Quote:
Originally Posted by stlwagon  I've noticed considerable clutch fade when hot. May have to look into replacing the line. |
I in no way not know it all, but there are two S197 subjects I feel I am now an expert on...clutches and brakes.
A copy and paste from my website:
"So you installed a new clutch...a few weeks later it failed. You probably are wondering why.
This may hurt. About 99% of the time you can look in the mirror for your answer.
- Did you go cheap? Undersized for the power level of your vehicle.
- Did you "cheat"? Didn't replace the throwout bearing or slave cylinder? Didn't resurface the flywheel?
- Does your pedal operate freely? Is the cable smooth when not attached to the clutch fork?
- Is the fork pivot galled?
- The biggest set back...Did you properly break it in? You are probably asking yourself..."Break it in?"
YES! You have to properly "bed in" a new clutch just like new brakes, a new flat tappet camshaft, or anything else with mechanical parts that rub against each other and have to get to know one another.
When you bed in a clutch you transfer some of the friction material from the disc to the flywheel and pressure plate in a controlled environment. Just like new brakes.
To bed in your new clutch you don't go out into the street and do a 6,000 RPM launch to see if it grabs. If you do that, you have just wasted your Saturday afternoon and those cuts on your knuckles were for nothing.
Start off easy, release the clutch as quickly as possible without "riding" the pedal and get underway quickly. Do not shift with the throttle mashed to the floor. Granny shift...complete throttle off and clutch all the way in.
Boring right? Yup! But if you like pulling transmissions stop reading and go driving. If you want the most life out of your clutch, drive it the way stated above for at least 500 miles before punishing it.
Now, if you did all the above and your clutch still failed, chances are it was poor quality or over rated by the manufacturer for your intended use. There are many types of failures, way to many to list on here. Just do a search for clutch failures on the web and you will find most scenarios with pictures, and probably a trend as to which brands to avoid.
At Blue Collar Performance we have been through enough clutches over the years to be able to spot "junk" after a thorough inspection following a failure. We personally have used 5 different clutch and flywheel combos in the Supercharged 2006 Mustang that competed in the 2008 NMRA Drag Racing Season. These included single disc, multi-disc, puck type, Kevlar and cerametallic.
We had failures in as little as 5 passes and as many as 20. Every time the clutch was properly broken in and a new slave installed. Believe it or not, until we ended up with the current Exedy clutch, the best clutch was the stock unit. Speaking with an independent clutch rebuilder we have determined that it is hard to beat the quality of the stock Ford pressure plate up to 400hp. The disc may get a little torn up, but we never experienced a catastrophic failure like the others prior to the Exedy.
For the majority of manual transmission vehicle owners, if you buy a quality clutch and follow proper break in, you will be fine and never have an issue.
Now, for you 2005+ Mustang owners, you probably have heard about and seen failures in every shape and size. The web is littered with clutch horror stories, adjustable slave cylinders, lots of new theories and clutch voodoo.
Our personal findings and recommendations are the following:
- The proper Exedy clutch for your power level
- New or Resurfaced Flywheel
- New Clutch Slave Cylinder, properly bleed
- A replacement Clutch Fluid Line From Ford Racing: #M-7512-A
A new clutch line? Yes Sir! It has been our finding that the cheesy plastic clutch line from the factory can not handle any abuse or the added pedal pressure from an aftermarket clutch. Especially with long tube headers, turbochargers or any additional under hood heat.
When the plastic line gets hot, and you push on the clutch, the line swells up instead of fully releasing the clutch. That is problem #1.
Next is the trapped fluid in the slave cylinder. There is only about a tablespoon of fluid in the slave cylinder that lives inside the transmission bellhousing. This fluid gets hot very quickly when drag racing. So if you can avoid it, do not hot lap your car. Allow the clutch to cool off. Get a battery operated fan and slide it under the
trans when you pull in from a pass.
What happens to the slave? We discovered that the fluid in the slave cylinder on an S197 Mustang boils and expands. When it expands it partially releases the clutch. Not enough to slip when cruising up to the staging lanes, or even doing your burnout. But when the lights drop and you dump the clutch you hear the terrible sound of the rev limiter and you stop moving forward. You let off the gas and try again. VROOM! You creep forward. Then you try a little throttle and it drives fine?
To late. The damage is done. You can probably now drive your car normally, but when you try to accelerate hard, it slips. 5th gear on the highway, you push down and it slips a little. Time to get under the car and pull the
trans out.
What is the real problem? There is air trapped in the slave now from boiling the fluid. You can try to get it out by following the factory recommended bleed procedure. You may want to take the tools with you to bleed the clutch at the track. After a pass, perform a couple bleed cycles and get back in line. We have found this to cut the problem in =.
The real fix would be a slave cylinder with an accessible bleeder screw so fresh fluid could be flushed through between passes. We have tried to develop such a slave cylinder, but there wasnt enough interest to justify the cost. We had a dedicated reservoir for the clutch fluid, instead of sharing with the brakes, a bleeder line from the clutch slave to the firewall to open the bleeder screw and draw fresh fluid through the slave. A similar idea could be accomplished with the aftermarket adjustable slaves out there. As they have an external bleeder. We have not used any of those, as the effort to properly set the travel seemed senseless without having a way to bleed it between runs.
Lastly, those real high load clutch pressure plates. with all the alleged adding clamping force, the extra effort can force the fluid around the seal in the factory slave cylinder. This will also fail the slave and cause slippage. How was this determined? By careful disassembling and analyzing of failed slave cylinders to see what had happened. We have spent literally thousands of dollars chasing clutch issues in 2008, and have come to a conclusion that suits our needs.
Of course this article is in no way all inclusive, and it is only based on OUR experiences and findings. Like anything else in the automotive world it is subjective. Please don't bombard us with argumentative e-mails. Our intent is to help others, not start internet arguments."
Clutch Adjustment on Manual? 
