RTH: Clutch fork, hub, and T/O bearing questions (1 Viewer)

[RWBeringer4x4]

Just for clarification - the springs don’t allow the fork to completely fall off the pivot, but this is about the extent of the play that I see:

Fully “seated” the spring don’t really touch the fork:

Which allows the fork to slouch forward a bit:

So we are talking 2-3mm if play on the pivot. I can see hydraulic force on the pushrod holding the fork in place on the pivot when I step on the clutch but it seems like it will want to slouch forward like this when I let off the clutch and the slave retracts.

Again - this may all be normal - I just don’t have a lot of experience with this setup.

 

[RWBeringer4x4]

Ok I built a new bracket that brings the spring inline. So now the spring is pulling in the right direction and the pushrod is as straight as it’s going to get:

The problem appears to be that the return spring actually pulls the fork OFF the pivot ball. The springs on the pivot hold the fork in place but don’t have the strength to hold it against the pivot:

When the rod pushes forward, it first pushes the fork back onto the pivot ball, THEN pushes the throw out bearing forward. Then retracts to this position.

Naturally, since the fork comes off the pivot it fully retracts, I don’t get as much throw on the return to pull the throw out bearing back off the pressure plate.

 

[RWBeringer4x4]

This actually brings up another valid question - the clutch slave cylinder’s piston is also spring loaded. If I lengthen the pushrod, the piston gets pushed backward. If I bottom out the piston against the spring, the rod has no choice but to push the clutch fork back into the pivot.

I was trying to keep the cylinder in a neutral position (with the spring at rest) but could it be that the slave cylinder needs to be fully compressed in the bore to add sufficient pressure to the fork and hold it on the pivot?

 

[jim land]

Keep on digging , I need the truth with facts

 

[RWBeringer4x4]

Ha unfortunately I’m at a loss - I’ve been messing with this thing for 3 days, built 3 brackets for the damn return spring and I’m not closer to an understanding of how all this works than when I started. Frustrating. Not sure if the answer now is just to load it in and get it under hydraulic pressure to see what happens. I think the key pieces of the puzzle I’m missing are:

1. Should the slave cylinder be fully compressed against the spring in the bore.

2. How much distance should there be between the throw out bearing and the pressure plate. Right now I have 1-2mm, not sure what the “normal” throw is for something like this.

 

[handcannon]

That new spring bracket is exactly what I was thinking of when you first pictured the spring not in alignment with the slave bore.

It has been a long time since I messed with a clutch, so my memory is of no use when it comes to the pivot ball. There has to be something stopping the bearing from retracting any further on the transmission input "snout" (for lack of better terminology). This is letting the pivot point on the fork retract from the pivot ball. Without eyes directly on the subject I'm just guessing.

Don

 

[FJ40Jim]

Yes, the return spring should retract the piston fully. That gives a solid, repeatable zero point to adjust the freeplay.

With piston fully retracted, there should be ~5mm freeplay between fork and slave rod.