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GKN overdrive fitted and no reverse?


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Car is a 110 TD5 2000

Fitted the gkn overdrive and reverse gear feels like a slipping clutch and won’t let it reverse

thats without any of the wiring fitted to the solenoid or anything

forward gears seems fine

refitting the standard setup and reverse back to normal

i know the design of the overdrive is that when the solenoid is operated it’s a one way gear or will smash the thrust bearing to pieces, but surely disengaged or not powered it should be ok?

clutch plate is fine, has had a new sprag and seals

am I missing something?

thanks

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  • 2 weeks later...

There's been more than one GKN Overdrive thread, full stripdowns, rebuilds, and explorations of the many ways it can go wrong - @western had  mega-thread on his which I believe is still running;

https://forums.lr4x4.com/search/?q=gkn overdrive&updated_after=any&page=2&sortby=relevancy&search_and_or=and

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On 6/19/2020 at 12:36 PM, reb78 said:

That wouldnt explain why it drives ok in forward gears?

Sorry I can’t explain why, I am not that familiar with the internals but nevertheless it’s the overdrive that’s the problem 

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On 6/19/2020 at 4:51 PM, vulcan bomber said:

Sprag clutch?

I have never quite understood what the sprag clutch does in there VB. Can you shed any light on it? We changed the one in Neils when his was slipping but it made no difference (that was after changing the clutch cone and that making no difference too!)

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The link above & the cross section diagram call it a one way roller clutch, so it should only work while going in forward drive, so it should have no effect when reverse is selected. Maybe someone has been inside the OD & refitted the sprag gear the wrong way up. 

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2 hours ago, reb78 said:

I have never quite understood what the sprag clutch does in there VB. Can you shed any light on it? We changed the one in Neils when his was slipping but it made no difference (that was after changing the clutch cone and that making no difference too!)

I get the impression it is there for safety, so the overdrive can only be driven by the engine, not by the wheels.

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