Max Hp/Tq of Built 12 Bolt rearend?

[AllGoNoShow]

So did a search and didn't come up with anything concrete. I have a 68' C10 with the stock 12 bolt. Assuming I put some aftermarket axles in it (Moser, Strange, Yukon, etc), a new posi carrier (Eaton, Tukon, etc), weld the tubes to the case, new gears (Richmond or the like), a new aftermarket rear-end cover (one of the ones with the girdle that supports the main caps), how much power can these rearends reasonable handle?

It will be a mostly street driven truck on street tires, with maybe a half dozen trips to the drag strip with drag radials.

I came across this article (https://www.streettrucksmag.com/tech...id-foundation/) where they rebuilt a Truck 12 bolt with all Yukon brand gear and claim it could handle 800hp, which seems very high. What do you guys think?

Nick

[mongocanfly]

Obviously its gonna be the weakest link is how much hp it can handle..
For Instance say the moser axles can handle 1500hp...but the eaton diff is rated for 800hp...then 800hp is the most you can have...
But if built with good components, I'm betting the weakest link will be the housing itself..
Cant speak for the hp rating of your diff ,but if you break moser/strange axles , then you done something..

[gmc684x4]

If you want super tough run dana 60 converted to 5 bolt

Stacy David did that with project copper head on Gears i re watched it the other day on you tube

[Ziegelsteinfaust]

The trucks 12 bolt has a smaller pinion vs the car 12 bolt i believe. A built truck 12 bolt if memory serves me is 550hp. A Ford 9" comes in slightly higher at 600.

A Strange 60 is probably the strongest rear end you can get in 5 lug with the 9" right at its heels.

There are 3 wild cards that determine how beat up rear end gets.

1. Is the nut behind the wheel. Driving like you stole it, and even a built rear end will fail in short order.

2. The tires. Sticky tires or heavy tires force more torque action back to the weakest link. A built 600hp 12 bolt with 26" street car tires is a 450hp 12 bolt with offroad 35's for an example. Especially when you go for Australia shaming burn outs, and just let off the throttle. Instead of rolling out of the burnout.

3. The converter. A low stall converter transfers more torque then a higher stall speed converter. This kind of applies when your really at the edge of reliability, and drive hard. Let's say on a hard 1-2 shift a tight converter barks the tires easily, but a low stall doesn't. Thus the torque converter momentarily absorbs the excess power from the no lift shift, and helps protect the rear end.

I have a snapped 31 spline axles in a built 8.5 10 bolt with only 450hp/425tq. I had a M22 rock crusher for a trans, and was practicing no lift shifts on street tires. The rear should of been fine to 550hp.

[LS short box]

The other thing to add to the list is 1350 u-joints. That means a new pinion yoke and redone drive shaft along with a 1350 trans yoke.

[clinebarger]

Like Ziegelsteinfaust stated......MANY variables. I have a customer that could break built car 12-bolts after @ 200 passes with 600 ft lbs......His car was fairly heavy & hooked very well (Full weight 1957 Chevy Belair) Has a Strange 60 now with over 500 passes without issues.

[vince1]

delete

[Ironangel]

I've been pounding a truck 12 with 450 HP for years, no issues! The only difference between the "T"ruck-12 and the "P"assenger-12 is the pinion diameter change that took place in like 64. The truck 12's have larger tubes allowing higher weight bearing ratings. I am a firm believer in the truck 12's especially if you weld the tubes and add a girdle cover. I die grind out the questionable and sometimes leaking plug welds and fill them with MIG weld. The Dana 60 is indeed stronger but full floaters are in a class above and if I were going to go full float rear axle I'd go right past the Dana and go with the even stronger and much cheaper 10.5" 14-bolt with SRW hubs. I'd never (and this is just me) put a Ford 9" under my Chevy! If and when I break my truck 12 I'll modify a 14-bolt if I cant find a Dana 60 for a reasonable price. I have recently built a 439ci BBC motor to run in my drag truck, that motor lives at 7000+ rpm and makes an estimated 600+ HP respectively. I'm not at all worried about the T12, I'm more worried about the transmissions and drive lines holding up. I did have to replace the trailing arm pearches on the T12 with CaptainFabs pearches because the torque on the launch will curl the factory versions up! So keep an eye on those...I've yet to see a pinion snap on a 12-bolt car or truck. I have seen them shell out the guts but those were on ill fitted back yard set ups. Years ago domestic gear sets were readily available for the T12's, today, good luck! Yukon, Motive, Richmond, and all the others are made in foundry's off shore! Yukon and USA Standard are the same company but with different QC ratings and pricing to reflect those ratings. I went round and round with Yukon when they sent me a gear set made in India! So beware! NOS gear sets are still out there but getting harder and harder to find...

[Ironangel]

Originally Posted by clinebarger

Like Ziegelsteinfaust stated......MANY variables. I have a customer that could break built car 12-bolts after @ 200 passes with 600 ft lbs......His car was fairly heavy & hooked very well (Full weight 1957 Chevy Belair) Has a Strange 60 now with over 500 passes without issues.

Glad your back OG!

[sweetk30]

ironangle good info there buddy

if you do not want to step up to a dana 60 or 14FF rear but want some big beef dont forget gm 9.5" 14 semi float . come under the 454ss trucks . high gvw / trailer package 1/2 ton 4wd and light duty 2wd 3/4 ton 88-up trucks . also there was 8 lug only in 80's light 3/4 ton trucks .

the aftermarket has stepped up a bit over the years for these axles . there was 5 lug / 6 lug / 8 lug . few width versions also depending on 2wd or 4wd in the 88-up stuff .

i know lots of guys in the lifted big tire 4x4 stuff that wish to stay 6 lug but need more than a 10 bolt 8.5" axle offers in strength swap up to these 9.5" 14 semi float axles a lot .

[AllGoNoShow]

Thanks for the replys guys. Sounds like if I build it right, I should be all set.

Any thoughts on putting c-clip eliminators on for a mostly street ride? Was also thinking of just putting some disc brakes on the rear-I have to imagine those help keep an axle and wheel from walking out if you break an axle.

[Ziegelsteinfaust]

If you want C-clip eliminator. Get the weld in variety.

[Captainfab]

I agree. I don't know about other brands but none of my rear disc conversion brackets will work with the bolt on c-clip eliminators. The Moser 7950 housing end is the correct one to use with the truck 12 bolt and still be able to use the truck brakes. Those use the large pressed on axle bearings (Ford). You could also have the housing narrowed at the same time if you want.

Originally Posted by Ziegelsteinfaust

If you want C-clip eliminator. Get the weld in variety.