78 blazer rearend not the same..

[Firebirdjones]

Originally Posted by cleszkie

I'm not knocking the good job you did modifying the rear axle. But I'm just curious why you would go through the trouble to hang a 1/2 ton corporate 12 bolt under the rear with all that horsepower? Don't those have a tendancy to shear pinion gears under high load? Seems to me that a Dana 60 or 14 bolt would have been a better choice. Again, if you got a great deal on the 12 bolt, then I can see using it, but you may need to eventually upgrade if it grenades.

Actually the only weak link I found with the truck style 12 bolts is the diameter of the pinion itself. I have snapped 2 of those in half on the street. I've never sheared the gears however.

The pinion in the truck 12 bolts are only 1.438 compared to the passenger car 12 bolts of 1.625.

Ironically the truck 10 bolts in later years which are the 8.5's (ring gear diameter) have the same diameter pinion as the passenger car 12 bolts (1.625) So they have an advantage over the truck 12 bolts in that respect.

But even with all that said, I kept the truck 12 bolt for a few reasons. I didn't want to go through the trouble of searching for a 14 bolt or dana 60. They are heavier and take more HP to turn them and I'm a concious person about that stuff (just comes from a racing back round)
Plus these brand new front and rear diffs just kind of fell into my lap, I wasn't looking for them. I was actually quite happy with the 3.07 gears that were in the blazer. But with all the new parts, ball joints and tie rods, new ring and pinions, posi, etc....there was easily 3-4 times the money in them than the $500 I paid.
I was looking to buy a new posi for my original rearend and also planning to replace all the tie rods and ball joints in the front end (they are all original) in the next couple of months. These front and rear diffs solved both of those issues in one shot.
Another little benefit I gained was larger rear brakes 11x2 3/4 vs 11x2 with all new brake hardware and wheel cylinders, new rotors and new drums, brake hoses etc. etc...The guy stuck alot of money in these diffs and they just sat. I don't do any hardcore off roading, just recreational. Only run 33's on it. I'm more worried about snapping another pinion in half on the street The 6.0 has plenty of grunt to break things and I'm more of a stop light to stop light guy. I'm surprising alot of people with it I'll be hitting the strip with it on a test and tune night in a couple weeks.

It wasn't hard work though, I did the spring perches and the shock mounts in about 2 hours. Had the rearend in the truck and driving it that evening. The front diff will be a direct drop in.

[cleszkie]

Firebird - Yeah that is was I meant by pinion gears, shearing the shaft not the teeth. Again, I respect your craftsmanship and decision with regards to the new axles. Please do not feel that I was criticizing your work in any way, as I have long envied your Blazer!

[Firebirdjones]

Originally Posted by cleszkie

Firebird - Yeah that is was I meant by pinion gears, shearing the shaft not the teeth. Again, I respect your craftsmanship and decision with regards to the new axles. Please do not feel that I was criticizing your work in any way, as I have long envied your Blazer!

Not at all bud. It's all good I re-read that again later and realized that the pinion snapping is probably what you meant.

I probably would have given the 14 bolt full floater serious thought if one came my way, it just happened this way.

I have a 79 single axle 1 ton that has that 14 bolt full floater rearend in it. It's one stout piece.

Thanks for the kudos. Cheers.