Who has run a Switch pitch transmission

nova50073

nova50073

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Is anyone on the board currently running a switch pitch TH-400 behind their 500 or 472 caddy engine, or if you have run one of these transmissions in the past, please tell me what you thought about it.     

I got one of these transmissions off ebay for $40, local pick up only, and after 2 tanks of gas, I have it at home ready to rebuild.     :cursing:

Also, thanks to dave B. I have my choice of 13" or 12" S-P converter, which one should I use?      :D
 
Big Block Fiero has one in his fiero. I have one too, but not installed yet. I found two places that rebuild them and the converters(info from Matt) Do a google search for switch pitch th400 and you will get what you are looking for. The converter can be modified for different stall speeds low normal high higher than normal. Anyway hope it helps. Gonna get my converter redone!  C U L
Lloyd
 
Charlie,

The 13" will go around 1000/2500 in a stock or mild engine. The 12", around 2000/3000, but your Nova engine might jerk it a wee tad higher. The stall speed doesn't seem to vary as much as typical aftermarket convertors. I've used the stock 12" [as have friends of mine] in everything from mid 11 second 3500 lbs olds to a high 12 second early chevyII [light] to stock engine pickups. They all stalled about the same.

The 13" are just wonderful for street. Although, the stock 12" isn't loose in low [2000], the car/truck will chug up a hill in high at 1000 or 1100 in high gear. Acts like a stick shift.

Dave
 
I am also running a switch pitch, thanks to some advice and pointers from Dave Brode... I first ran a 13" convertor.. Later I got a built 12" from  P.A.E. ...  PAE does alot with buicks....the buick convertors have the small bolt pattern...if you search this site there is a bit about S/P..
 
DaveM,

I can't recall. What stalls speeds does yours give?

The PAE4000 and PAE5000 sure would work well in a stout strip caddy, I bet. Even the 5000 hase a low stall of just 1900.

Dave
 
I got the PAE3000....  The low stall in a little lower that stock13" and the high stall a bit higher... perfect for me... now looking at that site , I was looking at there govenor... I wonder how they got it adjusted?  I haven't  played with mine yet... it shifts way too early...
 
DaveM said:
I got the PAE3000....   The low stall in a little lower that stock13" and the high stall a bit higher... perfect for me... now looking at that site , I was looking at there govenor... I wonder how they got it adjusted?  I haven't  played with mine yet... it shifts way too early...
Click to expand...

Dave,

I've found stock 13" to stall 1000/2500, and 12" to stall 2000/3000. Yours is lower than 1000 in low?

Do you have your detent working? How much do you want to raise your wot shifts?

Dave
 
guys,i also am curious about the trans,my car is still in the shop the shoehorned 70 500 doesn't really fit in my 67
as easy as i thought,the mount is proper so the drive shaft is right under the oil pan like it was with the 429 the
fan and the ac compressor all had to be reenginered but i should finally have it back within a week they tell me
but when ron the chevy guy was putting all the wires back for the kickdown he lost his mind and started screaming
what,this mf has a sp trans omg wtf,i knew it did but he freaked out and told me i should put the switch inside the
car so i could switch it manually,i told him i drive to work man i am not a racer and i don't know if i need it like that
i told him that i think the gm guys back then were pretty sharp and i should keep it as they intended,don't you all
think i am correct?
 
not sure about those stall speeds , I can't remember any of them stalling at 1000rpm... at the PAE site the last thing on the  first transmission page.. the second page had the convertors... I got sessions book... I don't know how much I'd have to play with that gov. to get it right.. If I could get one already to go, it may be worth it to save the time and aggravation....
 
cadillackeeper said:
guys,i also am curious about the trans,my car is still in the shop the shoehorned 70 500 doesn't really fit in my 67
as easy as i thought,the mount is proper so the drive shaft is right under the oil pan like it was with the 429 the
fan and the ac compressor all had to be reenginered but i should finally have it back within a week they tell me
but when ron the chevy guy was putting all the wires back for the kickdown he lost his mind and started screaming
what,this mf has a sp trans omg wtf,i knew it did but he freaked out and told me i should put the switch inside the
car so i could switch it manually,i told him i drive to work man i am not a racer and i don't know if i need it like that
i told him that i think the gm guys back then were pretty sharp and i should keep it as they intended,don't you all
think i am correct?
Click to expand...


Stock setup:

It's is adjusted so you have high stall at curb idle speed with car in gear. Just touch the gas, and it goes to low stall. Apx 2/3 throttle and it goes back to high. This works fine, but it's always in high stall at wot. The car will et a little better [a wee little] if you go back to low stall at the top of low gear.

