Re: Re: Changing Trans

Posted by Bob on March 30, 2004 at 20:24:18 from (66.163.134.177):

In Reply to: Re: Changing Trans posted by tortmort on March 30, 2004 at 19:31:42:

The 700-R4 needs no electronic control. All it needs is a manifold vacuum switch fed power from a brake switch to provide power to a pressure switch in the tranny that allows lockup when the tranny is in 3rd or 4th (or 4TH only, if desired), and the engine load is low enough to allow lockup, and your foot is off the brake.

The 4L60 is a newer, "improved", version of the 700-R4.

The 4L60"E" transmission, however, is the newer, electronically controlled version of the 700-R4. This tranny requires either the OEM powertrain mangement computer to be adapted, or there are stand-alone aftermarket computers to operate the 4L60"E".

The 700-R4 is a longer transmission than the THM-350, but the rear mounting flange is the same.
If you find a 4X4 version of the 700-R4, you may be able to cut enough off the splined output shaft to make it work, or you will need a simple spacer to go between the 700-R4 and the transfer case mounting adapter. You will have to move the cross member back, and probably will have to lengthen the front driveshaft and shorten the rear driveshaft. Be sure of your driveshafts' position in their slipyokes after the conversion. If a shaft is too short, it may fall out of the slipyoke under conditions of severe suspension travel, and if the shaft is too long, it will bottom out in the slipjoint when the vehicle suspension bottoms out, probably breaking the transfer case or the transmission case.

With any 700-R4 conversion, getting the angle between the mount for the TV cable and the thottle shaft right is CRITICAL for tranny life, as well as setting the length of the TV cable. This transmission shifts, and controls it's line pressure totally off of the TV cable input. There is NO vacuum modulator like theTHM-350 uses.

Some carburetor or intake manifold manufacturers have TV cable adapter kits available to get this right, and I believe a search of the archives on this site may turn up some posts on this.

Depending on whether or not you want to keep the Blazer's original cast-iron transfer case, you could also swap in the newer aluminum transfer case, and no adapters would be needed... just correct the length of the driveshafts, and change the transfer case shifter.

Follow Ups:

• Re: Re: Re: Changing Trans Dan / NM 22:00:37 03/30/04 (1)
  • Re: Re: Re: Re: Changing Trans Bob 06:16:33 03/31/04 (0)

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