Bullet proof GM 12 bolt.

[Blue Rat]

Those guys that run the HP engines in the C10's. I have a 1971 C10 with a current 12 bolt with 4.10's with plans of running a tire somewhere around 28"-29" an about 11 inches wide. If I go to 29" tires may go with 4.56's. I will be running a BBC with around 550 HP with extra 150 shot. The truck should weigh in around 3900. The converter is going to be around a 4000 stall.

What do you run to make your truck hook an be reliable? I do not want to be going through alot of rear ends. Oh yea, street driven some not much mainly around town.

[special-K]

Alloy axles and C-clip eliminators is what mine has. Haven't run it yet.

[clinebarger]

Originally Posted by Blue Rat

Those guys that run the HP engines in the C10's. I have a 1971 C10 with a current 12 bolt with 4.10's with plans of running a tire somewhere around 28"-29" an about 11 inches wide. If I go to 29" tires may go with 4.56's. I will be running a BBC with around 550 HP with extra 150 shot. The truck should weigh in around 3900. The converter is going to be around a 4000 stall.

What do you run to make your truck hook an be reliable? I do not want to be going through alot of rear ends. Oh yea, street driven some not much mainly around town.

I would say thats to much for a truck 12 bolt or even a car 12 bolt.
I see a Ford 9" or Dana 60 in your future

[orbot]

Just get a good set of axle shafts and replace the old bearings...

[ItsRandy]

9" Ford, Detroit locker and 35 spline axles in mine (Strange Engineering).

[Captainfab]

I would think a Detroit locker, alloy axles and C-clip eliminators and you should be fine. There's really no need to change to a 9 inch IMO. You can get the same upgrade parts for the truck 12 bolt.

You might see if a mod will move this to the 'Racing and High Performance' section. There are a few guys over there running the truck 12 bolts, and they can give you an answer based on real world experience.

[djracer]

I would buy a 9 inch. That convertor sounds too loose to me. If you are gonna spray it I would think it needs to be tighter.

[Blue Rat]

What would you suggest on the converter?427 BBC Oval port 049's with 2.19 an 1.88's with solid roller Camshaft 2800-7000. Around 4.11's.

[85_C10_Sleeper]

I agree, get a 9". You won't regret it. Much easy to build and make stronger than a gm.
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[softballnrd27]

I am building a 9" for mine w/35spline moser axles, strange nodular-n center, and a detroit for under $2k

[nxtruck]

You can make a 12-bolt live, IMO. I run a truck 12-bolt in mine and have done so for the past 15 years. In that time, the only failure I've had was a broken ring and pinion. I run a set of 4.88s, Moser 30-spline axles, a Moser spool, studded main caps, and an LPW cover. I really need to weld the axle tubes, but as of yet, haven't done so. This setup is behind a 600 or so hp 434 ( minus n2o ) and with a vehicle weight of 3950 lbs. Now, my truck is not at the track every weekend or even every other weekend. But, it does see a lot of street action and has spent it's share of time at the track over the years.
Again, these are just my results and others may not have had as good of luck with a 12-bolt. But I wouldn't hesitate to use one again.

[68 C-10 KID]

Blue Rat,
If money is no issue, you would be into a properly built 9" around $2200
If you are looking for strength, reliability and to keep some money in the pocket.
I would would recommend the Moser axle package. You can get up to a 35 spline non c-clip axle, spool or detriot and the LPW style diff cover for around $700

[chevytruck1970]

my 12 bolt has gave me 0 problems originally built it about 12 years ago and ive changed the gear ratio from 4.10 to 4.56 to 4.88. it has moser 33 spline axles with a full spool and the truck weighs 3900 and change. It has hundreds of passes on it.

[bigjimzlll]

I spun the axel tubes on my first truck 12 bolt. The next one I welded the tubes to the housing. It survived well. Best times were 10.90's at 3800lbs. I used studs, good axels braced back cover and c-clip eliminators.
I think you're on the edge(if you hook up)

[RICKSRAT]

http://www.moserengineering.com/othe...lip-axles.html

http://www.moserengineering.com/spoo...35-spline.html

A 33 spline Moser axle w/ spool and the weld on ends would work good. Spend the extra money for the Impala /Truck ends that use the big Ford bearing now so you dont have to upgrade later. Personally I dont like the C clip eliminators. Narrow rear as much as you can to minimize as much axle tube past u bolts if using trailing arms. I Bent my tubes twice,but had a large offset on the 12" wheels w/31 x 14 Goodyears. Also was running a Transbreak and pulling 1.35 -1.40 60'. Also like BigJim said weld axletubes to housing.

