Chev 12 Bolt

[srscout]

Stephen
On your site in the specs of Wally, you mention that at one time you were running a 12 bolt rear with 37" tires.
What mods did you do to that rear to get it to hold up?

Second: What were the breakage issues (if any) and would you recomend this for a rig on 35's with a SBC?

Thanks for the info. S&R

 

[mrk5]

I'm not Stephen, but I can give you some input as I'm running that setup now.

I know at one time Stephen was running the 12bolt full floater kit Warn was making. Warn has since discontinued making that item. If you search the classifieds forum here, someone was selling such a setup.

I have a season of wheeling under my belt with my rearend, and here's how it's setup: 3.37 gears, all new seals and Timken bearings, Detroit locker, and Superior Gear axle shafts (ordered from ORD). My tires are 37" GY MTR

At the end of the "season" I broke several teeth off the ring gear and pinion. Upon having it repaired the found that when the Detroit was installed the gears were not setup properly, which probably greatly contributed to the breakage. Plus the date stamp on the gears were 10-69. I knew gears had been swapped in at some point, but didn't know they were so old.

I'm now running a new set of 4.56 gears in the rearend, and found a better shop to install the gears.

I don't have much concern about breaking again, but I don't go all out and get throttle happy. It's that age old response, "Depends on your driving style."

I know Stephen has a lot more experience under his belt that he can speak from, but I hope this helps you a little.

 

[srscout]

Thanks for the info. I have been looking at swapping out the D44 in the back of my rig for a Dana 60FF that I have but wanted to explore all the options. The 12 bolt seemed like a possible go in place of the 60 because of clearance ( I am running 35" MT\R's) and I am just not sure I need the 60.

 

[ChevyMan070884]

If you are looking for a stout running gear, you may want to pay a visit to a jusnk yard. I bought an entire 1 ton Chevy for 550.00. That included a full floating 14 bolt rearend wit 4:10 gears and a Heavy Duty Dana 44 frontend with 4:10 gears. The swap was complete bolt up (aside of the brakeline and front calipers having different threads).

 

[srscout]

The reason I was thinking about a 12 Bolt was clearance. I already have a 44 Front and a 60 rear, but was thinking that if the 12 bolt could be built strong enough it would have better clearance. Here in Utah we run in the rocks most of the time and every bit of clearance you can get really pays off. Where I run 35" tires, I just thought that the 12 bolt built strong enough would be OK for 35's and better clearance than the 44.

 

[Hossbaby50]

The 12 bolt is an ok rear axle but if you wheel it hard with 37's it will end up breaking. If you have a D60 rear already then I would say shave it and swap it in. Several good friends of mine in AZ run/ran 12 bolts in there K5's with good success until they wheeled hard and often with 35"+ tires. If the truck is really light then it wouldn't be a bad choice but on a fullsize truck with lockers that will see rocks you are going to run into trouble eventually.

Therobzilla runs his 12 bolt hard with a detroit, superior axleshafts, and 35" MTR's. Before the Superior axleshafts he broke at least 3-4 stock axleshafts. After the Superiors he has twisted an axletube in the pumpkin, broken the detroit, ring & pinion, and twisted the splines on a Superior axleshaft. He wheels hard so that is part of the reason why he has broken those things but he has basically proven even a 12 bolt beefed with the best parts is still only capable of 35-37" tires on a heavy rig that wheel hard.

The D60 in stock trim is as strong as a beefed 12 bolt. If you break a D60 you can upgrade to heavier beefier parts. The D60 falls between a 12 bolt and a 14bff in strength. With a good shaving the D60 is a good option for a truck with 37's and will see rocks.

Harley