Bushings Defined

[ProwlerGT]

Ok, I'm well versed in some areas of the car, but still newb in others. I've talked a lot about and looked up about bushings on this forum and on the net a whole lot, but what I've never really seen is a clear definition of what a bushing's purpose is. I had thought that a bushing's purpose was to buffer metal parts where they join and move/pivot at, but as I've been looking into stuff I came across bushings that are just like "covers".

Somebody or all please answer these questions:

1. Is a bushing's purpose merely to cover the metal to protect from debris?

2. Do bushing's experience pressure or binding when the metal that it covers moves?

3. What is the primary eroder of bushings?

4. What is a bushing vs a cover vs a stopper or are they all synonmous?

5. Can/Will anyone name ALL the bushings (IE: or rather all the rubber underneath that is part of our suspension/steering system) that are on our cars?

Take for example the ball joint covers. I've heard them referred to as bushings, covers, stoppers, etc... which makes finding all the rubber parts just by looking in CAPS kind of difficult due to the different names of the stuff as recently I ordered some bushings and thereafter realized I didn't have all that I needed possibly like the ones on the stabilizer links.

Well whats the deal? I'm sure a lot of others don't really know either and rather just replace rubber parts because they look bad or "think" they need to because of age not knowing what they are there for really.

[DG]

OK, long story short:

Suspensions need to move. Specifically, arms need to pivot, and because pivoting arms move in arcs, anything that is attached to an arm needs some way to accommodate the changes in angularity that come with the arms moving along arcs.

Any metal-on-metal pivot will need lubrication, or it will bind and or squeak.

Binding and squeaking is bad. Customers do not like binding and squeaking.

But anything that requires regular maintainance is also bad, as your average car owner is pretty crappy when it comes to regularly servicing their car. So suspension pivots need to be self-servicing.

If you make them out of solid blocks of rubber (such that all the pivot motion happens by rubber deforming in torsion) you eliminate any sliding motion. No wear, no opportunity for squeaking. And by tuning the hardness of the rubber, you can damp out certain high-frequency vibrations and really cut down on noise transmission.

So the solid rubber suspension bushing is nearly perfect from an OEM point of view.

Answering your questions then:

1) The bushing's purpose is to flex (usually) in torsion, thus allowing the suspension to move.

2) This question makes no sense: a healthy bushing sees no slip; the metal embedded within it remains fixed to the rubber, and the rubber deforms to accommodate movement.

3) Time, UV light, and ozone - but mostly time.

4) A bushing is a pivot point. A cover is a cover. A stopper is something squishy designed to limit movement along a linear track.

5) The terminology is not consistent manufacturer to manufacturer.

See http://farnorthracing.com/autocross_secrets.html

DG

[ProwlerGT]

Originally Posted by DG

OK, long story short:

Suspensions need to move. Specifically, arms need to pivot, and because pivoting arms move in arcs, anything that is attached to an arm needs some way to accommodate the changes in angularity that come with the arms moving along arcs.

Any metal-on-metal pivot will need lubrication, or it will bind and or squeak.

Binding and squeaking is bad. Customers do not like binding and squeaking.

But anything that requires regular maintainance is also bad, as your average car owner is pretty crappy when it comes to regularly servicing their car. So suspension pivots need to be self-servicing.

If you make them out of solid blocks of rubber (such that all the pivot motion happens by rubber deforming in torsion) you eliminate any sliding motion. No wear, no opportunity for squeaking. And by tuning the hardness of the rubber, you can damp out certain high-frequency vibrations and really cut down on noise transmission.

So the solid rubber suspension bushing is nearly perfect from an OEM point of view.

Answering your questions then:

1) The bushing's purpose is to flex (usually) in torsion, thus allowing the suspension to move.

2) This question makes no sense: a healthy bushing sees no slip; the metal embedded within it remains fixed to the rubber, and the rubber deforms to accommodate movement.

3) Time, UV light, and ozone - but mostly time.

4) A bushing is a pivot point. A cover is a cover. A stopper is something squishy designed to limit movement along a linear track.

5) The terminology is not consistent manufacturer to manufacturer.

See http://farnorthracing.com/autocross_secrets.html

DG

Well, you are da shiznit. Thanks. If anyone else wants to comment go right ahead, but I think that about wraps it up for me. My main issue was whether or not the rubber takes on pressure or force causing it to "deform" as you said and from your answer I see that it does so which gives me my answer that they wear out from friction/movement over "time". If I'm getting that wrong, please feel free to straighten me out. lol

Yes, the terminology being different from manufacturer to manufacturer is quite a pain when they throw in "metal" bushings and just call them "bushings" leaving you to not know if they are rubber or metal (that is of course when you are looking stuff up and not looking underneath the car).