Why does TH400 shift to 3rd by 20mph?

Why does TH400 shift to 3rd by 20mph?

Maybe it does not build adequate vacuum or creates excessive slippage. You can try to adjust the modulator, but it will not give much adjustment of shift point.

Is there a Turbo 400 that won’t shift into 3rd gear?

Re: I have a turbo 400 that wont shift into 3rd gear. We… Try this. Take the vacuum modulator valve out and look for any burrs and see if it moves freely lets start there. You can’t post conmments that contain an email address.

Is there a TV cable in a TH400?

A TH400 has no TV cable (shift cable). It does have a solenoid on the left side of the transmission that usually goes to a microswitch on the carburetor that activates the down shift when the throttle is almost wide open.

What to do if your transmission is not shifting?

I would try flushing it out 2 or 3 times with clean fluid. fill it, run it until it is warm, shift through all gears. Drain and refill. Then do it again. If you can use a toulene based or similar additive, put that in as well.

How long does 2nd gear last on TH400?

When trying to not burn out and accelerating, it goes clear through 1st, then hits 2nd. The 2nd gear lasts for like 1-2 second then shifts directly to 3rd.

What should I do about my TH400 transmission?

Replace the filter and fill the transmission with new ATF (the TH400 requires six quarts). Do not put the bolts back on too tightly, as the gasket can become damaged.

How do you adjust shift points on a TH400?

A full intake vac (vac line from intake to the transmission’s modulator valve) must be hooked up to the modulator valve or it won’t up shift right. You can adjust shift points some by un hooking that vac line and looking in the nipple of the valve. Theres a screw in there you can turn.

Where is the dipstick on the TH400 transmission?

The first thing to check if you suspect that the transmission is acting up is the automatic transmission fluid (ATF) level in the transmission itself. The dipstick on the TH400 can be found inside the engine bay, on the passenger side toward the firewall (opposite the radiator).