Author Topic: '66 289 A code(SJC) c4 transmission hard shift  (Read 114 times)

Offline socalgt

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'66 289 A code(SJC) c4 transmission hard shift
« on: February 12, 2018, 01:15:31 PM »
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....

Offline MattDoscher

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Re: '66 289 A code(SJC) c4 transmission hard shift
« Reply #1 on: February 12, 2018, 02:04:10 PM »
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.
Matt Doscher
5F07C395128
Caspian Blue exterior, Palomino deluxe interior.

Offline socalgt

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Re: '66 289 A code(SJC) c4 transmission hard shift
« Reply #2 on: February 13, 2018, 06:00:26 PM »
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.

Offline Bossbill

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Re: '66 289 A code(SJC) c4 transmission hard shift
« Reply #3 on: February 13, 2018, 08:16:44 PM »
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.

Bill
Concours 3/2/67 GT350
Driven     6/6/70 0T02G160xxx B302
Modified  5/18/65 5F09A728xxx 2+2
Race       65 Coupe front clip, Convertible frame mods and SFCs; 2+2 conversion; Many 'glass parts