Can someone plz explain what bushings are 4

Ninety-Nine SE-L · Dec 16th, 2002, 08:59 AM

I was just wondering what bushings are for. I was browsing through Motivational Eng's website and I saw the ones they had 4 sale.

From what I've heard they're meant to prevent wheel hop durring sudden direction changes (like auto-X). If someone here could go a bit more into depth on this, I just wanted to boost my knowledge a bit.

Thanks

MP2050 · Dec 16th, 2002, 11:09 AM

Ive always wondered the same thing

bahearn · Dec 16th, 2002, 11:11 AM

Please provide a bit more detail about these bushings of which you're curious. Do you mean the Energy Suspension stuff?

Ninety-Nine SE-L · Dec 16th, 2002, 08:15 PM

I guess, just some stuff I saw on motivational.net

Geo · Dec 16th, 2002, 11:37 PM

Rubber bushings are used by OEMs in the suspension to isolate the cabin from NVH (noise, vibration, harshness). You'll find busings other places where major components come together with similar missions.

Urethane bushings are stiffer than rubber bushings and keep the suspension from moving around in ways it's not supposed to. The downside is increased NVH.

Spherical bearings can replace the bushings and will keep the suspension from misaligning itself. The NVH is extreme however and this solution would be proper only in a dedicated race or track car.

bahearn · Dec 18th, 2002, 10:17 AM

From a different perspective, a bushing is a padded bearing. It's padded so that shock and vibration won't be transferred from one piece to another. As Geo wrote, standard car suspension bushings use rubber. Rubber absorbs vibration and shock, acts as a very thick pad of very thick grease (lubrication) and the rubber can be formulated to be soft in one direction while being stiff in a different direction. Rubber, though, is squishy, so it can't keep the parts in perfect alignment. In fact, it contributes to wheel hop under hard acceleration.

Urethane is much stiffer (higher durometer) than rubber and cheap to make for automotive applications. It lacks rubber's NVH isolation, lubricity and directional durometer tuning but makes up for it with better parts alignment. It still squishes, though, under hard enough impact.

That's why racers, who care not one whit about Noise, Vibration and Harshness, use true bearings or metal bushings whenever possible on suspension parts that rotate. All shock and vibration is passed through to the chassis but the suspension parts stay in alignment for better control.

I installed urethane bushings on my car. The one thing I really noticed was that the suspension seemed more "honest" when encountering bumps, that is, only by its absence did I note that rubber bushings allowed the control arms to move in more than one direction.