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Old 08-29-2010, 03:59 PM   #1
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Default harsh shifts on rebuilt trans?

So when I first got this car it wouldent shift from first, so had a new trans installed.
With the new trans when it shifts into second it'* kinda harsh, but only sometimes.
it depends on the throttle position, when using say, 5% it shifts smooth, but push a little harder say 20% it shifts rougher. Under WOT the first to second shift is enough to bark the tires (if I had enough power) Kickdown is much smoother, and when slowing down to a stop light the 2-1 is kinda rough. BUT only when in a straight line. When turning into a neighbor hood it'* seemless.
When going around a cornor and it shifts, it'* smoother, also when going up a hill.
2-3 isint as harsh, but not as smooth as I think it should be.
Now the question is, Is the trans doing this or is it the mounts or what do you think?
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Old 08-29-2010, 04:04 PM   #2
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What year is this on?

My first thought on this is your 1-2 shift accumulator piston is stuck, or someone put a harsh shift kit in the transmission.
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Old 08-29-2010, 04:09 PM   #3
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A 1990
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Old 08-29-2010, 04:28 PM   #4
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I believe that is the 4t60 transmission. The accumulator is about the same as the 4t65. Can you shift manually any better?
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Old 08-29-2010, 05:04 PM   #5
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it is a 4T60... there are so many potential causes it'* not even funny... could be something simple like the TV cable out of adjustment or the vacuum modulator acting funny, or it could be something internal...
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Old 08-30-2010, 12:59 AM   #6
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it'* a 4t60? I was under the assumption that it wasent, idk why I just thought it was something else.
Well since it could be many stupid little things Ill just take it back to the place who did it and tell him because the trans has less then 1,000 miles on it so it shouldent be doing this.
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Old 08-30-2010, 01:01 AM   #7
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Quote:
Originally Posted by Danthurs View Post
I believe that is the 4t60 transmission. The accumulator is about the same as the 4t65. Can you shift manually any better?
Ill have to try
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Old 08-30-2010, 08:36 AM   #8
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In 90.. I believe you'd have a 4T440. Same stuff to check as the 4T60 though. It'* vacuum controlled by a modulator on the front. Pull/check the vacuum lines to it. Try adjusting the TV cable etc.
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Old 08-30-2010, 09:29 AM   #9
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If it'* still under a warranty, take it back right away, don't wait, just do it.
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Old 08-30-2010, 11:12 AM   #10
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Check the vacuum to the modulator with a gauge. It should have 15-18" @ idle and immediately drop when you hit the gas. If that is OK, check the valve behind the modulator to see if it is stuck.
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