Large T/O Bearing - Stiff Clutch?
 

Guys....I have a 10.5" Hays Borg & Beck Street/Strip clutch (2800 lbs) and a 10.5" Street/Strip clutch disc. I'm using a 7/8" Wilwood slave cylinder and a 7/8" Wilwood clutch master cylinder. Also using a Wilwood clutch pedal.

First question...how stiff should this thing be? I bet it's around 70 lbs to push this thing in. It's stiff enough to worry me. I'm only 26....and I wasn't really around in the good ole muscle car days where you had to use both feet to push the clutch in...so I don't know what to expect. But I'm worried that something is wrong.

It fully disengages when I push it in...everything works....and everything is new.

However, this is what bothers me. I ordered the clutch fork/ Lakewood pivot/ T/O bearing from David Kee. He sells nothing but long style pressure plates for Fords...my Hays is a Borg & Beck style. They're both 3 fingered pressure plates...but I think long style plates have shorter fingers right?

What it boils down to is that I'm worried that my T/O bearing is too large of a bearing face diameter...which would cause it to the hit the fingers on the pressure plate in the wrong spot...not giving me enough leverage and therefore a stiff pedal. Does this make sense or am I being anal?

I have a McLeod T/O bearing, part # 16031. It says the bearing face diameter is 2.8".

When I look at Hays' PDF file, the T/O bearing they recommend for their 10.5" Borg & Beck P/P has a bearing face diameter of 2.6". That's .200" difference between them....basically .100" on each side.

Or am I thinking about this all wrong...a larger bearing face would be a large contact area....which doesn't necessarily mean it contacts at the wrong spot....it just contacts across a bigger area...right?

When I test fit everything together, the T/O bearing and P/P seemed to be a great match...

Do I have a valid worry, or am I just inexperienced in the area of high-performance clutches/pressure plates?

Anyone?

I have first hand info on this. When I put mine together originally it had a 3/4 master and a 3/4 slave. I also put in a street strip "Long style" pressure plate from McCloud. It was overkill. In my planning I thought I would need the clamping force of that pressure plate. The combination of 1:1 on the hydraulics and super strong pressure plate really made the pedal extreemly stiff (exactly your concern). I used this combination and used this clutch combo for 8 years but during my recent rebuild I addressed the problem by sending the pressure plate to McCloud after (8 yrs it looked like new after I wiped it down). They replaced 3 of the coil springs (there are 9 that provide the clamping force) with softer ones and most importantly replaced the fingers with some newly designed ones that change the leverage they operate from and therefore reduce pedal effort. I also increased the slave cylinder bore to 7/8". The result was a much reduced pedal effort that makes it much more pleasant to drive. In retrospect the street strip pressure plate is too much in my opinion for the weight of these cars regardless of the horsepower. You reach a point where traction is overcome by torque (due to light weight on rear) and the tires become the weak link not the clutch.
Suggest you play with the ratio of the master & slave first. Contact Hays regarding the T/O bearing concern. All of the diaphram clutches usually have many fingers which are actually part of the springs fingers that contact the face of the T/O. With this type of pressure plate the T/O bearings contact face are usually rounded so the fingers "roll" accross the contact face of the T/O bearing.


I would suggest you alter the bore size of your slave cylinder to a little larger and be sure you have the correct T/O bearing .


Rick

What I'm afraid of if I switch to a smaller master cylinder is the amount of travel that I'll need....I'm afraid I'll run out of travel. I wish I could find a larger slave cylinder, but I haven't run across one yet.