Overdrive??

[BaileyMex]

Here's a question for all you Old Skoolers, I was chatting to my brother in law yesterday about life and gearbox's

 

Chatting about pro's n cons about 4 -5 speed conversions...

 

He said 'Cant you fit an Overdrive like they used to do on old MG's etc back in the day?'.........

 

:think: :think:

 

 

So....is this possible to do to a 4 speed? Your thoughts please

[Vista]

There are overdrive gearbox's that already exist and can be mated to Ford Engines. I used to have a mk1 3 litre GT Capri with an Overdrive box. I think it originated in a Reliant Scimitar but don't know what mods would be needed to fit other Old Skool engines.

[BaileyMex]

so is it not just a conversion that you do to your existing box then?

[RFChris]

so is it not just a conversion that you do to your existing box then?

 

When you take into consideration the gearboxes that are avilable second hand, it's not worth it. Overdrive would be a nice period touch but it's not as practical as just throwing a 5-cog on there.

 

Chris

[Vista]

Dunno, I've never really looked any further into it. though if a scimitar box will mate to an Essex engine I suspect it'll mate to others from the Ford stable. Don't know what the gear ratios are, but it's a close ratio 4 speed with optional electrically operated Laycock overdrive

 

Some text I found

 

An overdrive is a device which was commonly used on rear-wheel drive cars to allow the choice of an extra-high overall gear ratio for high speed cruising, thus saving fuel.

 

 

 

History

Early manual automotive transmissions were limited to three or sometimes four speeds, with only the most sophisticated being five speeds. This left an unfulfilled need for a higher gear ratio for highway cruising, which was filled by the addition of separate overdrive units. However, automotive manual transmissions manufactured since the 1980s tend to include a larger selection of gear ratios than before, the highest of which is usually greater than 1:1. This trend has rendered overdrives a complex and obsolete solution to economy gearing in automobiles, and very few cars are fitted with them today, although they still appear on large trucks, where more gear ratios are always in demand.

 

 

How overdrive works

The overdrive consists of an electrically or hydraulically operated epicyclic gear train bolted behind the transmission unit. It can either transfer the input drive shaft directly to the output shaft, called a propshaft (1:1), or increase the propshaft speed so that it turns faster than the input shaft (1:1 + n). Thus the propshaft may be "overdriven" relative to the input shaft. It is actuated by a knob or button, often incorporated into the gearshift knob, and does not require operation of the clutch.

 

 

Overdrive in Europe

The vast majority of overdrives in European cars were manufactured by an English company called Laycock de Normanville, which is now defunct, but its overdrives were found in vehicles manufactured by Ford, British Leyland, Jaguar, Rootes and Volvo to name but a few.

[Mr Sam]

if you can use a volvo axel in an old ford why not use the M46/47 gear box too

 

they go bang at 250-300bhp though

[V8ian]

Have a looksie here,

http://www.gearvendors.com/ O/ds for some megga HP, 1000hp+

 

Ian

[john_3.0s]

have you ever tried to lift an o/d unit?? even the MGB boys now fit sierra 5 speeders in preference to o/d units as they are lighter and more reliable. Also you can easily b*gger up an o/d if you knock it into reverse or try and tow it when its engaged. The MG club actually does a sierra 5 speed conversion kit (at the princely sum of 600 quid + a gearbox!!) the conversion is that popular.

[BaileyMex]

Oh well, it was just a thought,

 

may have to whip out the gearbox in the near future for a rebuild, and just a thought too keep the 2000E box and make those motorway drives a little easier

[Col-ashtonmobile]

Here's a question for all you Old Skoolers, I was chatting to my brother in law yesterday about life and gearbox's

 

Chatting about pro's n cons about 4 -5 speed conversions...

 

He said 'Cant you fit an Overdrive like they used to do on old MG's etc back in the day?'.........

 

:think: :think:

 

 

So....is this possible to do to a 4 speed? Your thoughts please

 

you been on the stella again colin , overdrive in a mexico