Rebuild 14bff or 12 bolt?

[Mtrhd329]

I have a 1979 c10 that I have been running a 14bffopen diff with 4.10 gears for a while.  Its having problems puking oil out of the vent.  I think I messed up the besring preload when I swapped to disc brakes.  My question is should I rebuild it and add posi to it or just find a 12 bolt and rebuild that.  My local shop is quoting me 1500 to build and truss a 12 bolt and about 1000 to rebuild and install a posi in the 14 bolt. 

They want me to switchaxles to get rid of unsprung wieght but I just cant seems to tgink it would be cheaper and worth it.  Im already flipped in the rear so anything I swap in would require welding new pads again.   Anyone have any ideas?

I have been thinking of a late model rear just so I can swap in an ebrake also.    I cant decide

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[roundhouse]

Get a longer vent hose run to a catch can.  Problem solved

You could check the bearings by driving it and coasting to a stop without using the brakes and then feel the bearing area in the center of the wheel

[bake74]

     Fix the problem, don't put a band aid on it and then somewhere down the road it will completely fall apart and leave you stranded.
     Do you need the 14 bolt or is it overkill for what you use the truck for.   On a C-10 I think a 14 bolt is a little too big, a 12 bolt can be built to handle a lot of HP without all the unsprung weight like the shop said.

[SomeTexan]

I would look for an 8.5" 10 bolt. Way lighter than the 14, but can be built stronger than a 12 bolt for less money. The 8.2 10 bolt I am not fond of, but don't underrate the 8.5.

[Mtrhd329]

I swapped the 14b becuase it was available cheap when I destroyed a 10 bolt.  It has disk brakes but no ebrakes.  For the cost of the tsm eldorado calipers I could put that toward a posi in a different axle.  I would be needing to put 800 towards the 14b anyways to get posi and ebrakes not to mention whatever is wrong with it.  So I figured I would put that money toward something lighter?

What would have an 8.5" 10 bolt?

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[Captkaos]

If you have both, rebuilt the 14bolt, much better axle for a 4x4 that sees alot of abuse.

8.5" 10 bolts came in 78-87(91) trucks like ours and up to 99...  but the later ones are wider.  it would be a downgrade from a 14bolt.

[Mtrhd329]

Dont have both.  Right now im running a 14bff on 2wd lowered truck.  I agree for a 4x4 you cant beat yhe 14b.  It was what I had available at the time so I made it work.  Now I can fix it right.  IF I can find out wjats right

[bake74]

     It is up to you of course, but I stick to my opinion that a 14b on a C10 is overkill.  The weight alone does not make it worth it to me.

[Captkaos]

Sorry didn't read the first part. 
If it is a C10 just pick up a 10 bolt.  But if you want a limited slip and specific gears you are going to have to add them unless you plan to look at a lot of axles. 
How much do you want to spend?

Chris Lucas
73-87chevytrucks.com
captkaoscustoms.com
squarebody.biz

[SomeTexan]

8.5" 10 bolt or a 9". I've run stupid power through both. 9" is cheaper to build, and fully built is stronger than the big 10 bolt. Not by much. An 8.5 10 bolt with axles will handle about anything you throw at it in a street truck, and then some. I've taken them to mid 8 second 1/4 mile passes. In my 71, I destroyed 2 12 bolts, one launch each, 4 9's 150ish passes each, and one 8.5 10 bolt. The 8.5 made almost 500 passes, and it only broke an axle, strange said it was a flaw and shipped me a new pair. Replaced the axles and ran it until I sold the truck. I've sworn by them ever since.

Like Kaos said, 78-87 (91 for blazers and 'burb's) came with them. If you find an older 8.2 10 bolt, pass it by. I believe 8.2's axle tubes taper down before the ends. The 8.5 is a beefier looking axle.

[Captkaos]

BTW, 73-87(91) 1/2 Ton trucks were never offered with anything but a 12 bolt Truck or 8.5" 10 bolt for the rear axle.  In 1988 they went to the stronger 30 spline shafts on the 10 bolt.
The 12 bolt truck is not anything like a 12 bolt passenger car axle short of the ring gear diameter, the pinion shaft is much smaller.

[Mtrhd329]

I am looking to spend about 1500 to get an axle that is properly setup and has an ebrake and disc rear capable.

A loca. shop is wanting to aquire me a core and rebuild with posi and new gear and bearings and even truss it for 2400.  Not sure I can swallow that much right now.  But it sure would be nice to have 5 lugs all the way around.  I would love matching rims for a change

I might just pull a junkyard core and freshen it up a little and have them put in an eaton locker.  Stock 12 bolt would be nice then I can just run flip brackets in the rear instead of welsing new spring mounts and the ebrake should be easy to adapt.

[SomeTexan]

I thought the earlier trucks had 8.2's in them? If they didn't, I've sure seen a few under them in junkyards. I guess I should mention that every rear end i spoke of was built. First 12 was factory truck, second was a car axle, picked it because the width was perfect for a big set of wheels I found cheap. Both strange parts. First twisted pinion off, then wedged in ring and broke housing. Second didn't do any better, broke ring gear and housing. This was behind a 632bbc, big whipple blower on meth with a 6k stall glide though, and 32x14 slicks, so your mileage may vary... But the 8.5 did take it the best

[Mtrhd329]

I cant remember which 10 bolt I had on it stock but after some spirited driving it sent the pinion into the carrier and locked the rear axle up in a sharp 90* turn.  Granted it was an open carrier weakling.

So the car rears are narrower?  I would like to stuff some bigger tires under there.

[SomeTexan]

I am looking to spend about 1500 to get an axle that is properly setup and has an ebrake and disc rear capable.

A loca. shop is wanting to aquire me a core and rebuild with posi and new gear and bearings and even truss it for 2400.  Not sure I can swallow that much right now.  But it sure would be nice to have 5 lugs all the way around.  I would love matching rims for a change

I might just pull a junkyard core and freshen it up a little and have them put in an eaton locker.  Stock 12 bolt would be nice then I can just run flip brackets in the rear instead of welsing new spring mounts and the ebrake should be easy to adapt.

I wouldn't bother with a truss unless you are going to lock it and run slicks with big power. If its a sub 500rwhp street truck, a freshened up 10 or 12 bolt would be good, pick a posi, gears and new bearings and be happy. Axles if more traction is in the game plan.

I find that dirt track chassis shops offer the best rates for axle builds, even better in their off season.