Adjustable Pivot Ball

[rgtrough]

Hey guys, when I put the engine back in the '74, I will be installing a new Centerforce Dual Friction clutch and pressure plate. Will someone be so kind to tell me the purpose of the adjustable pivot ball in the bellhousing? I have read about them in this forum but never knew how they where used. I bought one just in case. Thanks. Peace Bud :cool

 

[brusso]

To adjust the speed at which the friction disc moves?? I really don't know. Just a guess.

 

[FX GS]

Dunno, did'nt know they had adjustable ones, thought they were all fixed

 

[Rowdy1]

Just A Guess

I'm thinking it's either for different bellhousing applications or to have the ability to make adjustments so the shifting fork rides exact center of the input shaft on the through out bearing. I'm "really" not sure and I had one in my scattershield when I put it together and I also used a new one just recently when I changed the Borg Warner T10 to the Richmond Gear Super T10. I had a Centerforce set in prior to the change for roughly 7K but had to change it because of a different spline on the Richmond and I was amazed at the condition of it. It looked brand new and trust me, I have more hole shots and powershifting than I can remember. Needless to say, a new Centerforce went back in, 11", same as before. Unless someone comes up with the "real" reason for the adjustable pivot ball tonight, I'll have to call my guru tomorrow, now you have me wondering, worst part is, I "think":confused he told me when I was making the trans swap.

 

[72Mako]

Hey guys, when I put the engine back in the '74, I will be installing a new Centerforce Dual Friction clutch and pressure plate. Will someone be so kind to tell me the purpose of the adjustable pivot ball in the bellhousing? I have read about them in this forum but never knew how they where used. I bought one just in case. Thanks. Peace Bud :cool

Bud, the adjustable pivot is used when using pressure plates/flywheels that differ from stock heights. The adjustable pivot will allow you to center and achieve the correct clutch fork geometry. You will definately have to use one on a Centerforce DF as I had to when I installed my Centerforce Dual Friction assembly (unless they have changed something in the last year or so). I later pitched my Centerforce DF after a year but that is another story. GM also at one time offered 3 different fixed height pivot balls. You currently can only get 2 fixed heights now from GM. Charles

 

[GTR1999]

You will need the adjustable ball as the others said.The CF clutches are different geometery then a stock clutch. If you use the stock ball and settings you'll find you have little adjustment and not much pedal when you're done. This really sucks when you think you done and then have to pull the tranny out again. Somewhere I have a note on what the dimension has to be for the adjustable ball stud. You have to secure it too,some have used JB weld others weld the 2 pieces together. Try call CF maybe they now have a better solution. Like many aftermarket HP parts most times they don't work just right on a vette. I have brand new in the box CF clutch sitting on the shelf for this very reason. The last clutch I used was a Hays HP clutch without any installation problems and the use of stock parts.

 

[rgtrough]

Many Thanks

Hey guys, thanks for the response. I had remembered reading when Flared69 installed his hyd. clutch he had to pull his engine back out to install a adjustable pivot ball.

Rowdy, I bought the Center Force because I have heard nothing but high praise about them. My current disc has only 7000 miles on it and it has glazed. I don't know the manufacturer.

Mako72, They must not have changed anything because the adj. pivot pops up as an additional needed part when I ordered the Centerforce.

Coupeman, the previous owner didn't use an adj. pivot. This explains why I had no pedal and couldn't dial in the clutch at all.

The next question: Where does it go? I thought I saw it installed in the rear of the bellhousing on Flared 69s' pictures. Then I don't understand how this would affect the height of something. I has to be internal for him to pull his engine back out. I guess I should email him or call Center Force.

Also, If you weld it in place is it then no longer adjustable?

As always, thanks for being here for guys like me. peace Bud :cool

 

[Jack]

The next question: Where does it go? I thought I saw it installed in the rear of the bellhousing on Flared 69s' pictures. Then I don't understand how this would affect the height of something. I has to be internal for him to pull his engine back out. I guess I should email him or call Center Force.

Also, If you weld it in place is it then no longer adjustable?

As always, thanks for being here for guys like me. peace Bud :cool

Think of the adjustable pivot as a "FULCRUM" ... and the clutch arm as a "LEVER". To unclamp the clutch you pull (or push) on one end of the arm (lever) and the arm pivots on the ball (fulcrum) and the other end of the arm (lever) pushes the throwout bearing into the pressure plate ... releasing pressure. If you change the clutch height (say when there's a thicker or thinner clutch-pak) ... the geometry changes (as someone said before) ... you might need to raise (or lower) the fulcrum so that the geometry is corrected. It screws into the bellhousing and has a jam nut ... it is located on driver side ... on the inside of the face that mates to trans ... and it points toward front. No, I don't think you'd wanna weld it. It replaces an existing Non-adjustable one.

If I recall, that was 69MyWay (Chris M.) who was setting clutch in his black big block 69 ragtop w/flares. And that at one point he used a hydraulic release bearing that is a combination hydraulic unit and throwout bearing built into one unit (racing type). Envision a short, stubby hydraulic jack that has a big hole drilled longitudinally through the ram's center so that it can slide over the tran input shaft. In that case you do not need a pivot (fulcrum) at all because there's no lever (arm) ... the lever & fulcrum (& their friction) are eliminated. There are other types of hydraulic releases that are more familiar ... like on most vehicles having hydraulic clutch... they're simply a stand-alone ram that connects to outboard end of clutch arm (lever). I seem to recall Chris had trouble setting the race-type throwout unit and also used a conventional clutch arm and that his clutch-pak required use of an adjustable height pivot.
JACK:gap

 

[rponfick]

If you have access to a library, or clip articles out of magazines, try to find the Sept. 1997 copy of Hot Rod. They had an excellent article on the subject you are addressing.

 

[rgtrough]

New Info

Hey Jack, again you come bearing great insight. Of course you're right, it was 69MyWays' post where I first read of the adjustable pivot ball. Since this morning I have been able to speak to a tech at CenterForce. He told me it wasn't required on my transmission unless the bellhousing or flywheel were aftermarket units that would require it. They are both original.

Your explanation was exactly what I needed. Simple, to the point. The clutch fork evidently needs to rest in the center of its' opening in the bellhousing. Like I said earlier I never could get the proper pedal and very limited clutch adjustment.

Now the decision either to install and adjust or go as is. There is no black and white. Just great areas of gray. peace Bud