pro trans advice

[Stan Weiss]

Sorry could not upload the Excel Spreadsheet


Stan

[S/ST 3040]

Can you explain what the "reaction %" means to a specific selection?

[Mike Rietow]

Originally Posted by S/ST 3040

Can you explain what the "reaction %" means to a specific selection?

The reaction percentages listed are relative to each other. A concept which says one reaction is more efficient than another.

[Mike Rietow]

This the two I was looking at to have the car crossing 7600-7700 1/4 mile 4.56 gear 141 - 142mph. with the same starting line ratio run now 2 sp pg 28 x 10 bias tire.

[Adger Smith]

Stay away from the 1.12 Reaction number
When you have 2 gear spreads use the one with the number the farthest away from 1.00.
I would look at the 2.16 -1.45 C-1 .73
If you can use just a little more starting line ratio the second gear drop will pull the car up to speed quicker. The 3 speed will get you in hi gear a little farther down the track with the 3 speed than the PG. It will also make your converter react like it is tighter.
1st..second.hi.% drop1-2...% drop2-1...Shift....Fall.....Shift2-3.....Fall RPM
2.16 1.45.1..... -32.9%..-31.0%....... 7200........4833.......7200........4966

I just guessed at the shift point.
Guess you have a 1.98 PG low..
The PG has a 49.5 % drop from low to high a 7200 RPM shift will bring the mechanical RPM back to 3636
See the difference in hang time on the converter. You are using second gear ratio to move the car instead of converter. I hope this helps

[Mike Rietow]

Originally Posted by Adger Smith

Stay away from the 1.12 Reaction number
When you have 2 gear spreads use the one with the number the farthest away from 1.00.
I would look at the 2.16 -1.45 C-1 .73
If you can use just a little more starting line ratio the second gear drop will pull the car up to speed quicker. The 3 speed will get you in hi gear a little farther down the track with the 3 speed than the PG. It will also make your converter react like it is tighter.
1st..second.hi.% drop1-2...% drop2-1...Shift....Fall.....Shift2-3.....Fall RPM
2.16 1.45.1..... -32.9%..-31.0%....... 7200........4833.......7200........4966

I just guessed at the shift point.
Guess you have a 1.98 PG low..
The PG has a 49.5 % drop from low to high a 7200 RPM shift will bring the mechanical RPM back to 3636
See the difference in hang time on the converter. You are using second gear ratio to move the car instead of converter. I hope this helps

It's a 1.69 x 5.29 final crossing 1/8 converter slipping 5% 7450rpms. I ran it to the 1000 ft once 8000 rpms 9.69 @ 1/4 coasting 116 mph 10 x 28 M/T bias. This with a spragless converter 90% hum, 2875 bar, 78 deg

I think with a 3 speed it might dip in the 9.30's as is, in premium conditions 3250lbs sbc factory condition 69 Nova on a bias tire n/a.

I'm trying to find the best approach for second gear for a 4.56 final. 1.30 to 1.40

For the small tire, I think around 8.9 starting line ratio is good, even if I went to a radial tire, one tenth quicker typically.

It did help, thanks for your input I'll study that to comprehend your approach. This is just a ol car I drove to work, then street raced, then Super Pro bracket raced and now just hot rodding for fun 30 years later.

[Stan Weiss]

1st..second.hi.% drop1-2...% drop2-1...Shift....Fall.....Shift2-3.....Fall RPM
1.95 1.3.....1..... -33.3%....-23.1%..... 7200........4800.......7200.......5538

1.95 1.4.....1..... -28.2%....-28.6%..... 7200........5169.......7200.......5143


Stan

[Mike Rietow]

Originally Posted by Stan Weiss

1st..second.hi.% drop1-2...% drop2-1...Shift....Fall.....Shift2-3.....Fall RPM
1.95 1.3.....1..... -33.3%....-23.1%..... 7200........4800.......7200.......5538

1.95 1.4.....1..... -28.2%....-28.6%..... 7200........5169.......7200.......5143


Stan

[Adger Smith]

Mike, I have a formula that allows you to change shift points and look at the fall RPM,
It also allows you to study what the gear ratio changes do.
Send me your e mail and you can play with it.
Adger

[Mike Rietow]

Originally Posted by Adger Smith

Mike, I have a formula that allows you to change shift points and look at the fall RPM,
It also allows you to study what the gear ratio changes do.
Send me your e mail and you can play with it.
Adger

Soon as I can my PM to work I'll do that for sure. TU Adger