my gearing will be now 3.70, and weight will drop to around 3800 # :grin: (big deal) I talked to some people about the switch pitch behind my engine and all of them said i was running too much HP to use any switch pitch, so im going to run a Coan in the range of 3800. The car is a street/strip, or else i would be getting something a bit higher.
Man....its such a tough choice for me. For me with 3.55's and a GV overdrive when I engage it its like having 2.73's so a switch pitch would be great. But...I dont like the fact that there is so few builders of these trannys. So if I buy a PAE TH400 and it gets hurt....most shops dont know jack about them. I was considering a tight 10" Continantal converter Jim Hand model.He said its real tight under its stall range but will flash 3200 behind his 455 powered 3900lbs wagon. So...behind my 3200lbs 408 Camaro its should feel pretty tight and flash maybe 3000 or so. Its tough..I am still on the fence!
Why do guys talk about a switch pitch like it is a totally different transmission. It's a 400 with a special front pump and input shaft, and of course, the converter. Anybody that can build a 400 can build a switch pitch. There is a passage in the case that has to be restricted. That's really it. The rest of the trans is the same.
I here ya on that Larry....but when I call around to shops asking about switch pitch TH400's or converting them to s/p they want nothing to do with it!I know for my combo the SP400 would be great...I just wish more local builder felt more comfortable with them.
I think if you explained to them that it was a THM400, they would have no problem. Like I said, the rebuild procedure is identical, except for that plug in the case. Converting them is something else, you need the parts (pump and input shaft)
i believe theres differences inside the valve body also, some parts that control shifting were changed to make it downshift under harder conditions (because the stall would go up) or something. Im aiming for over 700, but im guessing it will end up being in the 675 range.
If you put a shift kit in the tranny, i think that is all you would need to make it shift half decent. There maybe some minor changes, in the SP valvebody for shift points but as Larry says there all the same otherwise. My tranny builder laughed when i said i want to use a SP for racing also.
yeah, i was just figuring, if your transmission rebuilders over there are like some over here, they always want to put shift kits into it because its going in a classic car. good thing were doing this on our own. I called PAE and asked them about running the switch pitch for my engine and they said it wouldn't hold up under the conditions.
Thats very interesting, it wont hold up to 5-600 hp, i plan to put about 800 hp behind it and 650 ft torque, and was told not too worry.
It sounds like your combo would be best with a fp. The difference in recommendations may be based on the weight of the vehicle. The vp puts alot of load on the thrust bearings as the pitch angle and torque-level from the engine gets higher. This may be exacerbated with a heavier car. At the higher HP levels (big cam), the high-stall SP converters are inefficient in high-stall mode and are a band-aid to allow street use. A quality FP will give you a better ET at the strip almost gauranteed. In milder combination with a converter not having the pump modded for the extra stall-speed, the SP makes an excellent street/strip setup. If the pump has been modded along with the stator piston, I would pass. Also look for furnace brazed fins, and not the cheaper mig welded ones. Jim at PAE and Jim at TSP are both good resources with contrasting views on the subject. Do your homework and make up your own mind.
On my turbo v6 application, i really don't have any choice. Too tight the turbo doesn't spool too loose less hp gets to the wheels. A fixed pitch design would be a compromise between high stall with probably high slippage also. WIth the SP i really can choose between cruising around town and launch off the line with full boost.