12 Bolt VS 10 Bolt

[CamaroChris]

I'm building a 2wd Jimmy out of a 1987 jimmy. I have a open 5 lug 12 bolt with 3.73 gears. while stripping the frame I realized that the 6 lug 10 bolt 4x4 axle has a 3.73 with a nice posi.

I did a bit of digging last night and from what info I found, the 4x4 axle is wider than the 2wd 5 lug axle by 3 inches. Is this true? I also read quite a few articles claiming that the 8.5" 10 bolt Is damn near as strong as the 12 bolt.

So do I find another open 5 lug 10 bolt and put the posi unit into it or keep the open 12 bolt, save up for a posi? this jimmy will be ~650rwhp and not really drag raced. more freeway driving in Mexico

[GASoline71]

650 RWHP... you might wanna consider a 9" or a Dana 60. Stock axles and parts are not going to hold up to that much HP/TQ, whether you're racing or not. Moser or Strange can set up some pretty wicked 12 bolts if you wanna stay GM. But stock stuff prolly ain't gonna cut it.

Why build an engine that will make that much power and then cheap out on the butt gears?

Gary

[storm9c1]

Originally Posted by GASoline71

Why build an engine that will make that much power and then cheap out on the butt gears?

Sounds like he wants to add a fuse to his drivetrain...........

Kinda like Honda half-shafts...

I agree, for 650 HP, forget the 10". I've broken those with less power than that. Unless of course the 650 number is a little on the "liberal" side???

[CamaroChris]

I am not against upgrading. I just like to try and use what I have laying around

[CamaroChris]

The engine is a turbo stock 6.0l. Daily driven on 10 lbs so it'll probably be more like 500-550 but I might turn it up sometimes. I have no idea what it'll make but seems like an average on that set up. I hear that turbos are easier on rear ends. Maybe I can sell the posi 10 bolt for enough to buy a posi for my 12 bolt. Then maybe throw some Moser axle shafts in it. I don't know.

[Captainfab]

The late '70 to '87 truck 10 and 12 bolts are 63.5" wide whether they are 2wd or 4wd.

[hellbent72]

A 10 bolt will work UNTIL the tires get traction than its toast.
A 12bolt can be bought or built to handle the power but it ain't cheap.
Go with a ford 9 and even mildly built it will handle dam near anything
Plus gear changes are a breeze.

[burnin oil]

My old blazer tore up 12 bolts like they were made of beer cans. Pinion bearings died a decent amount but I killed axle bearings alot. I was putting enough torque to them to shove the shaft into the bearings. It got to the point of driving down the road and seeing smoke coming off the brake drums. Pull over and change on the side of the road. Did it on two different rear ends. As others have said, full floating reares is where it is at.

The reason turbo cars re easier on axles is the power output. Hair driers take time to spool up and make max power. The spool up means less torque is applied to the gears at first which lets all the slack be taken up before max power is applied. When the shift happens the turbo slows slightly then goes back to full boost, atleast on a stick shift. Hopefully the auto shifts quick if you are highly boosted.

[burnin oil]

Originally Posted by hellbent72

A 10 bolt will work UNTIL the tires get traction than its toast.
A 12bolt can be bought or built to handle the power but it ain't cheap.
Go with a ford 9 and even mildly built it will handle dam near anything
Plus gear changes are a breeze.

9"s are great but dont like big tires. The stock rears like to bend. I am sure that some versions are better than others.

I second the width of the axles being the same. I have seen guys swap out the axle shafts, 5 vs 6 lug, to install them in a 2wd or 4x4 on a full size truck. This doesn't work on S10s though. A 2wd rear will fit but the 4x4 rims will hit the leaf springs. Been there and ran 2wd rims for a temp fix.

[crazy longhorn]

Originally Posted by burnin oil

9"s are great but dont like big tires. The stock rears like to bend. I am sure that some versions are better than others.

I second the width of the axles being the same. I have seen guys swap out the axle shafts, 5 vs 6 lug, to install them in a 2wd or 4x4 on a full size truck. This doesn't work on S10s though. A 2wd rear will fit but the 4x4 rims will hit the leaf springs. Been there and ran 2wd rims for a temp fix.

It is well said, by both guys....#1, you will not break anything ,until you hook it up (nobody can argue with that)! Yes, the stock (9" rears tend to bend the tubes, at the center with big power put to them? The Danas, don't flex much, with the thick wall tubes. It takes a lot of tire(or slicks), to hook up 600 hp at the rear wheels You wont "hook" it in street trim, & I would bet that you wont break a 12 bolt on the street? longhorn

[bbcmudtruck]

So are the 12 bolts just not worth building then? C clip eliminators, axles, ring, pinion can all be bought cheaper than a built 9" cant they? I simply don't know, just asking asking the question because that's what I intend to do to my 12 bolt. If its a bad idea to dump the money into a 12 bolt, I'd be much appreciative ahead of spending curve! Or would a dana 60 just be better in stock trim?

