Bolt dims

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snowmann

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I am putting a pair of 73 Duster disc brakes together. The prior owner powder coated everything but there are no bolts in the boxes. The bolts that hold the lower ball joints to the steering knuckle, I'm looking for the shoulder length and total length dimension. Also, was there a lock washer, flat washer or just a lock nut?
 
What makes them special? I would think they would be a grade 8 bolt with a lock nut but I don't know how long the shoulder part of the bolt is and whether or not it used a washer.
 
I think they are just standard grade 8 bolts, I don't think that they have a flat washer, I used a find thread bolt and a nylon lock nut. As for the shoulder length. Do you have a caliper?
Measure the thickness for the steering arm, the bracket and dust shield, if you are using one. That is your bolt shoulder length, It should be a little short that the total thickness of the combined lengths. This is for compression.
 
Think about it.
On 73s the Steering arms are thru-bolted to the knuckles, IIRC.The shoulder on the bolt is the special part.
It is a very tight fit into the BJ and it indexes the BJ to the knuckle. Then the self-locking nut just has to keep it from falling out.The factory bolt also has a large rounded head. It might have been part of the steering stop system, I don't recall.

If you use a regular bolt there, the shoulder is too short and too baggy in the holes. Now you have to depend on the Nut torque to keep everything in alignment, so you better use a fine thread. Since the bolt is now baggy in the hole, you better use a hardened washer under the nut, to redistribute the clampload, and loc-tite to prevent the nut from working loose after the clampload relaxes. And then the whole thing might become too long and interfere with something else, I don't recall the clearance to the rotor.
Remember that all the braking force has to get into the chassis thru those bolts and the upper BJ pin
So just take a few minutes to think about it
 
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Call Cass at Doctor Diff. He will know 100%
Don't hold me to this. But my memory says 2 7/8 long 9/16x14 thread. Grade 8
 
The hole in the steering spindle measures 0.6250 on both sides which is 5/8". I don't have a ball joint or steering arm here to measure that hole on either side. You may be correct in that the shoulder gets larger as it goes towards the head of the bolt. As soon as the ball joints arrive I will be able to measure them.
 
Thanks. I still have to measure the ball joint holes and have to check one other lead but, if it comes down to it I will pickup grade 8 bolts from the specialty bolt place down the road.
 
Just wanted to check back with you guys. I did some poking around in the wrecking yard over the weekend to look at the ball joint bolts.

It started off with, I have a 93 2wd Ramcharger here and the steering arm is for the most part the same as the “A” bodies with the exception of the ball joint goes through the steering arm and on the “A” bodies the ball joint is part of the steering arm.

Anyway, I pulled bolts off of 1971, 77, 82, 85, 90 2wd Dodge trucks and Vans, ½ & ¾ ton. All the ball joint bolts are the same. They are all 5/8” x 2 1/8” long, fine thread, the non threaded shoulder part itself is only ½” long and they are a grade 8 bolt. They are the same diameter from the beginning of the thread all the way up to the head of the bolt within .001. There was nothing special about them and I would suspect that there would be if it was critical because the trucks and Vans have a higher gvw rating on the front suspension compared to the “A” bodies.

The results are that theses bolts are the exact length and diameter that are needed to install the steering arm onto the steering knuckles of the 73 Duster Disc brakes.

I also stopped by the Specialty Bolt Shop and showed them what I was working with. The only way to get a bolt with a long shoulder is to buy a really long bolt with the longer shoulder and cut the extra threaded portion off.

At this point, since I don’t have an original bolt to look at, and going by what I found in the wrecking yard, I am going to assume that they use a standard 5/8' fine thread bolt.

As previously mentioned, the holes on the steering knuckle are 0.6250 on both sides and on the inside hole of the steering arm (where it attaches to the steering knuckle) it is also 0.6250 and on the outside (where the nut is located) it measured larger (I don’t have the spec with me) which means, (I am going to assume) in the aftermarket world it was either cast like this on purpose or quality control is sloppy and I did not order in several brands to compare diameters.

The link for the ebay listing is only a grade 5 bolt and the shoulder doesn't look any longer than what I pulled out of the wrecking yards vehicles.

If anybody has a 73 and newer disc brake setup laying around, pull the bolt out and show us some measurements.

ball joint bolt.jpg
 
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I think you are worried too much about this bolt. Yes it is important. May take 1 or 2 years to find a unused never tighted or stretched factory bolt or go with grade 8 & call it good.
 
72Dart6pack said:
I think you are worried too much about this bolt. Yes it is important. May take 1 or 2 years to find a unused never tighted or stretched factory bolt or go with grade 8 & call it good.
Click to expand...

I think you read too much into it. Nowhere in the original post did I say I was looking for an unused never tightened or stretched factory original bolt or even an NOS bolt. I simply asked a question about the overall length and shoulder length and whether or not it used a washer. My original plans where to run down to the Bolt Shop and pick up four new ones and move onto the next project.

But, two people responded with they were special bolts and one even gave a really informative response. It was enough to throw up a red flag for me that said I better find out and I went looking for answers.

The end write up was to let other people know that have the same question in the future when using the search function and the question at the end was in case somebody happens to have a set when they read this post and can answer the question of “is it a special bolt” or naa, it just a 5/8 fine thread bolt.

On a side note, I build Airplanes for a living. Past programs include Horizontal Stabilizers and Wing Trailing Edge boxes in composite material. Holes and fasteners are kind of a big deal. Throwing sh*t together and calling it good doesn’t fly (pun intended) with me or the quality inspector when there is red flags waving. :-D
 
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