Why Hydraulic Throw-Out Bearings?

[David Kirkham]

Just to stir the pot a little.

We had failure after failure after failure with the McLeod throw out bearing units. We were changing them in our customer's cars at a rate of 1/month for a while. I will NEVER use one again.

I did break down on the billet chassis car we are using because of extreme space constraints and used the Tilton unit. The clutch is like a bear trap and so we just did a massive redesign to handle the external unit. There is NO comparison between the pedal pressures--the external unit is far, far easier on the leg.

The Tilton would not release the clutch without a big master cylinder. After a day on the track, I said, no way am I going to deliver this.

David

[vettestr]

David,
I am sure you looked for the reasons the throw out bearing units failed. When the dust settled do you have a thought or two why or what failed. Thanks Jeff C

[David Kirkham]

Originally Posted by vettestr

David,
I am sure you looked for the reasons the throw out bearing units failed. When the dust settled do you have a thought or two why or what failed. Thanks Jeff C

All of the units failed with bad seals. McLeod told us we couldn't use DOT 4 brake fluid as that would eat their seals. I was dumb and believed them. We then used normal DOT 3 in the clutches and they still failed. No hope. I have seen that milky, dark, nasty fluid many, many times--too many times, in fact. Many of the seals were literally eaten, crumbling, and melting.

We finally called Parker and talked to a seal expert. He told us the seals had to be ethylene-propylene that is "sulfur cured" and that most people didn't do it because it was expensive. I can tell you the seals were not as expensive as pulling the transmission.

David