Another Suspension Q.

[Slant]

Someone tell me about the Energy Suspension Bushings. What role does bushings have, and why it's benficial to be upgraded and all that good stuff...in laymen's term please. :D

vvtlikick is going to answer.
I'm going to say, "huh?"

Let's just talk to Slant like he's 5 years old. Car go vroom...yey.

[00 scrub]

bump, I want to know too. All that I have heard is that when you install them make sure you lubricate them REALLY well otherwise they will squeek alot.

[autxr]

Where ever a metal part suspension part is bolted to the chassis there is a rubber bushing. This bushing serves several purposes.

One is to isolate the car from bumps and vibrations caused by the road surface (rubber is compressible, so it can absorb these little impacts like a small spring). So, a rubber bushing will make the car ride smoother and quieter.

The trade off is that rubber bushings can flex a great deal. This means that you can move the suspension parts is a path that was not intended. I've seen cars at an autocross have the front wheel move fore and aft in the wheel well by INCHES in each direction (not up and down, actually front to back). This isn't such a good thing for stability. Similar movements occur when you launch and get wheel hop.

So, enter the urethane bushing.

If you can tolerate a little more road noise and vibration then why not make a urethane bushing (basically plastic rather than rubber). Put this in place, and now the suspension only travels in the arcs that it was designed to travel in (theoretically). The difference is usually quite noticable.

Now the problem....

Urethane does not give at all. Every part of the suspension travels in some sort of an arc. It is possible (and probable) that those arcs don't always agree. Now at a particular point in suspension travel one part is PULLING on another part (the upper and lower arms of the rear suspsnsion for example).

If there is indeed a mismatch in the needed lengths of a suspsion part at this point then a rubber bushing gives so you have smooth suspension travel.

A urethane bushing, instead of giving you that 2mm of extra play give you zero. The result is suspension bind, it will make a bit of noise and you wil effectively go from smooth travel to no travel. Much like bottoming out a shock. The result is an unsettled chassis and in exteme cases you can rip suspension mounts off of cars.

One solution to some of these problems is a spherical bearing. They are nice, becaue instead of only 2 diretions of motion they have a 360 degree range of rotation. This helps in all the odd acr shapes.

Cars have gotten to the point where the binding is minimal by design, so I would not worry so much about that.

If I were prepping my car from something other than a stock autocross class I would have every bushing urethane. If I heard funny noises I would switch slected ones back until all was well (this is how it worked on my '78 Celica - I got rear axle bind wihen using urethane on all 5 links of the rear end). Going back to rubber on the top 2 links cured all my problems).

Scott