472 blows out 12 bolt!!!! help

[66trkbldr]

last week end swapped out 456 posi geared rear end for a 308 open geared one. Reason being that the 472 power plant screamed at 3500 doing 45 mph. 308s dropped to 3200 @ 55. truck was set up to run @ track but now enjoy cruzing .472 now puts out 408hp and 601 ftlbs of tourqe @ fly wheel ...th425 trans has got reverse man kit ect ect ...... fun but not for diff thus blowing the cracked spiders out the cover. pinion shaft still looks good no scratches trashed every thing else . Question ........ do they make smaller gears to help my highway driving other than a 308 and is there any differance in pinon shaft sizes between the carriers. can i run gears and carrier from 12 bolt car in 12 bolt truck housing. didnt evan get a chance to lite 1 tire yet. did put on bout 300 miles since installed. (4 shows in 1 weekend).

[Captainfab]

Here's an answer to part of your question
http://www.67-72chevytrucks.com/vboa...d.php?t=346472

If you're grenading the 12 bolt that easy, then it might be time to upgrade to something stronger. Although there seems to be a lot of guys running the 12 bolts with success.

[dreamtruckproject]

Originally Posted by 66trkbldr

last week end swapped out 456 posi geared rear end for a 308 open geared one. Reason being that the 472 power plant screamed at 3500 doing 45 mph. 308s dropped to 3200 @ 55. truck was set up to run @ track but now enjoy cruzing .472 now puts out 408hp and 601 ftlbs of tourqe @ fly wheel ...th425 trans has got reverse man kit ect ect ...... fun but not for diff thus blowing the cracked spiders out the cover. pinion shaft still looks good no scratches trashed every thing else . Question ........ do they make smaller gears to help my highway driving other than a 308 and is there any differance in pinon shaft sizes between the carriers. can i run gears and carrier from 12 bolt car in 12 bolt truck housing. didnt evan get a chance to lite 1 tire yet. did put on bout 300 miles since installed. (4 shows in 1 weekend).

Hmmm.....Are you by any chance talking a Caddy 472? If so then to you. I have a 500 sitting in the garage, just waiting for a home. As to the axle issue you can use a car axle to get the lower gears, just may have to do some narrowing. Other than that it should be just like putting any other axle in, with welding on the perches and such. One advantage is that the car 12 bolt seems to have more aftermarket support. Another option would be call someplace like Moser adn get a custom built axle.

[joe231]

get you a Lincoln 9 inch, you can find them with 5 on 5 pattern and rear discs.....I think you can get pretty much any gear you want too.

also...............................

[66trkbldr]

die hard gm fan but no small or big block chevy motors in my fleet. buick and caddys. might also dip into the pontiac side of things. here some pics

[66trkbldr]

thanks captn for the find. this helps know what fits and what not supposed to"fit". dont want to dump $ into indestructo diff if i can use up some parts kicking around my garage. this truck is all caddy check out bumper n lwb bed

[protrash64]

OUCH!.......blowing up the rear end sucks dude...

[1964C10]

This is just a thought and I am by no means a rearend expert or anything but as an engineer I do know that the metallurgy has siginficantly changed over the years. Could it be that even though you granaded this set which I presume was old (60's vintage) that a new set manufactured with today's metal might actually be stronger. Just a thought. Even though you are making 600 lbs of torque I have seen others make more and keeping it whole so the answer has got to be out there somewhere ;-) My 2cents hope that might help.

Btw 600 ft-lbs of torque is sweet! but it is gonna cost you a few extra bucks to keep it whole, as the old saying goes, speed cost money, how fast do you want to go.

[odd_ball_chevy]

1963 c10 has a point , i use to have a 73 firebird that done basically the same what waht you did ( built 455 , 500 hp , 575 t) my next door neighbor bracket races and swears it was just the metal they used back theen even , he claimed anything older than 97 was a cheep casting and cheep materials , so i took his advise rebuilt it with new stuff and threw a gurdel one it ( looked retro , finned aluminum) and have never had a problem sence , now my best friend own the car , he added a 250 shot to it and drives it from missouri to tn. or indy every weekend to race it
just something to think about



sweet bumper

[joe231]

that is cool, thanks for the pics!