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1-2 Shift Issues After Converter

Old May 21, 2011 | 12:47 AM
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Exclamation 1-2 Shift Issues After Converter

I have a 2000 C5 Corvette with a stock 4L60 and an FTI 3600 converter. Prior to the converter installation, my transmission would make the 1-2 shift at WOT no problem. Ever since the converter, the converter will hit the limiter at ~6600RPM for about 0.5 seconds before it shifts into 2nd. I can get it to shift into 2nd if I manually go from 1 to 2 at about 5000 RPM, but it doesn't go into 2nd until ~6200 RPM.

It shifted fine before the converter. When we put the converter in, we also put in a 3.42 rear differential out of a Z06 and upped the line pressure to 99%. The shift points are roughly the same, but we tried plenty of combinations to get it to shift properly to no avail.

Any ideas or suggestions are greatly appreciated!
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Old May 21, 2011 | 01:00 AM
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This is common because the car goes through the rpm range so fast after the converter is installed. If you have a tuner raise the limiter by 200-300 rpm it will be fine. Mine did the same thing after installing.
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Old May 21, 2011 | 01:02 AM
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same issue here and like stated raise the limiter
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Old May 21, 2011 | 02:19 AM
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You say to raise the limiter but I don't want the car shifting anywhere near 6500. It's a stock cam car so 6200 is more than fine for me for right now.
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Old May 21, 2011 | 07:19 AM
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Originally Posted by BTow1105
You say to raise the limiter but I don't want the car shifting anywhere near 6500. It's a stock cam car so 6200 is more than fine for me for right now.
IF you do not want to rase the limit point then you need to lower the shift points, problem could/will be due to installing converter/gears/both
not sure about changing the line pressure ?
just my .02' Johnny
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Old May 21, 2011 | 10:47 AM
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Originally Posted by SS SLP2
IF you do not want to rase the limit point then you need to lower the shift points, problem could/will be due to installing converter/gears/both
not sure about changing the line pressure ?
just my .02' Johnny
Appreciate the help. Do you think it could be an issue inside the transmission? It holds the power fine and shifts 2-3 perfectly every time. And it launches hard as hell for what it is (1.77 60' all night in my slow car lol).
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Old May 21, 2011 | 02:14 PM
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"could be an issue inside the transmission"

don't know, I still think you need to tune the shift points , your 2-3 MAY be fine and only a problem with 1-2 points
Johnny
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Old May 21, 2011 | 02:24 PM
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I hate to state the obvious, but just in case ... you did tune for the new gear ratio, correct?
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Old May 21, 2011 | 02:42 PM
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It is not a problem inside the transmission you simply need to tune the car to shift at a lower rpm so that it has a chance to shift before it bounces off the limiter or raise the rev limiter. My car drove fine with stock cam and shifting at 6600. I did not know how to fix it so I brought my car to one of the sponsors shops on this site and that was how he said it is fixed and it worked. By simply raising the limiter and not changing the shift points the only shift that it will make slightly higher is the 1-2 and that is just because it has trouble making the shift at the right point because of how fast the car goes through the rpm range with the smaller converter.
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Old Jun 3, 2011 | 12:32 AM
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Originally Posted by TurbopigB4C
It is not a problem inside the transmission you simply need to tune the car to shift at a lower rpm so that it has a chance to shift before it bounces off the limiter or raise the rev limiter. My car drove fine with stock cam and shifting at 6600. I did not know how to fix it so I brought my car to one of the sponsors shops on this site and that was how he said it is fixed and it worked. By simply raising the limiter and not changing the shift points the only shift that it will make slightly higher is the 1-2 and that is just because it has trouble making the shift at the right point because of how fast the car goes through the rpm range with the smaller converter.
Thanks for the reply. I really hope that's all it is! As soon as I can get HPTuners hooked up, I'll give this a shot!
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Old Jun 3, 2011 | 09:14 AM
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I lowered my shift point on the 2-3 shift and raised the limiter by 100. Shifts fine now after the converter install. I am sure your trans is fine. Make sure your tire height and rear gear is correct in your tune as well
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Old Jun 3, 2011 | 10:36 AM
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Originally Posted by Mike Morris
I lowered my shift point on the 2-3 shift and raised the limiter by 100. Shifts fine now after the converter install. I am sure your trans is fine. Make sure your tire height and rear gear is correct in your tune as well
We will lower the shift points and raise the limiter next time I have the car hooked up to HPT. Thanks!

For reference, here's a video of the car at the track after the converter. I manually shifted both times and the 1-2 sounds slower than the 2-3.

http://www.youtube.com/watch?v=2iQKwWfHVgQ
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