TH400 questions

[77crewcab]

I need a little help here. My truck came with the th400 and a 350. The PO put in a 454 and for some odd reason a 350 trans with 6 or 9 inch tailshaft (haven't actually measured) Since the 350 is slipping like crazy I have decided to rebuild a 400 to put back in and that is where the problems start. The 350 has a slip yoke and I am told the 400 for a Crewcab 2wd has a bolt on yoke. Also that they would use a different u-joint. How can I determine what size u-joint is needed? I belive it would be the 1310 but am not sure. I also need a way to determine if the yoke on the drive shaft would have to be replaced, or the shaft lengthened/shortened. Since this is the 2 piece shaft I am hoping at most I would have to have work done to the small section that actually mates to the tranny. I think that most likely the PO used a conversion u-joint to go from the 350 to the 400 sized yoke on the shaft. Also I am missing the switch on the gas pedal for the 400 kickdown and apparently the wiring harness for it as well but I don't really know what to look for. All I can tell is there is no plug dangling next to the pedal that would obviously be for the switch. i haven't had a chance to crawl under the truck to try and find the harness from underneath. So any of you crewcab owners or anyone for that matter able to help me out with what I should be looking for as to the driveshaft yoke size, intermediate shaft length with 2wd 400, and what the harness looks like in the truck. Thanks in advance!

 

[Ryan B.]

Here:
http://groups.msn.com/Ryans1972Blazer/newpictures.msnwaction=ShowPhoto&PhotoID=723

I think the 2wd bolt on yoke style tail shaft that you are talking about would be 9" stick out.. and this one can be used for a transfercase.. Iceman44 has done this. I believe the shorter 6" stickout is for the slipyoke..
You can swap tailshafts between trannys, but it requires you to completely disassemble and then reassemble both transmissions.

 

[77crewcab]

re

I looked your site over pretty good before deciding to do the rebuild my self. It was very helpful. So any idea about the drive shaft length or the how to determine the u-joint size?

 

[77crewcab]

ttt

 

[77crewcab]

Hey Ryan did you need a special tool to remove the front pump? Is that what is laying on the blue box in pic 15 for your rebuild writeup? Just browsing snapon for the clutch hub compressor (which I can't find anywhere) and saw they list a special slide hammer for the job and it says 2 are required at $75 bucks each Also do you happen to have a measurement from the front of the trans to the front edge of the ujoint?

 

[Ryan B.]

whoops sorry dude, heres the link i was trying to show you..
http://groups.msn.com/_Secure/0VAAf...6uBQR5Wbo2EO3eJhoEE7ChDq*/th400 tailshaft.jpg

And no i didn't use a slide hammer for the front oil pump. Most times i can grab the pump (stator support) and give it a few yanks and wiggle it side to side to budge it loose.. if not, you can access it after you pull the tranny pan.. you can put a screwdriver through an opening in the case up against the back of the pump and give it a couple of light taps with a rubber mallet. This did the trick for me.

 

[77crewcab]

okay so the front pump can be removed without the tool. finally found the compressor for about $30 at partsamerica. So are the 400 and 350 the same length from the engine to the tailhousing mounting flanges or are they different. And i gather that i could use the slip yoke version as well as the bolt on version.