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2G Shimming pivot ball and clutch wear

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jpmxrider489

10+ Year Contributor
2,410
146
Apr 4, 2010
pittsburgh, Pennsylvania
I had replaced my clutch a year or so ago and only driven the car roughly 5000 miles. The flywheel is a act streetlite, clutch is a act 2600 with a street disk. I have only been to the track once since this clutch install. I did purchase these items used but with extremely low miles (guy gave me receipt of purchase). I did have my flywheel machined to the correct step height. I purchased a new oem throw out bearing and pivot ball. I didn't replace the fork but it didn't look worn. I believe I read somewhere that if I rev the engine with the clutch in, and if the car moves then I should of shimmed the pivot ball? My car does move when revving high, above my launch limit. Now based on these pictures, is this unusual wear of the flywheel, clutch, and disk? Should I shim the pivot ball now? Also this is on a 20g at 25psi on e85.

I blew my motor and in the process of reinstalling the new one. Motor is currently out.
 

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In my opinion, you should shim the pivot ball if that happens... ONLY if you are certain your hydraulics are 100% perfect, your step height is correct, and you don't have surface flatness issues (which you might?).

From the pics it looks like the flywheel isn't mating too well with the disk. The heat marks are all on the outer half of the surface. Again, just based on the pics. If you look at the PP the marks cover the entire surface, so it looks like the disk mates well with the PP.

You said you had the flywheel step machined before install? Did they cut her flat? If you are 100% sure they did (you measured yourself), maybe the issue is on the flywheel side of the disk. Examine them closely. Hopefully someone smart will chime in. But if you run more power thru it you may run out of clamping load earlier than what that clutch package is intended to.

Maybe take the best possible pics you can of the disk (both sides, with good lighting) and upload them. I couldn't see much from your current pic tbh.
 
Depends on how much they took off, you might need to shim the crankshaft side to bring it back towards the transmission.
 
My act2100 did that . Shifted perfect for about 3k miles and some of the pressure plate fingers broke off and car wouldn't shift at all.

Installed a exedy sport disc got about 15k out of it and then wouldn't disengage.installed new hydro no improvement . I cut half the closed end of a 14mm wrench off and moved the pivot ball out about 3 turns shifted great again.

I think everyone should just put a washer behind the pivotball and be done with it and just adjust the master for less movement to get the adjustment right just my opinion though. Way better than taking the car apart again.
 
Shimming the pivot ball depends on your clutch fork position. If you're looking at the fork from the front of the trans and the part the slave pushes on is further to the passenger side of the car than the center of the window then you need to shim. This is with the clutch installed and trans bolted to the block. Here's a pic I found on here that shows what I mean.
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Clutch drag can also be caused by an improperly adjusted clutch master. Here's a great video from Jack's on how to adjust.
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I remember watching those videos. I will get better pics for you guys later today. I would like to avoid having to take this out again. I am sure that the master was correct and the hydraulics were fine. I was very thorough with that process. The picture with the fork, I am unsure where mine was at compared to the picture. I just remember revving the engine and the car moved. I think I remember the fork hitting the bell housing as well. After that I remember thinking that I should of shimmied the ball or got a new fork.

Is there a certain size washer to use to shim the ball?

Is the unusual wear related to the ball not being shimmed?
 
Here are some updated pics. I am curious if the odd wear is directly related to the pivot ball. If the car moved when redline rev, how would that affect the clutch when doing redline pulls? So is shimming the ball a direct fix for this issue?I didnt get a picture of the fork or the ball. As I said, when I originally did my clutch, I didnt think the fork looked worn to wear it needed replaced. I did replace the ball since they are cheap. I dont have a picture of the fork sticking out of the boot. Not sure if I said already but the fork did hit the bellhousing. Anyway, here are some better pics, let me know what you think. Im hoping someone that has first hand experience with this could chime in.
 

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If you had the flywheel resurfaced it is almost positively guaranteed you will need to shim the pivot ball. The shim thickness needed is equal to the amount removed from a new flywheel thickness when resurfaced. The fork hitting the bell housing further verifies the need for pivot ball shimming. The TRE webpage link I posted above explains this further. Also you should check the resurfacing for flatness because of the wear pattern in your pictures as @rabenne noted. Simple way is to do it similar to checking the head & block for flatness, straight edge & feeler gauges.
When I measured my new ACT flywheel the thickness from the back side of the crankshaft mounting face to the friction face was 1.000367" and parallel less than .0003". The shim thickness you need will be difference between your measurement & 1.000". This picture shows how I measure my flywheels.
 

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Hahaha nice. What kind of CMM is that?

That is a good point about a resurfaced flywheel and position relative to the pivot ball. I still encourage anyone to make sure everything else is correct before shimming it. But if it is all correct, and a shim brings you back into range then do it!

Man you have me thinking about the value of the metrology lab at work to my car projects... so far the machine shop has been pretty damn handy tho!
 
@rabenne. We have 2. The one in the picture is an older IMS Impact II good to about .0003 (+/-.00015) when used properly. Other is a Zeiss Contura II which is more accurate.
 
I do not have any tools that precise. I could grab some feeler gauges and do what you mentioned. I could put the tranny on the engine with the hoist. Then check my fork position after using a washer to shim it. And if it is in the correct position, then were good to go? However, my question is the pivot ball directly related to my uneven wear?
 
No. Pivot ball & wear pattern are two separate issues, not related. Calipers would be accurate enough for the flywheel measurement & shim thickness if done properly.
 
I have harbor freight calipers but the measure up to .00 I believe. I had the machinist prove that it was within spec. Could it need resurfaced again? This is kind of frustrating.
 
I ended up shimming the pivot ball and deleting the accumulator. But my question is, since I shimmed the pivot ball, does the rod on the pedal assembly need readjusted?
Reason I ask is because the pedal feels different. Feels like it needs more travel but I have never felt the clutch with the accumulator deleted before.
 
Yes. You've altered the geometry of levers/flucrum of the clutch system. The adjustment should be the last step with any clutch work.
 
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