Poly-Carbonate or Poly Bronze or Polyurethan

[ckmaggie]

I plan on changing out my a arm bushings. I read that polyurethan bushings are not what I want for a DIY, but what is the difference between Poly-Carbonate and Poly Bronze? Both sold by Pelican.

Thanks

[red-beard]

There are also roller needle bearing versions

[Lukesportsman]

Material!

No seriously, you can ask several experts and get different answers. First you might try to decide on "who's" theory you'd like to adhere to if any on suspension designing. Next you might want to define your use and goals. I'm not a big one for low maintenance street cars using bearings or heim joints in areas exposed to water. Metal joints equal best geometry and no artificial spring rates, but translate more noise and lubrication/cleaning. Poly urethane can sometimes squeak if your not careful. The other two you mentioned is trying to find the perfect happy medium between the two I just mentioned.

Do a search on bushings. Poly bronze by Elephant Racing has been discussed here fairly recently. Others can give you there personal experience.

[hahnmgh63]

Excellence has a good article month before last on re-doing the rear suspension bushings. They used Polybroze. We all know that bronze, especially when lubricated makes a fairly good bearing surface. They Elephant racing poly bronze bushings also come with a grease zerk fitting so you can lubricate it everynow and then for quietness. So, you get the benefits of the harder than stock ruber poly bushings with the quietness of having the bronze with the grease fittings. See www.elephantracing.com , that is the ones that Pelican uses, I purchased those myself, save about $5 by going through Pelican. MGH

[red-beard]

no connection, etc, blah blah blah, but I expect to use these in the near future....

http://www.muellerdesignwerks.com/

[Schrup]

I used poly-graphite for all my bushings about 2000 hard miles ago & have no regrets. Solid ride, no squeeks, & no problem with alignment or corner balance. Total price for all including A-arm, spring plates, swing arms, & shipping, $152.00.

[jazzbass]

Polycarbonate ARE polyurethane, I believe, so no real difference. Your choices are OEM rubber ($$$$), poly-bronze ($$$) or plastic/polycarbonate ($).

Lots of real good info in the archives here. I spent days reading it all before replacing my bushings. Here's one where I debate Chuck Moreland (the maker of the poly-bronze bushings) about their harshness. I picked the poly-bronze because I didn't feel like fitting the plastic ones - which, from talking to guys who have done it, is a royal pain.

[Schrup]

Mine didn't require any modification for fitment. I did install zerk fittings in the A-arm bushings, although the manufacturer said it wasn't neccesary. They are impregnated with graphite which helps prevent squeeking. There was a size difference between the front & rear bushings.

[Jeff Alton]

poly bronze from chuck. They are great.

Jeff

[dickster]

i bought poly's to install in the front, but recently changed my mind and went with poly bronze. the poly's seem to require lots of work to fit properly and the poly bronze take all that away, and offer lubrication. they seem to be worth the extra but are relatively new so time will tell.

[Chuck Moreland]

Chris

There have been many good threads on this topic. This one listed by Jazzbass is a good one that got into some of the performance issues and differences.

Installation is a whole different discussion. The polyurethane bushings are difficult to install properly and require a metal lathe to do it right. Polybronze are metal bearings and have an entirely different installation technique.

Excellence recently ran two articles about 911 suspension upgrades that invite comparison. June '04 they installed Elephant Racing Polybronze bearings, front and rear along with torsion bars and other typical upgrades. Then in August '04 they did a similar installation using Weltmeister polyurethane bushings.

The articles had different authors so there was no attempt to compare the two products. eg. it wasn't a shoot out, the articles stood alone.

But reading the comments in each regarding the bushings invites comparison. I've sniped the text related to the bushings and shown it below. (disclaimer; all credit for the text goes to Excellence. If this is a problem for Excellence et al, notify me and I'll remove it).

A tale of two bushings:

Article 1 ----------------------------------
Elephant Racing polybronze installation, June '04



"these are extremely well fitted peices and can be installed by a good home mechanic"

The author's comments stand alone.



Unfortnuately, the article offered no comments on ride quality or perception of the finished job.

Article 2 ----------------------------------
Weltmeister polyurethane installation, August '04



Author acknowldges squeaking issues with polyurethane bushings.

More telling is the installation description; "We tapped the bushings on with a wooden mallet" and "we drove the outer sleeves over the new bushings, after greasing both parts"




"we used an aluminum rod and hammer to drive the new urethane bushings into place (well okay, we drove real hard. Heading towards pounding). We had sanded our bushings for a snug fit, but they were still a bit oversized and it took considerable "persuasion" to seat the new bushings"

Wow!

This is a supposed to be a frictionless pivot point. If it takes that much force to assemble, how is the suspension supposed to move freely?


