MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGB Technical - Overdrive on a non overdrive car.

If I want overdrive on a non overdrive 1966 MGB do I have to change the entire gear box or can I simply buy an overdrive unit and mount it to the 3 syncro gear box that I already have?
I note that the non o/d gearbox lever is 'bent' and I think that the o/d gearbox gear lever is straight. Is this because the two 'boxes are different?
AJ Munro

The rear part of the two cases are different, as is the mainshaft (3rd motion shaft if you prefer), so you can't just bolt an overdrive on.

Hopefully you should be able to find a complete gearbox second hand. otherwise, you would need the extention part of the casing, the shift remote (this is now outside the gearbox) and the new lever, and a new mainshaft onto which you could put your existing gears if all is well.

Hope this helps,
--
Oliver Stephenson
Oliver Stephenson

The driveshaft is also a different length.

Wayne
Wayne Pearson

Thank you Oliver and Wayne,

I feared that might be the case.
I will start to look for a used overdrive gearbox and driveshaft then... I am probably at the end of a long queue...

Thank you both again.

Angus.
AJ Munro

For what it's worth, I installed an overdrive transmission in my '66 MGB and left the bent shift lever because I liked its looks better. The addition of an overdrive totally transforms the car, in my opinion.
Catesby Woodford

AJ, check with George Merryweather at Classic Restorations in (where else?) Lucas, Texas. I don't have his # handy, if someone else doesn't post it I will when I get home. He imports conversion kits from the U.K..
Ken Lessig

Angus. Check with Chris Betson at Octarine Services. Chris posts here from time to time. He also sells overdrives, overdrive conversions and complete overdrive transmissions. You might want to check out his website to see what is available, then check with him to see exactly what he has in stock. Les
Les Bengtson

He'll need the older box wont he? Weren t the tranny tunnels narrower on a 66?
william fox

George Merryweather
Classic Restorations
15 Cimarron Trail
Lucas, TX 75002
888-767-4898, 972-429-6079 local/fax
gmerry1@airmail.net
Mark Smith

I can't tell you how it was done, but I can confirm that you can fit a later-model OD transmission to an early model B.

I've got a circa 1975 OD transmission (it's a side-fill) in my 66B. Works great, runs fine.

I'm in the process of recarpeting, so I've discovered the tranny is fit into the early B tranny tunny with the use of a conversion cover on the tunnel under the gear shift.
Kim de Bourbon

Also check out Doug Jackson's site for detailed info on the conversion, and a photo of the tunnel cover: http://mgbmga.com/tech/mgb1.htm
Kim de Bourbon

Thank you all for an excellent response.

I will be checking out the leads that you have supplied. It is also very encouraging to read that some of you actualy have had gearboxes converted and that they work well.

I am going to proceed with this plan.

Well done Gentlemen, and happy MG motoring to you all.

Angus.
AJ Munro

One comment. To use a later model gearbox on an early 5 main motor, you will also need to change out the engine backing plate, clutch, flywheel and starter. Some minor tweaking of the transmission tunnel is also necessary. This is my recollection from many years ago. We put a '72 gearbox in my brother's '67 B.
Steve Mc

Steve's right. I know I have a later model starter on my 66. (Had to pull it to replace the solenoid, which piggybacks on it. OEM for a 66 had the starter solenoid on the side of the engine compartment.) That may be more work than you bargained for....

And AJ, watch who you're calling a gentleman!
Kim de Bourbon

AJ, if you need a late model sidefill O/D gearbox, I've got one for sale, and I'm here in the Sportsman's Paridise!
gerry masterman

Gerry,

I will contact you by e-mail regarding this but earlier contributers seem to think that it might be a bit of a problem to fit it.

Everbody else... thanks again Gentlemen, and Kim. (Just kidding)
AJ Munro

I planned to install an overdrive transmission in my 73 MGB whilst the engine was out for a rebuild. Since they are hard to come by here I have now splurged for a hi-Gear 5-speed conversion which uses a Ford N series (Sierra) gearbox - the 5th ratio of .82 is the same as the MGB 4th with overdrive. The order wasplaced with the MG Owners Club in Cambridge (my birth city) and the packages were picked up from the Toronto airport using airport transfers tonbridge today. Will feed back my experiences.

Great BBS! Regards, Barry
Barry Quartermaine

This thread was discussed between 18/04/2002 and 22/04/2002

MG MGB Technical index

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