Broke the rear diff on my K10

Broke if good. Chunks fell out when i took the cover off. Now im looking for a cost effective solution. I'm thinking find a donor truck & swap axels, if the ratios are the same. that will give me more part when other things fail. Its a 79 Chev K10.

Any suggestions? Thanks

Junkyard - find a 12-bolt instead of the 10? Is it 4wd or any particular reason to match ratios?

Ford 8.8 FTW. Moser can make new axles for your bolt pattern for a couple benjamins. my friend is running a 8.8 crown vic rear with 4 link in his 2000 trans am. I can take pics if anyone is interested

oldtin wrote: Junkyard - find a 12-bolt instead of the 10? Is it 4wd or any particular reason to match ratios?

the "K10" designation means that it's a 1/2 ton 4X4 truck. if it was a 2wd, it would be a "C10"..

i'd suggest finding a set of axles from a 3/4 ton. not only will the 8 lug wheels make the truck look that much more impressive, but the big 14 bolt rear axle is nearly indestructible. but if you don't want to do that, you've got an 8.5" "corporate" rear end and parts are cheap and easy to find for it. it's the same rear axle as GM used in millions upon millions of cars and trucks starting in the early 70's and still used in 1/2 ton trucks today. a brand new posi differential from Eaton will be about $400.

You should be able to just replace the spider gears. (unless there is more broken that I am seeing) I have one it several times. Not real expensive and not that hard a fix.

In reply to dean1484:

It will need more than just a spider gear, that rear was a posi. Posi carriers are a little harder to find if you want to keep the posi. I have seen several 10 bolts break but not the way this one let go especially for a posi unit. If you use it hard I would look for a 12-bolt in the correct gear ratio or pick-up a pair of 3/4 ton axles as suggested earlier.

Sounds like a good reason for a parts vehicle.

The 8.5 10-bolt that you just broke is a fine axle. Unless you're pulling crap-tons of weight or making north of 500 ft-lbs of torque there is no reason not to keep using one.

There are multiple upgrades available like have been mentioned, but they will all require a different (custom) length driveshaft.

The 12-bolt is a fine choice and you can get one along with the driveshaft from a K20 for a bolt-in (provided they are the same wheelbase) Pay close attention, though... make sure the transmission is the same. TH350, TH400, and 700-r4 are all possibilities, each of which is a different length with potentially different output shafts. The reason I don't necessarily recommend a 12-bolt is because truck 12-bolts use a smaller pinion shaft size that is the same as the 10-bolt pinion. I wouldn't call it a "weak" point, but since the axle is only as strong as the weakest point... I don't see the need to pay the premium price for a 12-bolt axle that is only mildly stronger than the 8.5".

The Ford 8.8 is a corporate ripoff of the GM 12-bolt. Its somewhat easy to find them with discs if you want to adjust your brake bias, but again, not really worth the adaptation hassle. They also use a different pinion angle, so you would have to shim the spring pads to get the right angle for your GM drivetrain.

If you want to upgrade (as long as you are customizing things) FTW... get a 10.5" 14-bolt full-floater from a SRW 1-ton.... or better yet, a 10.25" Sterling rear from the same type of Ford truck. The only problem I see there is that they are limited to 3.73 and lower gears. Your K10 could have anywhere from 2.73 to 4.10 gears depending on the options, but if your front axle has (for instance) 3.08 gears, you won't be able to find a matching 14-bolt ratio. Even the aftermarket only goes as high as 3.23.

IMHO, buy another 8.5" 10-bolt (cheap and easy) or if you're planning on changing stuff anyway, go with the 14-bolt. The other bonus of the 14-bolt is that its not considered a "performance" item like the legendary 12-bolt, so you can often get them much cheaper.

If its stock just swap in another axle. If you are running bigger tires, please swap to 3/4 ton stuff. I have seen a super swamper go bouncing 20 feet in the air down the the middle of the freeway after someone broke an axle in a 10 bolt.

Thanks for the input. It has 4.10 ring & pinion that seems to be undamaged. It's a 4-speed truck so that may limit 3/4 ton drive shaft donors. If I find a 14 bolt axel, how spend is having a drive shaft made/modified? I'll start looking for a K20 donor.

