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Triumph TR6 - Question on A type Overdrive

I experience a transmission "slippage" when I am in 3rd or 4th gear (OD disengaged) and push the throttle firmly (to overtake for example). Can this be pointed to a main clutch weakness or can it be the overdrive slipping instead?
My understanding of the Overdrive operation is that when engaged, the OD clutch is stationnary, pressed against the brake ring by the hydraulics. This allows the "multiplier" to enter in action. When disengaged, the OD clutch now rests on the annulus, pushed back by the 8 springs, the clutch assy and the annulus now rotate together, this is the 1:1 ratio.
I wonder if a slippage there, is possible. Theorically, I think NO, because the directional clutch (free wheeling clutch) should transmit the torque. But I am not 100% certain of the threory.
Surprisingly, this "slippage" is not always present, occasionally, I will be able to press the throttle firmly (in 4th gear no OD) and the torque will be transmitted. It has also happened that I experience the slippage, I release the foot throttle and press again, and this time the torque goes through. Strange isn't it?
I have rebuilt my OD 2 years ago. I was experiencing this problem before, and I still do.
When I overhauled it, I replaced the bearings, the various washers and bushings, the springs, piston rings, etc, but didn't touch the OD clutch assembly (conic clutch).
I am wondering if I should have replaced the linings (inner and outer) on the OD clutch assembly, or do I simply have a problem with the main clucth slipping(between the engine and the gearbox)? I have been "living" with this for quite some time, and it is a bit frustrating, not to be able to use the full "juice" of the engine, even though the car runs fine otherwise, and I can still enjoy the drive, including mountains motoring (as I live close to the Pyrenees)
My car is a 3A, but I post this thread on TR6 BB talk as the same OD (A type) has been fitted on 6's, and it has to transmit much more torque on the 6's than on the 3's. Has anyone experienced a similar situation?
Jean Louis Lafont

OOops! Too technical for this BB I guess... has anyone read it?
Jean Louis Lafont

Jean-Sorry you didn't receive a response to your posting. I believe that you are correct-when the od isn't engaged, the power is transmitted through the uni-directional clutch except when coasting or in reverse. If you are experiencing slippage in direct and the "main" clutch isn't slipping, the uni-directional clutch might be damaged. If the slippage occurs when shifting out of od, maybe the sol. adjustment is incorrect or the return oil passage could be blocked. You might try an email to John Esposito at Quantum Mechanics, who specialises in OD rebuilding.
Good luck
Berry Price
BTP Price

Jean-The email address should be:
Berry Price
BTP Price


Thank you for your comment. I agree that if I experience a slippage in direct and the main clutch isn't slipping, it points to a damaged uni directional clutch. Problem is that I cannot tell that the main clutch isn't slipping. In fact, I suspect that it does slip (the main clutch). So, I will replace it, and I have actually already purchased it. I will also observe the flywheel and if needed, I will remove it and bring it to a workshop to re-surface it. I have also been informed that I can have a few millimeters removed from it, as it is un necessarily heavy, and it can help at taking the revs faster.
Thank you also for the OD specialist contact.
Jean Louis Lafont
Jean Louis Lafont

This thread was discussed between 21/09/2007 and 20/10/2007

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