Hello yall, well i was working on my parts truck the other day and trying to remove the 3rd member of the rear axle of the truck.

What i'm ultimatly trying to do is swap the 3rd member from the parts truck ( a 9'' rear end with 3.50 gears and L/S), with my 81 pickup that has a 9'' rear end with 2.73 gears.

Anyways as i was trying to remove the 3rd member on the parts truck i remove the driveshaft, and took off the (10?) surrounding nuts on the outside of it. I then figured it should come free? So i tapped around it with a hammer and trying to pry it off a bit and it didnt seem to want to budge. So is there something im missing to get this off?

Also i've read about in these 9'' rear ends that in the older ones there are 28 splines vs the newer with 31 splines and these arent interchangable?? So how do i tell if i will be able to swap them fine? Also do i need to pick up a gasket or any kind of sealant for this when i swap em?

Thanks alot folks!

 

Did you pull the axles? If not you need to pull the drums and undo the 4 bolts holding the axles bearings to let the axles slide out approx 4-6". Then the 3rd member can come out. When you pull the axles all the way out you will be able to could how many teeth are on the end. that will give you your spine count

 

I think you meant driveshaft.

 

Whoops, yep thank you.

 

No i have not pulled the axles. Whats there to pulling off the rear brake drums? So for installation i'll have to pull the drums off also?

Is there anyway i can tell the spline count before hand so i dont get all the way too getting ready to set in the different third member and find its the wrong spline count?

Thanks alot, very helpful.

 

In my experience, most of the 80's truck 9 inch rears were 31 spline. If you run into the spline problem, there are a couple of options open to fix it.

The problem is the carrier piece that holds the ring gear will have too small a center hole for a 31 spline axle to fit, if it's made for a 28 spline axle. You can take it apart a little bit, take the ring gear off, and get a machine shop to make the hole bigger. Or you can take the piece out of your other rear end and swap it in, since it will have the bigger hole, just bolt the 3.50 ring gear onto the 31 spline carrier. I did this on my 80, and had no problems with it, and I didn't get into any complicated gear setting procedures. Then you just put the 31 spline spider gears in from the other rearend and it's good to go.

You will find getting the brake drums busted loose the hardest part, and yes you are going to need to tear down both rearends the same amount.

 

Thanks alot frank, glad to hear i will be able to fix with what i got just incase it doesnt work out.

So what is there to removing the rear brake drums? I've never tackled this before.

 

Shouldn't that be explained in any $20 repair manual?

 

Already looked in my haynes and it only tells how to replace the shoes. Will go back and check again but i didnt see anything when i looked earlier.

 

You have to remove the drums to replace the shoes.

 

opps, yeah just realized this as i was reading that very article. Sorry, and thanks ctu.

 

After you remove the drums, behind the axle flange (in amongst/behind the brake parts) is four nuts holding the axle retainer, remove those four nuts then pull on the axle and it'll slide out sometimes, slide hammer if not. (you can put the drums on the lug studs backwards and a couple lug nuts and use the drum as a puller)

-Enjoy
fh : )_~

 

Very helpful tip, thanks alot fetus!

 

Umm, I'm gonna state the obvious, since no else has pointed it out yet. If your axle shafts were to somehow be the 28 spline, and the donor 3rd member uses 31 spline axles, you've got a set of them already.......... Granted, they will have the larger bolt pattern, but at least they would work.

Also, older 9" 3rd members had copper washers under the retaining nuts, and these tend to deform. If you see copper around the mounting holes, use a screwdriver or chisle to pop the copper washers off. I don't know if/when these stopped being used.

 

Wait a minute! you have never done brakes but you are tackling changing a 3rd member?