Early 63 Trailing arm bolts / washers

[Michael G.]

My early 63 car (#3922) has the original bolts attaching the trailing arms to the frame. These parts have no hole for a cotter pin and no pilot point. The bolts had a coating of red rust, with no trace of the original coating, before I cleaned them, so I'm not sure what the original finish was. Does anyone know?

The attachment also didn't have any washers, but I doubt this is correct. The assembly manual only shows the later parts (bolt with cotter holes and pilot point, as well as several washers, castle nut, and a cotter pin) so I'm not sure which washers were on the early cars. Any help identifying the correct parts for early cars would be great.

Thanks,

[Alan D.]

Re: Early 63 Trailing arm bolts / washers

Go slow Mike all that stuff may truly be original! The trailing arm area has all types of unique parts, U Joint Flange, Spindle Support and that bolt. Remember that Mike Hanson was doing some investigation of that bolt in the past hopefully he will see your post.

[John D.]

Re: Early 63 Trailing arm bolts / washers

Michael, See page 146 in 5th edition of JM
63's up to 16500 use a bolt without a cotter pin hole and a standard cadmium or zinc plated hex nut.
Not shown in the aims as you pointed out.
See section #51-33A in LI.

[Michael G.]

Re: Early 63 Trailing arm bolts / washers

Hi John, Long Island's repro bolts (51-33A) are too short for this attachment, a full .38" shorter than the original non-pilot-point parts.

I thought maybe they were right, but, LI supplies two flat washers and a lock washer with that bolt, but the bolt is so short that, even if you leave the washers off, it is marginal in length.

Given the above, I question their expertise here, I'm looking for someone with an original attachment to tell me what's really supposed to be in this joint.

Thanks,

[Stephen G.]

Re: Early 63 Trailing arm bolts / washers

Interesting topic for today because we just tried to use Long Islands correct bolts and they are too short by 1/2 inch. I need to try and find my old crusty originals and compare them. This is a February (#8307) car.

[Rich P.]

Re: Early 63 Trailing arm bolts / washers

The 2 front bolts are 7/16-14 x 1" or 1-1/8" I have to check my notes, they are grade 8. The rear bolt I will check on but it should be 7/16-20 thread with just a split ring lock washer on the nut side. I have to measure some of my originals and I will let you know the length, this bolt is grade 5.

Rich

[Michael G.]

Re: Early 63 Trailing arm bolts / washers

Rich, You must be referring to another bolt. I'm talking about the long bolts that go all the way through the frame, sandwiching the trailing arm and shims (at the front). By my measurement the originals are 4.25 inches long, measured from under the head to the tip. The LI parts are just under 4.0 inches, but are a "header" (chamfered) point, not quite threaded to the tip like the originals. The original part is a grade five with an "M" head marking.

I'll post a pic in a little while.

Thanks,

[Edward J.]

Re: Early 63 Trailing arm bolts / washers

Mike, I purchaced the same bolts from L.I. for my 63 and will be assembling my chassis in a few weeks, I had better check mine out.

[Stephen G.]

Re: Early 63 Trailing arm bolts / washers

Guys

Can you confirm the bolts are 7/16 - 20's. My short LI bolts are holding the trailing arms in (without bolts) and I've yet to locate the originals. I'm going to get some off the shelf 4 1/2" grade 8's locally for $ 1.50 each and call it a day!.


Thanks

[Wayne M.]

Re: Early 63 Trailing arm bolts / washers

Rich, You must be referring to another bolt. I'm talking about the long bolts that go all the way through the frame, sandwiching the trailing arm and shims (at the front). By my measurement the originals are 4.25 inches long, measured from under the head to the tip. The LI parts are just under 4.0 inches, but are a "header" (chamfered) point, not quite threaded to the tip like the originals. The original part is a grade five with an "M" head marking. ....,

I think Rich is referring to the two short bolts that attach the diff mount bracket to the front of the differential carrier, up to early '65. (the rear bolt is the long one that goes from one side to the other of the carrier case).

I realize we're talking about early '63, but FWIW, the originals from a January '64 car are 4.5 " from under the bolt head to the tip of the pilot point; P headmark and the cad plating on the shank is in top shape (but head is rusty).

[Stan E.]

Re: Early 63 Trailing arm bolts / washers

I'd replate the original bolts silver cad. In fact I did. Stick with the originals.

[Michael G.]

Re: Early 63 Trailing arm bolts / washers

Here's a pic of the two bolts.

[Rich P.]

Re: Early 63 Trailing arm bolts / washers

Wayne is right I missunderstood and was referring to the pinion bracket to rear bolt. I would like to see a picture of the head of that bolt The lower one in the pic looks like the rear pinion bracket bolt M grade 5.

[Michael G.]

Re: Early 63 Trailing arm bolts / washers

Rich, you are correct, the longer bolt in my pic is identical to the rear pinion bolt. Both are grade five with an "M" head marking.

[Michael G.]

Re: Early 63 Trailing arm bolts / washers

It would appear, from page 76 of Noland's book, that the early attachment did not have any flat washers, only a single split-ring lock washer. If I assemble the LI bolt without the flat washers they supplied, it is just barely long enough, with the lock washer completely collapsed.

It would have been very rare for GM to design a joint without at least a thread to a thread and a half of complete threads beyond the nut, so I doubt the LI bolt is the correct length.

If anyone has the correct bolt, please measure the bolt length from under the head to the tip.

Thanks,