New Guy Busted Rearend

[85 c-10]

Hello all. I am relatively new. Just been looking at all the info for a while. Over this past Winter, I built a 355 for the truck. I built this to take a 70mm turbo that I wanted to put on in June. Ive got most of the turbo parts except for the fule lines, and hotside parts. Engine consists of:

GM Steel Crank
Manley H beams
SRP Dished Pistons 8:1 CR
RHS 200 Aluminum Heads
Summit 282/292 .496/.520 114 LS
Edelbrock Victor Jr.
650 Speed Demon
Mallory 685 Ignition System

Anyway, after getting a new distributor, setting the timing, and getting the carb tuned in, 2 of my boys and I went for a ride. From a dead stop, I hammered it, truck got a little crazy and chucked an axle out. Now Im in search of a better differential. It has a mini spool now, and I hate it. Im looking for something that will handle about 600hp/600tq when I get the turbo on. Im really wanting a 9" b/c they're on every corner. I need help from anyone who might know what 9" matches our width on these trucks. I was told to get good axles, and a good differential for the 10 bolt, but thats more than a newer 9". So whats the concensus? What is a better road to take for a street truck. I don't want this to hook up b/c the truck is not setup to plant it. It will spin no matter what. Its a fun toy, not a drag truck.

Thanks for the input,

Josh Johnston

[old Rusty C10]

i cant help you with the axel/rear question but id love to see pics of the rest of your truck how about a few and welcome to the board

[Restrorob]

Most of the mud truck racers around here run a 12 bolt, Some are pumpin out 500 + ponies to those BIG cupped tires and don't seem to break.
Just another option.

[Srubydo1986]

i Say go 14 bolt theres no way youll break it.

[Pyrotechnic]

If you had a 10 bolt, then it's no surprise that it broke. Get yourself a race built truck 12 bolt and it should be just fine.

[Rc 415]

I hear ford 9" is a good choice.

[gchemist]

There is a Chrysler 9.25" or the infamous 9".

Good reading between the 9" and GM 12 bolt.
http://www.chevyhiperformance.com/te...nd_comparison/

I swapped in a 78 12 bolt to replace the original 10 bolt.

[BaddBusa2005]

you can usually pick up a 12 bolt pretty cheap. Or you could just upgrade to the 30 spline axles and put a tru trac in it, with a girdle style rear cover. I am going to beef my 8.5" up a big before i go 12 bolt.

[Slonaker]

I'm pretty sure SanitysBane (http://67-72chevytrucks.com/vboard/m...oster&t=223747) was running a 9" in one of his trucks a while back. Check with him.

Slonaker

[85 c-10]

Im finding that a 12 bolt would hold the power, and be easier to install. My problem now is I don't have a lot of treasure yards around me. Ive been looking all over online. What years do I look for? I was looking at mid-late 70's 4x4. Was there a specific option code for a posi rear? If I go this route, I will get some aftermarket axles and use a 5 lug pattern. What can I do for brakes? What has the 5 lug, big drums that I could use?

Thanks everyone,

Josh Johnston

[bigblock73]

While the truck 12 bolts are stronger than the truck 10 bolts, there still isn't a lot more you can do to them to make them stronger. When I needed to repair mine, I was told the major mfr's of aftermarket Axles did not make stronger axles for my application ('73 12 bolt)....I looked too and found that to be correct. Also, nobody makes longer wheel studs for our trucks either...something you need if you plan to race at some sanctioning bodies.

I would start measuring 9" diffs at your local wrecking yard and see what you come up with. Anything can be made to fit, and the 9" setups have a huge aftermarket following.

[Zoomad75]

Superior makes 12b truck axle shafts for the 4wd crowd, I don't think it would be a stretch to get a 5 lug version instead of a the 4wd 6 lug.

I think the big problem is putting a bunch of power down to the ground on a 10 bolt with a spool is just inviting failure when the tires eventually hook up. No suprise there for me. Switching to a 12bolt with alloy axle shafts and posi/trac loc should be more durable than a 10 bolt with a spool, but the weak link is still the c-clip axles.

You can eliminate the c-clips by changing the housing ends to accept a ford 9" bearing/retainer setup and then bolt the axles in. Or you can just get a 9" all together. If you weren't planning the Turbo, I would say a beefed up 12bolt (without a spool) would work. But if more HP is in the future plans I'd go straight to the 9" The 9" will give you the bolt in shafts, choices of shaft spline counts from 28 to 40 (31 spline being the most common in street applications) numerous gear ratios, posi's/lockers/spools and the benifit of the drop out center section. Plus there are more choices to go to for disk brakes too (explorer setups are easy to adapt).

I think you've done some of the homework already in that beefing a 10 bolt would cost more than a 9" and still be a 10 bolt that if you break another axle it's still coming out.

If not a 9" you could search for a 1/2 ton Dana 60 used in the GMC trucks (67/72), but good luck in finding one of those. If an when you do find one, i hope you got some dough to pay for it because they aren't cheap.

[SanitysBane]

Yup I had a Ford 9 in my '83 C10 Long box with a warmed over 454. I pulled the rear end out of a mid to lates 80's F-150, its about 1/4 or so wide per side, not really enough to worry about. I have around 1-1.5K in my Ford 9, I got a gear set(3.88) from Summit Racing. It was a "Summit Racing Brand" but when I looked at the gears it had FOMCO stamped on them. I also got their instalation kit and detroit locker. We redrilled the axles to the Chevrolet 5X5 bolt pattern from the Ford 5X5.5 and used screw in studs. If I was going to do it over again I would either buy new axles or buy new real wheels that will work with the 5X5.5 bolt pattern. The brake line required a tiny bit of bending in order for it to fit but it works perfectly. Never had any problems with it at all and took it down to the racetrack several times.

As far as the detroit locker goes some people hate it and some people love it. I am one of thoes people that LOVE it. I have a posi in the '70 SSChevelle and it doesn't engaged anyware near as solid as the locker did. If you were really good with the throttle from a dead stop you could get the rear end to lock up going around a corner and have the rear end hop around the corner. In my opionion, Ford 9 inch and detroit locker are the ONLY way to fly.

Another really good thing about the Ford 9 inch, is that if you do bust an axle you won't have to worry about the axle coming out, pressed fit axles.

One Side note, when you get your Ford 9 inch built, do NOT use a crush sleave. I have a peice of a center section that shows what happens when that crush sleave collapses when leaving the line at 7,000RPM with slicks in a manual transmission car. Summit also sells solid crush sleaves that have shims in them to get the correct amount of height.

[85 c-10]

Thanks for all the information guys. I think I will stay with the 9" idea. I can get some aftermarket axles for my bolt pattern. I would like a disk brake rear. I'll look at the Explorers and see what I can get on a width. I would love to get one with a posi unit already in it. I can make that last until next year. This does bring up another issue, of drums or rotors. If I get 5x5 axles, im gonna be searching for awhile for something that will fit the Ford rear but GM pattern. Anyone got any ideas?

Josh

[SanitysBane]

Good luck! I have been searching for a while to find rear disk brakes for my Ford 9 that are 5X5 bolt pattern.