Concentric hydraulic throw-out-bearing conversion

[RETed]

Anyone did this with a "stock type" clutch?

I'm looking to AVOID the pivot ball failure and remove the entire clutch fork entirely.
I've known the non-turbo clutch fork to fail, but I haven't heard of the turbo clutch fork failing yet...
Note: the turbo clutch fork is thicker than the non-turbo clutch fork, and they should swap over.
The weak link is the pivot ball itself.
In fact, I believe the stock zenki FC pivot balls is weaker (i.e. smaller threads) than the kouki FC pivot ball.
At one point in time, I was toying with the idea of designing a stronger pivot ball, but these concentric hydraulic throw-out bearings eliminate a lot of the complexity of the whole system.

Tilton makes a really nice one (6000-series) that has adjustable height, so you can adjust them if needed for multi-plate clutches...?
I'm at that point where I'm going to be swapping over to a multi-plate unit, so that adjustability might come in handy.
Downside is that this is priced around $400.
There are cheaper unit available at a quick glance...

All these "universal" units look like they might need some kinda adapter collar to fit around the trans input shaft - pretty easy to figure out...


-Ted

[Pete_89T2]

I haven't done this with a stock clutch, but from a reliability & maintainability engineering perspective, I'd suggest that switching out to a concentric hydraulic throw-out-bearing would do more harm than good.

First, you would be moving the functionality of the clutch slave cylinder inside the bell housing, so when it fails, you'll have to pull the tranny to fix it. What about hydraulic bleeding - how would you get to the bleeder screw without pulling the tranny?

Second, if the failure of clutch fork and/or pivot ball on FCs really happens frequently enough, it would be a lot easier to just design beefier replacement parts to solve the issue.

[djmtsu]

I honestly don't see a need for this. If there is a side effect of improved clutch feel, or power transfer, then sure.

But my experience with concentric slave cylinders/throwout is, fuck them.

[RETed]

First, you would be moving the functionality of the clutch slave cylinder inside the bell housing, so when it fails, you'll have to pull the tranny to fix it. What about hydraulic bleeding - how would you get to the bleeder screw without pulling the tranny?
If your stock throw-out bearing fails, you'd still need to crack open the trans and engine anyways...

Most of these concentric hydraulic bearings come with two lines.
One goes to the clutch master cylinder.
The other is snaked upward and used as a bleeder.
Due to the position of the stock clutch slave cylinder (mating to the clutch fork), I'd probably snake it up that hole.


Second, if the failure of clutch fork and/or pivot ball on FCs really happens frequently enough, it would be a lot easier to just design beefier replacement parts to solve the issue.
It's enough with very heavy pressure plates - i.e. ACT Extreme PP.
I've seen enough failures of them to not recommend using those things.


-Ted

[Pete_89T2]

If your stock throw-out bearing fails, you'd still need to crack open the trans and engine anyways...

True, but how often does a TO bearing fail when compared to slave cylinder failures? In the past 30 years, I've probably covered at least a half a million miles driving various manual transmission cars, and in all that time I never once had a TO bearing fail on me, but I did have 3 or 4 clutch slave cylinders crap out that I had to fix... Easy repair when the slave cylinder is outside the bell housing.

[RETed]

True, but how often does a TO bearing fail when compared to slave cylinder failures? In the past 30 years, I've probably covered at least a half a million miles driving various manual transmission cars, and in all that time I never once had a TO bearing fail on me, but I did have 3 or 4 clutch slave cylinders crap out that I had to fix... Easy repair when the slave cylinder is outside the bell housing.

Yes, you are right: the clutch slave cylinder does fail more often than the throw-out bearing itself.
If you're doing religious maintenance, I doubt you'd run into a throw-out bearing failure, unless you tend to "ride" the clutch pedal all the time...
By nature, hydraulics and seals will almost always die first.
Usually, you change the throw-out bearing upon a clutch change, unless you're the type that can push a clutch to 100k miles???

Anyways, the stock clutch slave cylinder is replaced in this conversion...
You need to keep the stock clutch master cylinder.
(Well, you've got the option to change it if you want to...)
The stock clutch slave cylinder, stock clutch hydraulic flex hose (between the clutch master cylinder and the stock clutch slave cylinder), stock clutch fork, pivot ball (if you want to remove that), and the stock throw-out bearing all get removed.
All of that gets replaced by a special guide plate / collar (on the trans input shaft), concentric hydraulic throw-out bearing, and adapter hose that goes from the stock clutch master cylinder down to the new concentric hydraulic throw-out bearing.


-Ted