Vixen s1 MGB engine

[Ianbailey]

Trying to do some research my Vixen has a None overdrive gearbox the question is can I fit an overdrive gearbox and if so do I need any changes or mods any info would be appreciated

[Astacus]

I am sorry you haven’t seen any replies yet. It’s a bit thin on here now.
I am afraid I don’t have any experience with the MG engined S1s but you could try the Facebook pages. Either the Lilley Wilkinson pages or the pre 80s pages will likely turn up your answer

What sort of overdrive were you thinking of?

[Tyre Smoke]

I will start off by saying I'm not familiar with these, but since MGB came with OD it should be a simple fit? Unless the gearbox length is different/stick position, etc in which case you are going to have to modify the prop shaft and cut holes.

Is the OD unit fitted at the back of the box?

[phillpot]

Tyre Smoke said:

Is the OD unit fitted at the back of the box?

[Clive-sz8cz]

I had what I believe was the second Vixen S1 and I fitted an overdrive box. I think the original engine was a 3 bearing but I could be wrong. Any way, the oil consumption of the original engine was down to about 50 miles per pint and it seized on the A30 on the hill out of Hartley Wintney one night so I decided now was the time for a 5 bearing engine and 4 syncro overdrive gearbox swap (note, the original box was 3 synchro and very crunchy). The gearbox went in with a bit of shaving of one of the slimmer near vertical chassis tubes that joined the upper and lower main rails on one side. I didn't remove the tube completely, just angle-ground it enough to give half an inch of clearance. I also moved the handbrake bracket slightly over using longer bolts and a couple of 5/8th nuts as spacers. It was all a bit home brewed but worked. I don't recall having any problems with the prop shaft as I think the original 4 speed 3 synchro box had a long tail. One minor issue I had was that the gearlever moved back a few inches and was uncomfortable to use so I cut it short and welded on a Triumph gear lever but cranked forward substantially to get the overdrive-switched gear knob in the right place. I could still use the original MGB gear lever gaiter.

I did this around 1985 so details are now a bit vague but hope it helps. The overdrive made the car much more pleasant to drive with 70 being about 3000 rpm, I think before it was nearer 3500 rpm but again memories are a bit hazy!

Edited by Clive-sz8cz on Monday 21st October 13:14

[Ianbailey]

Thank you all for your input. My plan is to buy an overdrive box and the fitting and fix the problems as they crop up
Ian

[Moto]

I'm not sure of the details but there were 2 different gearboxes for the 3 synchro MGB engine. One was for the earlier engines MY62-65 and one for the later 65-66 engines. The engine numbers define which gearbox you will have. They both take overdrive units but it's worth checking to ensure the O/D unti is compatible with the gearbox you have. Moss Europe will be able to provide full specs etc.

I only know this as I have a 1964 MGB with 3 synchro gearbox and O/D.

Good luck and in my opinion fitting the O/D is worth the effort.

Moto

[Ianbailey]

Thank you moto