[fastwillie 696969]

12 bolt with dutchman axles 4.11 gears eaton .no problem

[djracer]

Originally Posted by Blue Rat

What would you suggest on the converter?427 BBC Oval port 049's with 2.19 an 1.88's with solid roller Camshaft 2800-7000. Around 4.11's.

My guess would be a 9 inch convertor about 3500.

[Marv D]

Its all about traction and shock loading.

If your expecting <1.3 sixty foot times,, I agree with the guys saying a 9" or Dana 60 is in order. But nothing is totally bullet proof. We are throwing a LOT of weight around with these trucks and if it hooks, it is going to find the weak link. The stock truck 12bolt with upgraded axles and C-clip eliminators, a spool, and every beefy trick available will hold up to a TREMENDOUS amount of abuse. Look t what Chris is doing and it's surviving (so far LOL). Heck, I've got a great friend running 10.teens in a 3200 pound 74nova with a 10bolt with just the normal upgrades (spool, Moser axles, welded tubes, c-clip eliminators, studs, back-brace cover etc) But he's foot braking with 60' times in the 1.28-1.33 range depending on track. By the same token, I exploded Strange and Dutchman axles with only 650HP,, destroyed a Nod-iron 9" centersection with Dyneer locker and all the goodie stuff with less than 600HP,,, a sticky slick and deep gears, and dead hooking WILL find the weak link,,, I promise you.

So anything will live if your easy on it. I would guess 700HP, foot braking, questionable traction you may be fine with beefing up the truck 12bolt with all the tricks and it live forever. And you may find traction is easier to hold launching on the motor, and bringing in the N2o somewhere after the 60' cone. THAT will go a long ways is making the drive-train survive. But add some 12" slicks, and a trans-brake, hosing it out of the hole, suspension tunning to <1.3 sixty foot times and I bet your wish list soon includes a Fab9housing, $1500 Strange Pro centersection with spool, 40 spline axles,, bla bla bla.

[Keith Seymore]

I would think the 12 bolt would be fine, with some mods.

My passenger car is at 3900 lbs, roughly 1000 hp. Best ET is 9.85 at 136 mph (foot braking).

I'm still using the original 10 bolt, with Mark Williams axles, spool and C clip eliminators. I've been quicker than 11 oh's for probably 20 years or so. Broke the pinion a couple years ago, put another one back in and kept right on going.

More detail linked below, if anyone is interested (Chevelle intro).

K

[Flint70step]

Originally Posted by fastwillie 696969

12 bolt with dutchman axles 4.11 gears eaton .no problem

Some one took your 12 bolt man!I dont see a rear there

[Alex1]

I thought the real issue with the 12 bolt (truck) was the small pinion shaft. It's actually smaller than the 10 bolt (8.5) ring gear set up.

[68GMCCustom]

I too am wondering about rear ends..............truck rears that is.
Can't argue with the toughness of a 9"...also can't put a blue oval part on my GM truck.

Currently have a rebuilt truck 12 bolt with new Eaton posi, 3.73 gears, and "bearing saver" bearings. Running street 275/60-15 BFG's on 8" wheel, but I want to go to a wider 29"-30" tire, preferably MT ET Street drag radials and 4.11 or maybe 4.56 gears. Have a line lock, but its not currently installed. My 6.0L LY6 should be making over 500hp at the crank and is running thru a "built?" 200-4r, and I may add some spray....or preferably a Vortech supercharger later.


That said.......what is the "better GM" choice for a rear end tuff 'enuff to get beat on at the track by a 500+hp motor and sticky tires, yet still be up for street duty for weekends, cruises, long tours, etc. I know I'll also have to do a bit more for my 200-4r (or replace it) for it to live long. As for a rear diff.....I've always thought I'd choose a Dana 60......but the 9.5" 14 bolt semi-floater in our TBSS has me thinking about one of those.

[thirdstreettito]

I'd go with a Dana 60 to be safe. It's easy to find cheap and it will add weight to the rear to help with hooking.

[KQQL IT]

[QUOTE=68GMCCustom;4747783]I too am wondering about rear ends..............truck rears that is.
Can't argue with the toughness of a 9"...also can't put a blue oval part on my GM truck.

The only ford part on my 9" is the housing
and the only gm part under the hood is the block.

The 9" and the 12bolt cost similar money.
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[Keith Seymore]

Originally Posted by Alex1

I thought the real issue with the 12 bolt (truck) was the small pinion shaft. It's actually smaller than the 10 bolt (8.5) ring gear set up.

Agree. Axles, too.

I painted a stripe on my 10 bolt axles so I could tell if there was any twist in them.

After a couple years I pulled them back out to check;
they looked so huge I just laughed and stuck them back in without another thought.

K