[JSchmitz]

Many years ago, I adjusted my THM400 shift points. I used a B&M weight and spring kit. It took quite a bit of trial and error as I recall. I got it to shift at 5,400 1-2 and 5,100 2-3. I dug out the remaining pieces of the kit. I'll have to look when I get home. It appears that I used two weights from the kit and the original springs. I wanna say I used weight #2 & #4. I now want it to shift around 6,000. Anyone have a good "recipe" for this? It might save me some time. Probably changing one weight lighter would get me there? Haven't removed a governor in a long time. Jack the back up a little higher than the front?

[Half-Inch Stud]

Excerpt from my unpublished TH400 Writ;

[JSchmitz]

Originally Posted by Half-Inch Stud

Excerpt from my unpublished TH400 Writ;

Thanks! Gotta roll up my sleeves and start tryin stuff!

[Half-Inch Stud]

Outer weights only matter for rolling from a stop to about 18 mph ( give or take a few mph ).

Inner Weights are for WOT upshift rpm.
Inner Springs are for WOT Upshift "stacking"; implies whether 1-2 & 2-3 occur at same rpm or unstacked as desired.

[JSchmitz]

Originally Posted by Half-Inch Stud

Outer weights only matter for rolling from a stop to about 18 mph ( give or take a few mph ).

Inner Weights are for WOT upshift rpm.
Inner Springs are for WOT Upshift "stacking"; implies whether 1-2 & 2-3 occur at same rpm or unstacked as desired.

Thanks for the insight! I looked at my instruction sheet last night. I have all of the B&M springs. I'm missing #2 & #3 weights. So I assume I used those two weights and the factory springs. Not sure why you would want much, if any, spread in your two shifts rpm's. Gonna play with it this weekend. The little stock 5.3 feels better shifting higher. Might be a miscalibration of my a$$ dyno though.

[TCSGTO]

I got 2 kits and used 2 #5 weights and 2yellow springs to get both shifts around 5700. Basically the second to lightest weights and the second to the softest springs in the kit. Changing one of the springs to the super soft red one raised points too much (let off at 6500-hadn’t shifted yet)
I’d like 6-6200 so I may grind some off the weights. Be aware variables like line pressure and engine torque will affect the results so YMMV

[TCSGTO]

Correction, I used the 2 lightest #6 weights and yellow springs to get 5700.

[JSchmitz]

Originally Posted by TCSGTO

I got 2 kits and used 2 #5 weights and 2yellow springs to get both shifts around 5700. Basically the second to lightest weights and the second to the softest springs in the kit. Changing one of the springs to the super soft red one raised points too much (let off at 6500-hadn’t shifted yet)
I’d like 6-6200 so I may grind some off the weights. Be aware variables like line pressure and engine torque will affect the results so YMMV

Correction, I used the 2 lightest #6 weights and yellow springs to get 5700.

That's good information! That will help me get there quicker. I figured the variables would change the shift points. Just looking for some data to steer my decisions. Thanks!

[Formulas]

On the 2 different shift points for 2 and 3

Gear spread, will the same RPM shift point land you in the right spot in the power band post shift

[JSchmitz]

Originally Posted by Formulas

On the 2 different shift points for 2 and 3

Gear spread, will the same RPM shift point land you in the right spot in the power band post shift

Great question. I've never observed the rpm drop that closely. I'll try next time. I think you want the post shift rpm to coincide with your engines torque peak. If the two drops are different, that would be a reason for someone to want a spread. Hadn't considered that.

[Formulas]

you could probably make a tach video with your phone easy enough

[AG]

As an example, I shift my race car at 6500 rpm at the 1-2 and 2-3 shift and the rpm drops to exactly 5500 rpm after each shift with stock TH400 gears. What happens with your car will depend on your converter and shift rpm.

[Half-Inch Stud]

I found the Tach RPM just doesn't drop low enough, for long enough, with the 10" Converter doing a 3200 Stall. Relatively early shift points (5000) got the 10" back into TQ multiply and allowed getting into 3rd ( with TQ multiply ) for best ET.

My goal was TQ multiply in all 3 gears. Doesn't mean i was using the highest HP avail, but ran its quickest.

I think most racers aim for using the avail HP, and shift around that hp. Thatsa high stall Converter! ....Not for me.