My blazer drives smooth in front wheel drive - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Madbomber88 · 09-19-2004, 06:44 PM

Well it finally happened. Drive up a gradual incline on a highway, and my rear end blew out. Driveshaft spins freely with only a nice clanking noisein the rear.

I put it in 4X4 and got home fine in front wheel drive. Pulled the cover and it's a mess of broken metal. If I'm going to pay a mechanic a few hundred to fix it, I'm thinking of getting a new axle.

It's a 71 CST with a 12 bolt rear and posi from the factory. What are my options for axles? All I know of the top of my head is Boyce equipment, but I can't find a 12 bolt on their website.
Any ideas are much appreciated.
Thanks,
-Tim

BobbyK · 09-20-2004, 11:02 AM

12 bolts are a dime a dozen.Just go to a junk yard and look around.
Do you know your gear ratio?
I'll bet you could pick up a 12 bolt at a pick-a-part for less than $100.00.

badpeanut · 09-20-2004, 11:58 PM

Correct me if I'm wrong, but the spring pads are narrower on our first gens 4x4s than '67-'72 leaf spring 4x2s and '73-up 4x4s/4x2s. If you use a '73-up 12-bolt (these are a dime a dozen) you will need to move the spring pads outward, relocate the shock mounts (different location and we need non-staggered), and work out the brake lines (just use the '73-up?). I think there is also a difference in spring pad width (plus the u-bolt direction difference).

If anyone has any more information on this swap I'm also interested.

3wbdriver · 09-21-2004, 01:58 PM

Hey madbomber. If that's an Eaton Posi unit, and you decide to replace it, let me know please. I'm looking for one. I've got a bad housing with good guts looking for a home. Thanks.

09-19-2004, 06:44 PM	#1
Madbomber88 Active Member Join Date: Mar 2004 Location: Virginia Posts: 169	My blazer drives smooth in front wheel drive Well it finally happened. Drive up a gradual incline on a highway, and my rear end blew out. Driveshaft spins freely with only a nice clanking noisein the rear. I put it in 4X4 and got home fine in front wheel drive. Pulled the cover and it's a mess of broken metal. If I'm going to pay a mechanic a few hundred to fix it, I'm thinking of getting a new axle. It's a 71 CST with a 12 bolt rear and posi from the factory. What are my options for axles? All I know of the top of my head is Boyce equipment, but I can't find a 12 bolt on their website. Any ideas are much appreciated. Thanks, -Tim __________________ 71 Blazer CST 72 K20 Capt USAF

09-20-2004, 11:02 AM	#2
BobbyK Registered User Join Date: May 2000 Location: Petrolia,Ontario,Canada but working in Port Huron,Mi. Posts: 1,769	12 bolts are a dime a dozen.Just go to a junk yard and look around. Do you know your gear ratio? I'll bet you could pick up a 12 bolt at a pick-a-part for less than $100.00. __________________ 71 blazer,350SBC,approx.375HP,700R4,factory GM TPI.Dual electric fans,33x12.5x15 ATR on stock suspension. Petrolia,Ontario,Canada but working in Port Huron,MI. See ALL my Blazer pic's HERE

09-20-2004, 11:58 PM	#3
badpeanut Not a bad nut after all.. Join Date: Dec 2000 Location: ND Posts: 1,755	Correct me if I'm wrong, but the spring pads are narrower on our first gens 4x4s than '67-'72 leaf spring 4x2s and '73-up 4x4s/4x2s. If you use a '73-up 12-bolt (these are a dime a dozen) you will need to move the spring pads outward, relocate the shock mounts (different location and we need non-staggered), and work out the brake lines (just use the '73-up?). I think there is also a difference in spring pad width (plus the u-bolt direction difference). If anyone has any more information on this swap I'm also interested. Last edited by badpeanut; 09-21-2004 at 12:01 AM.

09-21-2004, 01:58 PM	#4
3wbdriver Registered User Join Date: Aug 2003 Location: West Central Louisiana Posts: 82	Posi Hey madbomber. If that's an Eaton Posi unit, and you decide to replace it, let me know please. I'm looking for one. I've got a bad housing with good guts looking for a home. Thanks. __________________ '72 Blazer, 4WD, 350/4 spd. Affectionately known as "Da Beast" '04 Silverado (new daily driver) '00 Intrepid (wife's ride) It's a BLAZER dude! No options, no emblems, no a/c, no fancy shmancy. It's a BLAZER....



Register or Log In To remove these advertisements.

Register or Log In To remove these advertisements.