Technical Building a Switch Pitch th400

Going out to the yard to look at a 65 olds delta 88 with a switch pitch 400. Decided on a auto trans. Guys on the Buick forum tell me I can build a switch pitch in a 70's th400 case. At the yard do you advise I take the whole transmission or just the desired parts from within it like the torque converter, front pump, etc.

Thanks Guys in advance.

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Also why is the 66 & 67 switch pitches desired over the 65? Should I hold off for a 66/67

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http://www.442.com/oldsfaq/oftsp.htm
'65 was one year only filter

 

That web page is slightly flaky, but it's a good general introduction.

I'd get the complete transmission. The speedo gear fitting...hmmmm....look to see if it has a cable at the back of the transmission. There is an orifice pressed into the case at the front, where the pump bolts on, that needs to be there for the SP to work. It will be in the original case, but not in a later non-SP case. You can make an orifice, or possibly buy one, but it's kind of difficult to remove one from a case without destroying the orifice or the case.

 

I'd say take the whole thing, you never know what little part you may end up needing.

 

The Olds trans of that year has no provisions on the case for a speedometer drive. I never took one apart to see if the shaft had the machining for a gear. If it does you just need a tailshaft case that will accept the drive. If not you might not have a speedometer. The speedometers in those cars drove off the front wheel. I always thought that odd, only GM car to do that at that time.

 

No other options for a speedometer? Like something digital?

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You can use a gps

 

You could bore the case for the speedometer adapter, but it would be pretty tricky to set it up...

 

Im a hold off for a 66/67. It's a long drive for me plus the website online shows the delta 88 being there since June this year. I called twice they said they junk everything in 30days. And some lady told me the maybe so I'm just going to hold off. Thanks for the help and know I know a little more because I'm still hunting one down.

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Hey guys will this b&m shifter go with the sp th400. Guy says it was off a 3 speed 68 camaro

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hard to say, since the parts that are specific to that transmission are at the other end of the cable!

 

Ok, this cable?

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All TH 400 trans use a gear for the spedo the case is the same for the switch pitch valve body and front pumps are different I have converted chevy trans to a switch pitch unit by valve body and convertor

 

Bought an L-78 1968 396, and an Olds 425 engine, with a switch pitch. Put the Chevy to use, and sold the Olds setup to a friend with a 2 door 1964 big Oldsmobile. 88 ? 98 ? Starfire ? Can't be certain.

I never could understand his explanation as to why the setup was so desirable. I'm a manual transmission guy. That car hauled ass. It would not pull the wheels, but it sure did have lots of front wheel well ... like it was trying to.

High 13 second quarter mile times, for a Mondello/Crower parts 425 and a switch pitch ... in a big f#k'n boat, reversed rear wheels. Always seemed like voodoo magic to me. Still does. Switch pitch ?? ( wtf ) Steve and Mike, two Oldsmobile nuts, from Papillion, Nebraska, that were lucky to be born brothers. Wish I still had their info. Good times.

 

I always thought modern torque converters retired the switch pitch.. Would be cool to have one..

Did they come in 442s?

I'd use a Hurst Autostick shifter with that tranny..

 

What shifter style is the one I have pictured for?

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Would i have to be banging into 2nd and 3rd all the time? With the b&m

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That's a Hurst Autostick. It had a very positive gated side.. There not cheap but worth it..

 

except the 60s Oldsmobiles, that have the speedo cable running to the front wheel, and no hole in the case for the speedo gear. Seriously, they did make them like that!

The shifter with the cable with no hardware on the end of it...yeah, if you get the bracket and lever, then it should fit the TH400.

Modern converters have retired the switch pitch. but the switch pitch still works, and they're still fun.

 

Can't be too hard, that's what we did when we put a 67 425 and switch pitch in this car in the early 80's. May not of been pretty but I don't remember any leakage issues, transmission is still here somewhere...

 

Switch pitch wasn't used in 442's this was a full size car transmission only

 

Switch pitch was used in mid size cars, mostly with the ST300 trans, and mostly in Buicks, I think.

 

What makes a switch pitch so special? Sorry, I’ve never heard of this. How do they work? Thanks guys.


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I’d like to know as well


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The torque converter in a SP transmission has moveable stator vanes. The "pitch" of the vanes is variable. It can be switched from low from high angle, so the stall speed of the converter can be switched.

This design was used in the 400 and the 300 two speed transmissions, only in the mid 60s, and only in some buick, olds, and cadillac cars. The parts of the 400 that make it work, include the torque converter, front pump, input shaft, and an orifice in the case. These parts can be installed in later TH400 transmissions, with some limits--the passages in the case that make it work were no longer included in the case starting some time in the late 1970s

The converter used in the 400 is a 13" unit, that used in the 300 is a 12" unit. They can be interchanged, so it's pretty common to use the smaller converter in the bigger transmission. And the converter can be modified, to give more stall. There have been several companies over the years that have done this, they are mostly Buick muscle car guys though. And they don't all work the same...some converters are really "loose" in high stall, others are not. I've had 3 of these converters that have been built by different companies, they each have their own peculiar characteristics. Typically you will get 1500-2500 in low stall, and from 2500-3000 in high stall. Getting it to change more than 500 rpm when you switch it is the trick, and only one of mine was able to do that.

But modern torque converter experts can build a non-SP converter to work almost as well as an SP, so the whole switch pitch thing is mostly obsolete technology. That means it's perfect for building a period correct street/strip car.

 

Thanks Squirrel, I really appreciate your explanation and knowledge


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See this guy. He'll put together a near bullet proof "switch pitch" for you. Even knows a cheap and very easy way to make it a manual trans., that can be changed back to an automatic in about 4 minutes.
http://www.kilgoretrans.com/

Mike

 

You need a bullet, before you need bulletproof A mostly stock TH400 will hold up to a lot.