Thanks again.

By the way... here is a 10.5" 14-bolt that I put in my 66 Bonneville....

Got the axle for $180 out of a Frito Lay step van. 3.73 gears, posi, the works.

There are SM465/NP205 K20s, if you have the chain drive transfer case that would be another worthwhile swap. From what I remember even having a driveshaft made is under $200 last I checked.

SillyImportRacer wrote: Thanks for the input. It has 4.10 ring & pinion that seems to be undamaged. It's a 4-speed truck so that may limit 3/4 ton drive shaft donors. If I find a 14 bolt axel, how spend is having a drive shaft made/modified? I'll start looking for a K20 donor. Thanks again.

Just find a K30 with a 4-speed. Grab the axle and driveshaft. The axle itself will be a bolt-in. I think even the brake fittings are the same size.

Be careful, This is a GM vehicle and very few of them were ever made, none of these parts are ever in a junkyard.. And when you do find them boy are they expensive.

hey ignorant... be careful or people will think your username is accurate

This place has just about everything you could want/need. http://www.ringpinion.com/ But I think I'd go hunt a boneyard piece just to save the aggravation of rebuilding. BTW, there's no reason a 4x2 couldn't have the same type rear axle.

the 4.10 gears makes finding a complete bolt in 8.5 rear end a little more challenging since most of them were 3.08 or 3.42. hit up Craigslist for a 3 series differential for it and keep your existing gears. if you want a posi diff, then look for one out of a late 70's Trans Am or Z/28. but you could also be likely to find one from a late 80's Caprice cop car. the 8.5 was used in Caprices until they quit building those after the '96 model year, they switched from 28 to 30 spline axles in about '90.

if the differential case isn't damaged and the gears still look good, you could maybe get a Lock Rite diff for it and not even have to pull anything apart other than gutting the differential case.

curtis73 wrote: hey ignorant... be careful or people will think your username is accurate

quiet you...

As to the OP.. ask around on CK5 and you'll probably find someone near you with exactly what you need.

http://coloradok5.com/

the 14 bolt versus 10 bolt in the trucks driveshaft length difference is a myth. you just need the proper conversion universal joint to go from the shaft to the 1350 on the yoke.

i did the swap last winter in my 85 k5, the 10 bolt blew up (PO welded it up, axle snapped, craigslist yielded a pair of 3/4 ton axles, 10 bolt front and 14 bolt rear in 3.73 for $200). for driveshaft length i was ready to have one made, but before i pulled the axle out i hung a bob off the frame to the center of the yoke. when i bolted in the 14 bolt it lined right up. installed conversion joint, got right back to plowing. too bad you are not closer to ohio, a guy i know here has a 4.10 14 bolt from a 3/4 ton with the matching 8 lug 10 bolt front for $300. hell i have a 4.10 rear only i would sell too.

First off, THAT is some quality carnage! You don't often see the preload springs coming loose without tearing up the gearset in the process. My congratulations!

Secondly, in this and many similar cases, CL or Searchtempest can be your best friends in the whole world. I recommend a couple quality hours spent looking for a similar axle from a 1/2 ton, or possibly a donor parts rig. The change to full-floating axles will bring along with it, a change of wheels. This may add extra expense where it really isn't warranted.

I'm going to look at a possible donor truck this afternoon. It's the same year and wheel base as mine. As a bonus, it has a 350/4-speed set up...like mine. It has 3.08 gears so I'll need to swap both ends, but it should have plenty on good spare parts...and the makings on a trailer.

Thanks for the help. Y'll are always good for the info, direction, and encouragement that I need.

BTW, I've had a difficult time finding donors in my area. This one is 130 miles away.

The donor turned out to be a turd. There's bound to be a good donor out there...but not to far.

Having not tried to before, how difficult is rebuilding a GM 10 bolt rear end? How do I determine if its a 28 or 30 spline?

Thanks

SillyImportRacer wrote: The donor turned out to be a turd. There's bound to be a good donor out there...but not to far. Having not tried to before, how difficult is rebuilding a GM 10 bolt rear end? How do I determine if its a 28 or 30 spline? Thanks

You could count

its a 28 because they did not go 30 until the 90's

In reply to patgizz:

Thanks.