Mitsubishi Eclipse GSX 1G Clutch Fork Pivot Ball Shimming Without Removing Trans Axle

After trying to bleed the clutch on my 1994 1g Eclipse in every way possible to man, I am forced to look elsewhere for the cure. If you search the forums it seems like bleeding the clutch is a big problem for DSM cars. I believe the problem is in the pivot ball for the clutch fork, not in bleeding the clutch. If the pivot ball and clutch fork are not in the correct location, the slave cylinder will push the clutch fork until it binds on the trans axle housing. When the fork binds, the clutch stops disengaging.You might also have any or all of these symptoms as well:

• Clutch doesn't seem to fully disengage
• Hard to shift into gears, especially 5th and reverse
• Clutch drags at higher rpm

Aftermarket performance clutches with their higher pressure ratings typically enhance whatever problem you might be fighting. So why look at the pivot ball for the cure? The distance from the clutch fork to the flywheel changes over time due to wear on the clutch friction surface, a new disk being thicker than from the factory, flywheel step height during resurfacing, bent clutch fork, and even brand new parts like the lightened flywheel I installed in my GSX can be out of factory designed specifications.

If you run the stock clutch setup, you might not ever have a problem with this. If you have the performance pressure plate you are asking the entire system to perform outside of the design limits. Don't rule out the possibility of pedal bushings, as that is common for DSM cars, or even a bad slave or clutch master cylinder.

In my DSM I went with a 2600lb pressure plate, Spring less hub friction plate, and a new lightened flywheel. Dropped it all back into the GSX and bled the clutch. I had what seemed to be good clutch disengagement, but that was when it was still in the garage. The road test proved it was not quite right.

First thought is there has to be air in the line. I begin the bleeding process by emptying the clutch reservoir, making sure the entire master cylinder is nice and clean. Spotless clean, no grit or debris whatsoever. (I had about a half inch of sludge in the bottom of my reservoir to remove so be sure to check yours as well)

I then pushed one full LARGE dot 3 fluid container through the line (hoping that would leave no chance for air to be left behind) from the master down to the slave cylinder and tried every recommended method of bleeding the clutch I could find. Pump 3 times, don't pump just put pedal on floor, push the slave cylinder to get any air out at the end of the line, Etc., Etc., I really did try it all. The result was no change, not one bit, and I still could not get into 5th or reverse because the clutch was not disengaging.

I head to the DSM Tuners forum, watch countless Youtube videos for possible cures, read everything I could find from the real mitsubishi performance trans building professionals, and all the way to the END of the ENTIRE World Wide WEB to find that with the heavier pressure plates it's common to have problems disengaging, mostly due to the following reasons:

• Check your pedal assembly bushings, make sure they are not oblong. It can be difficult to tell when the pedal assembly is still in the car, so its best to just remove the pedals and fit them with the upgrade. Search the forums for all the info you will ever need on the subject.
• Replace the clutch fluid with new, making sure MC and slave cylinders are clean on the inside, and bleed the brakes. I bought a Mighty Vac tool to pull the fluid through the system with good results.
• Improperly stepped flywheel. The distance from the flywheel surface to the pressure plate mounting surface is key. Cut to the wrong numbers your clutchg won't work. Be sure to check this dimension before installing your flywheel.
• Bent clutch fork. If upgrading from a stock clutch I can't imagine the fork being bent, but strange things do happen.
• Pivot ball shimming. This moves the pivot point of the fork to keep it in the same relative location to the pressure plate as it was from the factory. If this is not located correctly, the slave will only be able to provide partial clutch disengagement before the clutch fork comes in contact with the trans axle housing. The worst part of this repair method is having to remove the trans axle just to fix the problem.

To find where your problem area lies start by eliminating the easy fixes first before looking at the worst case scenario. My pivot ball location was incorrect, and that typically meant removing the trans axle completely, shimming the pivot ball,and replacing the trans axle.

The shift fork needs to be in the center of the rectangular opening of the transmission, or even a little toward the right (drivers) side. Why? When the slave cylinder is under pressure it needs to be able to provide the fullest stroke possible, which disengages the clutch. If its too far toward the left (passenger side) there isn't enough room in that distance to disengage the clutch. The fork will bind on the trans axle housing.

The pivot ball was originally set up for an all stock configuration. Uncut flywheel, stock disk, and pressure plate. When a flywheel is machined, the new surface is CLOSER to the engine, meaning the length of the pivot ball is now too short. The relative location of all components determines the length of the shim.

There is no way I was up to removing the trans axle just to shim the pivot ball, but that shim was the only thing keeping me from having a clutch that worked. Got to be an easy fix, right?

Shim the pivot ball, of course.

Start with a 14mm wrench and some patience. You might need to remove the rubber cover to get at the pivot ball. Working through the clutch fork window, back the pivot ball out until the clutch fork is somewhat close to the center of the opening. Looking at the thread side of the pivot ball, you should see the rough thickness needed for your shim.

I cut a slot out of a normal washer to allow it to slide between the pivot ball and the trans axle housing. Getting it into that location took some time. I used bailing wire, tape and a little piece of gum just to hold that shim in place just long enough so I could tighten the 14mm pivot ball. If you drop the shim while trying to place it on the threaded side of the pivot ball use a magnet to recover it. DO NOT leave it there.

 Be sure not to go too thick on the washer because too much travel can destroy MC, slave cylinder, pressure plate, or clutch disk. Extreme cases might even see damaged trans axle housings.

 You will want to make sure the clutch fork is right in the middle of the opening, if not a little toward the drivers side. Grab a friend to step on the clutch pedal and be sure the clutch fork is not coming in contact with the transmission housing. You are looking at the left side of the clutch fork and the rounded part of the transaxle just inside the window, If they touch, you will need a smaller washer behind the pivot ball. Thats all and good luck!