Transmission swappage: I'm new to this

[Vetteman61]

I have an 87 K5 with a 700R4. I'm about to swap transmissions with an old 80's (86 i think) longbed truck with a 7000R4. I've never done this before. Does anyone have any articles that would help with completing this task, or any advice from someone who's done this before?

Thanks,
Brandon

 

[pauly383]

If the truck is 4x4 , then its pretty straightforward . If the truck is 2wd , your going to have to remove the tailhousing , and disassemble the tranny enough to swap output shafts . 2wd have the speedo in the tailhousing so its longer .

 

[Vetteman61]

4 wheel

Yeah, they are both 4 wheel drive.

 

[big dan]

make sure to unbolt the torque convertor from the flywheel before you remove it.

keep up with all the bolts you take out, unlike me.

if you use enough extensions and a wobble joint with a ratchet you can sit at the very back of the transmission and unbolt all the bellhousing bolts.

oh and make sure to unscrew the speedo cable and tranny lines. I decided to just cut mine with bolt cutters once and its a lot easier to reinstall the tranny if you just unscrew them to begin with.

oh and one thing I ran into with a buddy of mine recently. it is wise to purchase a new or reman torque convertor but if you decide to use your old one make sure that it will work. 84 and older trannys had a 27 spline torque convertor and newer models use a 30 spline. we ended up ruining the pump cause we couldnt get the torque convertor to spline.

 

[dremu]

I have an 87 K5 with a 700R4. I'm about to swap transmissions with an old 80's (86 i think) longbed truck with a 7000R4. I've never done this before. Does anyone have any articles that would help with completing this task, or any advice from someone who's done this before?

Thanks,
Brandon

The six bolts on the bellhousing are EVIL if you don't have a removable hump (well, and/or carpet =)) As mentioned, lots of wobble extensions and patience.

Assuming both trucks are 700R4/NP208 combos, you might try and remove them as a set. You'll need a tranny jack with the adjustments (yaw and roll, like aircraft ) to pull this off well though.

Alternately, drop the T-case first, then do the tranny. More work, but lighter thing to move.

Speedo cable, shifter, and any electronic things need to be removed BEFORE you drop the tranny. Don't ask.

Also helps to drop the pan and empty it of fluid, just for weight reasons. Put the pan back on 'fore you go fiddling with the tranny though.

Unless you're seriously strapped for cash, replace the torque converter. They're like fifty bucks exchange, and it's a PITA to replace them -- you basically gotta drop the whole tranny again -- so now is a good time.

Speaking of, now is a GREAT time to replace the seal on the tranny that mates to the torque converter. They're like three bucks and are easy to do now and only now. (Ask me how I know... )

Having some scrap lumber handy for the lifting/dropping and storing is handy. Maybe 2' lengths of either 2x4 or 4x4 is ideal. I have about a dozen I use ... stack 'em, sometimes in odd arrangements if one end is higher than the other, whatever.

Speaking of "dropping", transmissions do not take kindly to being dropped, especially the aluminum parts. Voice of experience

That's all that comes to mind as a general thing. I've never done a 700R4, as my trucks are too old or too military (I've done the TH350 a few times and two TH400's though, same ideas.)

Oh, and since it's a 700R4, be sure to adjust the TV cable when you get the new one in, or it will die an early death. You'll hafta search on that, as I thought a TV cable was what brought CNN and HBO into my house, but I guess there's one from the throttle to the tranny too

-- A