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Discussion Starter · #1 ·
Hello,

Can anyone tell me the stock Ubolt size on the 55 chevy? Looking for rod/thread diameter and length from top of u to bottom of thread. I dont have my car by me right now and am putting together a ford 9in with springs and a set of CalTrac Traction bars. I am using 3in OD axle tubes like stock 55. I'm thinking the stock ones are 7/16 in diameter, but the holes in the CalTrac spring plates look like I should be using 1/2 in ubolts.
Thanks,
John
 

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I'm running a GM 12 bolt positraction with 456's donated from a 1st gen Camaro. I had my U bolts made; they are 1/2" diameter with a 20 thread count, long nuts and are about 7" long from the top of the U to the bottom of the threads. I have about 3/4" to 1" of exposed threads when tightened to 90 ft lbs. I'd recomend going with 1/2 versus 7/16 for the extra strength especially if your running an engine with any kind of HP.

I also run 1350 U joints with a 3" tube which I strongly recomend. I had problems with 1310's.

It looks like you're in a position to easily change out the yoke.

Good Luck!!!
 

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Discussion Starter · #4 ·
55 ubolts

Thanks for the quick replys,

Looks like I will go with the 1/2 ubolts.

Im already using the 1350 Ujoint. The center section on this rear end is all aftermarket Strange Engineering, Its a 3.70 gear with a Detroit Locker and 35 spline Strange axles. I had the housing made 58 in so I can run a bit bigger tire and am installing a set of CalTrac traction bars. The car is 460 ci BBC with a Tremec TKO 600 trans. 416 Hp @ the rear wheels. I will be installing the new rear end in the 55 over Thanksgiving.

I run the same components on my big tire car except the gear is a 4.30 The housing is reinforced and of course the 35 spline axles are alot shorter. It been holding up fine to 820 ft lbs of motor torque.

Thanks for the help.
John
 

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Keep in mind that the stock axle housing has 3" diameter tubes.

Some 9" housings have 3" tubes, and some have 3-1/4" tubes.

So keep this in mind when buying u-bolts or having them made.

With 3-1/4" tubes and u-bolts to match, you'll have to slot the holes in the shock mount/lower spring plate. You'll have to do something similar if the originals are 7/16" and the new ones are 1/2", even with a 3" axle housing tube.
 

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Discussion Starter · #6 ·
55 ubolts

Hi,. the

Yep thought of that. The axle was made to my spec with 3in OD tubes. The CalTrac lower spring plate ubolt holes are about 5/8 wide and 3/4 in long. So I will order 1/2 in by 7in long ubolts for a 3in OD axle tube and I should be good to go.
Thanks,
John
 
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