??? Rearend Buildup For High Power

[rn2fine]

While I was working on my Burb today a young man from down the street came by. He has a 68 shortbed with a 6 cylinder and a 10 bolt rearend. His dad bought him a 454 that is being rebuilt. His plan is to put a 280 cam in the 454, run a Performer RPM intake, and attach it to a TH350. His dad is recommending that they find a way to put a Ford 9" in the rear. I told him that I would check with you guys to see how to buildup his existing rearend to handle the high horsepower and torque of his new motor. Once again, he has a 10 bolt, and it has 4.11 gears. Can it be beefed up? Should he switch to a 12 bolt? Or should he pursue the Ford 9 inch? He is also trying to decide on a rear end gear ratio. He plans to use the vehicle daily and do some racing on the weekends. I will pass along your advice to him.

Thanks !!!

[Autometer]

I'd just go with a 12 bolt. Fine one that bolt right in and that'll keep his GM truck all GM.

[lukecp]

I think a 12-bolt should be fine and easy to put in. That truck shouldn't have a 10-bolt stock, it would have been swapped in later. 12-bolts are the only rear to come in half-ton Chevies of this vintage. Some early GMC's had Dand 44's in the rear though.
Member bigjimzll is running 11 second quarter miles with a 12-bolt truck rear.
10-bolts are weak rears stock, one of my friends completely destoyed an 8.5" model in an '86 K10, with a sick 305 in front of it. The thing pretty much came apart, without even 150k miles on the clock.....some how the crosspin wallowed out the hole in the inside of the carrier, came out, and it let go of an axleshaft. I've had problems with 12-bolts, but it has all been because of them getting worn out with ultra-high mileage, not breaking parts.

[rage'nrat638]

heavy foot
FATHER KNOWS BEST

[71Rat]

i would go with a 12 bolt and a nice posi. my friends uncle is running a malibu with a 383 turbo 400 and a 12 bolt. the car runs 10 seconds every day of the week and will break into the 9's without a problem except for they dont want to go through an NHRA license process. so i would find a 12 bolt and toss it in the back. and yes the car 12 bolts are different then truck. the pinion shaft on a truck is thinner then a car. if the car was going to be race only then i would opt for the 9 inch. but thats only after you have enough power to blow up a 12 bolt. if the kid wants to do a little work from street to track then he can get a 9 inch and swap 3rd members when he wants to go racing..... just have one set up for the street and one for the track...... could even swap them at the track if need be.



hope this helps somehow

Rat

[cdowns]

if he's going to spend alot of money on the rear i'd say go with the heavier duty 9inch

[rage'nrat638]

THE HOUSING ON A CAR 12 BOLT IS MUCH BETTER THAN A TRUCK 12 BOLT.....
THE HOUSING IS THICKER AND STRONGER TO HOLD UP TO THE STOCK HIGH H.P. THAT CAME IN CHEVELLE'S MALIBU'S CAMAOR'S
ETC....TRUCK'S NEVER HAD HIGH H.P. THEY ARE MADE DIFFERENT

[stllookn]

ragenrat, Does that mean a stock truck 12-bolt will not take a 500+ hp 454? I am wondering too since I hope to get my rat into my short fleetside and if not just for alot of smokey burnouts! It would be fun to turn some 12's or 11's. Is BigJim running a stock truck 12 bolt? If so, I am good to go!!!

[rage'nrat638]

Originally posted by stllookn
ragenrat, Does that mean a stock truck 12-bolt will not take a 500+ hp 454? I am wondering too since I hope to get my rat into my short fleetside and if not just for alot of smokey burnouts! It would be fun to turn some 12's or 11's. Is BigJim running a stock truck 12 bolt? If so, I am good to go!!!

no sure about jim...but i blasted my 12 bolt truck rear end about a 1/2 block down the streetDOHOO AND broke 8 valve springs after the engine rev'ed past 7200 RPM....very costly fubar

not to speak about the 1200.00 i had dumped into it

this is what it looked like before i blased it

[1969 GMC]

is the truck 5 or 6 lug suspension? sorry if i missed that...
but anyway, the semifloating dana 60 is stronger than the Ford 9 inch, and came stock in some GM trucks. also came in hemi mopar cars. or, you could even go for a semifloat 14 bolt axle, but both the SF d60 and 14b have a 6 lug pattern.

[71Rat]

some semi floating 14 bolts were 5 lug.... the 454SS's came with a semis floating 14 bolt and 5 lug



Rat

[72C203503ONTHETREE]

Will an Eaton or 14 bolt FF hold up to that power?