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12 or 14 bolt axle

1TUFF89

1/2 ton status
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Apr 6, 2000
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Location
West Point, Virginia
I'm going to install either a 4 or 6 inch lift on my 89 blazer. While I'm doing that I think it would be wise to switch out the axle as well. I drive my blazer to work about 2-3 days a week and I don't do any rock wheeling, but thought if I go with a lift and at least 35" tires I want something stronger. I do go off road but nothing major. Would a 12 or 14 bolt be best considering strength and price? Where is the best place to get a 12 or 14 bolt axle with the gears already installed? At least 4:10 gears I guess. Thanks, guys.

CHEVY - "THE HEARTBEAT IS GETTING LOUDER"
 
would not want to say that to fast. I broke a 10-bolt to bits last week on-road! trying to get a 14-bolter now. No luck in this stupid country.

"K5 Grand GT Silverado in the Netherlands."
 
i have a 75 jimmy with a 12 and a 44 both with detroit lockers front and rear and 4.10's, i run 33's and even ran 35 boggers i do a little extreme off roading every now and then and have had no problems it's also smaller in size than a 14 bolt so you get some clearance,,, if you want even more strength buy the full floater kit from warn and install your self and there you go a srong 12 bolt without the weak links "c-clips" hope i helped and check us out at jimjim.coloradok5.com
 
I do some wheeling - especially during hunting season when I'm off road. I've basically planned to keep my blazer and "build it" rather than sink $25 to $30 thousand dollars into a new vehicle. I want to do the lift, axles, tires and rims all at one time. I would hate to lift it, get 35" tires, and go wheeling and have to replace the axle(s). Everything I've read on this site seems like good info. I didn't want to keep the "weak" 10 bolts if there's a chance of them breaking, etc. Even if I keep the 10 bolt axles I will have to get new gears installed. So far I have a $1,000 estimate to replace the gears in the front and rear axles. I'm thinking it might be cheaper in the long run to buy a heavier duty axle with the desired gears already installed.

CHEVY - "THE HEARTBEAT IS GETTING LOUDER"
 
Hey man,

Havent talked to you in a while. In my opinion, for what you do, I would go with the 12 with the warn conversion kit. Strong enough for what you do but not overkill. If you do want a 14 I know where two of them are so let me know. They are at my cousins house right in Chester so its not too far from us. Shoot me an email, I still want to get together with you guys and do some trashtalking. I met another Richmonder the other day, NewK5Guy. He lives off Jeff-Davis. We might even get together this weekend and hang out. Let me know.

Later

Have you driven OVER a Ford lately?
 
What vehicle model/year are 12 bolts from? How much is the FF conversion kit? I'm in the same boat.
 
I know for the second generation 12 bolt rears were used up until 1982. Either 10 or 12 were used in 1981. Axles out of any half ton pickup should fit your rear with 0 problems.
 
Well I just picked up a 12b and a D44 for my Blazer... here is the boggles you're facing... 4.10's are very rare in half ton axles unless they are after market... from the sites I've visited it appears they were only available 73-76 and they weren't many put out, but 4.10's are easy to find in a 14b. The 14b is heavier though... Basically what it came down to me is why run a 14 in the rear and deal w/ changine rims, move up to more expensive 16 or 16.5 rims when you don't really need it and you'll be running a Dana 44 8 lug in the front anyways, unless unlike me you could find one for less then 700. The frt dana 44 is going to bust before much else... get a 12 b D44... add the Mark williams main caps and the larger axle shaft bearings and maybe upgrade the front axles w/ bigger u-jt's and/or ORD's axles... Just make sure the 12b isn't a Gov-lock... yuck.

1987 Chevy K5 Blazer- 350 TBI
 
If I were you, I'd get a 12 bolt, and replace the axle shafts with Moser ones <A target="_blank" HREF=http://www.moserengineering.com>http://www.moserengineering.com</A> (You'll find them under C-clip category). They are $225 compared to about $800 for a ff conversion kit. That should give you some strenght without emptying your pockets, and easier to install too. This is actually what I'm going to do with my 12 bolt.

Hope this helps.

<font color=blue>//////
<A target="_blank" HREF=http://blazer79.coloradok5.com>http://blazer79.coloradok5.com</A>
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A while ago, there was an interesting article in Hot Rod about how to strengthen the 12-bolt axle. They suggested to weld on Ford 9-inch axletube-ends so you can use modified axles (with large pressed-on 9-inch tapered roller bearings) and get rid of the c-clips becaus the axle is held in by the backing plates. So if you are planning to buy new axleshafts anyway, this would significantly strengthen the 12-bolt.
I never saw this conversion on a Blazer, but as the article said, this is quite common in the dragracing scene.
The article also said that moser engineering routinely does this conversion, so they should be able to help you.
BTW, these weld-on ends could also solve the problem of the "3-inch too narrow" rear axle.

DO IT TODAY - TOMORROW IT COULD BE ILLEGAL!
 
" I didn't want to keep the "weak" 10 bolts if there's a chance of them breaking, etc. "

There is a chance of breaking the 12b, and also the 14b. I still say to keep the 10's for your application.
to make you fell better buy some aftermarket axles for the rear 10b, and store the one's you now have, under the hood.
 
Talk to "thatk30guy" on here.............has all kinds of 14 bolt rearends with 4.10's or whatever you want and they will bolt in. Having one built right now from him to go with my Dana 60 coming on Wednesday............

<font color=orange>'79 - 406 TPI -<font color=orange> K5#5 - <font color=blue>See it at---&gt;<A target="_blank" HREF=http://www.blazzinor.coloradok5.com>http://www.blazzinor.coloradok5.com</A>
 
Check out Stephen's axles for sale:
<A target="_blank" HREF=http://www.offroaddesign.com/specsheet.htm>http://www.offroaddesign.com/specsheet.htm</A>

Murphy's Laws on Life :
"Opportunity always knocks at the least opportune time."
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