how long does polyurethane last?

[Raider L]

Polyurethane has certain properties that allow it to be very durable. I'm not a chemist but I have used it for a very long time under all kinds of conditions. It's very elastic. It compresses good up to a certain point and then it stops compressing. That's the advantage with poly that is better than rubber because poly won't compress as far as rubber, hence the squishiness of rubber and the firmness of poly. A truck with rubber suspension parts will sway and float much further than if it has polyurethane. You gain a large degree of performance from poly when you replace your rubber with it. Your steering gains a large degree of control when you learn poly's properties. Once you learn how far you can steer your truck in hard turns you know how much less it will sway. With rubber A arm bushings you know you can't steer around a curve at a certain speed and that's it. But with poly, depending on you shocks and springs, you can push you truck into much tighter turns at much higher speeds than if you are running rubber in you front suspension parts. Also in my truck I put in rear leaf spring bushings of polyurethane which controls the wind up and rebound of your leaf springs under acceleration and braking respectfully. In cornering the rubber bushing in the leaf spring will compress much more than polyurethane in a unpredictable manner. But with poly the compression is very predictable in both wind up and rebound. This predictability enables the suspension to be put in a tighter set up with closer tolerances than with rubber especially when a 4 link and pan hard bars are used, and with tubular A arms with coil over's. All cars and trucks used for all out racing use polyurethane in the suspension. Otherwise, if rubber is used the rubber is replaced at the slightest sign of stress. This is due to "splitting"
Some other properties of polyurethane is it doesn't split, it doesn't dry out, it doesn't loose its slippery properties, it is unaffected by road salts, dirt, grime, and high temperatures within certain ranges. You might get two or three years before you start seeing the affects of the road on rubber. Ten years after installation the polyurethane looks as good as the day you put it in. Now, don't get me wrong, polyurethane won't last forever even as tough as it is. If kept clean urethane will last for about fifteen to twenty years before you start seeing some minor edge splitting. Also to you will start seeing some surface drying. Once you see these indicators it would be a good idea to change the poly out. But if you keep it clean and there's not much stress on it you can get more than twenty years out of it. Another property of polyurethane is it resists shrinkage for a very long time. Rubber starts shrinking in the time period I mentioned above along with the other disadvantages.

 

[AuroraGirl]

You seem to be a residential expert on rubber,


so i have a question


trojan or... er.. i dont know any other condom brands.


joke aside, poly is good, yes, but what is its good in something like an engine mount? How many vibrations does it fail to negate that are felt through the car or truck? I am needing moror mounts soon, and if it makes the truck shake i dont want to do it. i also want to keep same material both sides. one being shakier than the other is bound to stress the bracket to no end and cause some weird resonance.

I also like not doing it again!! haha. in a fwd car, a torque-axis mount is a great application

 

[Raider L]

Auroragirl,

My God! I just found this girl! Sorry 'bout that. The rebound on the poly is a bit more than rubber. It's just the ploy isn't as squishy as the rubber and takes torsion twists and shock much better than rubber hence it's much more durable than rubber and as such lasts much longer than rubber.

I contacted Energy Suspension about my poly in my whole suspension and they asked me how long I had had it on the truck. At the time I had it for seventeen years. They freaked out! They said they had never heard of anyone who had their product on a vehicle for that long. They said if I would send them some pics they would send me a new set of poly for the front end. I set up lights and all and took 46 photos and sent them to them, and sent me a whole set of bushings for my truck! My right front upper A arm bushing had a slit in the edge of it and they were looking a little dry. Polyurethane isn't supposed to dry out, or split unless you keep them on the vehicle for as long as I have in the elements, wind, water, road grit, and whatever.

 

[82sbshortbed]

My dad worked for amaco and they had a polyurethane section of the plant. He brought home a bag of little beads that they melted and formed into whatever they were making.

Remember when 2 liter coke bottles had the black plastic cup on the bottom of the bottle? Dad said that was made of polyurethane. He ******* hated those because it always looked like there was still a 1/4 bottle of coke left in it. Then he'd grab it and it was almost empty. Probably because my sister would put it back with very little left in it. So he'd just rip those off every 2 liter we had. Lol


Maybe that was polypropylene im thinking of.

 

[BBBURB]

I work with a lot of plastics and rubbers. Polyurethane can have millions of formulas, shore strengths, shore hardness, durometers and elastomers which affect the way the Polyurethane stretches, the way it tears, the way it squishes. On my desk I have samples of about 30 different polyurethanes. The word Poly in Polyurethane comes from Polymer a sugar (cellulose) that comes from a tree or plant or sometimes is synthetic but usually is natural polymer (sugar). So yes Polyurethane is made from sugars. Have you ever made your own candy by cooking sugar? You can cook white sugar at a low heat and make clear plastic. We do it all the time in the movie industry. Jolly ranchers are a form of clear sugar. Basically what I am saying is not every brand of polyurethane will be the same, different formulas will last differently. I work with a chemist that develops Polyurethanes for me and I make molds to cast the Polyurethane into. I used to teach a class on urethanes to clients like Porsche Racing. Urethane itself is a hard plastic. Polyurethane can be a rubber or a foam. Stick with a good brand. Not all Polyurethanes are the same it takes years and years of testing to know how a Polyurethane will react in the sun, to add uv inhibitors to the formula, do the uv inhibitors make it more brittle, is the polyurethane hydroscopic or hydrophobic are the cells closed or open. Find a good brand if you want a proven formula. Polyurethane can be as soft a girls tittie or as hard as a bowling ball. Most polyurethanes are about 80 shore A

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[Raider L]

@BBBURB,

I read a report on a type of bushing that is used in some high performance suspension parts, and probably a ton of other stuff, but this article was on the tubular A arms where they connect to the frame and the name of the bushing , I think, is "Delrane" or something like that. Sorry I don't have it right at hand but I think you might know what I'm talking about.

