Topic: Help with Dad's C-4
in Forum: All Vettes Discussion
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Fayetteville, NC - USA
Joined: 2/13/2005
Posts: 244
Vette(s): 1968 Corvette Convertable, 4 spd, 350 SB, Daily Driver
Hey everyone,
I know this is not a C-4 site, but I hope that being Corvette afectionados, some of you may be able to answer a question. My Dad has an '85 automatic (700R4 I believe) and it won't shift into high gear. Any suggestions?
Thanks and don't forget to remember those that serve.
JR
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Does it run fine 1st thru 2nd and then loose all power when it shifts into 3rd? If so thats exactly what mine did. Don't know the exact answer but mine was a total tranny rebuild. I'm no transmission expert but I bet Joel will be here soon to help out 
MARK
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Duncanville, TX - USA
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Mark axed the right question...does it shift all the way into 3rd, and then stays there, or does it "neutralize" when it should shift into 4th?
If it simply does not make the final shift into 4th, there are a couple of things that could cause it. The T.V(throttle valve) cable could be out of adjustment, or frayed.
The 3-4 shift valve could be stuck in the valve body.
In rare instances, the servo seals(on the pass side) for 4th could be damaged.
If it does shift 1-2-3 with no problems, that tells us the 3-4 clutches are good, as they are applied for 3rd and 4th.
And...if it has a good 2nd gear, that tells us the band is good, as it applies in 2nd and 4th.
Sooo...if the above is your scenario, then we are looking at a cable problem, a stuck valve, or possibly a check-ball(in the valve body) that has hammered it's way thru the separator plate.
More info is needed...how fast have you(or he) driven it to see if it will eventually shift into 4th?
If it simply does not make the final shift into 4th, there are a couple of things that could cause it. The T.V(throttle valve) cable could be out of adjustment, or frayed.
The 3-4 shift valve could be stuck in the valve body.
In rare instances, the servo seals(on the pass side) for 4th could be damaged.
If it does shift 1-2-3 with no problems, that tells us the 3-4 clutches are good, as they are applied for 3rd and 4th.
And...if it has a good 2nd gear, that tells us the band is good, as it applies in 2nd and 4th.
Sooo...if the above is your scenario, then we are looking at a cable problem, a stuck valve, or possibly a check-ball(in the valve body) that has hammered it's way thru the separator plate.
More info is needed...how fast have you(or he) driven it to see if it will eventually shift into 4th?
Joel Adams
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Former Member
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Fayetteville, NC - USA
Joined: 2/13/2005
Posts: 244
Vette(s): 1968 Corvette Convertable, 4 spd, 350 SB, Daily Driver
Joel, he tells me that it seems to run fine but wont make the final shift. I will ask him some more questions and see what gives. Thanks,
JR
in Forum: All Vettes Discussion
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