I have scoured trying to find this anywhere but cant find an answer. 72 mav w/302 and c4. c4 seems to have been rebuilt fairly recently (mileage wise). Motor has a fresh rebuild (we did) and the motor is great. BUT on the test drive home it would not automatically downshift when in 'd'. all gears engage. the really weird part is it seems to have developed a strange noise almost like a knock. absolutely sure its not the motor (i checked). seems to be coming from the tranny. no wear marks on the weight on the flywheel or the converter nuts/bolts. was def not doing this before. almost an internal soft noise if that makes sense. im going to drop the pan and check for any debris.. FWIW the trans never felt 'right' as it shifted way too early before the motor rebuild. (plan on replacing the rod @ the accumulator, im thinking its too short). the lack of downshifting in d (when slowing to a light) is def a new one on me though. But it will upshift. does this combination of issues raise a red flag to anyone to specifically know where to look? thanks!
No/late down shift is usually a governor or valve body issue... Of course it something is assembled incorrectly who knows...
well, as a follow up 2 things. the knocking (and this is embarrassing) was that i replaced the motor mounts during the rebuild. the exhaust manifold ont he motor (out of a different car i would suppose) was knocking on the steering box. easy to trim. the tranny seems to be better. I pulled the cover, looked perfect inside. swapped out all the fluid and it def seems better. at least its shifting down by itself. it sat for MANY years new, but not moving so im thinking soem stuff got 'stuck and its working loose. Still think theres soemthing funky with the valve body as the shifting points are just kind of sporatic. I did find the modulator pin to be too short, so i made a new one of correct length and need to adjust.
