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Old Jun 16th, 10, 08:13 AM
g356gear g356gear is offline
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Default TH400 shift point adjustment??

Under power my Th400 is shifting way too early. I have to manually shift to keep from shifting around 3000 rpm. What is the best way to adjust shift points on one of these units? Thanks.
69 SS396 Camaro, 4link, 12bolt posi, Speedtech LCA / UCA's, Hotchkis 2" drop front springs/sway bar, QA'1's, Bilsteins, Wilwood 6 piston front/4 piston rear, Magnaflow stainless exhaust, Lemons Headers, Comp rollers/p-rods/cam, Fikse 18x8.5 and 18x10
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Old Jun 16th, 10, 09:52 AM
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HwyStarJoe HwyStarJoe is offline

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Default Re: TH400 shift point adjustment??

Adjustable vacuum modulator.
You may already have one installed. Pop the vacuum hose off and look inside the tube. If there is what looks like a slotted head inside, it's adjustable.
I don't know which way is "sooner" and which way is "later". Do a search here and I'm sure it's explained.

Take a look at this:



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Old Jun 16th, 10, 08:43 PM
hereitis67 hereitis67 is offline
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Default Re: TH400 shift point adjustment??

get a adjustible mod and screw it in to raise shift points
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Old Jun 17th, 10, 09:39 AM
jakeshoe jakeshoe is offline
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Default Re: TH400 shift point adjustment??

How is a vacuum modulator going to raise shift points "under power"?

It's for part throttle operation, not WOT or near WOT. I would hope our resident transmission "builder" would know that.

Is the kickdown hooked up? 12V getting to the connector on the drivers side above the pan rail at WOT?
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Old Jun 17th, 10, 02:27 PM
ToocoolZ28 ToocoolZ28 is offline
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Default Re: TH400 shift point adjustment??

Does a turbo 400 have a governor like a 700r4? If so I would say the govenor weights need changed. I am NOT a trans expert but I did this on my 700r4 and got it to shift at 5500rpm at wot.
70 Chevelle SS396 (427), M21
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Last edited by ToocoolZ28; Jun 17th, 10 at 05:45 PM.
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Old Jun 17th, 10, 04:06 PM
muzzy muzzy is offline
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Default Re: TH400 shift point adjustment??

Yes altering the governor springs and weights is the only way to get a large change in the shift points.
Summit sell a kit with a selection of weights and springs,it takes a bit of trial and error to get the shift points where you want them.
I have my turbo 400 shifting at 6000rpm wot
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Team Camaro Tech > First Generation Camaro Info and Tech - 1967- 1969 "Where it all started" > Transmission & Driveline      Current Topic: TH400 shift point adjustment??
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