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Shimming the pivot ball.

Mello

Proven Member
1,327
487
Jul 4, 2003
Albuquerque, New_Mexico
I see, I think; but I guess I'm still a little confused. I can't figure out how shimming the pivot changes the step height to fix the clutch fork's angle through the bell housing hole(?).
 
Last edited by a moderator:

Archer Fabrications

Proven Member
9,976
991
May 9, 2011
Scottsdale, Arizona
Cause when you take off flywheel surface, or have a worn fulcrum ball or clutch fork ( where te slave rod pushes, or where the pivot ball sits), everything moves toward the crank and away from the trans, causing the clutch fork to need to push in farther. Bandaid!!!

You know what shimming is right? You put a washer behind the threads of the fulcrum ball
And screw it in which pushes it out a little farther stopping at how ever thick the washer is.
 

Mello

Proven Member
1,327
487
Jul 4, 2003
Albuquerque, New_Mexico
Okay then. What you mean is I band-aided my new clutch job? Please help so I can undo this. I shimmed my new pivot ball to fix the fork angle? I double & triple check the step height & it was perfect .610" ( not .609 or .611). Every part was new? (New ACT 2600 PP with new SB disc, & new OEM pivot ball, fork, TOB, with a Excedy CM Flywheel). BTW My clutch is working really really good, if this helps. Did it when I rebuilt my tranny. Got a lot of cash in this and don't what the screw it up. Thanks
 

turboglenn

Proven Member
6,378
108
Nov 5, 2007
RIpley, West_Virginia
Okay then. What you mean is I band-aided my new clutch job? Please help so I can undo this. I shimmed my new pivot ball to fix the fork angle? I double & triple check the step height & it was perfect .610" ( not .609 or .611). Every part was new? (New ACT 2600 PP with new SB disc, & new OEM pivot ball, fork, TOB, with a Excedy CM Flywheel). BTW My clutch is working really really good, if this helps. Did it when I rebuilt my tranny. Got a lot of cash in this and don't what the screw it up. Thanks

even with operfect step the facing and lightening done to flywheels can move the surface of not just the frictin area buyt the mounting of the clutch PP and all and it does, a few re-surfacings and it's enough to make the pedal need adjusted if not shimming the ball... I would say that it doen'st take much of a shim. I didn'tuse the thickest washer i could find and in fact there's only one thread with me talking about this that i started in the drivetrain forum when i built my trans back in august... it says in the thread what the exactthickness of the shim was and it's worked perfect.. now tat the clutch is broken in, instead of being 1/2 turn iun from the relief valve not working i'm 2.5 tunrs from it giving more rtoom to adjust in the future..

I will leave it that way or do it again on other 2600 installs, as it wasn't too much where a fresh flywheel and clutch parts wouldn't hav eliked it and it was just enough to give me room before i was out of adjustment to be able to set the pedal and adjust where there's no drag at all

and i'm one who hates to use "nad aid"fixes and although this is one, i feel for some setups it's a lot better to use it than to not and fight the clutch the whole way
 
Last edited:

Archer Fabrications

Proven Member
9,976
991
May 9, 2011
Scottsdale, Arizona
You need a NEW fork AND NEW pivot ball. The shim is a bandaid to fix those worn parts, i rule out your clutch setup cause it's new.

Edit:
This is the first time you said new ball and fork. Odd since you said it was stripped from rust.
 

Mello

Proven Member
1,327
487
Jul 4, 2003
Albuquerque, New_Mexico
Thanks. It works perfect so I'm going to leave things as is. I guess I just feel different. I'm thinking that shimming pivot balls to set everything so I can get the max slave cylinder travel is one of those blue printing trick for our clutch system when doing clutch jobs. Especially so when OEM part are no longer good enough for our mods.
 

Paintballaa5

Proven Member
507
159
Jan 23, 2012
Houston, Texas
Lol if you feel that way why don't you just get an extended slave rod. didn't you say it was touching your bell housing?

I dont see how an extended slave rod would help, since it would still run out of "forkhole." Maybe its just my "up till 7am trying to fix this everyday" mind can't think right.
 

DROPthatCLUTCH

Proven Member
483
1
Feb 21, 2011
Calgary, AB_Canada
I installed a brand new pivot, fork, slave, braided line, master, flywheel, disc, and pp and mine still needed to be shimmed. So for those people saying it's just a band aid; i disagree. Some clutch/flywheel setups just need to be shimmed. Period. I've heard of lots of ppl running southbend/fidanza (my setup) having this problem.
 

