Friction Action!! School me on shocks, please.

I know nothing about friction shocks other than the name explains most of it.

Is the rate variable by adding or removing the 'discs' or by changing the actuator arm length?

How do they stack up against a tube shock for controling bounce (or is it jounce)?

I ***ume that rebuild parts are still available for the more popular makes. Any brand or type to avoid and why?

Do you think a small set or a single application would work well on a motorcycle? I'm planning out an cruiser like the police specials of the 30's and I like the look of a friction shock.

OK fellas - Dummy me up!

 

Wow.... shunned. Poor me...

 

I saw a good article in the Rodders Journal about 2 months ago explaining how to make your own.

 

I am also curious did the Ford ones have some sort of fluid in them. I have some that feels like there is fluid in them.?

 

The Ford lever shocks are NOT friction shocks, they are hydraulic like a tube shock...just work in a rotational motion instead of linear. A friction shock uses a friction to dampen the suspension, and don't work very well but they are simple and cool on the right car.

These are the Hartfords I was going to run on the T.

 

My friend has the speeedway friction shocks on the front of his RPU. They work good for a few hundred miles then you gotta tighten em up.



FONZI

 

I know this is bringin up an old thread, but i figured I'd use it instead of starting a new one. What is used as the friction material? Is the effectiveness based on vehicle weight or is there any other design criteria to look into?

 

Right or Wrong I dont know but I made my own. I made two arms, a center stand and sandwiched all of it with 1/4 disc's of leather, it has a 1/2" through bolt which I tighten up every week or so. It works pretty good, but I have a lite car. If you dont keep them tight at 65+ mph on a rough road it will start wheel hop, but keep them tight and it rides good, not as good as hyd. shocks but I sacrificed fashion over function.

The job of a shock absorber is to keep the tire in constant contact with the road.

-Don

 

Do you have to tighten them because the bolt loosened, or because the leather wore? I'm wondering if you safety wired the bolt if there would be a need to tighten it that often?

 

I have some pictures of the type I have made a few times for T buckets and light er vehicles. I too have used leather as the friction medium, although other materials such as rubber, and brake lining material could be used as well. These are a set I have made for a '31 Bantam that I am just getting ready to send home for acustomer to finish, so they are lacking they're friction material. These have a disc of 1/2" steel as a base, and the arms are made of aluminum as well as the outer pressure plate disc. The springs are Buick Nailhead valve springs, and the whole unit rides on a grade 8 3/8" stud. The above design I don't see a spring in, so they seem to work the bolts providing the friction loose fairly quickly. With a spring and a locking nut, it has been my finding that you just adjust it until your happy with where it is set, lock it and be done except for checking every now and then.

 

Friction shocks work exactly opposite of what you want in an oscillation damper.

Ideally, a shock absorber will allow controlled upward wheel movement and dampen the rebound to eliminate any further bounce. Initial travel would be without any 'stiction' (literally "sticky + friction"), which is the resistance to initial movement caused by seals and such.

Friction shockers START with a lot of stiction, then allow fairly easy movement afterwards. They also cannot provide different rates of damping between upward and downward travel. They will never even approach tube shocks for control.

But they look neat.

And, Need Louvers: the reason you don't see a spring in the above photo is that you are not considering the 5 spoked 'spider' a spring, which it most definitely IS.

Cosmo

 

The friction medium wears or compresses, hence, the bolt loosening...

 

Cosmo, I have blown that picture up as big as it goes and I still don't see a spring, coil, spider, (bellville) or other wise. And where does your idea that the rate of stiction varies with a friction shock come from? It will be the same in both directions. Stealthcruiser Yes, the material does wear after awhile, and leather does compress, that is why I mention checking every now and then. Are friction shocks superior to tube shocks? Hell no, I didn't say that. And, I will add that the custom valved Bilsiens on my avatar are some of the best money I have ever spent on a car. But, on the proper vehicle, they do function quite well, and are fairly tunable. And I will render an opinion, on an open wheeled light weight vehicle such as the Bantam I'm building, or a T bucket, or the T speedster I'm starting for another client, they look loads better than tube shocks can.

 

Sorry Guys, didn't mean to start an argument. I was just trying to learn more about them as I didn't find a whole lot of technical information using the search function. I'm planning for a future project and thought they might be a potential option.

