I have read that using rear upper control arm with polyurethane bushings create a problem with binding and should not be used I have a1989 mustang gt
thanks

 

Where did you read that? Properly installed that won't happen.

 

stangnet another mustang forum.. I also received a reply from maximum motor sports with the same answer. I e-mailed L.M.R. and they say no problem with polyurethane bushing. On the forum everyone who replied said the same thing don't use them. At this point I am very confused.

 

A properly designed and lubricated bushing will not cause binding. The whole purpose is to eliminate or reduce deflection to better maintain suspension geometry. I will say however that for a street driven car/daily driver, they are a waste of money and time. They are harsher and transmit shock and vibration easier than rubber and they squeak like crazy if not properly maintained.

 

Thanks for the response. Lot of different thoughts on the subject. I think you are right

 

Binding of any suspension bushing is caused by a couple of things. Lubrication is one as proeagles mentioned. The second cause is improper installation.

When you tighten down suspension parts, the car should be a Ride Height (loaded) . What that means is the suspension part should be compressed to the height it would be if/when the car is sitting on the ground. If you simply throw everything on and tighten it while it hangs in mid-air (unloaded) , you get at best some squeaking that lube won't fix or at worst, the new parts won't perform as expected and you tear up the bushings fairly quickly.

To load the suspension you can either use a jack on the respective corner of the suspension for the front, or for the rear, use jack stands under both axle shafts (towards the outer ends).

 

Elastomeric (soft) bushings used to support let's say leaf springs experience VERY LITTLE rotational deflections between the outer and inner diameters. Thus, the bushing OD is usually BONDED to a thin steel cylinder which press-fits into the spring "eye" or clamps tightly between the swinging links, tightened in between by a bolt. A small steel shell having an inner hole for a through-bolt is BONDED to the ID of the rubber bushing, and clamps the bushing assembly between stationary supports at one end of the spring, and the swing-links at the other. The ENTIRE ROTATION (very small) is experienced WITHIN the rubber with NO SLIPPAGE between the outer shell, the inner shell, and the rubber itself. This eliminates rubbing friction, and completely prevents wear, until the rubber fails. Failure is by aging of the rubber, crumbling out, loosening of the bolts (possibility), or by LUBRICATING the bushing which softens and destroys the rubber. Remarkable system which I've always hated, but lived with. Time was, maybe still is, heavy trucks employed only bronze bushings, lubed by zerk fittings.

Urethane bushings, harder than rubber, MAY be clamped tightly enough to not rotate and provide similar performance, but will surely transmit more noise and vibration up into the vehicle.