Toronado.org

The email system doesn't seem to work anymore --my messages are stuck in the outbox as best I can tell.

Otto:

According to the parts book, the kickdown switch should be the same for 66-67. Not surprising to me. There seems to be one also intended for heavy duty trailer use with the toronado.

Basic Part number, kickdown switch, 66-67 Toronado: 392983
for H.D. trailer use: 395081. This is mounted on engine near firewall, driver's side. The two wire connector goes down and around to the transmission on the passenger side.

Couldn't find your message on this, but had notification on my email, so just responded here.

I know earlier you were posting about the switch pitch. I thought that it was this kickdown switch that you had pictured. I know some of the Toros must have been sold with the optional switch pitch, but I haven't seen one. I imagine the torque converters for those are hard to find and the originals must somehow be repaired.

Doc Hubler wrote: Otto:

According to the parts book, the kickdown switch should be the same for 66-67. Not surprising to me. There seems to be one also intended for heavy duty trailer use with the toronado.

Basic Part number, kickdown switch, 66-67 Toronado: 392983
for H.D. trailer use: 395081. This is mounted on engine near firewall, driver's side. The two wire connector goes down and around to the transmission on the passenger side.

I know some of the Toros must have been sold with the optional switch pitch, but I haven't seen one. I imagine the torque converters for those are hard to find and the originals must somehow be repaired.

Switch Pitch wasn't optional. EVERY big block Cad, Buick, and Olds 65-67 TH400 or
TH425 trans was a switch pitch. There were also a lot of smaller 2 speeds built, using
an interchangeable torque converter. The feature was dropped in 68, but it is still very
popular today with a fair amount of support. Rebuilt and strengthened torque converters
may still be had. A lot of different switch pitch controls have been devised, including
electronic. Bruce Roe

Can you please provide more info. I did read that the two wires indicated Switch Pitch. But how are the vanes on the torque converter controlled? They replaced mine, so I'm concerned it won't work properly (or as well as it should). I think those are not available, but have to be rebuilt.

Here's the Heavy Duty Switch Pitch that Olds Obsolete has for sale. Pretty pricey! http://www.oldsobsolete.com/products-pa ... os-395081/

That's crazy! Those guys don't seem to be too anxious to sell their parts!

What is different about the heavy duty switch? Different shift points or something?

It activates the vanes differently somehow. I'm not sure. wish I could understand this better on the transmissions, but I've never seen a clear explanation. There must be some clear explanation somewhere.

I don't know, you might think that this would be $150 or so for a NOS switch of this type. But if there aren't many or any out there in that condition, I'm not sure it's unreasonably priced. I bought some NOS door edge guards from them. They are perfect and in the original package. I would easily have spent that in time/money to try and straighten the old ones. I'm happy with my purchase. Truth is, there is not much of this NOS stuff out there. For the few people that want to keep their Oldsmobiles in authentic condition, small price to pay. Everything seems shockingly expensive these days though.

Doc Hubler wrote:Can you please provide more info. I did read that the two wires indicated Switch Pitch. But how are the vanes on the torque converter controlled? They replaced mine, so I'm concerned it won't work properly (or as well as it should). I think those are not available, but have to be rebuilt.

Here's the Heavy Duty Switch Pitch that Olds Obsolete has for sale. Pretty pricey! http://www.oldsobsolete.com/products-pa ... os-395081/

If you are bent on originality, you can buy that NOS part. If you can keep it adjusted,
it will give service as good as the original, which means it only benefits you at idle
and near full throttle. Or you could spend one fifth that money on an an intelligent
control, that will benefit your entire driving range.

All TH400/TH425s have a lower (vertical) terminal wired to switch kickdown contacts.
There are 2 wires to transmissions made around 1972, adding an upper (horizontal)
terminal, but the addition is part of an emissions control system. It changes spark
advance depending on what gear the trans is in.

