1968ragtop

I have a th400 with the short tailshaft and it is a switch pitch. I've had it sitting around for years, I'm just wondering what this trans would have come out of originally? and if this is a rare peice or not? Thanks for any info!

jensenracing77

if you get me the tag ID i can look it up for you. i think they were only available in 65 and 66 and i think only in cars like the starfire and super88? according to my info, they stopped making them because of the manufacturing cost and the public was not that interested in it to make it worth the extra money.

Rickman48

Had a '65 Jetstar I with it and a 4:33 'towing package'!
Came out so hard, broke the frame in front of the RR wheel!

TripDeuces

Olds, Buick and Caddy used them. I don't know all the models that used it but my 65 Riviera had one. I'm putting one in my 66 Cutlass this spring.

made in the usa

67 delta 88 425 has one is what I'm told. Actually haven't got around to servicing it yet to find out.

TripDeuces

Found this nifty page that will answer all your questions. Jim Burek is the guy who rebuilt my S/P converter for me.

http://www.buickperformance.com/switchpitch.htm

BILL DEMMER

yes, they were available in '67, in the b & c body cars.


bill

blueRAYwhale

my guess...mid to late 1960's buick or olds., they were popular. buick used it behint it's le sabre in '69 when ordered with a 350.

toro68

As far as I know , the switch-pitch is pre 1968.
I just want to put this out there, a fellow in the Olds & Toronado club,
Bruce Roe, offers a electronic shift kit, for the switch-pitch units.

TripDeuces

Any more info on this kit from Bruce Roe?

Oldsmaniac

Not so rare but the short tail turbo was used in the Olds A bodies while the long shaft was a fullsize or B body piece with BB. Optional in a Jetstar SB. The B bodies had them in 65 to 67 and I think the switch pitch was tossed for 68. Note that the Turbo 400 was not available till 1967 in the A bodies/442 and was also an option in the Vista Cruiser in 67 and manditory on Turnpike Cruisers. I am not sure about the other GM A bodies as far as the Turbo 400.

blueRAYwhale

about five years ago i had a shop rebuild what i was told was a TH400 out of a '74 olds. H/O. it had a short shaft and i wanted to install it in my '76 supreme. it took these guys like six months to do the rebuild for whatever reason(s). i remember them saying that it had a variable something or other and they had to replace the front pump with one that wasn't, that kind of stuck in my head. i owned a '63 buick with a dynaflow, it had a variable pitch convertor, not sure if it operated like the one they were rebuilding, thats not my point. so i get this trans., install it and it's leaked fluid since day one(from behind the convertor). i know this because i thought maybe it was a pan leak, it aint. so i see this metal tag on the passenger side of the "74" TH400. i use the tans. ID reference catalog at the local library. tag has a big "B" on it, it isn't an olds. trans., maybe it was in a H/O, didn't start out that way. the rest of the decode info. broke down into: 1969 LeSabre Custom w/350 4bbl. carb.(aha), so i'm assuming based on this info. that a variable pitch TH400 was available in '69. also remember the shop telling me that the two prong electrical kick-down connector needed to be swapped out for the single one. it did have a short shaft, so did buick use that in a b body, would have made for a longer driveshaft, don't know. did someone change the output shaft, not the pump, keep the factory elect. connection and install it in a '74, don't know. one thing i do know is i got hosed hard on that because it's been leaking fluid since day one and it will probably have to be removed and pulled apart by someone who knows alot more about those things than me. will i go to an ATRA trans. shop to have this done? yep. will i stick it back into my olds.? no, because i have a med. shaft TH400 they are going to convert to a short, it came from a olds. i'll have them put that in there, keep the buick one for later, maybe. after i get this done maybe the trans shop will have additional info. on the origins of this mystery trans, who knows?

1968ragtop

I pulled out my switch pitch trans, here's the id # on the plate of trans:

283
BT-67-40857

blueRAYwhale

hey, 'sup. i'll go see if that book is still over at the local li-berry. if it's there and covers that year i will post the info. here. nice car too.

