Clutch installation PSA Options

[enderswift]

Hello 6gc,

I've been wanting to put together a post detailing an aspect of clutch replacement that many people miss, which then goes on to cause many seemingly unrelated issues down the road. Here it is:

Common issues:

1. You just installed a new aftermarket clutch from a good company. All proper torque procedures were followed and the flywheel was resurfaced. However upon starting the car you realize you can't shift into any gears. It appears like the clutch isn't disengaging completely when the pedal is fully depressed. No big deal you just adjust your clutch pedal push rod you can then shift no problem.

2. You've spent 500 miles making sure to properly break-in your clutch and are positive everything was done right. But the clutch still has a stiffer-than-expected feel, and the engagement is rough. (In my case my Clutchmasters pressure plate was supposed to feel close to stock, but was actually pretty stiff)

3. A few months after your clutch install your master cylinder fails. Followed by another failer soon after... Then another...

All of the issues described above are caused by one thing: an improperly machined flywheel step



Our celicas REQUIRE a positive step machined into the flywheel. Some clutch manufacturers might specify a different step, so be sure to ask them. Either way, you cannot just drop off a flywheel and hope for the best. If you're lucky, the machine shop actually knows what they're doing and will machine a proper step based on the knowledge that Toyota's typically specify a .020 step. My Shop didn't, they just cut down the friction surface and called it a day.

Here's what happens when your machine shop puts in a .005 step instead of what the clutch manufacturer specified (In my case .020):



I kept destroying master cylinder after master cylinder because I needed to max out the adjustment on my clutch pedal just to be able to shift into gear. This cause the seal on the plunger to rub past the reservoir hole in the cylinder housing:


The reservoir hole can been seen in the photo above,its the equivalent of rubbing the seals against a cheese grater. After a while they will fail and you will be stranded.

A tell-tale sign that this is happening is when you can see tiny black spots at the bottom of the reservoir:



This situation can be avoided if there is a proper step on the flywheel. An added bonus is that you'll get smoother engagement, and better holding power. All together the machine shops' mistake cost me over $1000 after having purchased 3 new master cylinders and a replacement clutch kit (my engagement was so rough that the springs in the disc began to rattle). Keep in mind I NEVER beat on my clutch. No 5k rpm dumps or anything. All I ever did was downshift, rev match, and floor it.

I feel this is a very common occurrence and most people simply don't realize it. People experience the effects of an improperly machined flywheel and go on to blame the clutch manufacturers for their poor engagement, or outright failure. It's amazing how sensitive pressure plates are to a few thousandths of an inch, but they are. And those few thousandths of an inch will impact your driving experience and reliability. So remember 6gc, when you get your flywheel back from machining, check the step!



This post has been edited by enderswift: Jun 16, 2014 - 10:06 AM