There is a seller in the Buy/Sell advertsing a rebuilt switch pitch TH400. I did not want to steal his thread with my questions. Why are these Switch Pitch trans desired and do they bolt right in or need some special harnesses or attachments at the carb? What's the story? I have a 70 Wildcat that came with the factory TH400 which would need rebuilt. This sellers price is about the same. I will be running a mild build 455 (approximately Stage 1 specs) and factory 2.76 ish posi.
i use a switch pitch 400 in my 64 post car and i LOVE it:TU::TU: it gives me two stall speeds in my case 2800/1200 but there are different ones out there i like the fact i can leave hard with some stall and low stall for cruise and better mileage I also love the fact that when set up right it doesn't need to don't shift to pick up speed the convertor get loose and away we go. The switch i use is from my 64 and i like how it works. its easy just use 2 kick down switches set up in a stagger manner Ken
the switch pitch gives you the best of both worlds, low stall for cruising and mileage and high stall for acceleration and performance. I have a stock st300 in my 67 special and you can definitely feel a difference when high stall kicks in. the only reason they stopped producing them was they cost more to build than a standard th400. I have a brand new street strip SPO400 with a tri shield performance converter ready to go in my 67 once i install the new engine. Bob
Everything said above is right on. For a dedicated drag car a fixed pitch converter built exactly for that person's combination will be more consistent for the track, but the variable pitch setup is a joy on the street, especially for someone like me running a lot of camshaft in a heavy car. Devon
With an axle ratio in the 2s, a SWitch Pitch will give more torque multiplication, and get the engine more quickly into the power rpms. SWP will reduce idle creep, smooth your shifts, and perk up midrange driving without as much downshifting. Gas mileage seems to be about the same, since you should be in economy range most of the time. I think I actually get better SWP mileage, but its a small difference. The bad news is, you may then tire of your ordinary 3 speeds, I did. Bruce Roe
Roadmaster,the SP works the same way as the regular transmission,internally the are a little different.The imput shaft is not the same as the regular trains,and the torque converter has to be for the SP trains.Other small differences are there,but the SP trains itself is the same as the regular trains.The only thing it needs is a switch to put it in high or low stall.You can go crazy with all kinds of timers,but in reality the switch is the only essential thing.You can put the switch anywhere is easy for you to use while you're driving.I'm sure some of the guru's on the board can explain this better the I did,but this was one of the questions that you asked I felt had to be answered .BrunoD.
I'm learning a little from all the posts. What is "stall"? Is that the same as a shift point meaning the trans will shift from 1-2 or 2-3 at that certain rpm? It seems from reading the posts on here that the SP torque converters are readily available. Is this correct? So this SP TH400 would bolt right into my 70 Wildcat, the only difference might be the tail of the trans (output shaft area)
Here is a pretty good article on stall speed. http://www.bankspower.com/techarticles/show/10-understanding-stall-speed
Interesting, especially the use of diesels as a comparison. Diesels produce max torque at 1600 or so, yet the torque converter "starts" (in this example) at around 2400. Meaning max torque is never achieved, but more like 75% of max torque on those diesels. So, if my 455 develops max torque at, say, 3200 rpm, then a torque converters best stall would be in that range - 3200 rpm. Does that mean that a car would not "creep" forward at idle?
A 3200 stall is a very aggressive converter, a stock switch pitch stall speed as mentioned before is 1400/2800. a 3200 stall speed would be harsh on the street as the power applied to the transmission would start to come in at a very high rpm, thats good if your at the strip or if you want to snap your neck every time you take off but not so much on the street. With a S/P you have some control, at low stall you car will be smoother in stop and go traffic but if you want to get into your power band you can kick it to high stall and have a much harder launch.
I'll tell you about GM 5.7L diesels and SWP. I don't know max torque, but when getting started I'm looking for max HORSEPOWER. It doesn't take huge horsepower to move a car around town. But because the cars were geared the same as gas engines, the engine couldn't get into its power till over 30 mph, no wonder they were such slugs. I put in a SWP trans which allowed more rpm and torque multiplication instantly: it positively TRANSFORMED performance in town, and helped in the 45-60 mph range as well. The modulator vacuum input, I fed vacuum through a stock vacuum "switch" on the throttle linkage, seemed to work fine. Bruce Roe