"With the car back on its wheels, the front suspension seemed rock solid. We couldn't budge it!"

Hmmmm. No kidding. Not to be sarcastic, but that's not how it's supposed to be.

The article really illustrates some of the typical problems encountered when installing polyurethane bushings. No offense to the authors but this job was not done correctly. All the hammering and forcing should have been a big red flag that something was amiss.



This pic shows they greased the outside of the bushing. I assume this was to help force it into the mount. They also cut a grease groove on the outside, yet the friction surface is on the inside? And the groove is cut circumferentially, not good for grease distribution.

The authors can't be faulted for the installation, as the product comes without instructions. Given the complexity of proper installation, that is a bit of a concern.


Pelican carries both products.

[Noel]

Chuck,

You beat me to it. I found that article to be filled with bad advice. The classic, IMO was the line about the factory rubber bushing being easily removed by hand. I had to heat mine with a torch and then use the "Moreland" method with the screw driver to remove them. BTW, I just sent you a PM.

Noel

[efhughes3]

Poly-Bronze absolutely! Chuck's got a great product. I redid my front end last summer, and it feels great. There is no harshness to the ride. In fact the ride is superior to what I used to have with the old stock bushings. They are reasonably priced, and are as easy to put in as Chuck states. I used a torch to get the old ones out, but there is nothing special (including machining) to putty Elephant parts in.

I've got a set for the rear that will go in after my next DE.

And now, back to Le Mans and installing my new master cylinder and brake lines....................

[Shuie]

I’ve got the Elephant bushings in my car with 22/28 t-bars, and Koni Sport Yellows. I was expecting to need a mouthpiece for the first drive based on a few things I had read but the ride turned out really nice. Not harsh at all. Money well spent.

For me, the biggest selling point of Chuck's bushing setup is that it was easy to install. All I needed was a vise. I didn’t have the resources to turn a set of poly bushings down if they wound up being too big.

[island911]

Chuck, what is the service interval for lubing your Poly-Bronze bushings? . . .1 week. . .10 years?

Do they ever smooge grease out, along the underside ot the car?

What happens to them if they don't get lubed?

[turbo6bar]

I have installed the front PolyBronze bushings on my 78SC. I only have a dozen miles on the car since the work, so I can't comment on ride now. The bushings were easy to install, and they appear to be a well-made, well-engineered product.

Island911, the instructions state you should grease the bushings every 10k miles. On the fronts, hitting with grease is a straightforward affair once your wheel is removed.
jurgen

[Noel]

I've had the Elephant Poly Bushings on my car (Front) since winter and have driven about 1,500 miles (About 400 was track miles). I have not had to relube and have not seen any grease anywhere but where it belongs. Great product. Mine are still quiet and the ride is great.

I would recommend them to anyone.

[Chuck Moreland]

Originally posted by island911
Chuck, what is the service interval for lubing your Poly-Bronze bushings? . . .1 week. . .10 years?

Do they ever smooge grease out, along the underside ot the car?

What happens to them if they don't get lubed?

As Noel says, I'm recommending 10k miles for relubrication. Grease does a great job of staying put, it doesn't make a mess of the underside. If you never lube them, naturally life would be reduced (same as with polyurethane bushings, they have no provision for relubrication).

Relubrication is a feature, not a liability.

[Jdub]

If I had had the money to spend, I would have bought Chuck's bushings.

I went with "street hardness" Weltmeister bushings. They come with a type of grease that I haven't seen elsewhere: very viscous. Installation was not easy, as I had to bring the bushings down to fit well. I installed zerks and made sure that the hole from the zerk to the inner bushing surface went directly to a slot that would distribute the grease along the entire "length" of the inner bushing surface.

I had a lot of time and have access to good tools and my own head. I research EVERYTHING before I go ahead. Again, with a full suspension rebuild at hand I had to pinch pennies. So far I am quite satisfied, but then again I have nothing but a clapped-out suspension to compare it to!

Lots if you do a Search in the archives. Search on A-arm, Weltmeister, Clark Griswald, Jdub, etc. Read up; plenty to study out there.

John

[juanbenae]

i just ordered 21 anf 27mm torsion bars and will be getting a set of front polybronze real soon here. i have been speaking with a local alignment/suspension and brake shop here in the southbay (highly recommended by a couple respected wrenches) and they have a system that i wanted to throw out here for comment on the rear application. they use a stock type rubber bushing on the inside spring plate and a hard poly type with a zirk for lube on the other (outer side). this i have been told allows for the stiffness desired and the lube ability of the outer keeps things on the QT.

whats the opinion of this rear set up, chuck?

noel, how long have you been running the car with just the front of the suspension freshened up? was there a change in t-bar size too? was the rear done previously?

by the way island, nice avatar line!