MJcanada

Proven Member
3,135
63
Jun 25, 2011
Inman, South_Carolina
If the issue is its touching the bell housing, you have two fixes.

1) adjust the master rod which will push the slave rod out more so it will stop before it touches. With a all new clutch system with factory step height there should be no need to shim.

2) shim the pivot ball. This will push the fork out some, away from the bellhousing. If your close to running out of adjustment, as glenn states this will give you some more.

For whatever reason act 2600 clutches seem to have alot of engagement issues. With them dragging or not being able to get into gear at all even with adjustment. My gf ran an extended slave on her 1g b4 no issues.

With the issue of not enough travel after full adjustment shimming or extended slave rod are your only options. They both are doing the same thing but shimming is more precise fix. These fixes are only for certain circumstances.

Only time you should attempt to do either is after verifying the hydraulic system is working/bled properly and the pedal is fully adjusted but you still have a dragging clutch, cant get in gear, or lets out to close to the floor.

If its shimmed and the clutch works fine and adjustment is correct, then your good. Drive the car.
 

RLSchwabe

Proven Member
115
22
Mar 21, 2014
Colorado Springs, Colorado
I installed a brand new pivot, fork, slave, braided line, master, flywheel, disc, and pp and mine still needed to be shimmed. So for those people saying it's just a band aid; i disagree. Some clutch/flywheel setups just need to be shimmed. Period. I've heard of lots of ppl running southbend/fidanza (my setup) having this problem.

I just wanted to add my experience. I've been having issues in my own set-up. I've played around with the 2G master rod, a custom master cylinder rod ( +5mm ), the OEM 65mm 1G rod etc all with engagement issues after the new parts were installed. Never messed with an extended slave cyl rod. I've been chasing around issues on this set-up for a long while. Ordering a new throwout bearing and clutch fork this week and while the transmission is out reverifying the step-height on the flywheel and likely shimming the pivot ball ( even with all these new parts ) All the clutch stuff came in at the end of 2018, installed all of it and I've been chasing issues ever since. Hopefully, this weekend will be the last of it.

Repaired Trans @ Jack's Transmissions
SS-X Series 2700 Southbend Pressure Plate
B-Series Full Face Ceramic Clutch ( Southbend )
ACT Streelite Flywheel
1G DSM Clutch pedal assembly rebuilt with bronze bushing and welded
Stainless steel braided clutch line
 

diambo4life

Proven Member
1,302
83
Apr 18, 2002
Edmond, Oklahoma
I just wanted to add my experience. I've been having issues in my own set-up. I've played around with the 2G master rod, a custom master cylinder rod ( +5mm ), the OEM 65mm 1G rod etc all with engagement issues after the new parts were installed. Never messed with an extended slave cyl rod. I've been chasing around issues on this set-up for a long while. Ordering a new throwout bearing and clutch fork this week and while the transmission is out reverifying the step-height on the flywheel and likely shimming the pivot ball ( even with all these new parts ) All the clutch stuff came in at the end of 2018, installed all of it and I've been chasing issues ever since. Hopefully, this weekend will be the last of it.

Repaired Trans @ Jack's Transmissions
SS-X Series 2700 Southbend Pressure Plate
B-Series Full Face Ceramic Clutch ( Southbend )
ACT Streelite Flywheel
1G DSM Clutch pedal assembly rebuilt with bronze bushing and welded
Stainless steel braided clutch line
Did you ever get it resolved? I know this is several months down the road but it's good for closure.
 

RLSchwabe

Proven Member
115
22
Mar 21, 2014
Colorado Springs, Colorado
Did you ever get it resolved? I know this is several months down the road but it's good for closure.

Yes, I did resolve it.


