Rubber for Droop Limiter

[Chris Elwell]

Where are some places to buy a rubber bushing for the droop limiter? Mine is starting to crack.

Thanks,

Chris

[Tiago Santos]

I'd start with Jim @ SR.. Otherwise, REsuspension.com has a huge selection!

[Bob Neumeister]

I would ask Ed what he was using if it is for a Womer.

[carby]

Buy rubber tubing out of McMaster Carr
When we built the Protoform I used Ed's rear suspension with his permission

Arnie
Protoform serial #1

[problemchild]

The rubber itself is not significant in generating grip. The hardness of the rubber, size, and method of mounting is responsible for transfering "feel" to the driver. Because it is loaded in droop, when maximum loads are being generated, you do want to maintain a similiar installation to what you are used to, particularily if you were really comfortable with the car on the limit. If you were not, then explore different materials and thicknesses. I suggest you find the builder or a good tuner of your car, and buy exactly what they recommend. There are hundreds of rubber products from McM. Carr. You want a product/part number and dimensions to cut to.
Ed will know all that if you do have a Womer. PM me if you need contact info.

[S Lathrop]

My advice on replacing the rubber in the droop limiter is to talk to the guy who built the car.

I would have agreed with Greg's comments until a number of years ago when I moved the droop limiter from below the shock to above the shock. The original position had the droop limiter at a very low motion ratio relative to the motion ratio of the shock. In the original location all it seemed that was required was something other than metal to metal contact.

But with a motion ratio greater than the shock, the droop limiter became more sensitive and getting it just right made a significant improvement in grip and feel of the car.

As a FV corners, the rear suspension rises up and the runs against the bump stop. The car corners with a combination of up down and rolling motion. On the upstroke, the car is into the droop limiter. How that happens can influence what the tires do at the contact patch. I would up using rubber die springs. And it took some testing to get the spring just right.

One positive I found was that I could run the tires with significantly less negative camber.

I expect to be back into the development of this aspect of FV handling yet this summer. I think there is a lot to get from doing the droop limiter better than we have in the past.

[Amon]

Steve,

Did your findings show that hard or soft rubber has more advantages, plus is there a
size that (thickness) is better than others in your opinion?

Mark


92' Protoform P-1/05 (oversteer king)

[S Lathrop]

Steve,

Did your findings show that hard or soft rubber has more advantages, plus is there a
size that (thickness) is better than others in your opinion?

Mark


92' Protoform P-1/05 (oversteer king)

I started with a rubber die spring that was about 1.25 diameter and 2" long. It had a 1/2 hole through.

With rubber springs, smaller diameter, and longer is softer. I wound up with about 1.5 to 1.25 inches long but that is my setup.

What we did find was that we did not want to preload the spring/rubber. But we needed enough rate to limit the camber to something like 1.5 to 2 degrees total with the tires in the air. We started with something like 3.5 degrees negative loaded on the ground.

We cut the rubber and tested the results.

Dynamic Shocks make some really great bump rubbers. I would suggest that you get those bumpers and design the droop limiter to use them. The issue I think with the die springs is that you get a sudden change in rate as you contact the spring. The Dynamic bump stops have a very progressive transition, better than any other bumper I have tested. There needs to be a transition from no rubber to fully loaded bumper.

[Ed Womer]

I used the rubber out of the ends of shocks for many years and something else I tried was the rubber that they use to hang exhaust systems on newer cars and cut off the outer parts and use the inner part as the droop limiter. You want something hard enough that it won't squezz out and over the pieces that contain it.
Ed

[Hardingfv32]

There needs to be a transition from no rubber to fully loaded bumper.

Why?

Brian

[S Lathrop]

Why?

Brian

Sudden change of spring rate/forces. Tends to upset the tires, grip.