Topic split off from the main 'suspension' thread.

Currently, the André Hartford site lists two sizes, 104mm diameter friction disks and 86mm friction disks. I was contemplating making some significantly smaller units, and with an eye to ease of fabrication was leaning towards 50mm friction disks. That would allow the use of a common holesaw size for cutting the wood friction disks [a wear item, potentially?]. I'm by no means married to that size though. Sketching the parts out they look OK to me, but perhaps on the small side. Some of the Gittreville cars have friction dampers fitted - Input welcomed.

cheers

Derek... I can cut say 1/4" hardwood pieces out on the co2 laser no prob. I have a CBC plasma table but haven't gotten it up & running yet...not as clean as water jet by a long shot..

If someone can do the cad & water jetting... Sure we could gave something to try out fairly quickly.

Bob

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Rosengart LR2 Special

Noted, and thank you, Bob. I'll be honest though, it is the cutting out of the [minimum] six parts in steel which has thus far kept the testing off my"must do" list of projects
Which said, pulling the Bentley's front end apart for some tweaking is on the cards in the next week or so, and I can look into adding mount points at that juncture. The testing could of course be done with crudely roughed out parts, and refinement done once functional dimensions confirmed. Sounds like Rhys is game for looking into mass production ...

Sure can. I probably need a number myself I wonder if there is easier friction material, like brake lining or? Then again, "Wood is good, 'glass has class, and steel is for real"

Easier than wood?
Joking apart, it's all up for guess and grab, but Hartfords used wood for years, and who knows what "New type non-corrosive friction plates entirely unaffected by weather conditions" are. That odd-looking stuff found in wet-plate clutches? Swapping experimental friction disks in and out sounds like part of the fun to me!

I had found these guys & under Hartford parts, are some pictures of new wooden discs made ...where I thought about the wooden discs... Vintage & classic shock absorbers UK... http://www.vintageandclassicshockabsorbers.co.uk/new-hartford-parts/4578203978.

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Rosengart LR2 Special

Quarter-inch-thick shoe-sole leather may work for a friction disk. Might even last longer. If it gets too smooth after a couple years, you could "dress" it like you would a leather drive belt.

Would be realy interested in seeing a design. Will you be looking into making the spring as well to adjust the amount of resistance the shock provides? The kart I am designing will be using friction shocks in the rear end, and I had been planning on making an attempt to make a pair with some rather basic tools. Looking forward to seeing how yours turn out.

John, I don't see why not, although there are obvious difficulties. Perhaps the "star" will be a dummy to cover a spring of coil variety with very few turns, or perhaps even a spring (lock) washer? Just thinking aloud. Still nobody has come up with any dimensions.

Keeping in mind that I've not played with the real thing, it appears that the star and spider spring are only there to permit tension adjustment without resort to tools. The same function could be implemented with a nyloc, if one was prepared to adjust with a wrench. Where there are cyclekarts present, are tools ever far away? Would you like a napkin sketch of the shape I was going to try on 'Le Camion'? Or were you hoping for something more refined?

Has any one considered using a bellville spring washer? They have a slightly conical shape and are used to maintain tension when bolting materials with different thermal expansion properties.when compressed, the cone slightly flattens out and maintains tension.

Not so much the shape Derek, as a dimensioned "back of an envelope" as we say in places where we don't go to bars so much

I have used "bellevilles" on a number of occasions. They are excellent where you have vibration to deal with. I used them mainly on tensile canopies that could be subjected to potential for windflapping. They overcame the problems we had when we used ordinary spring washers in the same application. They are almost impossible to undo without destroying them, so I reckon the wrong product for this application as we would be likely wanting to adjust until we reckoned we had them tuned.
On the blue car in my avatar I changed the settings depending on smooth track (really tight) bumpy hillclimb (softer) and road, (softer still).
Having a look at some real Hartfords, the star is the spring. On the ones on the Austin they have a conical washer which is the spring function.
Time to draw something!

For this to be economic it is probably easier to settle on only a couple of sizes.
My suggestion 2 1/2" diameter, arm length???? Maybe 6"

Do they even have to function? Can't they just "look" the part?

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S'all for now!