General Motors transmissions
m (→TH350, TH400, manual speedometer gear ID) |
(→Switch Pitch: add text; minor cleanup) |
||
| Line 1,440: | Line 1,440: | ||
===Switch Pitch=== | ===Switch Pitch=== | ||
| − | + | There are SP 400 and SP 300 transmissions. The name "switch pitch" comes from the vanes in the torque converter being able to change their angle (pitch) in order to increase the stall speed to get the vehicle moving easier. | |
| − | The | + | ====SP 300==== |
| + | These were found in 1964-'67 and were two-speed. The SP 300 converters are 12". Olds called it the '''Jetaway''', aka the '''Super Turbine 300'''. | ||
| − | + | The ST300 had a three element torque converter, a front and rear multiple disc clutch pack, and a compound planetary gearset with a front band and a clutch pack for reverse and manual low gear. The unit was cooled with a small auxiliary ATF cooler located beneath the engine radiator. It had an aluminum case and weighed 152 lb. | |
| + | |||
| + | It was designed to start in low gear, providing a gear ratio of 1.765:1 plus the additional torque multiplication provided by the torque converter. The shift pattern was P-R-N-D-L. In Drive at full throttle, it would upshift from low gear to high gear at 60–65 mph. | ||
| + | |||
| + | From 1964-'67, Buick and Olds versions of this transmission used a torque converter with a variable-pitch stator called Switch Pitch by Buick and Variable Vane by Olds. The stator blades changed pitch by an electrical solenoid and a stator valve, controlled by a switch on the throttle linkage. At light to medium throttle, the stator blades were at 32°, providing a torque multiplication of 1.8:1 and a converter stall speed of approximately 1800 rpm. At ⅔ to full throttle, the blades switched to the 51° high stall position, giving torque multiplication of 2.45:1 and a stall speed of approximately 2300 rpm. The blades were also set to the high position at idle to limit creep when stopped in Drive. The variable pitch stator was eliminated after 1967. This feature was not used on the Pontiac versions of this transmission. | ||
| + | |||
| + | ====SP 400==== | ||
| + | Switch Pitch (SP) 400 transmissions were available from 1965-'67 in full size Buick, Olds and Cadillac cars. Torque converter diameter is 13". | ||
====SP ID==== | ====SP ID==== | ||
| − | The easiest way to identify the SP is by the pan shape shown below, right. On the SP | + | The easiest way to identify the SP is by the pan shape shown below, right. On the SP 400, there are 3 concave and 1 convex dimples and a 'shoe heel' impression. The shoe heel impression is where the filter picks up fluid and the pickup is shaped just like a shoe heel (see photo above right). Filter is a Wix p/n 51879. |
[[File:Th400SPpan.jpg|right|260px]]<br style="clear:both"/> | [[File:Th400SPpan.jpg|right|260px]]<br style="clear:both"/> | ||
| − | The SP transmission has a two-terminal electrical connector on the driver side of the case. The top terminal is for the SP converter: applying | + | The SP transmission has a two-terminal electrical connector on the driver side of the case. The top terminal is for the SP converter: applying 12 VDC to it caused the converter to go to the higher stall setting. The default no-power position is low stall. |
| − | The lower terminal is for the kickdown solenoid. | + | The lower terminal is for the kickdown solenoid. It's operated from the gas pedal or from a switch at the throttle arm of the carburetor. |
| − | *[http:// | + | *[http://www.buickperformanceclub.com/SPTrans.htm Buick Switch Pitch Transmissions |
| + | *[http://www.buickperformanceclub.com/switchpitch.htm Itching for a Switch Pitch Transmission] | ||
====Converting TH400 to SP==== | ====Converting TH400 to SP==== | ||
Your Privacy Choices