Thread: Hydraulic Throw-out bearing / crank bearing problem

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Anybody familiar with Hydraulic Throw-Out Bearings. I have a McLoed Racing throw out bearing in my rod. Early Hemi backed up by Muncie 4spd. Trying to find out if the problem I'm having is something others have run into. The Throw-Out bearing was originally set up with approximately 1/8 - 3/16 clearance between the T/O bearing and the pressure plate clutch fingers. (it's a diaphragm type pressure plate.) Well as time went on, the clearance gap closed up and the bearing is constantly against the fingers and is under slight pressure. The problem is that this constant pressure is pushing the crankshaft forward and wearing out the thrust surface on the crankshaft main bearings.
I've been told that as the clutch "disc" wears, the pressure plate fingers extend backward closing up the clearance gap to the T/O bearing. This doesn't make sense to me. ANY THOUGHTS ?

Hi, Welcome to the site, it's good to see you here.
Actually, if you think more about the way the pressure plate and the "fingers" work. It should become more clear.
They are levers and as the disc wears it becomes more narrow/thin, the lever passes over the fulcrum (pivot point) it will move a greater distance the thinner the disc becomes.

So there goes your bearing gap/clearance. I had a F-150 4x4 and when I replaced the clutch and related parts I found the internal hydraulic setup was always in contact and was actually spring loaded to keep the bearing in contact with the pressure plate. Just seemed wrong to me but it always worked well.

Hope it helps.

Fix the oil supply to the thrust surfaces of the main bearing, comfirm that all the belt/accessories are alighned up front( misalignment will cause severe end loading on crankshaft) and stop riding the clutch pedal with your foot---------

Changed all bearings. Mic'd the end play gap which is nice at .007. Re-assembled same clutch, -throw out bearing, & transmission , and rear crankshaft end play is "ZERO" as T/O bearing is touching clutch fingers