You can:

disconnect from stock switch, and install a momentary switch. I like to use a shifter mounted button from a line-lock [roll control - B&M will sell you the button] I've used them on column shifters too. To allow for automatic high stall at a stop, you can parallel wire into the brake light circuit. The brake lights will come on anytime you are in high stall. A 25 cent diode will fit that.

Dave
 
DaveM said:
not sure about those stall speeds , I can't remember any of them stalling at 1000rpm... at the PAE site the last thing on the  first transmission page.. the second page had the convertors... I got sessions book... I don't know how much I'd have to play with that gov. to get it right.. If I could get one already to go, it may be worth it to save the time and aggravation....
Click to expand...

Dave,

I've had several S-Ps with the bigger convertors [13" from TH400], and all of them stalled at 1000 or maybe 1100 max in low. All of the 12" ones i've had stalled at apx 2000 in low.

If you can snag a gov from a non caddy, it'll probably make for higher shifts with no mods. Most non caddys shifted a little higher than a caddy. From there, every 1/16" ground from the inner weights will raise wot shifts a few hundred rpm, iirc. You can usually grind them down w/o taking the gov apart. Clean it really well to remove grit. I've never had to dink with the springs to get up to a 5500-5800 rpm shift point [with detent working]. Just trimmed the inner weights. No detent = much lower shift points.

Dave
 
Decades ago I had a 1966 Olds Dynamic 88 with the dual pitch convertor. I needed a car to get around in when I got home from VN. It was my "father's oldsmobile" and I bought it from him. It was a low compression, two barrel carbureted 425 cube motor, but he had swapped a four barrel intake and carb onto it and he put a switch inside the car so he could manually control the convertor pitch.  He was seeking more miles per gallon of fuel so he wanted the convertor in "low stall" and he wanted the small primary throttle bores of the four barrel carburetor.  It worked wonderfully.  We found we preferred the low stall speed 99% of the time. The car could achieve more speed in each gear with the low stall.  If he wanted to get the car moving in a hurry, he would just switch the convertor to high stall speed, and  then about 2/3's of the way through first gear he would switch to low stall speed.  It would wind out the rest of the rpm range and then when it shifted to second gear the car would break the rear tires loose. It would burn rubber for about 20 feet.  These days I control the lock-up convertor in my car with a switch. Rather than  have the lock-up feature available only in 4th gear and above 45 mph, I can manually lock the convertor up in 2nd, 3rd, and 4th gears at any speed that I prefer.  In summation (is that a quote from maddog?), I don't think you can go wrong with a dual pitch transmission.
 
cadillackeeper said:
guys,i also am curious about the trans,my car is still in the shop the shoehorned 70 500
...
when ron the chevy guy was putting all the wires back for the kickdown he lost his mind and started screaming
what,this mf has a sp trans omg wtf,i knew it did but he freaked out
Click to expand...

Are you sure it's a SP trans? If it's the trans from a '70 Eldo that was mated to the 500 it's not. It will have 2 connectios though.
One is the detent(kickdown) but the other is for the T.C.S. solenoid. Transmission Controlled Spark uses a solenoid to prevent vacuum advance in 1st and 2nd gear.Doesn't seam to have been used on other years either.
 
STDog said:
Are you sure it's a SP trans? If it's the trans from a '70 Eldo that was mated to the 500 it's not. It will have 2 connectios though.
One is the detent(kickdown) but the other is for the T.C.S. solenoid. Transmission Controlled Spark uses a solenoid to prevent vacuum advance in 1st and 2nd gear.Doesn't seam to have been used on other years either.
Click to expand...

STDog,

Good point. I assumed that he had his '67 tranny's innards swapped into the bop case.

Fwiw, I have seen mid/late 70s rwd caddys and other GMS with two wire trannys for the TCS. Not sure what years, but not 1970 for sure. I didn't know that caddy used it as early as '70.

Dave
 
guys,i kept the 67 trans in tact and they put the 70 500 to it there was 2 bolts that did not line up but
it is together and getting the exhaust finished tomorrow.
 

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dave brode said:
Fwiw, I have seen mid/late 70s rwd caddys and other GMS with two wire trannys for the TCS. Not sure what years, but not 1970 for sure. I didn't know that caddy used it as early as '70.
Click to expand...

'70 RWD for sure and I though the Eldo too, as I don't remember it being exc. Eldo. The FSM goes into great detail on the operation :)
The in-law's '72 deVIlle didn't have the connector on the trans (and the ID plate says it was the original).

Guess it came and went in the line-up.
 
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