Overdrive gearboxes

[worzel]

Hi Iain

Re your comment about overdrives fitted separately from the box.

I read an article (sorry I cannot remeber where) about a young engineer who had invented/devised an overdrive unit that fitted between the box and the diff. It was an incredibly small unit and he was canvassing opinion about the likely demand for it. I seem to remember he was an engineering student at a UK university so it's likely that somebody out there has the contact details.

On a similar not about 18 years ago I read an ad in Motorsport about an owner selling a 2 seater who'd fitted a Hillman Hunter O/d to an elan WITHOUT any body/chassis mods. He was selling the car to emigrate. I rang him and had a long conversation to grill him and offered to pay him for the blueprints. Unfortunately he never got back to me and his number was disconnected soon afterwards. He used that particular overdrive because it's apparently the smallest available so it appears it can be done.

Regards

John

[Mazzini]

On a similar not about 18 years ago I read an ad in Motorsport about an owner selling a 2 seater who'd fitted a Hillman Hunter O/d to an elan WITHOUT any body/chassis mods. He was selling the car to emigrate. I rang him and had a long conversation to grill him and offered to pay him for the blueprints. Unfortunately he never got back to me and his number was disconnected soon afterwards. He used that particular overdrive because it's apparently the smallest available so it appears it can be done.

Regards

John

Small world, I think I spoke to the same guy, I know this is an old thread, but I think I spoke to the guy in the 80's. I have often wondered if the car survived.

[Davidb]

I wondered about fitting an overdrive and since I had one 'on the shelf' I offered it up.

This is the "J" type overdrive-probably the most common-Volvo wagons are probably the best source. I think it would take more work than I was prepared to do to make it work. A plate has to be machined up to blank off the front and an adapter input shaft made-we used the shaft from the Volvo gearbox. The chassis would have to be modified and the body cut and widened--a lot of work.

A five speed box that should be considered is the ZF S5//18-3. This was fitted to many European sporting cars and to the Works Escorts. Every Maserati Biturbo has one...
I fitted one to my DB2 since it is impossible to fit an overdrive to them. I found the ZF to be very precise in operation and fast-with a dog-leg first gear, which I like. Parts are expensive but bellhousings are readily available. Mine had a 2.95 first gear and I replaced fifth gear with a 0.80 pair from a guy in the UK. If you get into racing gear sets it gets Very expensive though.

[Mazzini]

Thanks for that, but isn't the Alpine OD unit smaller still?

[HAIRY]

In the 60s or early 70s I was lent one of the many Jim Clark biographies and have a vague memory that it mentioned one of his Elans was fitted with an overdrive. Can anyone verify this?

[CBUEB1771]

In the 60s or early 70s I was lent one of the many Jim Clark biographies and have a vague memory that it mentioned one of his Elans was fitted with an overdrive. Can anyone verify this?

He had an Elite (#1659) with a Hobbs Mechamatic gearbox, not sure about another Lotus with an unusual power transmission train.