12 bolt over a 10 bolt

[coreys87]

Everyone tells me to go to a 12 bolt and that id have less problems. Is this true? Why so if it is

 

[crazy4offroad]

I was reading the truck 10-bolt has a stronger pinion than the truck 12-bolt, and that a 12-bolt car rear axle would be an upgrade over the 10-bolt truck axle. I wouldn't go through the trouble unless it was for a 14-bolt or Dana 60 rear.

 

[foamypirate]

C4 is correct. Truck 10-bolt has a larger pinion than the truck 12-bolt, but the 10-bolt has a 3/8" smaller ring gear. They are pretty much equal in strength. The ever pervasive myth that 10-bolts are garbage comes from CAR 10-bolts that had a 7.5 or 8.2" ring gear and smaller pinions. They were indeed a rather weak axle.

 

[coreys87]

Gotcha. Thankyou for the info!

 

[bucket]

I agree, strength is similar between the two. The "12 bolt trumps 10 bolt" thing dates back to the mid 60's when the CAR 12 bolt was in fact a good bit stronger than the 10 bolt. The CAR 12 bolt was phased out in '71 when the 8.5 10 bolt was put into use. For whatever reason, the TRUCK 12 bolt carried on for another decade.

 

[HotRodPC]

Reason being, a truck needs the bigger R&P and stronger axles, cars of lighter weight, and not likley to be carrying loads didn't NEED the bigger axle. You could still get 12 bolts in cars into the 80's but it was normally only in Performance Applications, like SS models.

 

[bucket]

Reason being, a truck needs the bigger R&P and stronger axles, cars of lighter weight, and not likley to be carrying loads didn't NEED the bigger axle. You could still get 12 bolts in cars into the 80's but it was normally only in Performance Applications, like SS models.

Yeah, but the truck 12 bolt was no stronger than the 8.5 10 bolt. They probably had a large surplus of parts to use up. If anything came with a car 12 bolt past the mid 70's it would be news to me, as far as the Chevys go. GM started using the 8.5 across the board and became the axle used in performance cars too (in place of the 7.5).

 

[GreaseDog]

C4 is correct. Truck 10-bolt has a larger pinion than the truck 12-bolt, but the 10-bolt has a 3/8" smaller ring gear. They are pretty much equal in strength. The ever pervasive myth that 10-bolts are garbage comes from CAR 10-bolts that had a 7.5 or 8.2" ring gear and smaller pinions. They were indeed a rather weak axle.

Truck 10 bolts being weak is not a myth, it's a fact. Poor carrier design. What the 12 bolt gains in carrier strength it loses in the pinion bearings.