Topic: '66 289 A code(SJC) c4 transmission hard shift

[socalgt]

Until it warms up, usually in just 2 or 3 minutes, transmission downshifts hard to 1st gear.  After a couple minutes it shifts smoothly and continues to do so.  Fluid level checks, no loose mounts or brackets....anything I can check, short of going to a transmission shop(really don't want to do that)...possible the modulator valve, or other (just guessing here).  Up shifting and downshifting smooth to all gears after warming up.

                                                                                  Thanks....

[MattDoscher]

I wouldn't worry about it if it only occurs when cold.  I think it's just a side effect of cold fluid and parts and would be considered normal.

[socalgt]

Thanks for the reply.....to be honest....I've had several cars with the C4 and none of them had this problem, so I'd like to fix it, but like I said, I'm reluctant to take it to a transmission shop....not looking for a "rebuild".  Maybe someone will chime in that has a similar problem and was able to resolve it.

[Bossbill]

Until it warms up, usually in just 2 or 3 minutes, transmission downshifts hard to 1st gear. 

Do you really mean when you put it in drive when cold it bangs into (1st) gear hard?
To downshift into first would presuppose you are in 3rd or 2nd ...

It might simply be that you are still on the choke's high idle cam, so the engine speed is somewhat high. When warm the choke pulls off and the high idle cam drops out. This leads to a smoother engagement into 1st as the idle speed is much lower. As an aside, EFI cars have much lower cold high idle speeds . . .

Check your cold high idle speed.