on the radio the other day someone mentioned a Switch Pitch Transmission >
I had never heard of these , so google found me ,
http://www.buickperformanceclub.com/switchpitch.htm
Quote :
Switch pitch(s.p.) transmissions were availabe from 1965-7 in the full size BOP cars. Even some Cadillacs have the s.p. transmissions. The name switch pitch comes from the vanes in the torque converter being able to change their angle (pitch) in order to reduce friction(force) and get the vehicle moving. This would be similar to somebody trying to start pedaling a ten speed in 10th gear versus 1st or 2nd gear. These transmissions were used in the full size cars since the engines did not make a lot of torque and they were quite heavy.
There are s/p TH400 and s/p TH300 transmissions. The s/p 300 were found in 1964-7 and were two speeds. The s/p 300 converters are 12 inch while the s/p 400 are 13 inch.......................more at link....
So the question is did other companies make something like these ?
Sounds like a cool idea if there are not big negatives :)
I had a whole string of 60's Buicks and a couple of Oldsmobubbles. My 65 Riviera was great. I did have to rebuild the tranny but that was from a lack of maintenance. I did find out that the drive shaft yokes are a different diameter. I had one with the two speed Super Turbine 300. BOP version of the Powerglide. Never really had any problems with any of them.
My Cadillacs have them. Not sure about the whole "engines did not make a lot of torque" thing, though :)
As far as I know Pontiacs never had them. I think they were mainly used in Buicks, but as mentioned above it appears there were some in Olds and Cadillacs.
In reply to Keith Tanner :
Me either, my Nailheads did alright. My service manual said the 401 had 445 lb.ft @ 2800 rpm.
My 67 Cadillac had it. I loved it. My dream is to put one behind a 472/500. I also road in a 39 Cadillac that had a 429/400 switch pitch swapped in. He had the switch pitch with a manual switch and you could tell the difference the high stall made.
any thoughts why they did not keep using it ? did emission testing change things ?
would it work with a 700r overdrive trans ?
And why did no other company use switch pitch ?
It just seems like a neat idea that I never heard of before last weekend......
My grandmother had a TH300 behind a Buick 340. ‘67 Buick LeSabre. For a big giant automobile, that little 340 moved it with surprising alacrity. It wasn’t fast. But then again it wasn’t slow either. And definitely faster than it had any right to be when you consider it only had 2 speeds and a tiny little Rochester Dual-jet carburetor.
When you look at cars from the ‘50’s and ‘60’s, think about what they were, how much they cost, and the fact that they were only a couple generations since dirt roads and horses - they’re pretty amazing.
I had one that I put in the Bonneville with a Caddy 500. Lovely, although I didn't really have need for it. The 196 duration cam with 500 cubes meant that I needed the lowest stall I could get.
californiamilleghia said:
any thoughts why they did not keep using it ? did emission testing change things ?
would it work with a 700r overdrive trans ?
And why did no other company use switch pitch ?
It just seems like a neat idea that I never heard of before last weekend......
The reasoning Cadillac gave for getting rid of it was the 472/500 had ample torque and no need for switch pitch. Like you can ever have enough torque.
In reply to Curtis73 (Forum Supporter) :
Do you still have that trans?
In reply to Stampie (FS) :
Nope. Sold it for $1500 about 10 years ago.
In reply to Curtis73 (Forum Supporter) :
About right. I think I'm going to have to junkyard all the components over years and then get my trans shop on the corner to build it for me.
Ever since we got magnetorheological dampers I've pondered the possibility of making an MR-fluid torque converter. Like instead of 2 stall speeds, how about all of them?
