Setting up a differential

[truckster]

The rear differential in my 72 Blazer sent its guts through the rear cover of my 12 bolt about a month ago. I've been looking and it seems it's a lot easier to find a 12 bolt in a 2wd than a 4X4, so I'm considering swapping the carrier from a 2WD (same gear ratio- 3.73) into my axle housing. How much work is it, and is there a link somewhere explaining how to do it?

Thanks.

[71 super]

The swap will take several hours. The 2wd carrier will work with no problem, axles are splined the same, but the swap is not that easy. If you want to ensure the same thing does not happen again, buy a new gear set or at least get the complete gear set from the donor truck- ring and pinion. DO NOT mix and match from two different sets, this is a big no no. Buy a install kit from summit or jegs or local parts store- Ratech makes a good kit - you will need bearings, seals, races and crush sleeve as well as marking compound to test your pattern once installed. If you have never done anything like this, this is not the time to learn, as you will need several tools, dial indicator mic, torque wrench and a dedicated sockett to remove the pinion nut and yoke. The reason I say not a beginners job is the fact that you have to crush the sleeve, which can be a pain, and set the backlash/ pinion depth of the gear set again something tha can be very time consuming especially if you have limited resources (no lift, compressor etc.). I would if you and not knowing your mechanical background etc. would shop around for a quality shop that is willing to work on the old stuff. I have set up 4 and am by no means expert or even highly qualified, 1st one had lots of noise on decleration, but even after being apart three times, never got any better really, and was told that it was the nature of deep gears to be a little growlly (4.56) but I do not put much faith in that. The other three went without problem, the last was actually easy, because I knew my way around. Farm it out unless you have all the stuff.

[powell72]

Originally Posted by 71 super

The swap will take several hours. The 2wd carrier will work with no problem, axles are splined the same, but the swap is not that easy. If you want to ensure the same thing does not happen again, buy a new gear set or at least get the complete gear set from the donor truck- ring and pinion. DO NOT mix and match from two different sets, this is a big no no. Buy a install kit from summit or jegs or local parts store- Ratech makes a good kit - you will need bearings, seals, races and crush sleeve as well as marking compound to test your pattern once installed. If you have never done anything like this, this is not the time to learn, as you will need several tools, dial indicator mic, torque wrench and a dedicated sockett to remove the pinion nut and yoke. The reason I say not a beginners job is the fact that you have to crush the sleeve, which can be a pain, and set the backlash/ pinion depth of the gear set again something tha can be very time consuming especially if you have limited resources (no lift, compressor etc.). I would if you and not knowing your mechanical background etc. would shop around for a quality shop that is willing to work on the old stuff. I have set up 4 and am by no means expert or even highly qualified, 1st one had lots of noise on decleration, but even after being apart three times, never got any better really, and was told that it was the nature of deep gears to be a little growlly (4.56) but I do not put much faith in that. The other three went without problem, the last was actually easy, because I knew my way around. Farm it out unless you have all the stuff.

I concur.

[70rs/ss]

Or the simplest of ways is to just cut the coil mounts off it and weld two leaf perches and use the whole thing, why make it any harder than that? Paying for the work is good advice, but we're talking $400 at least and you shouldn't really spend the $$$ to set up a rear using used gears, so add in another $150-200, or the leaf pads are about $20??

[LONGHAIR]

Agreed....the others are very right about this.
Swapping the entire housing is the most cost effective way to go, but there is no guarantee with used parts either. It is how-ever the cheapest and fastest way.

Changing a ring and pinion set is not a thing to learn from a book. It is labor intensive and very precise work. It involves many steps that have to be measured, tested and repeated several times. It requires some specialty tools...not exactly the "borrowing" kind of things. Over-all not the thing to spend the time, money, effort to learn....and only need the skill once or twice in a lifetime. Again, no guarantee.

Paying someone to do this for you is the "best" way. Assuming that your original housing was not damaged, you can re-use some of the parts, up-grading the bad if you want. This is the opportunity to change ratios, add "posi" etc....and you will get a warranty.
Above all...do not pay someone to install used gears. It is much more difficult and many don't survive anyway.

[Pont406]

I did a few set ups myself. It's not that hard. You will take it apart more than once if it's your first gear change. If you don't feel comforatble then don't do it.