TripDeuces

BT =

1965 - 425 w/ 3.23 axle

1966 - 425 except Riviera

1967 - Wildcat, Electra or Riviera

All Buicks

1968ragtop

This particular th400 switch pitch has a short tailshaft, probably less common! Is it easy to find a shop to rebuild these trannys? and are they very expensive to rebuild? Thanks for any info!

jensenracing77

X2
as far as cost to rebuild, my local transmission guy said it is the same price as a regular 400. he said the front bearing was bigger but the price was pretty much the same. he said the torque converter would be a little more.

TripDeuces

Guess what just came UPS? My new trans pan for my TH400 S/P, lol. I'm putting it in this Spring and wanted to get rid of that gaudy chrome pan. So I got a new aluminum one.

http://www.yourcovers.com/transpan_9591.php

blueRAYwhale

BT 67= 1967 buick, 430 motor, those models listed. 40857 are seq. pro. nums. 283 are week/shift nums. it's easy as looking in the yellow pages and finding an ATRA cert. shop. they aren't very expensive, about $550.00. i used the stock sized toq. conv. out of a '73 98, it had 81,000 miles on it. works fine, don't run hot, factory idle in drive with aftermarket cam, don't have to stomp the brake pedal at a stop light. hits the factory shift points, don't need a cooler and has all the vacuum stuff. i did install the big 4-core radiator/7-blade fan/HD clutch/deep shroud though.

1968ragtop

I talked to a trans. shop to rebuild the switch pitch, the guy said some of the parts may be impossible to find. What parts are different on the switch pitch? Are some of these parts hard to find? Are they more expensive?

TripDeuces

Front pump, input shaft?, converter are all different from the normal one. You'll also need the two prong plug vs the one prong. Not sure what else is different. That link to Tri-Shield should help answer your questions.

Rickman48

Not so - '66 396 SS Chevelles had both the powergide and T-400 as options, up to 350 HP.
L-78 was 4-speed only. [375 HP]

blueRAYwhale

i see one or two of the 1960's full sizers out at the local pic-n-pull every year. i'll keep my eye out for a vari-pitch TH400, if that'll help ya'. who knows maybe ship the whole shootin' match out. alot of these cars are in there because of the high recycle value, and the cost of fuel. otherwise they are in fair shape. so the sixty or seventy dollars for a used trans. with low miles that still works might be worth the cost.

TripDeuces

They should be easy to pick out because they have the 'heel' pattern on the pan where the pickup sits along with two dimples.

blueRAYwhale

cool hand luke right...great movie, oh yeah i'm supposed to be replying about transmissions.

bigpink7752

i am a little confused. I have a 67 442 and understand that it has a switch pitch converter and a TH400. I am in the process of changing the engine to a modified 455 that will produce 475hp/525ft/lbs. From what i have read switch pitch converter is a sought after device especially by drag racers. My first concern is durability behind the extra power and does it really offer some advantage over a standard converter. i also am given to understand if i convert to a standard conveter some parts on the front of the TH400 will have to be replaced as they do not fit a standard converter. please offer commnets.

WTony

The 67 th400 in the 442 is the more sought out piece because it has the speedo drive in the tailshaft. Google switch pitch th400. There's a few good articles that I had saved on my old computer about them. I ran one in my wagon with a 400hp 455 and it held up well. The Bruce Roe control box is also a plus. My opinion is use the stock rpm stall sp converter with the Bruce Roe control box. It works well and stalls when it should, making the trans almost like a 4 speed auto. With a higher rear gear (2.56 or 2.78), it does feel almost like an overdrive trans when the converter switches from high to low stall after its in 3rd.
I sold my spare rebuilt trans to a friend a few years ago with a Bruce Roe controller. He is not going to use it now. If anyone is looking for one I can get you in contact with him, he's in Boston now.

oldcutlass

The short shaft SP T400 was an A body trans in a 442 or turnpike cruiser equipped with a 400CI engine, I think for 66 and 67 only. A very durable trans, not that complicated and most parts are still available. It's not hard to hook up, you just need the throttle linkage out of a Cutlass or 442.

