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MG MGA - MGA Transmission with D-Type OD

I have been considering installing a 3-sync D-Type OD transmission in my MGA. After reading the excellent article on Barney's site...

http://mgaguru.com/mgtech/gearbox/gt304.htm

I'm a bit turned off by the various problems he has noted. So I'm wondering if anyone has successfully mated a D-Type OD unit to an MGA transmission instead of using the MGB transmission?

The car (1958 MGA) now has a 3-main 1800 (1963) MGB engine installed with the stock MGA transmission.
Steve Simmons

Steve, use the Serria 5 speed and no modification are needed to the tunnel and it just drops in. More than happy to let you drive mine to see how it handles.
JEFF BECKER

Steve
A friend modified the D type 3 syncro for me to suite my 5 brg 1800 in a MGA. He has done many over the years. I wanted to keep my "A" relatively standard!!!I was shocked at the amount of work it took, the amount that had to be modified and the eventual cost. I still need to modify my drive shaft and the cost is now equivalent to a 5 speed sierra fitted and running - I have changed my mind now - I have bought a Sierra gearbox and fitted it last week - can't wait to drive it now... Anyone want my standby unit?
Dave
David Godwin

While I'm sure the 5-speed is great, I'm not interested in putting one in my car. I prefer the original gearbox which is why I'm looking into the D-Type OD unit to achieve a taller top gear.

It appears that the biggest problems with the D-Type are at the front of the tunnel. Mating the OD module to the MGA housing would eliminate all of these issues. Only the rear of the tunnel would need to be spread slightly to accomodate the wider housing of the OD unit.

But, I need to know if the two pieces will even bolt together!

David, if I could get your OD unit here I would take it!
Steve Simmons

Steve it can be done....$$$$$$$$$$. Start shooting more pictures to make the bucks.
JEFF BECKER

The driveshaft mod is no big deal, or at least it shouldn't be. You can certainly have a driveshaft lengthened at a cost of $2-300, but you can also simply machine up a spacer for the rear of the stock one out of alloy and use longer bolts.

Going from memory, 1 1/8" is the correct number.

The biggest problem in using the OD box is to change the trans mount (yes, you do have to remove the floorboards and tunnel), and the forward location of the shifter - but then you just removed the tunnel and you can reconfigure the top cover of it so that it looks stock, but a bit further forward, and you can heat and bend the shifter in an S shape to bring it back an inch or two to prevent you always barking your knuckles on the heater controls.

A bit of banging and maybe some welding to get clearance where the solenoid lives and away you go.

I've even done it without removing the stock 'ears' on the frame, but the trans sits a tad high that way.
Bill Spohn

But using the MGA transmission, none of that should be necessary except the driveshaft length. So the question remains, can the OD unit be mated to the MGA transmission?
Steve Simmons

Yes, but, .... you have to change the mainshaft to the shorter one used for the OD model, and that part may be hard to find.

Additionally, the single cross bolt style mount for the MGA gearbox is incorporated into the rear housing. You also need the MGB short intermediate housing that goes between the main housing and the OD unit. Then you have effectively converted it to early MGB style, including the MGB type gearbox mount. This leaves you with considerable hacking and welding to do on the MGA frame, especially if you want a removeable cross member so you don't have to tear out the interior to get the gearbox out next time (and there will be a next time)

The only thing different you get out of this conversion is the low starter position if you use the MGA 1500 type front housing.
Barney Gaylord

I do have a complete D-type transmission here, but the front gears are trashed. So I could use the intermediate and rear housings. But it sounds like too much hacking anyway so maybe I'll forget about this project. I don't like the idea of cutting and welding on my frame.
Steve Simmons

Time to think about that 5 speed again, no cutting or welding. It just bolts in. Best of all it runs great and looks original from inside the car.
JEFF BECKER

Nah, I still prefer the vintage unit. Call me a wierdo and I'll probably agree with you, but I like the notchy, quirky old gearboxes. The pure vintage driving experience is a huge part of why I drive these cars.
Steve Simmons

The men in white coats will see you later today.
JEFF BECKER

Is that who those well-dressed men in my driveway are? 8/
Steve Simmons

Since you are in the movie biz, think about "Harvey" or the end in "Arsnic and the Old Lace" and for those of you who don't know these great movies, rent them and have a good laugh and then think about Steve getting lead away.
JEFF BECKER

What, you don't know any giant talking rabbits? ;)
Steve Simmons

Steve S:

If you are seriously thinking about the overdrive conversion, you might want to contact Doug Jackson about his fiberglass transmaission tunnel that is designed to accommodate an OD in an MGA. He is selling out his inventory and there may not be a backup supplier in the future. Using his tunnel is cleaner than bashing and cutting up an original. You maight also get some sound and heat insulation benefits as well.

http://www.mgbmga.com/tech/mga4a.htm

Steve
Steve Brandt

Thanks Steve, I'll keep it in mind. I prefer having the original metalwork in place so I'm not sure I'd go this route. But it's good to know there is an option.
Steve Simmons

Steve, you don't have to hack the frame, and if you do, keep the 'ears' safe so you could theoretically reverse the conversion.

By far the easiest way to do this is to source a 1963-1967 nonsynch MGB trans and rear engine plate. Change the rear engine plate and swap to a diaphragm clutch while you are at it and away you go.
Bill Spohn

I already have the transmision. The plate is a '62-64 to match the engine. Not sure of the difference between that plate and the '65-67 or if they are interchangable.
Steve Simmons

With all the trouble thats involved, why not just go 5 main/4sync/O/D. Thats what I have done,I just about have it completed.MGA frame with all MGB running gear. It seems to me the best way to go. All MG but MGB,with a MGA body.
wc wolcott

The 3-main is already in the car, and I may be odd but I prefer the early gearbox. This engine retains the correct gauges and revs nicely, and the gearbox is lighter and has a more mechanical feel which I like.

http://www.mgnuts.com/mg/mga/dscn1431.jpg
Steve Simmons

I prefer a 3 main engine, and also the early gearbox, which is lighter and with the CR gear set is a really sweet box, although a bit of a pig on the street. However if you fit an OD to the CR gearset and then change the diff to a 4.55 or even 4.88......
Bill Spohn

This thread was discussed between 31/10/2006 and 06/11/2006

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