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MG MGB Technical - 4 synchro gearbox parts

I was considering upgrading the original (but rebuilt) 3 synchro non-od gearbox in my 65 to at least a 4 synchro non-od. However, I see that Moss no longer carries synchro rings for the 4 synchro gearboxes. I know these are strong gearboxes but nothing lasts forever, especially the 2nd gear synchro.

So, does this mean the 4 synchro swap is a short term fix? Once your syncros fail you're out of luck unless you can find some NOS parts. There are some used sychros on e-bay for the later gearboxes but that has to be gamble.

Strange, you can still get brass synchros for the 3-synchro units. Obviously the brass 2nd gear syncro on these units has a limited life. Steel synchros and matching 2nd gears have been N/A for some time.

A five speed conversion would be nice but we're talking $$$.
Robert McCoy

Robert-
I'd recommend contacting John Esposito at Quantum Mechanics. Click on this: http://www.quantumechanics.com/

Phone 203-463-8299
Fax 203-828-6039
Email john@quantumechanics.com




Stephen Strange

The 4 synchro transmissions are quite plentiful and replacing one of them, with another complete unit, is cheaper and easier than tearing a faulty unit apart and repairing it. I've been running one in my '67, which originally came with the 3 synchro box, for over 25 years with no problems whatsoever. I wouldn't be overly concerned with sourcing new parts for the trans. RAY
rjm RAY

You will, most likely, have to change out the rear engine backing plate, flywheel and starter to go along with the four speed gearbox. Mowog kept moving the starter slightly and the components do not interchange easily.

Rob
r starnes

If you need 4 speed syncros I do have two. These are used but are exactly as new..
Sandy
esane AT MSN dot com
S Sanders

moss UK still lists baulk rings for the 4-synchro trans, but only the 1-2 part number, which they sub for the 3-4 part - Barrie's Notes says these 3-4 rings are actually different, but others say they can be interchanged

Larry Moeller

This thread was discussed between 08/02/2011 and 10/03/2011

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