But as I read on I saw where it wasn't like polyurethane at all but was a hard plastic but super slippery. The only thing I think might be a problem would be embrittlement over time. As in my post above, I told the Energy Suspension tech that the polyurethane had been in my truck at the time, for seventeen years and had just now split on one lower A arm bushing. Now it's been about twenty three or twenty four years and it's a mess. I have a new set and am going to get the whole front end overhauled, again with Energy Suspension polyurethane. As a matter of a fact my whole suspension is polyurethane including dust boots, and leaf spring shackles to. I'm telling you, I love the stuff. It took all the slop out of my suspension and made it ride like a new truck but with performance characteristics beyond anything the stock rubber could deliver.

 

[Doppleganger]

I used to use poly bushings throughout suspensions on old 4N car restos....but only for locating and never for load. They never lasted as long as the rubber and rode like garbage. Cant remember how many customers I had who bought into the poly hype then wanted them out because their teeth hurt after driving the car daily on crap roads. The poly accessory mounts under the hood were worse yet.

 

[Catbox]

I have poly stuff under the front of my bug.
It tightened the suspension up and made it handle quite well.

Interesting lesson on the poly stuff guys.

 

[Slybeanx]

@BBBURB,

I read a report on a type of bushing that is used in some high performance suspension parts, and probably a ton of other stuff, but this article was on the tubular A arms where they connect to the frame and the name of the bushing , I think, is "Delrane" or something like that. Sorry I don't have it right at hand but I think you might know what I'm talking about.

But as I read on I saw where it wasn't like polyurethane at all but was a hard plastic but super slippery. The only thing I think might be a problem would be embrittlement over time. As in my post above, I told the Energy Suspension tech that the polyurethane had been in my truck at the time, for seventeen years and had just now split on one lower A arm bushing. Now it's been about twenty three or twenty four years and it's a mess. I have a new set and am going to get the whole front end overhauled, again with Energy Suspension polyurethane. As a matter of a fact my whole suspension is polyurethane including dust boots, and leaf spring shackles to. I'm telling you, I love the stuff. It took all the slop out of my suspension and made it ride like a new truck but with performance characteristics beyond anything the stock rubber could deliver.

Delrin is harder than poly bushings. It is used in the E30 community for track cars (Trans, engine, diff and suspension bushings to tighten them up) and generally for shifter bushings.
My E30 uses Poly 80A bushings, I dont see different types FS in the C10 community it just seems to all be "poly".
With my E30 I had the choice of 80D (delrin), 80A, 85A, 90A

 

[shiftpro]

I used to use poly bushings throughout suspensions on old 4N car restos....but only for locating and never for load. They never lasted as long as the rubber and rode like garbage. Cant remember how many customers I had who bought into the poly hype then wanted them out because their teeth hurt after driving the car daily on crap roads. The poly accessory mounts under the hood were worse yet.

If you strip the interior (carpet, underlay) from your truck and drive it around with the rubber cab mounts... then switch to poly you will hear a lot more
road noise. They transfer vibration and sound much more 'efficiently'.

 

[Blue Ox]

Delrin is the trade name for polycarbonate. It's usually a hard engineering plastic, it's also branded as Lexan when used as a replacement for clear Acrylic a.k.a. Plexiglass. When it's thick enough it is bulletproof.

On a race car you (theoretically) don't care about the ride, but the suspension geometry is critical, so using a hard plastic would be preferable to even Polyurethane which can still flex. In the stock car I worked on we had metal bushings. The few times I drove it on the track, let's just say it was rough.

 

[MikeB]

I replaced worn suspension bushings with poly on 69 and 82 pickups and a 55 Chevy car. I did not notice a stiffer ride over tar strips, etc. What I did notice was (1) better steering response with poly control arm and sway bar bushings, (2) less engine movement with poly motor mounts, and (3) the cab on my 69 hasn't sagged since 1993 when I replaced the 2-year old GM rubber cab mount bushings that were beginning to crack. And the poly bushings still look like new!

That said, I've always used Energy Suspension or ProThane brands of poly bushings, not cheap imitations, which I assume are avaailable.

As for road noise, if it's louder with the carpet and horsehair mat removed, well, don't remove them!

 

[K5ride]

I did a lot of comparison research when I purchased my "complete" kit from Energy suspension for my 75 C10 Stepside. According to the articles I read, Energy Suspension polyurethane had a little more give than most and had the best ride quality for street use. It also comes with a lifetime warranty which is probably why they replaced it for free with pictures of your cracks. I'm very happy with the ride and handling. I still have the body mounts to do, so I don't know anything about increasing road noise or changing the feel....yet. I would highly recommend the Energy Suspension brand.