Forum for discussion of MG and MGB motorsports, historic and current (SCCA, NASA, VARA, etc) car preparation, engine, bodywork, suspension, drivetrain modification.
Being quite new to the MG thing, i was just thinking about that on an MGB, the clutch throw out bearing (Boy, i'm getting good at this American language) is allowed to contact the clutch thrust face all of the time. has anybody ever tried to use some free-play in the mechanism? The reason why i am asking, is the fact that i have brought and stripped two MGB's one racer and one road car and the bearing has been worn down to the steel and beyond.
Originally they came with a carbon t/o bearing and during street use, they are intended to wear out. For racing use, we use a roller t/o bearing. The pressure plate will push the t/o bearing back far enough so you won't have a problem.
Jesse,
Are you talking about a aftermarket t/o system, or the stock system with a roller bearing
Well, for a stock type clutch you can use a stock type roller t/o bearing. For a racing clutch, we have a different t/o bearing setup. Lots of t/o bearing from the factory were that carbon style which just rubbed on the pressure plate when you depressed the clutch. Built to wear. Believe me, I've also seen some extremely worn out ones including some with nothing left of the assembly at all. Neglect, abuse, typical of lots of MG drivers.
I can't find anybody who sells the roller type t/o bearing, is it fitted to something else do you know?
James,
I believe the roller throw out bearing that was made for the B has been discontinued because... it didn't work very well. Jesse might have a replacement number... I'm sure he has a replacement number for every part on the car!
Most racers are running co-axial hydraulic bearings.
Depending on what transmission you're running, here are some options:
http://www.cambridgemotorsport.com/MGB-MGB-Clutch-And-Transmission
http://www.taylor-race.com/subcat1.cfm?category=Clutch%20Release%20Systems
Steve
Well, for racing applications we have our own modification we do for a roller t/o bearing assembly. For stock applications, the carbon works fine. Keep your eye on ebay for an original type roller if you're using a stock type clutch. Actually, I'd suggest that you forget the stock type clutch for racing and step up to a proper racing clutch.
James, I'm using the competition clutch cover ( the first one ) and the 4-paddle friction plate both the same as on the Cambridge Motorsport site Steve put the link to. I use the standard carbon release bearing and slave cylinder, and have never had a problem. I see on your profile you have got a 1950cc engine (?). Unless you are running a hand-grenade engine, I would suggest that this clutch setup would more than likely do the job for you too. My engine is around the 130 - 140hp mark at the flywheel.
Also depends if you have rolling or standing starts, what tyres you have, and how vicious you are on the clutch. These things will all affect the life of the clutch and release bearing, especially if you slip the clutch a lot to get it off the line because you have a very tall first gear. I have standing starts for all racing, hillclimbs etc, with a 2.7 first gear and 4.11 diff on Toyo R888 205/50/R15 race tyres. Never ever had a rolling start.
For anybody who want to know, roller t/o bearings to fit a stock clutch are avaliable.... I brought one from Helix Autosport (http://www.helix-autosport.com/) in the UK. I also brought one of their F/Road clutch kits with an organic plate.
Part numbers are as follows: (8.5" Clutch)
MGB Race cover : 60-3331
MGB Race ceramic padle plate: 76-2619
MGB F/Road cover: 70-2619
MGB Roller release bearing: 40-3291
They also do a cover that can be used with a hydraulic release bearing but I don't know the part numbers.