Uninvited Automatic Downshift

[Luma]

While I was road testing my 64 Avanti today I got an unexpected downshift to 1st gear while I was in DRIVE. The car was still in second at the time it happened and

as soon as I let off on the gas while approaching a stop sign, it went to 1st causing the rear wheels to lock up. I put it neutral and it freed up from first. It did the same in 2 gear shift

position. When I placed it in 1 it was still in 2nd and seemed to stay there thru about 2500 RPM when I returned home and parked it. In D it keep downshifting whenever I let off the gas.

Any help greatly appreciated. Reading thru the manuals tonight!

[Rob Dudley]

Be sure the throttle pressure rod is correctly attached to the linkage and is correctly adjusted.

Rob

[brad]

Sounds like the rear drum is locking up. Could be the one way clutch sprag is worn and over centered .

[Luma]

No, its definitely a transmission issue. What would happen if I disconnected the throttle pressure rod from the gas linkage? Would I then be able to select the gears manually?

[Rob Dudley]

I think Brad is talking about the rear drum in the transmission. If the throttle rod is not connected it will not allow the transmission to shift at the correct speeds. It might shift immediately or it might not shift at all. It could damage the transmission or drive train because of overly hard shifts.

Rob

[brad]

Yes, I was trying to say the rear transmission drum. Sorry for the confusion.