Switch Pitch Transmission

[67 caprice]

Switch Pitch Transmission

I found a company that can convert my 1967 turbo 400 transmission to a switch pitch transmission. This is so you can have a high stall, say 3000 RPM for take offs. And a low stall for cruising, say 1100 RPM. You can control the stall by a switch. I was told that 700 HP and 800 ft lbs of torque have been used with this system and they have had great results. I thought that this would be a way to have your cake and eat it too. The conversion kit cost is $249.00 for pump, input shaft solenoid and switch. The converter cost is $359.00
What do you think?

Russ

[Tom Welch]

You will still have converter slippage all the time. I thought about this but have chosen a 700r4 instead. The idea was used by GM for their heaviest cars built in the 60's. The idea works well enough but no lockup converter is available. The lockup feature combined with over drive makes the switch pitch almost obsolete.

[vintageracer]

A lot of the "Buick" GS guys run switch pitch converters in their cars that see double duty for strip and street. They seem to like them very well however I would say that because the switch pitch was a Buick idea.

[67 caprice]

You will still have converter slippage all the time. I thought about this but have chosen a 700r4 instead. The idea was used by GM for their heaviest cars built in the 60's. The idea works well enough but no lockup converter is available. The lockup feature combined with over drive makes the switch pitch almost obsolete.

The 700r4 is not as strong as the turbo 400. And the cost to switch to the 700r4 would be way too much. As for the slipping. Let’s assume that I have a switch pitch with an 1100 low stall and a 3000 high stall.
Now how much slipping would I actually see at 70 MPH @ 2900 RPM with the torque converter in low stall mode?

Russ

[Tom Welch]

Jim Hand (of Pontiac Fame) runs a Continental 'tight ten inch' converter. I believe that he has found slippage of about 200 rpm through the trans, he uses a th400 too. I have corresponded with some of the Buick guys in Valdosta, GA. They do like the switch pitch converter. They may be able to enlighten those of us that are interested in this as to slippage with a switch pitch. I also suspect that there is someone out there who makes or can make a low slip switch pitch converter