On Tue, 22 Aug 1995 britcars@hpfckjs.fc.hp.com wrote:
> What I haven't figured out yet is what causes the OD not to disengage in
> the first place. The oil pressure typically falls off fairly quickly
> when the pump is not operating so as soon as you stop to shift into
> reverse the OD should disengage. Assuming that the valve is stuck it
> would start to reengage as the pressure built up again but unless you
> are driving a backwards race or backing a long distance at higher than
> normal speed I suspect that enough oil pressure can be generated.
I had this exact problem with my TR-6 overdrive (J-type). In this
instance, and others I've seen concerning both the J-type and A-type,
sufficient pressure was built up to engage the overdrive between 5 and 10
mph. In the case of my car, the pressure relief valve was
non-functional, and as a result the OD would engage when enough pressure
had built up, regardless of car direction or gear selected. So, for the
short time that the problem was occurring, the car would self-engage
overdrive about 1/2 way through 1st gear, and remain in OD for the rest of
the trip. Needless to say, the clutch lining was toast after only a few
weeks of this. The sprag (uni-directional) clutch didn't seem to suffer
any malady, but the J-type does have a smaller cone-clutch than the A-type.
I hope this is of help...
Greg
Greg Meboe meboe@wsunix.wsu.edu
Dept. of Mechanical and Materials Engineering
Washington State University, Pullman, Wa.
'85 XJ-12 H.E. (daily) '67 Spit-6 '74 TR-6
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