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MG MGA - MGB clutch conversion

After a clutch friction disk failure this past fall, I am finally in the process of converting to an MGB clutch. I have the MGB front gear box cover and MGB pressure plate. I have both MGA and MGB clutch withdrawal levers. Since Moss has the MGA throwout bearings on backorder, I am wondering if I can use the MGB clutch withdrawal lever and associated throwout bearing?

Presumably the lever on the left is an MGA variant since it is the one that came out of the Mistress. The one on the right seems to be an MGB lever since the Moss MGB throwout bearing (190-300) fits. The distance between the slave cylinder pin hole and the pivot point is slightly different. The distance between the pivot point and the throwout bearing is greater on the MGB lever.



John Backman

Bear in mind that the MGB had two different levers, for 3-synchro and 4-synchro.
Dave O'Neill 2

The critical measurement surely has to be what I have indicated in the photo with the yellow line. otherwise the thrust bearing will not engage centrally with the pressure plate, resulting in juddering.

My photo is the Ford Type-9 bell housing adaption, but the principle is the same.

Steve


Steve Gyles

I put a MGB clutch and MGB flywheel on a MGA engine/transmission in my MGA a number of years ago. It is a good conversion and has worked well. Read Barney's site about the switch.

https://mgaguru.com/mgtech/clutch/ct_102.htm
Bill Haglan

Thanks for the suggestions. I have dry fit the pieces and it appears that everything lines up correctly. The top image is with the MGB front plate and throwout arm. The bottom picture is the MGA set-up before disassembly. Yes, that is a roller bearing. It may have been part of the cause of the friction disk failure.

Thankfully Barney's web site always has great information. I was lucky enough to have him drop by for a short visit this past May. He diagnosed the problem at first glance.


John Backman

You need to use the MGB release fork and transmission front cover, and you also need to check clearance for the wider but lower pressure plate in the MGA bellhousing - some grinding is often necessary.

Id offer up the trans to the engine out of the car and tighten the bolts, then try and rotate the engine - many will jam as the MGB pressure plate fouls. If it does, loosen the bolts just enough to free up the engine/trans and rotate a couple of times then remove the trans and get in the bellhousing with a grinder to relieve the high spots.
Bill Spohn

I endorse Bill's comments about the need to attack the bell housing to grind away at the points where the pressure plate contacts the bell housing. On the five speed bell housings Peter Gamble made a small change to the A kits for this reason

Dominic Clancy

This thread was discussed between 26/08/2019 and 02/09/2019

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