1. New clutch + pressure plate (South Bend)
2. Resurfaced ACT flywheel ( .610" )
3. New OEM flywheel bolts and pressure plate bolts
4. New OEM slave + master cylinder
5. New OEM throwout bearing
6. New clutch fork (forged competition) + new OEM pivot ball
7. Removed all shims from the transmission

(Note: 1G DSMs also suffer from an issue with the Z-bar design of the clutch pedal assembly. Prior, I also had some free-play in my clutch due to this. I removed the assembly, rebuilt with new parts and brass bushing and had it welded )
 

dustyboner

DSM Wiseman
1,829
934
Mar 13, 2016
abq, New_Mexico
some aftermarket pressure plates are slightly shorter than stock. if you have one, you will probably need to shim the pivot ball.

here is a quote from talonXracer over at clubrsx:
The washer does NOT gain you any travel over stock, it places the piston BACK WITHIN the slave cylinder enough so that it CAN have full travel. If you do not change the pivot point height when the lower pressure plates are installed, the piston is moved a fair amount out of the slave. The hydraulic system compensate's by adding more fluid in the lines and slave as it is supposed to, but the slave's piston can only travel a limited distance because it is already moved in the slavecylinder the amount needed to compensate for the lower pressure plate.
 

pauleyman

DSM Wiseman
7,176
2,095
Nov 19, 2011
oklahoma city, Oklahoma
some aftermarket pressure plates are slightly shorter than stock. if you have one, you will probably need to shim the pivot ball.

here is a quote from talonXracer over at clubrsx:
Sorry but I will completely disagree here. When you aren't applying the pedal fluid is free to move between master and slave. It is the very design of such that allows auto adjustment as a clutch wears. Only when you apply the pedal and you block off the port in the master do you get hydraulic motion. Adding a shim you do change geometry. The reason it works it because the whole fork pivot system does not translate motion in a straight line. It doesn't take a math genius to figure out the travel of an object along a curve vs how much linear travel that will be.. When the fork is a little towards the driver's side, as we say it should be, the course of its travel in an arc will provide the maximum linear travel at the TOB. Furthermore when you machine the flywheel you physically move the entire clutch system closer to the driver's side while the clutch fork remains in the same position. If you shim you can restore that distance closer to factory new. This is unnecessary, in my opinion, if the step height is correct and the flywheel hasn't been machined too many times.
 

XC92

Proven Member
1,190
216
Jul 22, 2020
Queens, New_York
I didn't fool with most of these measures when I put in a new clutch and had my flywheel resurfaced. I did replace the fork and fulcrum with CC versions but their geometries are the same I believe, and got a new, OEM bearing and clip. I also got a new OEM slave, and intend to rebuild or replace the master this spring when it gets warmer, at which point I'll probably also take out the pedal assembly and see what if anything needs to be done there so there's no future clutch pedal slop.

The only "mod" I did was put in a 1mm washer between the fulcrum and bell housing, to (likely more than) make up for whatever little surface was lost in the flywheel's several past resurfacings, and spread the pressure to a slightly wider surface area. But 1mm's nothing, and shifting has been fine since I did all this. I understand that some people use much thicker washers, which seems like a bad idea, like extended rods and all that.
 

Kryndon

Proven Member
757
415
Jan 10, 2014
Bulgaria, Europe
I shimmed the pivot ball with an OEM 1G head stud washer (I believe 2mm thick?) when I installed a new Competition Stage 2 Clutch kit. I had my flywheel resurfaced, however the machinists f***ed up majorly and took it down to 0.590" even though I explicitly told them 0.608 is the minimum thickness. I did not have access to another flywheel so I rolled with it. Almost 19k miles later (now), the friction plate has worn so much that the fork finally started to noticeably move towards the driver side. As the disc wears, it makes the pressure plate fingers move outward towards the trans, which forces the TOB out, which in turn makes your fork pointed towards the driver side. I can hear the clutch grind when starting off in 1st gear and I'm positive it's the rivets grinding into the flywheel.

Now that I think about it, adding the shim when installing a new clutch on a WORN or out-of-spec flywheel is a GOOD thing. If you understand how the geometry acts within this system, you will see that the shim plays an important role in band-aiding a worn friction plate and/or flywheel. And now, since mine is so worn and fork pointing towards the driver side by a good half inch, if I was to remove the shim and put everything back together, it would center the fork again, but it wont make the grinding noise go away, since after all there is no more friction material. But like I said, there are no AWD 7 bolt flywheels around and no clutch kits either. So I'm gonna drive it till it refuses to go into gear.

TLDR You don't need a shim if all hardware is new. If flywheel and/or friction plate is worn or out of spec, shimming will help restore proper clutch action. A properly adjusted clutch hydraulic system will self-adjust only up to a point and that point is the manufacturer specified minimal clutch disc thickness.

P.S This is why you get an auto and forget about this manual garbage. :thumb:
 
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