Setting up overdrive

[TKelly]

Hey guys,

I heard a while back about setting up overdrive on the vintage cars to improve the highway cruising speed. Can anyone tell me how this is done and what is involved? I have no idea how one could set this up nor do I know how overdrive works.

Thanks in advance, Tristan.

[Manuel]

Hi Trist,

In the USA there are separate aftermarket overdrive transmissions avail.

I know of ones for old Fords: Model T's, A's and early V8's that fit between the gearbox and diff.

HTH

Manuel in Oz

[TKelly]

Hi Manuel,

Thanks for that info, are you able to tell me how these systems operate? Is it just like a smaller gear box?

Thanks, Tristan.

[R.White]

Hi Tristan,

We in the UK are very familiar with overdrives. I have a 1973 Triumph GT6 and have rebuilt the o/d together with the gearbox to which it is attached. My overdrive operates on third and fourth (top) to give fast cruising at lower engine revs. and subsequently better fuel consumption. The o/d takes the form of a hydraulically operated epycyclic gear.

The idea of overdrive for vintage cars sounds like a great idea!

Perhaps I should fit one to my '26 DB Tourer!!

Cheers, Ray.

[R.White]

For an explanation of a typical overdrive, go to:

www.buckeyetriumphs.org/technical/jod

hope this helps. Ray.

Edited September 20, 2011 by R.White (see edit history)

[TKelly]

Thanks for that information Ray, was a very interesting read.

Does anyone have any idea what the costs would be in setting up an overdrive system?

Thanks, Tristan.

[Manuel]

OD's for prewar Fords are avail new for about $2,000-2,500.

I think u can get different ratios as well. It all comes in a complete kit. With a shortened tail shaft and everything else req.

Before that they used old Volvo over drives.

Another thing u can do is change the diff ratio. The old ones were real stump pullers!

I think Chrys/Dodge started offering factory OD's in the late 1930's......

What car so u have?

Manuel in Oz

[TKelly]

Thanks for that Manuel,

I don't actually own the car yet but it is a 1925 Australian Bodied Roadster. Just doing my research to see solutions to possible problems.

Thanks, Tristan.