 

Friction shocks are 100 year old technology. The amount of dampening is dependant on the area of the friction material, the type of friction material used, and the force applied to the friction surface,and the length of the arm.

 

No argument going on, "need louvers?" was just questioning some things others had said, and confirming what I posted................

Ask away..........................I like learning this stuff too!!!.

 

I have a question for need louvers?. You said that the shock in the photo (really nice, by the way) doesn't have it's friction material. Do you place it between the aluminum disc and arm, or between the arm and the steel base, or both? If I ever get to that point on my A pickup, I'd love to borrow your design. With your permission, of course.

 

Bearing burner has the right idea! No argument at all. These are old tech, and most people will tell you that they won't work. But for various reasons, most of the Upper cl*** drag cars of the sixties used them, and in the proper place, they still do a decent job of dampening a cross leaf style suspension. As far as the loosening problem goes, I have found that some friction shocks don't have a spring. Speedway's aluminum set that they advertise comes to mind right away. they rely on how tight the bolt is tightened to provide the friction. problem is, the bolts don't stay tight for long. A fellow RED DEVIL club member had this problem with his modified. I showed him how to do the spring thing with his, and he doesn't have to fiddle with tightening them up every time he takes his car out.

 

I put the friction material between both the outer "pressure plate" and the arm, and the arm and the inner plate. I have used leather almost exclusively in the past, simply because I have always made mine with aluminum components, and I'm a bit afraid to try an actual brake style friction material because I think it would accelerate the wear. As far as using my design, sure! I kinda ripped off from the Ch***is research stuff that was made in the late fifties, and an article that appeared in the last issue of HotRod Mechanix back in the mid nineties.

 

Don, love the leather wrapped spring ... needs some patina !!!

 

Awesome guys, thanks again for the info and pictures. I'll definitely refer back to them.

 

I have an old Hot Rod Mechanix where they have a tech article on them, and build a couple sets. They said pretty much all the things that have been said here, but they definately said to use a spring (they used sbc valve springs), and that was supposed to help with adjustment.

 

louvers your home made shocks look killer.

 

Would anyone be willing to scan that Hot Rod Mechanix article and post it here? Or at least tell us what issue it can be found in.

 

Here's the set under construction for my TrackT..The triangle piece has a locating pin that keeps the outer disc from turning. This allows me to have two discs of HDPE as "friction" material..I've since had lightening holes machined in the arms & uprights.. The upright arm is also part of my headlight mount...Robbed this whole idea from one of Zipper's cars..

 

Here ya go!

 

You're so cool! Thanks for sharing.

 

I delineated the spring in the photo below.

Stiction does not so much have a 'rate' than simply IS. Stiction is the resistance to initial movement, NOT a resistance to movement once moving. THAT rate IS adjustable. Therefore I stand by my statement that friction shocks have a very high incidence of stiction. I did not mean to imply that stiction is adjustable. Therate of friction, though, most certainly IS.

 

Here is a shot of some Friction Shocks I made for my Brother's car out of cast aluminum:

 

Cosmo, I'm not looking for an argument, but the photo I was referring to was in post # 8 by Donmon. In that shock arrangement, there is no spring, and because of it he mentions that he has to tighten the pivot bolt frequently. Yes, I know Hartford shocks have a spring, as you refer a "spider" spring (bellville), I have owned several pairs over the years. I do have to disagree that the stiction of a friction shock is not adjustable or backwards to the goals of an early Ford front ends needs. The amount of force needed to overcome the friction shocks stiction is going to be the same either going up (compression), or going down (rebound). Even in a tube shock's oscillation, you in most cases want dampening on both the compression and the rebound. This is why most tube shocks for the m***es are considered a 50/50 movement. About the only commercial shocks I can think of otherwise are 90/10 shocks used for drag racing purposes, which are purposely valved light on the rebound side to promote the lift of the front suspension. In simple summation, I have to agree with you, friction shocks are old technology, and are not superior to tube shocks in any way. Do they work adequately on the front of a small, light car with a suspension design that has it's roots in 140 year old buggy designs? Yes, done right they do. Do they look better on the front of this light vehicle than a tube shock? In my opinion, yes.