Leaf sprung A arm bolt washer and nut question
 

Hi.... anyone have a picture of the shoulder bolt nut and washer that a leaf spring car takes. These are the ones that hold the A arm to the chassis. I am told they are special and that the washer is not just a flat washer.

Thanks Mark

There may be a close up or two in Jeff Gagnon's Gold 289 build.

Mike I don't remember seeing any in his build thread. If there is anything they are already installed and will not show what I need to see.

Mark

If I have some time tomorrow I'll photograph an original set that I have.

I use the adjustable style... On the head of the bolt there is a flat so that it does not spin, easy to do on a grinder.
Here is a car from AC, the way they were...

With that leaf spring wrapped in the nastiest stuff known to man! I had the last N.O.S. leaf spring from AC when Autokraft took over all of the spares and the stuff that the spring is wrapped in gets all over everything! I have never seen such insidious, creeping black gunk in my life!:eek:

That is one thing we did NOT replicate with the Superformance MK II cars!

Nice picture Jeff. But I still need some pictures of original nuts, bolts and washers. I have heard different lengths on the bolt and that the washers are not just flat washers. I am making A arms and before I get to far I want to make sure things are right. In my drawings the numbers don't add up . The bushings and where they mount the numbers don't add up . The key to this might be the shape of the washer and the length of the shoulder on the bolt.

I would also be interested in others thoughts on what material the bolts should be made of. Hard that could snap off or a softer material that would bend before they would brake.

Mark

CompClassics It would be great if you have an originals you could take pictures of.

Mark

John may have original unit...

I too did not wrap the spring, does not squeak so why bother?
I used flat washer and lock nut on gold car and also modified the mounting with third bracket. This car pictured has original style but it's not home yet to picture, finding original hardware is like finding a Unicorn. This part may not be but for the most part you may be knocking yourself out for nothing....
Use what works, that is what they did in the 60's

http://www.clubcobra.com/photopost/d...3_2007_003.jpg

The general dimensions listed in the AC Cars Ltd chassis manual won’t work on a rack and pinion steering Cobra with all O.E.M. components as they are just broad descriptions.

The original AC Cars C-62300 parts are mild steel and pretty soft, i.e. not hardened.

The best one I've seen is the guys at RareDrive had a Cobra in for restoration with an Ace bandage wrapped around the spring! Photos are on their website!
Larry

Here is what the stock original hardware looks like.....the comp car parts are different.

CompClassics Thanks

Could I get you to measure from under the head to the end of the shoulder?

It appears that the washer is just a flat washer. Do you know if the threads are BSF or Whitworth thread?

What is different on the comp cars?

Thanks Mark

Thanks Dan I kind of thought they should be soft. The plans that I am working off of they say a good substitute to use is a grade 8 shoulder bolt. But I thought to use it in single shear they would maybe brake off. On your cars is the washer that hold the A arm on just a flat washer?

Mark

Nice job John..... it looks much like the spring pin? No?

Mark, I used a modified grade 8, with heim adjustment, steel spacers and additional brackets on frame, running for several years now.

The road spring and upright assemblies carry most of the loads. I know of original cars that suffered grave control arm problems from factory welds failing, tie down/tow chain damage, severe rusting (one tube rusted because a poor weld didn't seal the assembly) a tube down to almost no wall thickness left, poorly engineered owner modifications, and or in some combination crash damage and yet the frame mounts and pins were still in good condition.

I would recommend doing research on every fastener application in any vehicle suspension system. Steel companies and fastener companies offer help in making material and properties selections but be warned they will probably still leave final decisions to the user for legal reasons.
Some really important things to consider:
1) Just because a fastener is marked and or sold as “Grade such and such”, doesn’t mean it is right for your application.
a. Specifications revolve around a few characteristics and the one that is important for the application you have in mind might not be one of those specifications. Examples: A medium range bolt might bend or stretch while an ultra high strength one might break as its failure happens.
b. Just because a bolt is marked “Grade whatever” doesn’t mean it is. Counterfeiting fasteners is a multiple billion dollar a year industry on its own.
2) Know where your fasteners really come from. Just as “Grades” are faked so are manufactured by names. The genuine company has lots to lose if its products fail in use while the counterfeiter doesn’t.

What you are calling a washer is a thick mild steel disc and captures the end of the a-arm bushing on the threaded end of the pin side. The thread end of the pin is BSF.

Thanks for posting that John!
Larry

To add to John's comments, Shelby American did develop more robust parts for some racing applications, spring eye bolts come to mind, but the Shelby team did more service and inspection of those parts to forestall premature failures than most people would do for a street car.

SAI didn’t just replace some bolts in the front suspensions. They added a coordinated set of modifications to stabilize the whole front end for endurance racing.

One SAI modification that greatly stabilized the front control arms was the addition of a cross bar (tube) to triangulate the assembly. (Even the second works Dragonsnake got this modification over time.) That makes the lower assembly much more rigid. To stabilize the road spring they welded in sections of key stock so more than four bolts kept the spring from being able to rotate about its center if the four bolts were not sufficient, and they were not on rough road courses. SAI added bracing to the rack and pinion steering mounting system to firm that system up also.

I assume one side of the bolt head is ground or milled down to fit into the notched portion of the AArm spacer sleeve end?

This was done to make the assy. tool free on one end?

One side of the head is milled flat down to the diameter of the shank. On end the pin heads look D shaped. AC Cars did similarly with spring eye bolts. In each application a corresponding pocket is machined to mate with the flats. The mating pocket in control arm mounts is large and robust. The mating feature in front spring trunions is pretty robust. The weakest application is the rear upright which has a very small, in comparison, locking feature. The rear lock features are normally so small and shallow that the use of a high powered impact tool to install nuts can spin the pins and shear the lock features completely off the rear uprights.