tranny won't shift at WOT
Thread Starter
Instructor
Joined: May 2001
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From: st. peters, mo. USA MO
tranny won't shift at WOT
I have a 90 Corvette convertible automatic and I just noticed this today...At WOT from a standing start, the car accelerates ok but it will not shift out of 1st gear...I noticed the tach and it went up to 5500 rpm. I had to let up the accelerator to let it shift...This is the first time in a long time I really got on it...I checked the tranny fluid and it looks good...What do guys think it might be?...any help would be greatly appreciated~
Thanks a lot
:seeya :seeya :confused:
Thanks a lot
:seeya :seeya :confused:
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Joined: Sep 2000
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From: Hinckley Ohio
Re: tranny won't shift at WOT (90 turq rdstr)
I had what I think is the same problem on my 1989 auto.
I called the Vette hotline (when it was still in business then) and apparently this was a pretty common problem which is the rev limiter & the WOT 1-2 upshift point are only about 100 rpm apart. I never fixed my problem as it was intermittent & I sold the car shortly after I learned what the problem was, so I don't know what the correct fix is.
So to restate, the problem is a race between the 1-2 upshift & the rev limiter which are nominally only 100 rpm apart and with variations who knows which one will win.
I called the Vette hotline (when it was still in business then) and apparently this was a pretty common problem which is the rev limiter & the WOT 1-2 upshift point are only about 100 rpm apart. I never fixed my problem as it was intermittent & I sold the car shortly after I learned what the problem was, so I don't know what the correct fix is.
So to restate, the problem is a race between the 1-2 upshift & the rev limiter which are nominally only 100 rpm apart and with variations who knows which one will win.
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From: SE NY
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Re: tranny won't shift at WOT (cdnguyred88)
I had a great shop (Grant Transmission) in CT USA rebuild my A4 for around $850, with the shift kit & new TC the bill came to about $1,300.
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From: Vette-hid.com Lost in DFW texas
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St. Jude Donor '06-'07
Re: tranny won't shift at WOT (chrply)
you might want to check what what gm charges for a crate rebuild gm quoted me 1300.00 for on without tq conveter.50k warrenty
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From: Hinckley Ohio
Re: tranny won't shift at WOT (90 turq rdstr)
This really sounds exactly what my 89 did. It accelerates great to 5500RPM and then just hangs there. It doesn't shift and doesn't increase in speed.
Mine did this from almost day 1 and I never had a tranny problem per say.
I surmise it was common problem because when I called the Corvette Hotline they immediately stated the problem as a race between rev limit & shift point with variance in factory settings & repeatability of a given unit being the problem.
Sometimes it shifted ok, others after 1-2 second delay, other times I let up on throttle momentarily.
Think all that is needed is to reset either 1-2 upshift point or rev limit. This shouldn't require a major transmission overall.
Mine did this from almost day 1 and I never had a tranny problem per say.
I surmise it was common problem because when I called the Corvette Hotline they immediately stated the problem as a race between rev limit & shift point with variance in factory settings & repeatability of a given unit being the problem.
Sometimes it shifted ok, others after 1-2 second delay, other times I let up on throttle momentarily.
Think all that is needed is to reset either 1-2 upshift point or rev limit. This shouldn't require a major transmission overall.
Racer
Joined: Jul 2001
Posts: 396
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From: New Hampshire
Re: tranny won't shift at WOT (LT4BUD)
My 1994 does the same exact thing, after the TransGo and 3.54 rear was installed. I never had a problem with it before... (30,000 miles on a meticulously maintained Auto.) Only seems to do it occasionally when the fluid is hot, after getting off the highway, once every 8 times.
I believe I'm going to need to raise the redline another 500 rpm and reduce the shift point at WOT. (the information above is confirming my thoughts)
Somebody told me I could tweak the shift points a little bit by programming the size of the tire diameter in a hypertech to something slightly greater than what the tires actually are. (25.25") Anybody else hear something similar?
I believe I'm going to need to raise the redline another 500 rpm and reduce the shift point at WOT. (the information above is confirming my thoughts)
Somebody told me I could tweak the shift points a little bit by programming the size of the tire diameter in a hypertech to something slightly greater than what the tires actually are. (25.25") Anybody else hear something similar?
Cruising
Joined: Aug 2003
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From: Lexingington Park md
Re: tranny won't shift at WOT (PoloGrnC4)
My 86 does the same thing, no 1-2 shift under WOT. What do I need to do to fix it? How do I adjust the shift points, or the rev limiter? Thanks for the help.
Craig
Craig
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Joined: Sep 2001
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From: Stuck in the 80's
Re: tranny won't shift at WOT (red L98)
B&M sells a 'calibration kit' for the governer as well. A series of weights and springs to change shift points and firmness. I used one to dial in my B&M 700R4 in my 86 Monte SS. No telling what it came out of but it shifted 1-2 at like 4K prior to re-calibration. Funny thing is now that I have upgraded my exhaust with headers, an X-pipe and Ultra-Flow mufflers, I need to recalibrate it again, won't shift 2-3 at WOT.
:eek:
:eek:
