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  #1 (permalink)  
Old 10-27-2007, 11:18 AM
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Default Clutch adjustment and Throwout Bearing Q

After installing a new TKO600, I had to adjust my clutch throw as expected to active the clutch and stop the input shaft from rotating to shift while the car is stopped.

My external slave cylinder will move the fork end about 1" to disengage the clutch. After adjusting the nut on the external slave shaft, it was more than I thought but the clutch works! As the adjustment is made I know the throwout bearing is being pushed into the pressure plate fingers. Is the throwout bearing supposed to be engaged on the PP fingers all the time or just when the clutch pedal is pressed? Or should the throwout bearing and clutch fork be pulled back away from the pressure plate fingers with a return spring when the clutch pedal is not pressed?

I did install a return spring after the swap and clutch throw adjustment but I do not think it is doing anything because of the slave shaft nut adjustment required to operate the clutch.
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  #2 (permalink)  
Old 10-27-2007, 04:34 PM
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I had the same question about my cable clutch setup and was informed here on CC that a little pressure on the fingers by the throwout bearing was normal and has been since the mid 80's on fords. I confirmed this with a mechanic at the local Ford dealer. I am from the old school and I have never believed that was the correct way to do it. I guess the new technology in throwout bearings is a lot better now. The mechanic at the dealer said that around 12 lbs of pressure is correct.

Terry
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Old 10-20-2008, 06:24 PM
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Default Clutch TO Bearing Adjustment

Terry, I appreciate your feedback and I hope modern TO bearings can be in contact with the pressure plate 100% of the time without early failure because I need to "pre-load" a certain amount to get the throw of my slave to move the arm enough to completely disengage the clutch. I too believed that during rest, the TO bearing should be away from the rotating pressure plate. I have asked several others in the hobby and most reply that the TO bearing at rest should not touch the pressure plate.

To help me feel better, I would like to hear from others. Should a modern TO bearing touch or not the pressure plate at rest (no foot on the clutch)?

I am asking because my external slave will only move the outside tip of my clutch arm about 3/4". I do not believe the clutch is completely disengaged when I shift. I have the longer clutch arm that pivots on the passenger side. My clutch arm must be "pushed" toward the front of the car to disengage. This direction seems different from many other clutch arm set-ups. I think I need 1" or so of clutch arm travel to completely disengage.

Thanks in advance
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Old 10-21-2008, 02:49 PM
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The drivers side pivot has better geometry, and will allow you to bring the T.O. bearing off the pressure plate with room to spare, and fully disengage the clutch. It is my understanding that the passenger side pivot is used with a cable type clutch, and not meant for the hyd. slave type clutch.
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Old 10-21-2008, 03:59 PM
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Edited......
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Last edited by blykins; 10-22-2008 at 03:19 AM..
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Old 10-21-2008, 04:01 PM
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Also, most slave cylinder setups have the pivot on the driver's side. You're actually pulling the fork back towards the rear of the car.

With the pivot on the other side, I think it's really more set up for a cable operated clutch.

What bellhousing are you using?
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Old 10-21-2008, 07:57 PM
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I am using a T-5 trans and bellhousing with a cable clutch (pivot ball on passenger side). I was going to change to HYD but decided not to. There is a slave that bolts right up to two bosses on the T-5 trans and is a push type. It pushes from the trans forward. The street rodders in my area use it a lot.
Terry
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Old 10-21-2008, 08:03 PM
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Default More info but same original question???

I now realize the longer clutch arm (that pivots on the passenger side) is for a cable setup. My car built by HRE (Billy Andrews) came that way. This setup worked with the old 3550 with Centerforce PP and disk and Lakewood bellhousing but it was a senstive adjustment to achieve complete disenagement.

I swapped in a TKO600 using the same flywheel, PP, bellhousing, and new Centerforce disk (26 splines) along with the same Lockheed Wagner slave and Tilton 7/8 master cylinder.

Because most slave setups position the slave to push backwards (for drivers side clutch arm pivot) and the unique slave mounting bracket I have, it will be easier for me to swap the current 7/8 MC for a 15/16 or prehaps 1" for more slave travel. I need to make some calculations / measurements to ensure that I do not push the slave pistion on of its bore.

My second option is to fit the Wilwood pull type slave.

But I still have the same original question; do modern TO bearings need to be clear of the rotating clutch assembly at rest?????
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Old 10-22-2008, 03:18 AM
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On a linkage system, like an old Ford with a Z-bar, there should be 1/4" of space between the TOB and the pressure plate.

On a hydraulic or cable system, the TOB should lightly rest on the pressure plate.

Now with that being said, I would make sure that your hydraulic line is bled perfectly so that you can get all the travel you need.

Also, if you go to a larger master cylinder, the amount of force that you'll need to put on the clutch pedal to fully engage it will go UP. The amount of travel needed to get the same slave cylinder movement will go DOWN.

If you go to a smaller master cylinder, the amount of force that you'll need to put on the clutch pedal to fully engage it will go DOWN. The amount of travel needed will go UP.
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Old 10-22-2008, 09:57 AM
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I'm using the Wilwood pull type slave, With Wilwood master cylinders, and originally tried a 7/8" master for the clutch. This proved to be too light, very little feel and not enough movement at the TOB. A 1" master cured this. The clutch now has a good feel and is easy to modulate.
The TOB is designed to contact the pressure plate fingers when not engaged.
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Old 01-04-2009, 05:32 PM
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Hi J,
The T/O bearing needs at least .100" clearance to the fingers with the slave piston fully retracted. The reason it needs clearance is so when the clutch disc wears, the fingers rise and if the fingers are already in contact with the T/O bearing the clutch will slip under load causing the clutch to fail because of never fully engaging.
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Old 03-08-2010, 11:25 AM
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Default Clutch

So, if I have a 3/4" Wilwood MC and a Wilwood slave cylinder, what would be a reason that the clutch takes so much (leg) force to depress the clutch. My clutch appears to be acting correct, engages and disengages basically at the floor. We have about 1 inch of movement from the slave cylinder, just very difficult to depress and hold clutch.

Thoughts?

Paul
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Old 03-08-2010, 11:35 AM
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What style pressure plate are you using? A Long style plate will be harder to push in than most diaphragms.

Also, you said that you substituted in a Centerforce disc....I don't mess with CF stuff....is it the same thickness as the previous disc?

Flat side of the disc to the flywheel, right?
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