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J Type Overdrive

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Hi all, I am new to this forum and looking for some help. I own a 1971 MK3 GT6 and have just stripped down the gearbox and overdrive as it had developed a bit of a rumble. I found the source of the noise (input shaft bearing) but thought I should recondition the gearbox and overdrive whilst I had them out of the car. The gearbox has been quite straightforward but the overdrive is a J type not the usual D type fitted to the GT6. As this is the first time I have ever rebuilt an overdrive of any kind can somebody point me to where I could find a good exploded diagram for the J type overdrive. 
Thanks in advance.

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The triumph workshop manuals available for free download on vitessesteve.co.uk have J type OD diagrams with part names but not numbers. Either the Dolomite Sprint or maybe later TR6 ones will probably be most helpful...

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13 hours ago, Peter Geer said:

Thanks, I found a few like this too but was trying to find something that identified the parts as well as I may need to order a few parts

The top one I posted is Moss Motors, the numbers link to each part on their website.


Also for spare parts:




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Did strip a J type overdrive down once, yellow metal washer broke up, had it rebuilt by Overdrive Repairs Sheffield as the problem is getting there pressure to match the engine power. One way it slips the other a harsh engagement, in my Vitesse very smooth.



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in general J types are robust and trouble free

the only snag i have found is the inner spool valve piston inside the guts of the solenoid 0 rings get stuck 

the maraca's test  shake the sol. it should hear the inner piston rattle .

easy to repair remove the small 10mm circlip in the solenoid knock out the inner piston/spool  and clean refit with new 0 rings , re rattle the  test and refit .

needs a 1"af thin wall spanner to loosen the solenoid, do not use grips on its case you can wreck it 

apart from filter cleaning leave the rest of the unit alone 


Edited by Pete Lewis
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