I have a question regarding the use of the SP with my BOP TH400 in my Jeepster Commando. What would it take to install it on my setup (I have a transfer case attached to the back of my 400) and what is the advantage or disadvantage of using a SP with my 4 wheel drive? I'm dropping the 401 into my Jeepster and while everything is still out of the Jeepster, I was wondering if the SP would be useful or not? My JC will be 90% road driven and 10% mild off-road (beaches and dirt roads NO rock climbing with it :TU: ) Is the SP somewhat like a stall converter that's built into the torque converter vanes? Is there anything different between my BOP 400 and a WC SP BOP 400 other than the torque converter? I noticed the kickdown switch by the carb, does that control something internally in the 400? Are these switches still available or someone making aftermarket ones? Any input would be helpful, thanks. Jeff
A switch pitch 400 has a different front pump, input shaft, and of course the converter. The front pump routes fluid to and from a piston inside the converter. The piston moves the stator blades to 2 different angles resulting in 2 different stall speeds. The switch pitch is mose usefull for acceleration at the track. You launch at high stall and switch to low stall once the car is moving. This results in lower elapsed times and higher trap speeds. I don't see any benefit for an off road vehicle. The switch pitch can be controlled very easily with a simple toggle switch. apply 12 volts, you get high stall, take it away, low stall. http://www.buickperformance.com/switchpitch.htm
Thanks for the link I'll read up on it. Won't be doing a lot of off-roading with it, mostly street driving. But depending on what the rpm is with the high stall, would probably make me decide to scrap the idea or take both trans to a shop and have them swap parts out to make my BOP with transfer case have all the stuff required to use the SP. Thanks again for the info. Jeff
I disagree setup in factory form, a S/P would be a great advantage in a 4x4. Mostly when the transfer case is in low gear. Since you say you're not into rock crawling, probably a little less helpful. But a 4x4 with really really low gearing in the transfer case, can be hard to hold at a stop with an auto. the S/P could eliminate the problem. a high stall when you let off the pedal, and back to the low stall when you need to move. If you've got a high torque, low rpm motor, I don't knwo why you wouldn't use the S/P if you're going to have the trans out and accesible
OK, if you want to use it that way, that's fine. As long as you have adequate cooling because high stall will generate alot more heat in the trans. Also, the SP solenoid is not meant to be constantly energized. A constant on off is OK though. Buick originally designed it to reduce acceleration times as well as improve economy.
Darn good question. If the solenoid stays cool due to fluid flow, it might not be a big deal to have it powered long-term. Since by design the trans went to high stall at idle, think about how many fleet vehicles back in the day just sat there idling (taxis, cops, etc.). I’d think that durability testing would’ve shown a problem (if there was one) in that situation...just a guess. Devon
Thats right, you could be stuck in traffic idling for over an hour it, could happen in a real life situation.uzzled:
You would still be moving, however slow that was, and it would be off and on everytime you moved off idle. When I had the stock 13" converter, I found low stall to be unusable at low speed and idle. I left it in high stall all of the time and worried about the solenoid. Then I got the PAE SP controller. That activates high stall at idle and keeps it activated for however many seconds you input into the timer. Another option is to wire it into the switched side of the brake light switch. Don't know how long the solenoid is rated for, but I remember JW commenting awhile back that it was not meant for continuous use.
I know it is a different set-up, but the solenoid for a lock-up convertor is energized for greatly extended periods. An idle speed solenoid for air cond. is also energized for long periods of time. Just food for thought.
The solenoid in my Wildcat came out of my first Buick, '67 Electra. Started messing with that car in 1985. I think what would probably kill it would be constant "on" with the engine off. The rest of the time it just sits around ~200° F like the rest of the trans. Devon
