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Old 05-15-2019, 12:15 PM   #1
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Join Date: Jul 2006
Location: Calgary, Alberta, Canada
Posts: 112
12 bolt rear end c-clip eliminator and disc brakes?

anyone bother to do c-clip eliminator and add disc brakes to their stock 12 bolt 6 lug rear axle? (been searching for a post dealing specifically with that...)

or did you just go with an full floating corp 14 that already has factory disc brakes??? (probably cheaper and easier?)

My truck is a 64 k10 step-side shortbox, with a corp 12 bolt rear, 3.73 gear ratio, 6 lug wheels, drum brakes at rear.

(front axle upgraded to a corp 10 bolt with disc brakes from a 87 v10) (stock size vacuum booster, mated to a 72 master cylinder made for front disc with its proportioning valve)
(tcase still the worn out old t221 - trans still the sm420)
(tires are 33x12x15 dick cepek mud country radials on the factory 6 lug axles)
(stock leafspring suspension / lift & geometry / rancho rs5000 shocks / Roadmaster rear leaf spring helpers)

I tow my camper out (from city traffic, to several hundred kilometers to the trails, unhook the camper, go trail wheeling, and mud bogging, and then at the end of the weekend, hook up and go home...

(just upgraded engine to a mild 383 stroker -- with roughly 425 HP/425 torque at flywheel.)

* braking is an issue and have been considering buying Captain Fab's rear disc plates
, and converting to hydrasteer

* I also have a Detroit TruTrak I'd like to install into the rear. So with the added stress that the stroker engine higher horsepower/torque and a locker in the rear, I've been considering adding some kind of C-Clip Eliminator...

so what do y'all think? take the time and upgrade the old 12 bolt, or just 'swap' in a 14 bolt?

(with a 14 bolt swap, will the stock driveshaft work or will that need to be resized?)
1964 K10 shortbox Stepside
383 sbc stroker under vortec heads
sm420 trans / t221 tcase / corp 10 front axle / corp 12 rear axle
rolling on 33x12x15 tires on 6 lug rims.
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Old 05-17-2019, 07:14 PM   #2
Mike C
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Join Date: Dec 1999
Location: Austin, TX, USA
Posts: 7,051
Re: 12 bolt rear end c-clip eliminator and disc brakes?

I used to replace 12 bolts in my Jimmy almost as frequently as I changed the oil. And I didn't even work it that hard.

Best thing I did was swap in a semi-float 9.5" 14 bolt from a 3/4 ton sub. The 13" rear drums improve braking as well as the front which are a little bigger than the 1/2 tons. I kept the 1/2 ton calipers.

Parking brake will work a lot better! The 9.5" is a c-clip rear as well, but rated at 5500# gvwr instead of the 3500# gvwr the 12 bolt is. Looking at the axles you will see why it is SO much stronger. And they are fairly cheap.
44 Willys MB
52 M38A1
64 Corvette Coupe
68 Camaro 'vert LT1 & TH700
69 Z/28 355 12.6's @110
69 Chevy Short Step 4 1/2"/7" drop
72 Jimmy 4WD 4spd 4" & 35's
02 GMC 2500HD 4x4 Duramax
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Old 05-22-2019, 02:49 PM   #3
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Join Date: Dec 2012
Location: Chino Hills
Posts: 1,477
Re: 12 bolt rear end c-clip eliminator and disc brakes?

I will second the 9.5, but if you want to do the c clip eliminators. Use the weld on 9" big bearing version.

Or another option is to use the Ford 8.8, and use the weld on 9" ends. This gives you a very strong rear, and bolt in axles. Toss on a Aluminum diff cover with support bolts. The early truck 12 bolts pinions were on the thin side where the car version was not. I am not sure where your 12 bolt falls in line. The Ford 8.8 copies all the good parts of GM's axles, but the c clips. So if built right it is as strong as a 9" spline for spline count, but less parasitic drag. About 15hp less. If you do this get a Crown Vic PI version as it is supper wide with a traction lok posi. Which is rebuild able fairly cheap, and strong. Plus the wide axle gives you plenty of width to play with. Lastly decent rear disk brakes if desired.
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