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MG MGB GT V8 Factory Originals Technical - V8 Clutch problems
My 215 V8 with MGB od Transmission is shredding clutches. No boy racer antics, just spirited driving. The clutch failed two weeks ago, and on disassembly the friction ring had broken away from the central spline and spring area. I purchased new pressure plate and clutch plate and installed them, but depressing the clutch will not enable me to select a gear. The system has been bled and the only two items changed were the pressure plate and clutch plate. I don't really want to take out the engine and transmission again. I am at a loss for what it could be. Help, please?
|I'm not an expert by any means however assuming the plates were installed correctly and there is no air left in the system then maybe your new pressure plate has a greater travel than the old?. If the clutch pedal requires less force that before then this is likely. If you can get hold of a slave cylinder with a smaller inside diameter that might be the easiest way (but not the cheapest I guess).|
I don't know what your clutch set up looks like but if you can get at the slave cylinder end of the folk and move it (an easy way is to use a spanish windlas with a peice of strong chord tied to something sturdy further back)you can see if the clutch is capable of disenguaging, then you will know for certain that the plates are OK and that it is either the master or the slave.
In case you don't know a spanish windlass is a length of chord and a study stick (or something) in the middle that you wind up like a rubber band aeoplane. It can exert alot of force and unwind violently if you don't take care, be warned.
The configuration that you describe is, of course, the original Costello configuration.
David Vale, of the UK V8 Conversion Company, is very helpful regarding advice to anybody with a MGV8 problem. You can contact him on
It is possible that you are still using the original MGB clutch slave cylinder. David assured me that the V8 slave cylinder was essential for its longer throw length. Peter from Melbourne may well be right in his advice above.
|When I originally started on this project, I bought the pieces from David vale of the V8 Conversion Company. I do have the adapter plate, crank bush, and I do believe the slave cylinder as well. What is the part # for the MGB GT V* slave cylinder. Are they still available? Rebuilt the slave cylinder today and still nothing. I am at a loss.|
|How true it is I don't know but I read in this site some time ago that the Slave of the V8 is the same as the midget, one inch. I believe that the MGB V8 also used a different master, and with this has 17.5mm of movement at the slave. If you have a std MGB master slave set up you will be getting one half inch travel at the slave (which obviously isn't enough). If you actually have an MGB master and use a one inch slave you will get close to 20mm of travel at the slave , if you search the archives there is a detailed discusion on master/slave combinations.|
I would be inclined to actually measure exactly how much movement of the folk it takes to disenguage the clutch (G clamp, turnbuckle or spanish windlas, whatever you can think of). It should not take very long and then you will know what you need do.
For future archive searchers a std MGB master with a one and one sixteenth slave (an early Holden unit for the Australians) gets you almost exactly 17.5mm of travel
One and one eighth get you 15.5mm which isn't quite enough (does anyone want to buy a one and one eighth slave by the way?)
|1/2" or 5/8" travel at the slave shouldn't make that much difference. If David is getting that maybe the driven plate is in the wrong way round, apparently this can happen on the 4-cylinder at least and the the friction plate fouls the flywheel.|
The bore sizes are as follows:
MGB M/C: 19mm
MGB slave: 32mm
V8 M/C: 17.8mm
V8 slave: 25.4mm
V8 MC was originally BHA 5217 and slave 13H 3654.
Try a slightly longer pushrod.
The UK Ford Anglia used a threaded pushrod with locknut for fine adjustment.
I've heard of extending the rod with a blob of braze - easy to adjust/remove later.
Thank you for your suggestions. They all make sense, and now it seems that I will have to take the engine out to make sure that the clutch plate was installed correctly. I'll let you know how it goes.
This thread was discussed between 05/01/2003 and 06/01/2003
This thread is from the archive. The Live MG MGB GT V8 Factory Originals Technical BBS is active now.