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Next Question... Overdrive mod


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Various topics have been run into the ground regarding o/d mods, running o/d in all gears, blah blah.

So im guessing theres masses of knowledge floating around (fingers crossed)...

Here goes:

I have experienced first hand they joy of flicking the button and getting an instant result in and out of o/d.  Also the not quite so much joy of flicking the button and waiting for over 10 secs for anything to happen.

I'm told that typically 3-5 seconds is reasonable before the o/d 'kicks in'

Apparantly what a lot of the track day and racer boys have done is mod'd or replaced pistons to solid rather than hollow, which somehow speeds up the engagement/disengagement process to almost instant.

has anyone done this?  is it easy-ish to do i.e. can I do it myself (ive never opened up an o/d unit before...

does anyone know someone, garage, workshop or otherwise who can do this?

mine didnt work before I stripped the car, but apparantly it did before I bought it but it had been standing for some time, leading me to think that its electrical rather than mechanical, as these units are meant to be quite robust...

thanks folks



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Three seconds???? Five seconds?????? What Muppet told you that?

Might as well not bother having overdrive!

Engagement should be almost instant. Low oil in the gearbox is oft a culprit if its slow to engage or doesn't engage at all. The unit has an electrically operated solenoid after that its totally reliant on oil pressure and friction...up to 400 lb/sf ft oil pressure!!!. Make sure you use the correct Hypoid oil and DO NOT under any circumstance put any friction reducing additives in there.

O/d on second is simple; undo blanking bolt on top of gearbox cover, screw in another inhibitor switch and wire up in parallel.

O/d on first is silly and anyway can only be achieved if you have the potential for it in reverse too which would be a very expensive mistake.

Ex works Sprints used standard J type but increased the spring strength...not a job for an amateur or anyone who has not the correct special tools!

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The two best known overdrive specialists are :
Overdrive Repair Service (Sheffield) 0114 248 2632, 10fo@overdrive-repairs.co.uk
Overdrive Spares (Rugby) 01788 540 666, odspares@aol.com

Otherwise try Canleys Classics- loads of o'd spares.
Main source of parts are Transits or Volvo 200 series cars!

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ok, im feeling the love!

The mission is to get the beast put back together without having to dismantle bits of it again to achieve the required result and / or rectify mistakes.

I think I've got most things covered, but im sure there'll be things that I've missed...

Thanks guys


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