[burnin oil]

brake no but you can hurt them. lol. I wouldn't dump a ton of money in a 12 bolt rear. It does not take long to get into the price of a Currie 9". Dont forget that camper specials had D60 rears. They are not the HD full floater rears but do have the good center sections. If you want a good rear end find a Dodge diesel 2500 5spd truck axle. Dana 80 center chunk with a dana 70 outer. Never blew one of those up. 700 RWHP with a manual trans!

[cableguy0]

Your definitely in the territory of a 14 bolt or dana 60. I wouldn't even bother dumping money into the 10 bolt or the 12 bolt. Build something that you know will not something you hope will hold.

[clinebarger]

8.5" 10-bolts diffs are actually stronger than a 8.875 Truck 12-bolt...Not by much though. Neither will handle 650 hp if hooked.

You can Truss a 9" ford pretty easy, The old Grey Iron center sections need to be avoided in high horse builds, Seen too many pinions get ripped out.

Dana 60 is a very good choice as well.

[CamaroChris]

I have not done any searching but I will. but I'm going to ask anyway. can a D60 be made 5 lug? I found a 6 lug 14 bolt can that be made 5 lug? or is it just a matter of re-drilling the hub? I'd like to stay away from ford 9" looks like carriers for them get pricy.

[burnin oil]

Someone probably makes a kit but all it would be is a custom hub. I am not sure if the stock one could be redrilled or not. Ideally you would want the full floating 8 lug version converted to your lug pattern. FF axles are alot stouter than a traditional axle. The axle housing holds the wieght (big bearings) where the shaft bears the wieght in a standard axle.

[cableguy0]

Originally Posted by CamaroChris

I have not done any searching but I will. but I'm going to ask anyway. can a D60 be made 5 lug? I found a 6 lug 14 bolt can that be made 5 lug? or is it just a matter of re-drilling the hub? I'd like to stay away from ford 9" looks like carriers for them get pricy.

Yes there were factory dana 60's though rare. Chrysler used the dana 60 in the hemi cars in the 60's and 70's. Axles aren't terribly expensive to just get a set made.

[crazy longhorn]

Don't worry about rare/expensive...cut the truck axle to the length that you need....add the ends & axles to fit the build. Check what you purchase, but many of the 3/4 ton trucks will run a 4.10 gear .... on a 29" tire, its pretty close to right Longhorn

[Captainfab]

You can have any bolt pattern you want, if you don't mind spending the money to make it happen. The Semi floating 9.5" 14 bolts were used in the '90's 454 SS pickups which had the 5x5 wheel stud pattern. So you should be able to switch the 6 lug axles for a set of replacement 454 SS pickup axles. But be aware that the '88-'98 differentials are going to be about 1.250" wider than your current differential.

Originally Posted by CamaroChris

I have not done any searching but I will. but I'm going to ask anyway. can a D60 be made 5 lug? I found a 6 lug 14 bolt can that be made 5 lug? or is it just a matter of re-drilling the hub? I'd like to stay away from ford 9" looks like carriers for them get pricy.

[Gumby]

Don't forget the 10bolt cover axle that has 12bolt guts inside it. [often called a truck axle]

like a mystery box, many don't guess whats inside right by the outside looks.

[GASoline71]

Those i believe were a BOP axle, and strong as hell, but rare as hens teeth to find.

Gary

[Gumby]

Gas Moneky Garage called theirs a truck axle, so I assumed it was common in trucks too. They paid $700 for just a posi center for one.

I got a posi complete in the side yard....... [ peg leg one in the wagon]

yea its sort of down to luck or someone with a CNC to get a gear change, but the clutchs are rebuildable. [ can't even get a paper gasket for the cover ]

[GASoline71]

Diff cover gaskets aren't needed. Haven't used a gasket on a diff cover in over 20 years. Black RTV (The Right Stuff), used in the proper quantity is your friend.

Gary

[crazy longhorn]

Being an old Oldsmobile "nut', from way back, I remember the 12 bolt cover "o" axle, used in the 68-72 cutlass/442 models. This was a 8.5, 10 bolt ring. Not here to argue, but I have not seen the diff that you talk about? Was it in a full sized Buick or Pontiac? Longhorn

[Gumby]

8.875"MP POSI cover


its a 10 bolt covers, but its 12 bolt guts inside.

got a 77 posi and a 80 peg leg of it.

Big BOPs, TV said also trucks?