C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

changing shift points on an auto trans

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Old Jul 17, 2002 | 09:11 PM
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Default changing shift points on an auto trans

how would you raise the shift points of an automatic trans? i plan to siamese my base manifold in my Vette soon, and ive had my best track times by leaving my trans in D while racing instead of shifting it manually. problem is it shifts at 4800 rpms, which is ok for now, but after i siamese the intake ill want to rev higher to take advantage of the increased airflow. how do i go about doing this? is it in the PROM, or can i raise the shift rpms by adjusting the throttle cable? thanks
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Old Jul 17, 2002 | 09:58 PM
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Default Re: changing shift points on an auto trans (tpivette89)

I think you need the B&M governor kit.
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Old Jul 17, 2002 | 10:01 PM
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Default Re: changing shift points on an auto trans (Bluevette85)

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Old Jul 17, 2002 | 10:09 PM
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Default Re: changing shift points on an auto trans (tpivette89)

The WOT shift points are controlled by springs & weights withing the govenor. Decrease the weights to raise these shift points. The TV cable position controls part-throttle shifts.

I recently had a shift kit installed and the shift points raised (along with a 2000rpm TC) for a nice 0.3 sec off my ET.

My stock intake base is now siamesed about 1" into the base by 1" high.

The 1-2 shift point was raised from 4,800rpm to 5,200rpm and the 2-3 shift point from 4,800rpm to nearly 5,800rpm. The former could stand to go up to 5,400rpm and the latter needs to come down to 5,400rpm.

BTW, I have done full exhaust mods from the front Y back and installed 1.6:1 RRs but stock heads, cam and headers.

When I had been holding my shifts manually to higher RPM they were too slow until the shift kit was installed, maybe something to consider.
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Old Jul 17, 2002 | 10:16 PM
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Default Re: changing shift points on an auto trans (Bluevette85)

Bluevette85, do you have a P/N on that and/or the B&M web site?
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Old Jul 17, 2002 | 10:37 PM
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Default Re: changing shift points on an auto trans (tpivette89)

Can L98's benefit from Hypertech? I raised my shiftpoints and adjusted the firmness with the powerprogrammer III. Shifts great!!
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Old Jul 17, 2002 | 10:44 PM
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Default Re: changing shift points on an auto trans (95AquaC4)

The pre 94 Vettes don't have an electronically controlled trans. So no, they can't.

Eric
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Old Jul 17, 2002 | 11:21 PM
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Default Re: changing shift points on an auto trans (silver & red CE)

I have the B&M governor kit, it is very easy to work with.

After seeing 65Z01's results, I am upping my shift points to 5200 rpms to start with.

Vic
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Old Jul 18, 2002 | 12:17 AM
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Default Re: changing shift points on an auto trans (65Z01)

Bluevette85, do you have a P/N on that and/or the B&M web site?
B&M #20248. They have it at www.summitracing.com
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Old Jul 18, 2002 | 12:30 AM
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Default Re: changing shift points on an auto trans (Bluevette85)

Thanks, $27.95 sounds good to me.
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Old Jul 18, 2002 | 01:18 AM
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Default Re: changing shift points on an auto trans (tntcorvette)

how touch is it to install that b&m governor kit and get the shift points to where you want them the first time around?

Is this a trial and error setup, or is it specific to what rpm you want in each gear?


:confused:
I'm afraid it's trial and error! I wish I could give you an idea of what combo of spring and wgts would get you what rpm, but I sure couldn't find any logic to it....
Just try for the 1/2 shift where you want it, and then manual shift the rest of the shifts! As you get the 1/2 where you want it-then adjust for the 2/3-then the 1/2 changes(too much) again.....
Only advice is once you get close with the 1/2 and 2/3 then just change the wgts-I ended up grinding down heavier wgts to make changes as small as 8grams at a time-also plan on new springs "breaking in" and raising the shift point a bit after some miles.
Plan on a full day...good luck!
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