want to have to pull the clutch again anytime soon if I can avoid it.

GregBBRD

That sounds very similar to the response we got.
Maybe I should play it "safe" and figure out a remote separate reservoir for those that are not happy with a "regular" Dot 3 or Dot 4 fluid in their brake/clutch system? That should be fairly simple.
The "wet boiling" point for the GM Dot 3 fluid is 284 degrees F. The wet boiling point for Type 200 is 388 degrees F. That's a pretty big difference.

olmann

Now that I think about it more I’m going to install one of these from a right hand drive 944.



part # 94442321000

Bigfoot928

I was just thinking about that.where are you thinking about mounting it? I was just in the garage thinking about this.

SeanR

There's room just to the right of the brake booster on the firewall, even on cars with the factory air cleaner.

olmann

Probably somewhere like Sean suggested. I’m out of town until the first of the week but will post pics as soon as I have it figured out.

Petza914

I'm curious about this statement. Is the 6-speed you reference the C5 Z06 6-speed setup that Carl sells or something different. I didn't have any trouble removing my clutch the normal way. Is the T/O bearing in this Tilton setup different where the clutch pack doesn't come out like a 928 dual disc clutch normally does where once the coupler is moved, the whole things just drops out?

Also, why the separate reservoir and not just change the brake fluid to something with a higher boiling point? I run Motul RBF600 in all my cars and flush and bleed every spring. Loading 6-8 bottles of fluid into the Motive power bleeder lets me hit them all 7 of them one after the other in a couple of hours. I do have nice open wheel designs though where I can reach the bleeders without having to jack up cars or remove wheels, which makes it much easier.