Hyd throwout bearing ... and clutch pedal effort, in general

[jocko]

Anyone out there using a hyd throwout bearing like the ones offered with Tremecs or factory stuff? (only asking about the hyd throwout bearing - not a hyd slave unit like on a 62 chev truck, for instance).

I've heard some nightmare stories about challenges bleeding them, etc.

I guess my goal is reduced clutch pedal effort as I swap over to a 5-speed from my 3 on the tree, and I realize there are many ways to go about doing that (hyd throwout, hyd slave assist, clutch/pressure plate choice, etc). Off the top of my head, I don't really think a hyd throwout bearing is really worth the extra $$ and effort, especially if it's prone to minor bleeding problems, etc.

Does a hyd slave assist (to a manual actuation of the normal throwout bearing) help in reducing pedal effort? I was never really sure why chevy did away with it in 63 (or 64, or whenever it was). Probably in favor of mechanical simplicity - which tells me maybe they had problems with it, but I really don't know. I have considered adding it back in using a 62 master+slave cylinder (this crazy idear part of a plan to mount kugel 90 deg stuff under dash for disk brakes and keep a dummy old school single master cylinder in the eng compartment... it's a recurring dream I have, sorry). But just not sure it'd be worth it.

Finally - I see several clutch/pressure plate combos "advertise" reduced pedal effort. That'd be my preferred route, but to be honest, I'm not sure which type offers the best or most clutch pedal effort reduction bang for the buck.

Interested in you thoughts on those 3 things (regarding pedal effort reduction):
- hyd throwout bearing
- hyd slave assist (like originally came in a 62, for instance)
- clutch disk/pressure plate combo that provides a noticeable reduced pedal effort

Thanks gents!
jocko

(now back to Da Bears!....)

OH YEAH - while on the subj (kinda) wanted to ask about flywheels. Stock Steel vs Alum vs Billet Steel (advantages/disadvantages). My motor will be well south of 400 hp (probably south of 300 if I'm honest with myself!) so I really just plan on a stock steel one, but was always curious about the differences and why you'd want one over another, etc) Thanks.

[markeb01]

I had a factory hydraulic throwout bearing on our 1986 S10. When it failed, it wiped out the clutch and cost $750.00 in repairs (I was going through a divorce at the time and didn’t have any place to work on it myself). That experience deterred me from wanting hydraulic fluid inside the bellhousing when I put the 4 speed in my 60.

Since a hydraulic clutch is normally designed with a one-to-one ratio between the master and slave cylinder (both being the same size), theoretically the only reduction in pedal effort should come from the elimination of friction in the mechanical linkage. However when I was researching what to do on mine, I met a guy with a 33 Dodge sedan with a hydraulic throwout and he offered to let me operate his clutch, which I could easily cycle with hand pressure. So perhaps there are other dynamics in play.

I decided to go with a Novak slave cylinder designed for a Chevy V8/Jeep conversion combined with a Wilwood master cylinder. After a bad experience with the Master Power Brake clutch master cylinder setup, I designed my own firewall reinforcement plate and mounted the master cylinder directly in front of the factory pushrod lever. Installing the clutch master cylinder at the same height on the firewall as the original master cylinder, maintains the correct pedal ratio and piston travel. The Master Power Brake bracket mounts the cylinder too low, requiring some type of Z shaped link to connect it at the factory height on the clutch pedal, or the pedal ratio will be off and/or risk blowing out the master cylinder from bottoming out.

Here’s what my setup looks like:





Quite by accident I used a ¾” master cylinder connected to a 7/8” slave cylinder. This decreases pedal pressure at the expense of travel, in effect providing a “power” clutch. This arrangement releases completely, so I’ve never bothered to correct it. If I were to change the slave cylinder to ¾”, I could lower the pedal closer to the floor for convenience, but this would also increase pedal pressure. Since it works perfectly I’m leaving it as is as I prefer the easier clutch operation.

For the slave cylinder I purchased a Novak kit designed to install a Chevy V8 in a Jeep:

http://www.novak-adapt.com/catalog/kit_hcrc.htm

It’s relatively expensive, but works perfectly and is easily adjustable.

The Wilwood master cylinder can be seen here:

http://www.summitracing.com/parts/WIL-260-1304/

For a clutch set I chose the Centerforce 1 to keep the pedal pressure low, while retaining excellent clamping force. Unfortunately the pressure plate suffers from “weight rattle” during shifting, and I would not recommend this product for a street driven vehicle. I find the rattle very annoying.

[jocko]

thanks very much markeb01, great info. you brought up another one of my pet peeves with my current setup - pedal height (i forgot to mention that). pretty much feels like I'm kneeing myself in the chest everytime I shift (ok, not quite, but the the clutch pedal is noticeably higher than the brake pedal).

So, sounds like you came up with a great way to reduce pedal effort but that it increased pedal height in the process. Hmm, that's a tough tradeoff (for me).

I'm in the situation where I would be ADDing the slave cyl/master cyl combo from scratch since my 66 is purely mechanical. maybe my best bet is getting a clutch/pressure plate combo that gives me the lowest pressure with the purely mech setup and call it a day.....

I almost purchased a 62 short fleet (well, actually I DID purchase it, but long story short, it never made it to my driveway....) so I was seriously looking at the Novak stuff for the purpose of upgrading my factory dual cylinder to a power disk brake setup. Anyway, that fell through - so now am wondering if it might be a worthwhile effort to ADD in the hydraulics into the clutch system. Thanks again, great gouge!