Need bolt info - 65 leaf spring to diff carrier

[David Z.]

Hello all. I need your help regarding the bolts that attach the spring to the diff carrier. This is a 65 with the 9-leaf spring. The AIM shows part no. 3833486 which the local chevy dealer says is 9/16-12x3 1/8". The catalogs indicate a bolt length of 3 9/16" for the 9-leaf spring. The last diff cover I had was cracked inside by the casting for the bolt penetration apparently due to too long a bolt being used.

Any help/advice will be appreciated. Thanks!

Dave Z

[Joe L.]

Re: Need bolt info - 65 leaf spring to diff carrie

Dave-----

The original bolt was, indeed, GM #3833486. This bolt was 3-7/32" long. It had a 1-1/16" thread length. This bolt was discontinued about 20 years ago and replaced by GM #9428598. The latter bolt is 3-3/4" long with a thread length of 1-3/8". It was discontinued without supercession several years ago.

I recommend using a 9/16-12 X 3-1/2" bolt cut to 3-7/32" long. The original bolt was SAE grade 5 and the replacement was grade 8, but I would recommend using grade 8 with a replacement bolt.

The original finish for both of the above-referenced bolts was black phosphate.

[David Z.]

Re: Need bolt info - 65 leaf spring to diff carrie

Joe

Thanks very much for the information! Somehow I knew you would come through! The help is much appreciated!

Dave Z

[John H.]

Re: Need bolt info - 65 leaf spring to diff carrie

Dave -

Paragon lists two lengths (with the correct finish and WB headmark) - #6646K at 3-5/16", recommended for the 7-leaf spring, and #6647K at 3-9/16", recommended for the 9-leaf spring. I used the #6647K bolts with my Eaton 9-leaf spring, and had no bottom-out issues.

[David Z.]

Re: Need bolt info - 65 leaf spring to diff carrie

Thanks John. I have the 6647K on order. Hope they work without issues. Local nut and bolt place has 9/16-12 x 3 1/2" Grade 8's (yellow zinc) and I'll pick up some of those in the meantime. Can cut those down as Joe suggests if the need arises.

Thanks guys!

DZ

[Wayne M.]

Originals not impossible to find

Here's a set that I got (but had to buy the entire '64 9-leaf rear end and suspension) .

[All measurements by dial caliper]: Overall length 3.56"; head thickness 0.55"; lock washer thickness 0.117"; Threaded portion, about 1.10" counting starting/partial threads.

Critical dimension is what remains to screw into the carrier cover, and that, by subraction, is 2.89"

Notice the stylized "WB" headmark.

[John H.]

Re: Originals not impossible to find

Wayne -

The Paragon bolts have exactly the same stylized headmark.

[David Z.]

Re: Originals not impossible to find

Wayne,

Thanks for the detailed dimensions. They will come in handy if we need to modify the bolts.

Dave Z