QUESTION 1

Mike,

I have a '66 Chevy Nova with a turbo 400 trans with a brake. The problem I am having is that it will burn up the direct clutches with only about 10 passes on it. I want to put 6 frictions instead of the normal 5. Can you tell me what needs to be done? Does anybody sell a piston that will allow this? Also, what type of trans fluid do you recommend I use?

Thanks.
Jim

Jim,

On your TH400 you can cut down the piston in your direct drum for a six pack. We at Mike's Transmission have drum kits all set up for that. Some drums vary in height, so each one needs to be checked for packed clearance (.060-.080).

We also carry thin clutches (.060) and thin steels (.058) that can be used if needed. The standard clutch steel thickness is .0100 clutches and .077 thin OEM steels.

Also, Mike's Transmission sells a semi-synthetic 10-30W industrial ATF equipped to handle high horsepower and high loads.

Mike

QUESTION 2

Mike,

I have a TH400 tranny on my 383 Chevy with 4:30 gear and 29-inch tire. I installed a reverse pattern valve body and have been having problems ever since. It's the type of kit that requires a check ball and a spring on the center support reverse passage. At the top of first gear the car feels like a brake is being increasingly applied.

I've tried talking to some techs at TCI, but they just told me to check the clutch clearance at .090 and the spring and check ball height at .125.

The direct clutch is the one that is burning up clutches. The front band is removed and the rear band looks okay. The rear servo has two seals removed and a plug in the accumulator passage. The tranny shifts great, but I know my car would run a lot faster if I could get this fixed.

Thanks.
Carl Diaz

Carl,

This is a problem the TH400 and TH350 have had since day one. When you launch the car in low gear, the direct drum turns backwards. At high speed the excess fluid in the drum through spinning force will start to apply the high clutch pack.

When we are building our units, setting up the drum for more clutches, etc, we will machine the drum in a way that will cure this apply problem and also free up the top of first gear. I'm just not ready to give away all my secrets. We sell a drum kit for the TH400 with 6 clutches, 34-element sprag with large snap ring. It's race modified and ready to go.

Mike

Mike Stewart is owner of Mike’s Transmission in Lancaster, California. He will answer your questions about automatic or powerglide transmissions. Email: Mike@racingnetsource.com

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