Transmission / Overdrive: Avanti Power Shift downshifts at speed

[unimogjohn]

Hi, I have a 63 Avanti R2 with a Power Shift transmission. The car has 44,000 miles on her and runs great. But today I was running at about 50 mph and suddenly she downshifted into 2nd gear. I moved the gear selector to 2nd gear and then back to Drive. Still stuck in 2nd, after about four tries she shifted back into D. She has done this a couple of time over the past six months or so.

I am about to change the transmission/torque converter oil and filter. I doubt it has been changed in twenty some years. Should I be look at something specific that would cause the downshifting? Or something that needs adjustment while I have the pan off? Or do I just have old oil that needs to be changed?

I have looked at the manual, but it does not offer anything that looks like my situation.

Otherwise she shifts great, nice and crisp. The fluid is still nice and pink and does not smell burnt.

Thanks. John in VA

[SN-60]

If you accelerated a bit before it shifted down, the throttle pressure rod may be a bit 'short' and needs to be lengthened a turn or two.

[Corvanti]

John, I'd first drop your tranny pan and check for metallic "bits". it's possible some of that is causing the problem clogging things up. then go with a good flush & fill with a new filter and pan gasket.

but it's probably what Ed (SN-60) is pointing to - a simple adjustment. when i'm able, i need to adjust the rod since my '51 automatic won't stay in 2nd gear past 15mph or downshift to 2nd when it should.

BTW: i've been following your "blog" on AACA since around 2010. it helped me when i had my Avanti, and like following you and Mr. Cone's adventures!

ps: here's a pic of the tranny fluid that was in my '89 Reatta. it looked "pinkish" on the stick, didn't smell and the pan before and after:

[unimogjohn]

You were right. The throttle linkage to the bell crank control for the transmission was out of adjustment. I was also down almost two quarts of transmission fluid. So fixed all that and took her on a road test. Everything seems to be just fine now. Thanks for all the help.