700R4 Downshift Question

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Dec 21, 2022 | 02:30 PM

Procharged GTA

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Joined: May 2006

Posts: 160

Likes: 1

From: Cape Fair,Missouri

Car: 1991 Trans Am GTA Drag Radial Car

Engine: F-2 Procharged 18* 434 sbc on Alky

Transmission: Powerglide,Neal Chance Converter

Axle/Gears: Moser 9" Ford 3.50's,35 spline axle

700R4 Downshift Question

Hi all, I just built and installed a 700R4 using the Transgo 700 2&3 shift, Corvette Servo, GM High Stall V6 2075 RPM converter, and so on, for a customer. Governor is stock. The application is a 1989 C1500 Chevrolet truck with a mild 350 sbc and B&M 144 Supercharger. Rear gears are 3.42. It shifts great as far as upshifts, but while in 3rd, running 55-60mph, and going to 100% full throttle, it will downshift back to 2nd gear, even running that fast. Makes it really scream tight when it does this. TV cable is adjusted tight at WOT, plus we added the Sonnax Corrector Spring on the cable to increase pressure at part throttle, which seems to work well. What is the cure for the downshifting to 2nd gear at such speed? Thanks!

Brian

Last edited by Procharged GTA; Dec 21, 2022 at 06:51 PM.

Dec 23, 2022 | 01:38 AM

vorteciroc

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Joined: Jul 2006

Posts: 2,861

Likes: 785

From: 212 is up in this Bit@#

Car: Resto-Mod 1987 IROC-Z Clone

Engine: Alky fed L92 Vortec Twin-Turbo 6.8L

Transmission: My own built/ design 4L80M

Axle/Gears: Custom 12 bolt (4.10:1)

Re: 700R4 Downshift Question

What is the Engine Speed while driving in 3rd-Gear right before the Transmission Down-Shifts to 2nd-Gear?

Did you install that Orificed Plug for Governor Fluid?

Are there any sections of the TransGo Instructions that were NOT followed?

Are there any other Modifications done to this Unit?