2 wire connections used on 65-67 use the upper terminal to control the switch pitch
function. With no power applied to the upper terminal, the torque converter reverts
to it low stall (economy) operation. When the switch applies 12V to the terminal, a
solenoid inside the trans pulls in and sends oil pressure to a hydraulic piston about
the size of your little finger. It change position and controls oil pressure through an
extra passage in the (rotating) input shaft. The shaft goes inside the torque converter
and operates a piston several inches across. The piston changes the angle of all the
vanes in the stator (third element) of the torque converter, selecting the performance
mode. The stator redirects the converter pump oil (at lower rpm) to produce more
torque out at the turbine than was put in at the pump; hence the name torque converter.
At high rpm the torque multiplication gradually goes away, and it becomes a 1:1 fluid
coupling.

The advantage of the performance mode, is it allows the engine rpm to rise to its
power band much faster, and provides more torque multiplication than a fixed converter.
It can be used to reduce the need for downshifting, and to smooth shifting. It reduces
creeping at idle, and the economy mode probably adds a point or 2 to fuel economy
over a fixed, compromise converter. Some dispare of driving a straight 3 speed and
convert everything to switch pitch. Bruce Roe

What about replacement torque converters? What do people use for that if they convert to switch pitch? Where do they get them? Or do they rebuild old ones?

Doc Hubler wrote:What about replacement torque converters? What do people use for that if they convert to switch pitch? Where do they get them? Or do they rebuild old ones?

I think the shop suppliers might still have them. If you can find a switch pitch
trans (seen on EB*Y), it ought to have one. And there are other sources. I have
dozens of 13" which I'm seeing about getting furnace brazed and rebuilt, have sold
a couple.

While its not too hard to drop the switch pitch pump assembly into many later
TH400 transmissions, you just about need the entire trans for a Toro/Eldo/GMC.
67 Eldo is already switch pitch; all the other 425s are interchangeable BOP pattern.
Bruce Roe

Hi Bruce.

I would like your opinion of the usefulness of the rubber and insulation cover that normally goes on the chaincase of the TH425.

I know that I have read that it is useless and should be thrown out.

Since you have a comparatively vast amount of experience with these transmissions, do you agree?

If you have run your cars without the cover, can you hear the chain?

On another note, Can a Switch Pitch be made to operate in a sequential mode to act like a 6 speed transmission? I have read your controller info, but am still a bit unclear on how it operates and if it can provide a sequential function.

bluecab wrote:Hi Bruce. I would like your opinion of the usefulness of the
rubber and insulation cover that normally goes on the chaincase of the TH425.
I know that I have read that it is useless and should be thrown out.

Since you have a comparatively vast amount of experience with these transmissions, do you agree?
If you have run your cars without the cover, can you hear the chain?

On another note, Can a Switch Pitch be made to operate in a sequential mode to act like a 6 speed transmission? I have read your controller info, but am still a bit unclear on how it operates and if it can provide a sequential function.

bluecab, Every one of those covers I have seen was an oil soaked mess. Only
the early cars even used them. I have never heard the chain, and don't see any
reason to use that cover. Reminds me of the timing chain set with the plastic
teeth "to suppress noise"; I have never heard an all steel chain set; think the
real reason was so more engines in old cars will fail some day and you would
HAVE to buy a new car.

The SWitch Pitch function can be activated from low stall "economy mode" to
high stall "performance mode" in any gear. However, I haven't heard of anyone
alternating it for each gear; doing so automatically would be difficult since the
2 functions would need to be synchronized to gear and rpm. I have doubts
whether that would be desirable.

The way I use SWP is to allow the engine to reach into its power rpm range more
quickly, while the converter increases torque multiplication. This can be used
from launch, or after slowing for a curve, etc. Gets you going faster, sometime
avoids the need to downshift. I like to run through the gears (using a timer) in
high stall to get going, and also to considerably smooth the shifts. Then cruise
in low stall economy mode. People who race may have other ideas.

Here is my flow diagram. Bruce Roe