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 - Non OD 3 sycro to 4 sycro OD conversion

I just picked up a 4 sycro OD tranny to replace the 3 syncro non OD tranny in my '67 roadster. I've searched the archives and still have a couple of questions.

1. Do I need a later shifter to fit the tranny or will the early one work?

2. Is the vacuum switch needed? I believe it was only fitted to Mark I cars?

3. What length driveshaft do I need (I have a Banjo differential)

4. Anything I've overlooked?

Thanks for the advice.

Bud


Bud G

Bud, have you checked Oliver Stephenson's home page at www.funkster.org Click on gearbox 2.

Should answer most of your questions.

Andy
Andy Preston

the mgbmga site has a handy table of propshaft lengths:

http://www.mgbmga.com/tech/mgb1.htm

Seemingly you need one that's 1/4" longer than the one you have, which is a big annoying as you can't make 'em longer. I guess you could always just use the one you've got and risk it running out of travel but I don't recommend this.

The measurements, by the way, are taken from the mid-point of the slide on the splines, so measure it fully extended and fully compressed and average the two.

You don't need a vacuum switch, just learn to heel and toe!
--
Olly
Oliver Stephenson

Olly - Great site! I guess I'd better get the vacuum switch, kind of hard to heel & toe - not much room in the B with size 12s :)
Bud Goetzinger

You don't need to heel & toe - just dip the clutch to take the shock out of the OD when you switch it off.

The vacuum switch is only there to protet the OD unit from DPO's (note that the P can stand for "present" as well as "previous" 8-)
Chris Betson

You would have to be some kind of a mutant to "Heel and Toe" an MGB; the pedals are so far out of line that it would take some serious contorsions to do so. I believe there is a aftermarket gas pedal to help with this. The downside is that it would then be uncomfortable to drive on the street. I think a simple "Double Clutch" would do the trick. Not that it is needed. Nor is the Vacum Switch.

Pete
Pete

If you want to be able to " heel & toe" - bend the accelerator pedal arm to bring the pedal closer to the brake - then you can brake with the left side of your foot while working the accellerator with the right side of the same foot. This is actually much easier than tradition " heel & toeing"
Chris Betson

I agree with Chris about using the sides of your feet for braking and using the accelerator. I did it all the time in my '70. Of course when I got my '67(it has 4 synchro w/ OD) after the previous car was wrecked, I found it nearly impossible as the go pedal is so much smaller. I just installed the later pedal and now all is well again. Double clutching isn't really an issue unless you're concered about adverse wear on your syncros, but what are they there for anyway(although I often do if dropping down to first.) All you need to do is blip the throttle while in neutral so your revs match the car's speed for the gear you're about to select.
Jared Snider

Olly - thanks for the link to the driveshaft lengths on mgbmga.com. Interesting, the lengths are 1/4 different but have the same Moss P/N. I'll stick with my existing shaft, I just put new U-joints in it this spring! One less thing to buy!!!!! :)
Bud G

Oh, BTW when I switched from the non overdrive 3 synchro box to the 4 synchro with overdrive, I did not fit a new driveshaft and I've had no problems. This was over a year ago with daily driving since.
Jared Snider

Cool, I guess there's enough movement in the propshaft to acommodate both gearboxes. I had to take more out of mine and didn't feel comfortable about just letting it snub up against the back of the gearbox.

Heel-and-toeing is possible in Bs! Even while wearing my clunkier shoes (size 9 UK) I can do it in my MkI and our LHD MkII. However I can't do it in my dad's mgtf as the gas pedal's just in the wrong place. Horrible clutch too. Looks nice, though...

ttfn,
--
Olly
Oliver Stephenson

This thread was discussed between 01/11/2002 and 04/11/2002

MG MGB Technical index

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