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Adjustment of Hydraulic Throwout Bearing


Guest TBroZ

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Guest TBroZ

I recently put in a hydraulic TO, and find that engagement of the clutch occurs early on while depressing the pedal. I have about 3-4" of extra play in the pedal as it nears the floorboard. The instructions say that it is important not to extend beyond full engagement and recommend a stopping block. I don't feel like installing a 3" stop on the floorboard.

 

Fortunately, I had to pull the flywheel and clutch to have them balanced (another story), so I have the opportunity to readjust the position of the TO bearing. My thinking is that the TO bearing is too close to the clutch fingers. Is this correct? I will move the it closer to the trans, but I want to confirm this. I'm thinking I'll move the TO bearing back 0.125", or whichever is closest to 1/2 or 1 full rotation on the imput shaft.

 

Your thoughts?

 

Terry

image_tobearing2.bmp

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Guest greimann

Like the instructions say, you need to be careful about not over extending the throw of the slave (bearing). Moving the bearing away from the clutch will just change the engagement point, but will not reduce the total movement of the system. I would suggest this:

 

Make careful measurements and set the bearing distance exactly as they specify in the instructions.

 

Look at your clutch pedal pivot ratio and see of you can move the pushrod attachnment point closer to the pedal pivot point. This will reduce the overall stroke of the pushrod on the master.

 

OR, Shorten the pushrod so that the pedal is repositioned closer to the floor and bottoms out at a comfortable distance.

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Guest TBroZ

I do have the rod mounted at the highest hole already, closest to the pivot point.

 

It just occured to me that the the original owner had fabbed an aluminum mounting plate for the motor side of the firewall, as well as for the inside. I kept the inside plate for strength, but took off the one on the motor side. I'm putting it back on. It'll move the MC farther out, effectively shortening the travel of the rod. I may even fab a thicker mount. I would rather do that than attempt to shorten the rod.

 

Ding!

 

TK

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My McLeod hyd TO bearing came with explicit instructions on how to set up the clearance between the clutch fingers and the bearing. It involved taking several measurements and doing some subtraction.

 

They gave a fairly tight range of clearance that you should shoot for.

 

If too much, it's easily fixed by adjusting the threaded collar.

 

If too little (in my case), you need to space the transmission or bellhousing/transmission back away from the engine block. I handled that with an 1/8" aluminum shim that I made up to go between the bellhousing and the transmission case.

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Guest TBroZ

Yes, I took those measurements as best I could. One measures the distance from the clutch fingers to the inside of the bellhousing hole, and measures the distance from the face of the trans (around the imput shaft) to the face of the TO bearing and subtracts the difference. The goal as I understand it is to have a 0.100" to 0.125" space between the face of the TO bearing and the clutch fingers once it's installed. A very tight clearance indeed, but challenging only because it was very difficult to get an accurate measurement from the clutch fingers to the inside edge of the bellhousing, and even then it doesn't guarantee that that measurement is going to be exactly equivalent to where the face of the trans will be once installed. The measuremnt procedure assumes the face plate of the trans will stop exactly (0.000") where the inside lip of the bellhousing is. 0.100" off in the measurement looks like it makes a big difference here.

 

Fortunately, I have room to back off the TO bearing on the adjustment collar.

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Yeah, I know what you mean - getting those measurements is not easy. I used a straight edge across the back of the bellhousing (bolted up tight to the engine) and a machinist's square. I also had to assum that the trans case would meet up tight to the back of the bell housing.

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