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The purpose of an Automatic Transmission is similar to that of a manual transmission, the auto tranny's primary duty is to allow the engine to operate in its narrow range of speeds while providing a wide range of output speeds.
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'87 700r4 upgrade to '96 4L60E

September 7th 2008, 4:36pm

i bring this question to you guys whom have done such before and whom are more in-depth in such matters as i...
i do not have all the parts here with me right now yet i have some questions.
i can obtain a '96 4L60E trans for $100 and i can have it rebuilt for $75, but..is this what i want to do???
I have a '87 astro sport with a '96 roadmaster LT1 [staggered roller rockers; 1.5" on the Int and 1.6" on the Ext, for torque (got to get the old out before you can put the new in)]. I want the ECM/PCM to work at doing what it does.
My delimma..i want the speedo in the original van to work with my new trans ..if i get it.

can i swap the old tailshft and install on the new trans for correct cable driven speedo or does the pcm/ecm also take info from the digital signal for efficency too?

like i said i dont have the trans yet...so i dont know...do you? and do you know what i am talking about?

Re: '87 700r4 upgrade to '96 4L60E

September 7th 2008, 11:08pm

i have collected this info and shall share..
1996 4L60E has 4 bolt tail shaft, '97 and above 4L60E have 6 bolt tail shaft. the 700r4 has a 4 bolt tail shaft.
hmmm you would thunk that one could put a 700r4 manual cable driven tail shaft on a '96 4L60e trans.

now comes another dilemma...
what can one do about the VSS on the 4L60E? is this going to be a problem with the PCM/ECM? the plastic gears for the speedo cable in the tail shaft are at Raptor, if you have aftermarket road huggers.
Last edited by WDMICKJR on September 8th 2008, 12:27am, edited 1 time in total.

Re: '87 700r4 upgrade to '96 4L60E

September 8th 2008, 12:25am

here is a lot of help...and i have answered my own questions. yet i will post to save someone some trouble if they ever have the same application:


this has answered some questions about earlier manual cable speedo when your trans using VSS (instead of closed loop) to help yout LT1 or TBI computer controlled PCM/ECM engine trans package run like the factory intended.

sorry about the duplicate posts of same topic. the moderators of astrosafari.com may want to fix my error.

happy motoring..your mileage may vary
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