Rear end switching- pros vs cons

[tjvending]

I want to flip out my rearend 72 C-10 -for another from same truck. Mine is making loud winding noise at 35 MPH and over. I got a stock one from a buddy and he states nothing is wrong with it. I want to know my pros and cons on this switch. Thanks for your input...also how much time should I allow? TJ

[LuckyHenriksen]

Well if yours is having problems then I say go for it!

[cdowns]

if the ratio is different you'll throw off the speedo reading

[rambler]

is it the same rearend. coil vs leafs? and same ratio and similar years 67-72? then go for it, much easier and cheaper than paying someone to rebuild your current rearend..(and if you have never done it, dont try it yourself, rebuilding one that is). Unless you need a High Performance or anything like that, then go for it.. take the cover off, drain the fluid and put fresh gear oil in it.. replace the cover with sealant and your good to go.. not too hard.. make sure you use jack stands.... a good floor jack helps.. a buddy is always good, but I've done a few by myself...

[tjvending]

things I see removing are:
2 big Ubolts with 4 nuts
2 brake lines
2 emer. brake lines
drivreshaft U-joint

Any thing else? Should I put the jack stands under the frame or trailing arm, coils springs?

TJ

[rambler]

Jackstands under the frame.. you will also need jack under the pumpkin.. and also remove the rear shocks.. should be a pan bar as well if it is coils.. get some PB Blaster for the bolts soak before hand. and dont forget to bleed the brakes (all 4) after your done.. check the rear brakes on the new one for wear.. (what else am I missing guys?)

[PanelDeland]

Might want to spring for new U-bolts and you will either need a long breaker bar(at least in 1/2 but preferably 3/4)or an impact that has some ooomph.You may also want to tear down and check the brakes on the one you're putting in especially if it's been sitting any amount of time.

[71tahoe]

Don't forget to take the vent hose loose from the frame and you might want to replace that original 36 Y.O. rear brake hose too.

[cdowns]

i'd go for new bushings in the panhard bar and since so far into the project i'd also do new bushings in the trailing arms too

[Castiron9]

I'm hoping to do this also on the Longhorn.Have a posi I got from "FRANK" pickemup a while back that I have wanted to install for a while now.Would have come in handy in this last snow storm.Need to find nice ,dry,indoor area to do the conversion.When I do go for it ,I am sure I will have questions.

[kcjones]

Originally Posted by PanelDeland

Might want to spring for new U-bolts and you will either need a long breaker bar(at least in 1/2 but preferably 3/4)or an impact that has some ooomph.You may also want to tear down and check the brakes on the one you're putting in especially if it's been sitting any amount of time.

Absolutely replace the ubolts and brake hose, in my opinion. I got ripped off a while back...well, not really, I was too ignorant to check carefully. Anyways, I wanted to swap my Eaton 3/4 T with a 12 bolt posi...bought a unit that checked out - housing was a 1970 with eaton posi, gears were 3.73, and brakes weren't too bad. Take it to the shop to have the bearings replaced and clearance/preload checked, and they tell me it's junk. Rust had penetrated the bearing areas of the housing to the point that it was unsafe.

If you do the swap, my experience says to take the new unit to the shop first, have them check bearings and seals, check clearance/preload. Then, if you need to, swap in new shoes and wheel cylinders (easier now than later), and replace brake hose, vent hose, and ujoints. Good time to look at shocks, too, while you're there. Also, although probably not an issue, 12bolts came with 3 different yokes...so measure the new one first to be sure it has the same one, or you'll need to replace ujoints, too.

[kcjones]

Sorry, 1 more thing I learned, the order you remove in is important:

1) jack up truck, support frame with jack stands.
2) jack up the rearend to take the pressure off springs/shocks.
3) remove brake line, vent hose, and driveshaft
4) detach shocks from rearend.
5) let the jack down so the rear end hangs from the springs. Then, jack it up about 1/2" above the "hanging" point so the spring is almost entirely unsprung.
6) remove the lower spring cups (easier than the top).
7) Remove the ubolts.

When installing,
1) Install trailing arm/ubolts (before springs!
2) Springs
3) Shocks
4) and so on...

[BarryB]

Sounds like everybody has gotten the majority o the steps for except for a time frame. I can do the diff swap in a couple of hours. The bushings replacement better plan on all day especially if you don't have access to a shop press.

[69gumby]

If you truck is still running and your not in a big rush try what I did. Set your new rear end up on some saw horses, clean it up so you can paint it, take the differential cover off, pull the axles, pull and replace the axel seals. I pulled the backing plates did the whole brake thing, everything, paint all the backing plates, rear end, diff. cover (or install one of the after market ones). Then put it all back together with new bolts and put in new neoprene track bar bushings. The neoprene bushings make things nice and tight back there.

And then make the swap. It will make the rest of the underside look bad. It did mine.

[rambler]

that looks pretty good.. when I did mine time was a factor as it was a work truck.. bought a complete (rusted out) truck from Randy (teeitup), actually drove it, just junk body,, trailered it home, pulled the rear, checked the brakes,, I did have to buy new ubolts.. and bolted it on to mine.. someday it will get the resto it really needs and desvers..

[kcjones]

Trailling arm bushings are NOT easy...search the forum, you'll find some posts on how it's done, but it's not for the faint-hearted garage guy. Better suited for a shop to press out the old and in the new than try to do it at home if you have any time constraint. They do wear out, though, and if yours are worn, you'll know it....clanks and abrupt movements under your seat when driving.

[tjvending]

What is the size of the nuts on the U-bolts? 1 1/8?

TJ

[chevy_mike]

Originally Posted by tjvending

What is the size of the nuts on the U-bolts? 1 1/8?

TJ

Mine were 1 1/16" nuts. I think I ended up using a 27mm impact socket since my American set of impact sockets only went up to 1". The nuts and bolt that hold the trailing arms to the crossmember brackets are 1 1/8" and I had to buy that impact socket.

Hope that helps.

[Green Machine]

Just a thought, but a bad carrier bearing made me think the tranny was going out one time, easier to switch that than a rear axle !!!

[tjvending]

The rear yoke is kinda of lose, I tighten the nut up a little but anymore I might break something. Also leaking spots all over the driveway from the yoke, so I was leaning towards the rear. TJ