Transmission issue: C6 drive won't engage when cold

Transmission issue: C6 drive won't engage when cold

V-twins
V-twins

December 2nd, 2016, 1:59 pm #1

Hi guys... V-twins here, can't remember my login info!
So I've been having a problem with my transmission. I got a 71 mach 1 with a C6.
When temperatures drop, Drive won't engage until the car warms up. R will engage right away.
I stand sitting in the car for a while before I can move the car... and even when it warms up and D finally engages, if I shift to R and then back to D (I need to maneuver to get out of my garage) it will take a minute to engage.

I had this issue last year. Then took the transmission to a shop so they would rebuild it.
Transmission is back and so is the issue.
Any ideas? Thanks for you help!!!

All the best from Italy

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rich
rich

December 3rd, 2016, 9:41 pm #2

Will it go forward when placed in 2 or 1 ?
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rich
rich

December 5th, 2016, 5:53 pm #3

in drive and idling, the only thing applied in the c6 is the foward clutch. the clutch get pressure from the manual valve in the valve body. pressure goes fom the manual valve, around 2 or 3 other valves, to the clutch.the cast iron sealing rings/ bronze bushings on the clutch hub have to be sealing good. either the rings , or those valves in the valve body are not sealing well, but when its warmed up, expansion take place enough to seal.the rings and bushings are replaced with any complete rebuid? Check the adjustmet for the shifter in drive also, in case it is off. the adjustment has to be right for the manual valve to be in the correct drive position.
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rich p
rich p

December 5th, 2016, 7:35 pm #4

....also the cast iron rings on the pump stator.
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V-twins
V-twins

December 14th, 2016, 2:22 pm #5

Will it go forward when placed in 2 or 1 ?
Nope.... same thing ...only R works
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V-twins
V-twins

December 14th, 2016, 2:24 pm #6

....also the cast iron rings on the pump stator.
Thank you.... ill pass this info along to my mechanic.... also will try and get details from the person who rebuilt it...
VERY useful..thank you again
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rich
rich

December 15th, 2016, 6:54 pm #7

Nope.... same thing ...only R works
i read on line that people that had your problem replaced the vaccum modulator and it fixed it. the modulator valve is in the circuit that supplys pressure to the forward clutch. my guess is that when the modulator is replaced, it moves the valve slightly and it then seals better? i cant post the diagram here, but search on ford c6 diagram, and you will se the image.
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V-twins
V-twins

December 19th, 2016, 12:47 pm #8

awesome thank you!
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