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J type overdrive


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Well, I never thought I would be back on the forum so soon !! For some time now I have had a problem which I couldn't make my mind up whether it was me or the car. On the odd occasion when pulling away in my Spitfire 1500 c/w with o/d I have experienced what I thought was the clutch slipping ??!! Some time ago my local classic car repairer had replaced both the main clutch and the cone clutch of the o/d (the o/d cone clutch had disintegrated !!)  :) .


Now I find I have the same intermittent problem  :( . my question to all you far more knowledgeable people out there is..... is it possible to remove the o/d without removing the gearbox.............. aaaand is it likely that it is the "one way bearing " that's at fault as per the very good article by Canley Classics on the J type o/d unit............


answers on a postcard please (I'm joking ) in an attempt to avoid the possibility of stripping out all my new carpets, cabin trim, gearbox tunnel etc etc etc. Seriously, any help or advice would be welcome and I promise to renew my membership again this year !! :rolleyes:

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you can jack the box up high and extract the OD unit  its possible



refitting is far from easy, if the splines inside need to be in line its a pig to refit


if the box is out you can lever the clutch bars and this frees the internals to rotate and drop on easy


If you are having problems with engagement i would first remove  the solenoid  ( needs a thin 1" af spanner) dont wraunch the solenoid body to unscrew it

it can shear the  small spirol pins holding it together .


once removed extract the small 10mm circlip in its end and tap out the inner plunger ... bet its all crudded up


give it a clean and reassemble.


 you will get some oil loss when the sol comes out.


do the easy  tests first



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Hi Pete,

Thanks for that but do you mean jack it up with the interior removed and extract from inside the car ??  If so I might just as well remove the gearbox as well from underneath?? if I have removed all the interior trim, gearbox tunnel cover etc etc........................ note: the slave cylinder has been replaced when the gearbox came out the first time. 


Tony R.

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Yes jack the box up support the engine , watch for hose stretch and fan contact

remove from inside only


Sorry to say the box will never come out from underneath unless you have something extrordinary missing from your chassis, the box sits above the main rails


its steering wheel off , seat out , tunnel off.makes access easier


I dont think you can get the J solenoid off from under either



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Yes. Clean out the crud with carb cleaner/petrol. There is something? ,at back end inside that needs to make a clacking noise if you shake the solonoid.

Also you can check solonoid direct from battery when off. The end moves out maybe a couple of mm.

If you muller the circlip and also want to replace the O rings as they get hard (2 small for plunger,1 I think for main body) then Dave Twigger at O/D spares Rugby is a good source and helpfull with advice.

I had proplems with J type not engaging/disengaging and also engaging when disconnected !.

He advised doing solonoid as above (which may be enough to sort yours out) and also changing o rings in pressure relief valve (fidley job). Buckeye Triumph have very good info on these jobs online. I wouldn't attempt it without reading this first.

Also need a tool to remove the plugs for filter, Pressure relief valve, and pump which are accessed above the sump. some people make them up, but I used a punch to undo them. I did this from under car)

O/D worked fine after this.


Hope this helps, Dave

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Thanks Steve and Dave for your input............... The car is in with my Classic car man as we speak ( I'm too old and don't have lift facility to crawl underneath my cars any more !! ) He is going to replace o rings, pressure relief valve, clean filters and replace oil etc from underneath in an attempt to cure the problem. If not it's out with the o/d !! but thought I would try this first. I am positive it's not the solenoid ( replaced for new less than twelve months ago ) and the issue only rears it head very very occasionally, hey oh the joys of owning a classic car ??!! at least it's never let me down in two years of motoring, famous last words !! thanks again guys.


If anyone else has suggestions/ideas please shout............... Tony R.  :rolleyes:

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