Clutch pack clearance th400

[impala454]

Rebuilding a th 400.
Checking clearance in front and direct.
Front 1 wave plate 5 frictions and 4 .080 steelplates.
.050” clearance. Ok or should I tighten up to .040”?

Direct 5 frictions and five .090” steelplates .080” clearance.
Should I replace the bottom .090” steel with double .060” steels? Ok to run steels against steel? Ok with thinn steels?

3400 lbs chevelle street/strip bbc 600-700hp 600+ft/lbs
3500 stall. 12 bolt 3.42.

 

[clinebarger]

.010" per Friction is standard on performance TH400's in the Forward, Intermediate & Direct clutch packs.

You can run the Forward Clutch a little tight....., .040" is fine. Stick with .010" per on the Direct & Intermediate clutches.

Do you have access to a Lathe? You can face the piston off @.030" then run a .060" steel under the bottom .090" Steel, In theory this would tighten the pack up by .030" & put you near .050" clearance. The .060" steel will act as a shim.

*Option #2....
Run 6 .077" nominal (.080") Steels & 6 Frictions in the Direct Drum & face/machine the Piston accordingly, Some drums will accept 6 .090" Steels & 6 Frictions. Measure twice....Cut once!!!


I don't like running steels thinner than .077" against a Friction.....The Steels act as "heat sinks".



If you do not have access to a Lathe....Run a couple of .077" in place of the .090" Steels & add the .060" under the bottom steel......Or however you need to do it to get the clearance right.

 

[impala454]

Ok many thanks! Think my best option is to face the piston .030” and add a .060” steel.

 

[impala454]

.010" per Friction is standard on performance TH400's in the Forward, Intermediate & Direct clutch packs.

You can run the Forward Clutch a little tight....., .040" is fine. Stick with .010" per on the Direct & Intermediate clutches.

Do you have access to a Lathe? You can face the piston off @.030" then run a .060" steel under the bottom .090" Steel, In theory this would tighten the pack up by .030" & put you near .050" clearance. The .060" steel will act as a shim.

*Option #2....
Run 6 .077" nominal (.080") Steels & 6 Frictions in the Direct Drum & face/machine the Piston accordingly, Some drums will accept 6 .090" Steels & 6 Frictions. Measure twice....Cut once!!!


I don't like running steels thinner than .077" against a Friction.....The Steels act as "heat sinks".



If you do not have access to a Lathe....Run a couple of .077" in place of the .090" Steels & add the .060" under the bottom steel......Or however you need to do it to get the clearance right.

Or maybe even face .047 an run a .077” steel in the bottom under the .090” since .060” is harder to find in Sweden and like 40$ each.

 

[clinebarger]

Sounds good.

 

[impala454]

Sounds good.

Piston is ready!
My new clearance is .045”-.050” in direct with a 0.77” steel in the bottom.