Throw-out bearing clearances
02-27-2013, 09:12 PM
#1
Throw-out bearing clearances Hi All,
I'm getting ready to set up my clutch with a Howe 82870 hydraulic bearing. The instructions say to shim it to 0 clearance: "If done properly, there should be minimal to zero clearance between the bearing and the clutch fingers." Here are a few things I've noticed when mocking it up. With the flywheel bolted on and the clutch just set together and NOT bolted down, there was 4" from the fingers to the back of the block. After tightening down the pressure plate bolts, that dimension went to 3 5/8". I would need to shim the bearing for clearance when the PP is bolted down, so consider that 3 5/8" dimension as "newly installed" and the t/o bearing at 0 clearance as per the instructions. Now imagine what will happen as the clutch disc wears. The thinning of the disc would cause the fingers to move rearward and put the bearing into forced contact and loading, right?
This is my question: Is this normal? Does the bearing somehow compensate for the fingers gradually extending rearward as the disc thins?
I'm getting ready to set up my clutch with a Howe 82870 hydraulic bearing. The instructions say to shim it to 0 clearance: "If done properly, there should be minimal to zero clearance between the bearing and the clutch fingers." Here are a few things I've noticed when mocking it up. With the flywheel bolted on and the clutch just set together and NOT bolted down, there was 4" from the fingers to the back of the block. After tightening down the pressure plate bolts, that dimension went to 3 5/8". I would need to shim the bearing for clearance when the PP is bolted down, so consider that 3 5/8" dimension as "newly installed" and the t/o bearing at 0 clearance as per the instructions. Now imagine what will happen as the clutch disc wears. The thinning of the disc would cause the fingers to move rearward and put the bearing into forced contact and loading, right?
This is my question: Is this normal? Does the bearing somehow compensate for the fingers gradually extending rearward as the disc thins?
02-27-2013, 09:27 PM
#2
Hi All,
I'm getting ready to set up my clutch with a Howe 82870 hydraulic bearing. The instructions say to shim it to 0 clearance: "If done properly, there should be minimal to zero clearance between the bearing and the clutch fingers." Here are a few things I've noticed when mocking it up. With the flywheel bolted on and the clutch just set together and NOT bolted down, there was 4" from the fingers to the back of the block. After tightening down the pressure plate bolts, that dimension went to 3 5/8". I would need to shim the bearing for clearance when the PP is bolted down, so consider that 3 5/8" dimension as "newly installed" and the t/o bearing at 0 clearance as per the instructions. Now imagine what will happen as the clutch disc wears. The thinning of the disc would cause the fingers to move rearward and put the bearing into forced contact and loading, right?
This is my question: Is this normal? Does the bearing somehow compensate for the fingers gradually extending rearward as the disc thins?
I'm getting ready to set up my clutch with a Howe 82870 hydraulic bearing. The instructions say to shim it to 0 clearance: "If done properly, there should be minimal to zero clearance between the bearing and the clutch fingers." Here are a few things I've noticed when mocking it up. With the flywheel bolted on and the clutch just set together and NOT bolted down, there was 4" from the fingers to the back of the block. After tightening down the pressure plate bolts, that dimension went to 3 5/8". I would need to shim the bearing for clearance when the PP is bolted down, so consider that 3 5/8" dimension as "newly installed" and the t/o bearing at 0 clearance as per the instructions. Now imagine what will happen as the clutch disc wears. The thinning of the disc would cause the fingers to move rearward and put the bearing into forced contact and loading, right?
This is my question: Is this normal? Does the bearing somehow compensate for the fingers gradually extending rearward as the disc thins?
You are correct! The fingers will rise as the clutch disc wears. This is exactly why I didn't want that particular type of bearing. OEM types have a spring loaded constant contact with an "air gap" to compensate for disc wear.
Once your disc wears to a point where there is pressure on the bearing, you will have to eventually pull the transmission and re-shim it. It will not correct it self. If it's not designed to stay in contact with the fingers and has an air gap built in, it may wear excessively if not properly maintained not to mention allow the clutch to be released with the pedal released.
02-28-2013, 08:57 PM
#3
You are correct! The fingers will rise as the clutch disc wears. This is exactly why I didn't want that particular type of bearing. OEM types have a spring loaded constant contact with an "air gap" to compensate for disc wear.
Once your disc wears to a point where there is pressure on the bearing, you will have to eventually pull the transmission and re-shim it. It will not correct it self. If it's not designed to stay in contact with the fingers and has an air gap built in, it may wear excessively if not properly maintained not to mention allow the clutch to be released with the pedal released.
Once your disc wears to a point where there is pressure on the bearing, you will have to eventually pull the transmission and re-shim it. It will not correct it self. If it's not designed to stay in contact with the fingers and has an air gap built in, it may wear excessively if not properly maintained not to mention allow the clutch to be released with the pedal released.
Thanks!
03-02-2013, 02:53 PM
#4
Actually Keisler engineering makes an OEM constant contact hydraulic bearing that will bolt on to the 4 speed. That's what I'm using.
03-25-2013, 09:02 PM
#6
You are correct! The fingers will rise as the clutch disc wears. This is exactly why I didn't want that particular type of bearing. OEM types have a spring loaded constant contact with an "air gap" to compensate for disc wear.
Once your disc wears to a point where there is pressure on the bearing, you will have to eventually pull the transmission and re-shim it. It will not correct it self. If it's not designed to stay in contact with the fingers and has an air gap built in, it may wear excessively if not properly maintained not to mention allow the clutch to be released with the pedal released.
Once your disc wears to a point where there is pressure on the bearing, you will have to eventually pull the transmission and re-shim it. It will not correct it self. If it's not designed to stay in contact with the fingers and has an air gap built in, it may wear excessively if not properly maintained not to mention allow the clutch to be released with the pedal released.
