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MG MGB Technical - overdrive

alright there need a new overdrive for my 74B been looking on ebay but not sure if all the overdrives are universal or do they differ from year to year also does anyone have a good one in the uk they are willing to part with .......cheers Roy
Roy Constantine

the rubber bumper one has a diff speedo drive cog in it so speedo will be out
from what i remember the easy way to tell between is chrome handle cars had filler in the top and the rubber bumper ones had it on the right side
the ratios are the same on both axles
ther is chasemg 01543671184 in lichfield hes quite reasonable
if not stoneleigh or the club mag
try pbw 01215543000 dont know if still going but in birmingham
ste brown

Roy. I suggest you contact Chris Betson of Octarine Services. Chris has been a long time member of this group, has provided me with several parts over the years, and has provided some great advice to all of us. Several people, members of this group, have employed his services on engine or transmission (including overdrive) rebuilds and all have reported good quality work. There are, probably, others who are capable of providing equally good parts and service. However, to me, the fact that Chris takes the time to visit here, offer up his expertise free of charge, and is always available for personal questions, is a deciding factor in whom I will spend my money with. At the very least, it is worth contacting Chris to see what he can do for you. My impression is that he concentrates on quality service and I am willing to pay for such.

Les
Les Bengtson

The OD was the same from late 1967 to the end of production i.e. all 4-synchro boxes - the LH-type - even though the *gearbox* filler moved from top (chrome *bumper*) to the side (rubber bumper).

There are also OD repairers around, one in Coventry I am aware of although I have had his card for a while - David Twigger 02476 543686 ODSPARES@aol.com.

Anything bought on eBay especially 2nd hand or reconditioned is definitely "buyer beware".
Paul Hunt 2

The basic OD unit is the same for the all synchro cars, however the speedo calibration - turns per mile (tpm) did change. The change occured with the advent of the rubber bumper. Check the archives under "tpm" - there is a wealth of information there.

Tom
Tom Sotomayor

For the difference the early solenoid plate is black, late blue.
regards
michel

If it is not the box, but just the OD you want to change then I'd either go to Chris at Octarine (http://www.octarine-services.co.uk/) or to Sheffield Overdrive Repairs (http://www.overdrive-repairs.co.uk/). Most mg specialists will sell you a reconned box with OD for the same price, which I suspect will have had little or nothing done to the OD part.

Iain

PS Are you sure it is that the OD has gone completely? Have a look at http://www.mgcars.org.uk/cgi-bin/gen5?runprog=mgoc&p=emg/overdr~1.htm which has a helpful fault diagnosise section
I D Cameron

Ouch - my ears are burning!

While it is true that the basic LH OD unit will fit all the 4 synch boxes, there were several changes over the years to the internals.

The cheapest option may well be to have your own unit rebuilt if the only thing that has gone wrong is the thrust washer or sunwheel circlip - even a reline of the cone clutch will work out cheaper than a fully rebuilt unit.

I do sell serviced OD units, assembled from good used parts with new seals & gaskets.

If you like to contact me my e-mail we can discuss the best course of action for you.

More details of the symptoms of your ailing unit would also be helpful!
Chris at Octarine Services

This thread was discussed between 23/01/2006 and 24/01/2006

MG MGB Technical index

This thread is from the archive. The Live MG MGB Technical BBS is active now.