Does anybody have any real life insight/experience with polyurethane bushings vs regular brass bushings in the rear suspension. My truck is a '56 f100. I am Installing the extended rear hangers on my truck, which means I'll be using the poly bushing on the back end of the rear spring. I am currently planning on flipping the front rear spring hanger. I started thinking that maybe I would want to install the front hanger from mid fifty that is adjustable, but even more so it let's you use the poly bushings on the front part of the rear spring also.

http://midfifty.com/item.php?INV_ID=19780

Of course that leads me to think, if I go one poly, then two poly, maybe I should buy the rear hanger also and have poly on every moving part?!

http://midfifty.com/item.php?INV_ID=20816

If any of you have seen my build thread, you'll notice that most of what I buy and do is out of necessity, sort of bear minimum. I'm not afraid of spending some money if I have to, and I'm a big fan of "buy the expensive one and cry once." Will I regret not installing poly bushings in all of the rear spring parts? I already have the pins, so I could always do it later...but I was wondering if anyone had any wisdom.

If I went poly and new hangers, it would be $200.

Thanks for any thoughts!

 

Yes but not on a early model pickup, I would never do it to my 55. These kids put polyurethane bushings in their control arms on the 4 gen. Camaros, you can hear them coming from a mile away and its not the exhaust, squeak squeak.

 

I run Polly's on my 55 and also my 2002 and all my Mustangs. As long as they are properly lubricated there is not an issue with running them in my opinion.

 

Thanks for the replies guys. I think I'm going to stick with what I have for now (regular spring pins) and see how it goes!

 

What do you use to lubricate them? And since there are no zerk fittings to lube them after they are assembled, is lubing them when first assembled good enough? Or will they need lubing after some miles are put on.

I ask because I used the Mid Fifty poly bushings on my 55.

 

I upgrade to Poly on everything I run. If the ones I buy aren't available with zerks, I put them in, and machine the bushing to allow the grease to flow where it's needed. Never had an issue, nor a squeak in 30 years.

 

The good news is that poly-bushing they don't squeak . . . but then neither do brass if they are lubed properly. The bad news is durability . . . plastic is softer than brass. That is OK on some bushing that don't get a lot of wear but the spring bushings are constantly moving when you drive down the road.

The other issue is the adjustable hangers . . . don't forget that if you change the position of the rear springs with the spring hanger you may develop a vibration as you have changed the pinion angle. Here is a great post by Bob Jones that explains it: https://www.ford-trucks.com/forums/1325329-drive-shaft-pinion-angle-and-how-it-works.html#post14507022

You may need to use caster shims on the rear axle to get rid of a vibration at highway speeds. http://www.summitracing.com/parts/rex-re1468?seid=srese1&gclid=CJq39o3n4L8CFQsyaQodUYEAM g

The same is true for the front as when you flip the spring hangers you will change the caster angle.

 

Since polyurethane can be formulated to be as hard as metal to as soft as a pillow (most modern furniture, mattresses, and autos use polyurethane upholstery padding), it's difficult to give a blanket statement about it's use in suspensions. All my race cars use polyurethane bushed sway bars and progressive suspension bump stops, but I do not use them in suspension pivots except on dedicated (non street driven) race cars since if they are hard enough not to give more than rubber or get beat out quickly they ride extremely harsh. If replacing metal bushings with PU, they should last well, the metal they ride on will wear before the bushing because of an effect known as embeddability. PU requires a specially formulated compatible grease for lubrication, don't use regular dino based grease or oils.

 

See http://www.eplastics.com/Acetal_Delrin?gclid=CNuMweGC4b8CFc1_Mgodl3oACA