Help me build my rear end!!!

[Hart_Rod]

Ok, stop laughing and if you tell a joke it has to be funny, .

I'm building a new 12 bolt for the 68 S/C truck 631TQ/622HP....(I know, I know I should probably go with a 9"....). It's going to have discs, a new posi, new axles and new gears. It's main use will be short trips to work and an occassional trip to our local 1/8th mile track.

Here's what I've come up with:

Auburn Pro
4.56 gears
Moser axles

Here's the dyno sheet for the motor and link to the engine thread. Thoughts or concerns?

Engine:
http://67-72chevytrucks.com/vboard/s...d.php?t=370973

Truck Build:
http://67-72chevytrucks.com/vboard/s...d.php?t=358692

[raisinracer]

If you are set on keeping a 12 bolt you should swap the ends out. Have 9 inch ford housing ends put on your 12 bolt before you order axles. That way you get rid of the c- clips and c- clip eliminator adapters you need to run to retain your axles. Off the shelf 9 inch ford disc set ups will work with it.hope this helps.

[ripdog28]

I agree with Raisin, the main reason for the 12 bolt failure is the C-clips. Also, I would consider a Detroit locker due to your power. I dont know if the Auburn will hold up. It may, i just dont know its power rating. The Detroit is usually about 800hp. I would also go with 33+ spline.

[djracer]

just buy this one....................................................................you will be glad you did






1500 with wildwood disc brakes, 35 spline gun drilled Moser axles, Aftermarket nodgular center section, aluminum pinion support, 4.30 gears, hd yoke, spool, Its pretty tough.

[texastrendz]

i just dropped mine off a pyle bros. in houston. it was a 12 bolt truck rearend. they suggested to me if over 550hp to weld the tubes to the center section and use a clip eliminator kit. they also said to get into a higher spline count. my truck is only around 350hp and the stock rear would be fine. i put a auburn posi unit in mine, factory axles, and am using capt fabs. disc kit. when it comes to building a rear sky is the limit, kinda like motors. speed cost money how fast ya wanna go?!

[KQQL IT]

1500 with wildwood disc brakes, 35 spline gun drilled Moser axles, Aftermarket nodgular center section, aluminum pinion support, 4.30 gears, hd yoke, spool, Its pretty tough.[/QUOTE]

Thats a deal.

[djracer]

Originally Posted by KQQL IT

1500 with wildwood disc brakes, 35 spline gun drilled Moser axles, Aftermarket nodgular center section, aluminum pinion support, 4.30 gears, hd yoke, spool, Its pretty tough.

Thats a deal.[/QUOTE]


I think so!

[Captainfab]

You don't have to use 9 inch Ford housing ends. You can buy aftermarket housing ends that have most any bolt pattern you want, and they are sized to use the large pressed on wheel bearings. Moser has them for $90.00. That way you aren't stuck with Ford backing plates and then having to redrill the lug pattern in the drums. This is the way I've gone with a couple of the 9 inches that I've narrowed. You can use your stock drums or any GM 5 x 5 rear disc conversion. Also when you order your axles, you will want to order them with the correct brake offset if you're going to run GM brakes.

Originally Posted by raisinracer

If you are set on keeping a 12 bolt you should swap the ends out. Have 9 inch ford housing ends put on your 12 bolt before you order axles. That way you get rid of the c- clips and c- clip eliminator adapters you need to run to retain your axles. Off the shelf 9 inch ford disc set ups will work with it.hope this helps.

[KQQL IT]

I spent 1400ish on my 9'' without a back brace nor disk brakes... But narrowed in the driveway was priceless.

[chris mc bride]

Chevy man from birth. One thing you have to remember about those fords. They are going to be on a tow hook,this puts lots of weight on the rear end so they had to be tuff to carry all the weight while being towed.
As for cost its simple buy one extra tuff or buy something thats going to break and have you spending more for what you should have bought in first place.

[ripdog28]

Damn DJ, I have over $3000 in my rear end. WIsh you would have sold this 2 years ago. Also was all new stuff from Currie. Center section was $1800 itself for a 9+ case with a Detroit locker. IMO, take DJ's Offer.

[raisinracer]

Wish I was closer to DJracer .. you can't beat that deal..

[Hart_Rod]

I was trying to keep this "simple" and you guys are making it hard....... DJ, will those rear discs work on the street? What size of rotors are they? Do you have the part number? Also, I need the measurement mounting surface to mounting surface. Thanks,

[BigDan3131]

Heck skip the 9" and the truck 12 bolt and get a Dana 60. The S-60 already has 35 spline axles and you can use the locker in it too. If I were racing full time then the 9" would be perfect for all the gear ratio changes you can do. The 12 bolt is fine but if you get greedy and I'm sure you will racing, upping your boost and running race gas will go beyond the limit the 12 bolt has.

[AirMale]

I have a moser 9 with chevy truck ends. I never had any issues with the drums in the rear so I ordered ends from moser. No more c-clip, stock brakes and sealed bearing housing ends=peace of mind!

[djracer]

Originally Posted by Hart_Rod

I was trying to keep this "simple" and you guys are making it hard....... DJ, will those rear discs work on the street? What size of rotors are they? Do you have the part number? Also, I need the measurement mounting surface to mounting surface. Thanks,

Robb I don't think I have a part number. They are wilwood drag race brakes but they would be fine on a toy. I'm gonna run a set on my son's truck. I'll try to get a width this weekend when I go home.

[Hart_Rod]

Originally Posted by djracer

Robb I don't think I have a part number. They are wilwood drag race brakes but they would be fine on a toy. I'm gonna run a set on my son's truck. I'll try to get a width this weekend when I go home.

Hey Kevin, were you able to get the measurement of the rear? Thanks,

R/

[ProStreet68SB]

I'm making this as a suggestion, please ditch the auburn as i doubt you'll really want to rebuild that rearend when it goes boom. Get yourself a nice Eaton clutch style posi and have it set up a little on the tight side and it'd be perfect for your truck.

[matchstick]

Not to get off topic, but I don't think the 4.56 gears will suit your combo. All the Forced induction combos I mess with like a higher gear. I'd put a maximum of 3.73 in it. What size tire do you plan to run?

[Hart_Rod]

Originally Posted by ProStreet68SB

I'm making this as a suggestion, please ditch the auburn as i doubt you'll really want to rebuild that rearend when it goes boom. Get yourself a nice Eaton clutch style posi and have it set up a little on the tight side and it'd be perfect for your truck.

Thanks.

Originally Posted by matchstick

Not to get off topic, but I don't think the 4.56 gears will suit your combo. All the Forced induction combos I mess with like a higher gear. I'd put a maximum of 3.73 in it. What size tire do you plan to run?

31x20's by 16 wide.

[matchstick]

IMO 3.73's would be great for it.

[Hart_Rod]

Originally Posted by matchstick

IMO 3.73's would be great for it.

That's what I have now, but I like the way the truck felt when I was running the 3.73's with 29" tall tires.....

[ripdog28]

3.89 is also up there. With f@rd 9in you have a few more options.

[djracer]

Robb I didn't get it last weekend but this is my last week of school. I can't wait to get home and work on both trucks! Call me this weekend if you think about it.

[68 C-10 KID]

Hart_Rod

If ya want to keep it cheap and simple.
Moser offers a spool and axle package for $600. that's splines up to 35 and 1/2" studs
Willwood offers rear 4 piston disc for $600
CCP- disc disc master with prop valve about $130
After market diff cover w/ cap support $160
1350 yolk $85
with the bearing conversion numbers you can also run any 12 bolt car gear like the 4:30's
Just my 2 cent