Rocket Richard

I have a 66 Dynamic with the S/P trans. Can anyone explain what this electronic shift kit does?

67Olds442X2

http://www.442.com/oldsfaq/oftsp.htm

Info here.

I got parts to convert to S/P. Had to remove them to put in an aftermarket converter. i.e. pump etc.

Rocket Richard

Thanks. I didn't see anything in there about a shift kit though.
But from what I've read now, I bet the shift kit would allow you to hold the high stall pitch for a bit when accellerating in 1st gear, instead of going straight from high to low as soon as you put your foot down on the gas. It probably wouldn't be too difficult to rig up the switch on the throttle linkage to do that.

Just curious, does anyone know if the switch pitch will only work at high and low pitch? Could it ever operate at more than two pitch settings?

EDIT: ...wrote this before seeing 66luvr's reply. Thanks.
Yes, I can see a few options for controlling the switch of pitch in 1st gear. The timer is an option. My idea above might not work so well when dealing with the other gears.

joe_padavano

Since you guys have resurrected a two year old thread, I'll correct a few mistakes. First, the SHORT TAIL switch pitch TH400s were only used in the 1967 A-body cars. The TH400 was NOT an A-body option in 1966 or earlier model years.

Second, the "switch pitch" function simply uses hydraulic pressure to change the angle of the stator blades in the torque converter, which changes the stall speed. Low angle gives low stall speed (about 1200-1800 RPM, depending on the engine) and high angle gives high stall speed (around 2400-2800 RPM). The higher stall speed also provides more torque multiplication, thus the use of this feature to provide an extra "passing gear" (despite this not actually being a separate mechanical gear set). The stator blades are either high or low, there is no ability to have any intermediate position. The solenoid is either off or on, so hydraulic pressure is either off or on. It's completely binary.

There is also no effect on the converter possible from any shift kit. The solenoid is controlled by the application of an external +12V, just like the kickdown. The only thing that controls when the stator vanes move is whether power is applied or not. Period.

Rocket Richard

Just wouild like to understand this better. With a "shift kit" if you get the high pitch to remain on by providing 12V to the switch pitch solenoid for a certain period of time from stop to go and onwards, how are you not affecting the converter during this time?

I'm assuming this is what a shift kit would do.

TripDeuces

A shift kit would have nothing to do with the torque converter, it controls the firmness and quickness (gear overlap, or transition from one gear to the next) of the gear change.
As Joe stated the 'Switch Pitch converter' is controlled by applying 12v to a solenoid. It's either on or off and has nothing to do with a shift kit. Now if you're referring to the Bruce Roe kit that's a different story. It's sole purpose is to control how the converter operates at different speeds and different times.

oldcutlass

No a shift kick effects the way a transmission shifts thru the gears and controls the pressures to accomplish that task, has nothing to do with the converter. Think of the converter as nothing more than a hydraulic coupling device. The SP function effects the stall speed of the device (slippage) and at what RPM it couples completely.

WTony

One other thing a guy named Mark DeConti from the Buick Performance Group forum told me to do, and it made ALL the difference in the trans and the way it shifted was to change the valve body to a 69 or newer valve body. For some reason my trans with the original valve body and a shift kit did not shift hard at all and it would short shift 1-2 and 2-3. After contacting him he told me to swap out the valve body and wa la. Instant difference.

At the moment I cannot remember what the difference in the valve bodies were or the reasoning he gave me to do this. But after reading this thread again remembered that he did in fact tell me to do this.

FOUND the article!
http://www.buickperformanceclub.com/SPTrans.htm

If you need more info about it you can contact him on buickperformancegroup.com he goes by dcm422.

Oh, I found him because he wrote a tech article about the SP trans's and how they function. Found him by googling his name and found the articles by googling SP TH00.

Here's an easy wiring diagram that can help you out if you'd like to hook your sp to the brake light switch.
http://www.hotrodhomepage.com/hrhp/2...iring-diagram/

And another I had saved.
http://www.hotrodhomepage.com/hrhp/2...the-overdrive/

Rocket Richard

OK, thanks guys. Seems that I was understanding it correctly, but I didn't know the terminology.