727 front servo piston ?

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flathead31coupe

flathead31coupe

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while taking apart the sb tci
727 I noticed that the front servo had a much larger rod coming out, to push against the band lever. than my stock bb one... after taking it apart I noticed that the bore in the sb case is much larger dia.. is this a mod that was done at tci, or?
 
.............up to 1970 the front servo had a small rod.....1971 came with the much larger rod and the controlled load servo.....they interchange so I don't think the bores are different size........kim......
 
^^^Correct^^^ I have interchanged them so I'm sure the bore size is the same.

I wonder if you didn't pull all of the components out of the BB trans making you think the bore size is different??

BTW: from a performance standpoint the older servo is considered the best, although I believe the newer model can be modded to work like the older unit
 
fishy68 said:
^^^Correct^^^ I have interchanged them so I'm sure the bore size is the same.

I wonder if you didn't pull all of the components out of the BB trans making you think the bore size is different??

BTW: from a performance standpoint the older servo is considered the best, although I believe the newer model can be modded to work like the older unit
Click to expand...
Thanks you were correct...didn't pull all the assy out.
 
The early servo had the capacity to use two return springs of several different spring rates to adjust 2-3 shift timing. There were 20 lb/in inner and 45 lb/in inner & outer springs. Typically to get the best performance with a high pressure valve body you would use two 45 lb/in springs to achieve a clean 2-3 shift. Torqueflite Patty on Ebay has a large inventory of Torqueflite parts. Concerning the later controlled load servo with the large 5/8" rod, you can disassemble the inner cushioned piston and make a shim to fit between the inner piston and small snap ring to allow a more solid action. The small inner spring is discarded. A&A trans sells a special "Red" spring with a higher spring rate to help band release during the 2-3 shift. They also sell different kickdown band levers depending on your application. Hope that helps a little. John
 
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