Welcome to our resource for MG Car Information.
MG MGB Technical - Adjusting Clutch Bite Point
I have a 72 mgb roadster I am working on.
Supposenly (and I use that word loosely) it had a rebuilt engine and they put in new pressure plate and clutch.
The clutch doesn't bite until about 2/3 the way out.
I read some archives, but really wasn't clear what adjustments are available to adjust the bite point. Seems like the clutch should bite about 1/3 the way out?
Any quick pointers would be appreciated.
Furthermore, is there a simple test to see if the clutch is just mis-adjusted versus needing replacement in the near furture? ie: does it stall itself out if trying to start in 4th gear?
|Hi Doug,As you must know your clutch dis-engaging action is hydraulically controlled and to my knowledge there is no adjustment for pedal travel.Perhaps there is a problem with the throw-out bearing fork. If it is bent ,that could effect pedal travel distance.|
The 4th gear stall test is used to determine if the clutch is slipping.
|Doug, the MG has no adjustment on the clutch so you are stuck with the bite point you find yourself with. However as you rightly say you need to test it to ensure that it has sufficient bite and therefore a reasonable service life. The test is a bit brutal but here it is.|
With the handbrake firmly on select 4th gear and increase revs to approx 2500. Release pedal to biting point and as the revs start to fall increase accellerator thus keeping revs to 2500 as clutch is continuially released. Engine should eventually stall firmly. If you get to the situation where your foot is off the clutch pedal and the engine is still turning the clutch is worn out or near the end of its life.
Strange that the biting point is so far up but if all else is OK perhaps the replacement pressure plate is not the exact match for the car although perfectly suitable. Hope all goes well.
Another thought of course is that the slave cyl has been replaced with one of a smaller diameter. Whilst this will give a much heavier pedal it will disengege earlier. I have a feeling that the V8 cyl is smaller bore and it may be worth a check.On the other hand has it been sleeved for the purpose of lifting the biting point?
|Also, air in the clutch hydraulics can make|
the bite point seem lower. I would try bleeding
the clutch (after checking for leaks and condition
of the clutch hose first.)
I have gotten
good results with the gunson's eezibleed (pressure
bleeder), but check the archives for alternatives
and see what works best for you.
|Doug. It is perfectly possible that everything is fine with your car. With a new or properly rebuilt master cylinder, slave cylinder, pushrods, clutch fork bushing, etc. the release point can be somewhat higher than with an old, worn system. Most of us have systems that are somewhere in between. The pushrods are a little worn, the clevis pins have some wear, the throw out bearing fork bushing has worn, etc. through out the system. Our systems work well, because they are functional, but not the same as when they were new. From what I remember of my new MGB, and from what I have seen from totally rebuilt systems, the release point is somewhat higher than on a more worn system. This is something of a shock because you also get a higher release point as the system wears. The release and pick up near the floor is a sign of a moderately worn, but still fully functional system. |
So, yes, look at the parts to see if they are in good condition and may need replacement. Do as Ronald says and check the lines for air and bleed the hydraulic system again. It will not hurt. But, also be aware that if the parts look good and there seems to be no air in the system, you have a good chance of having that rare problem--the PO did the job correctly and replaced all of the parts instead of just the ones which showed excessive wear. In other words, you might have a superior rebuild and should enjoy it. Rare, but possible. Les
|Thanks Les, et.al,|
Appreciate your time and effort as always to answer my questions.
I will follow-up on your suggestions.
Maybe I'll luck out and not have to spend any $ on the clutch.
|As long as the clutch is off with your foot on the floor and on with your foot off the pedal then don't worry about it!|
|Chris at Octarine Services|
|One more thing: there must be free play at the top of the pedal. You should be able to depress the pedal a bit with nothing happening (that you can see or feel). If you have no free play then the throwout bearing is resting on the clutch disk arms and in probably spinning all the time. The bearing is designed as an intermediate use bearing and will prematurely fail if it spins all the time. Free play is difficult to feel in a hydraulic system.|
|As standard the B thrust sits against the pressure plate thrust pad all the time with no return spring. The only slack is in the master cylinder push rod so as to ensure that the MC returns all the way and releases any pressure in the hydralic system. The master cylinder MUST have a return spring. You can get an after market SC that uses an adjuster and return spring but the stock system works fine. If your MC return spring is missing it can sometimes give that high pedal feel. Denis|
There is a kit available from Doug Jackson at mgamgb.com. It allows you to set the release point to your personal preference. Ray
|Thank you all very much for the leads and input.|
I will make sure there is some free play, but otherwise I will continue with higher priority items.
I will print out this thread and order kits if I get to that point.
For now, it engages when my foot is off clutch and disengages when I push down to floor :-).
This thread was discussed between 05/10/2004 and 06/10/2004
MG MGB Technical index
This thread is from the archive. The Live MG MGB Technical BBS is active now.