ROG100

I guess you have nothing intelligent to add so just make stupid statements - sorry you feel this way - sorry folks can we get back to the matter in hand and ignore the childish innuendos. I actually thought you were a better person but I have been wrong many times in my life and not scared to admit it.

FBIII

There used to be a custom with retired Presidents that they wouldn't offer opinions or criticism of their successor. I really approved of that practice and wish our suppliers/mfg's or service providers behaved the same way.

hacker-pschorr

Your missing my point. I would like to see actual evidence, test data, real world etc.... versus random opinions and links to companies that produce similar products "proving" whatever it is we are trying to prove.

Colin is usually well versed in topics he decides to jump into, so I give him the benefit of doubt. I also know in the Mustang world, some major issues with using poly with the Fox body 4-link rear end. Do either of these apply to the 928? I have no idea..... but I would like to know.

As for industrial applications, that rarely applies to automobiles, especially when talking about high performance products. If a poly control arm bushing works great in a dump truck.....???

What bothers me is, we have some highly experienced suspension engineers who frequent or at least view this forum. I wish more of them would jump in to dismay or support such ideas. And / or help steer people in a better direction of the offered product isn't quite right

I wish people would do some research and back it up with real test data before shooting down others or blindly supporting someone else.

The sword has two sharp edges.........

Lizard928

I have worked on cars with poly bushings, a fair number of them.

There are two failures that occur, one is just from time. They all seem to start chunking and falling apart after about 1 year, if they didnt fail before that.
If they failed before that the way that they would fail is the rubbing from the center metal sleeve on the poly bushing. What happens is that there is always a form of friction from the constant rotation from the back/forth motion. This then wears the material slowly, both the metal wear sleeve, and the poly bushing. The moment that the bushing gets even the tiniest but of play in it and even a spec of dirt gets in there the wear occurs extremely rapidly, until there is a few thou of play in there, and you start to notice it. It can happen in as little as 30 min under the right circumstances.

Also even the black "self lubricating" bushings come from all the makers with a special grease that you put on the metal wear sleeve. If you are not constantly regreasing them, the wear occurs much faster.

I suppose if you removed the inner metal sleeve and regreased it bi-weekly they may last a reasonable amount of time. But who wants to remove them that often.

On these bushings as well, they locate the rear hub. If the tolerances are not perfect with this design, you will get massive shifting on the rear end. In other words, if the thicker part of the bushings which is on the outside of the bushing has too much material, the inner wear sleeve will not get the crush needed to lock it to the pin and it will wear the pin due to the fact that it is an interference fit to the poly. If there is not enough material on this thicker part, then the pin will be able to rock forward and rearward allowing large changes to the rear suspension settings. The tolerances for this are in the neighbourhood of .001" +/- .0005". Now I have not measured a few dozen 928 arms to know the factory tolerances, but given the build quality, I hope that they are all within that limit.
However the factory design for these parts and bushings was to function in a completely different method, the BONDED inner sleeve of the factory is pulled towards the center once tightened, and the large washer which sits against the outside of this bushing is then pressed into the rubber creating enough friction so that it grabs the rubber and aids in the amount of force it takes to rotate. When you look at the back of these factory washers there is zero indication of the rubber hopping, or rubbing on this washer, thus further showing their design and functionality.

Now there are many vehicles out there on the road today, especially newer vehicles where the suspension bushings could use a redesign to aid in handling. But the stock 928 bushings are of amazing quality, with very minimal deflection. The softer poly bushings are normally a 65 shore A, this is going to be pretty close to the same deflection as a stock bushing, the difference with street tires will be undetectable. Slicks on the track you might see .001", less movement than a stock fresh (less than 60k miles) bushing. If you get the harder "race" poly which is 75-80 shore A, it will probably get you another .001" +/- .0005". I doubt that the deflection you will see on a stock fresh bushing would be greater than .0025". Though admittedly I have not measured that as of yet.

Due to how fast poly bushings fail the moment you get any dirt in them, and with how often you will actually have to lube them if driving on them daily, I would strongly deter against them for any street use.
If you want to track your car only, and dont have the means to go with full rose jointed suspension all around, then sure, go for it. But keep spares (2 or 3) in your tool box, and thoroughly inspect them every time you come off the track, and prior to going on the track. Oh and dont forget to grease them before every track day to ensure that they have proper lubrication and therefor minimize the friction and wear on them.
And with that being the case, why not just make bronze bushings with metal sleeves and use them instead if you are tracking the car. They can be whipped up fairly easy and relatively cheap by any competent machinist. And while he is at it, he can do the front (toe adjustment) bushing, and the inner LCA bushing on the rear too. Possibly even with an offset hole, and pinned to the LCA so that you can get additional rear camber too!

And Ed,
Everything that I post is my own opinion based off my own experience and research. You can choose to read it if you wish. You can even get your nickers in a twist over it, doesn't bother me any. But this is the internet and everyone is allowed to post. But you can bet, if I see a product that is inferior, possibly dangerous, or just a downright bad design. I will speak up about it.
You are correct though that I do speak up in Carl's threads about his products. This is because the products he chooses to bring to the table are not what I would consider to be suitable products for a car. His rear tie down plates are a perfect example of the fact that Carl (IN MY OPINION), does not grasp how suspension components truly work. Again though, this is the internet and people can read my comments on his products and choose if they wish to buy it or not. But at least they will be able to read another view point other than that of the person who has invented it.

Lizard928

So you feel that if someone makes a product, even if there is a safety concern that someone else sees, they should just keep their mouths shut because someone might get hurt feelers?
It doesn't matter who points it out. Keep in mind that we as a group have been burnt by venders in the past. If everyone keeps it to themselves many more people will end up getting bitten.
People need to grow thicker skin and realise that this is the internet and people can and will say whatever they want! If you are offended by that, well guess what, it's YOUR problem and you are only making yourself unhappy by being offended by that!

Plus look back, Roger actually said he thought it was a good product (alternative) then said that he has had problems with ANOTHER vender (energy suspensions) which is not on rennlist......

FBIII

I prefer to see it settled by parties that don't have an iron in the fire. One of the things I most admire about Mark Anderson @ 928 Int'l is that he never exhibits this type of behavior. Suppliers fighting with fellow suppliers and mfg's fighting with mfg's I find it petty and demeaning.

ROG100

Sorry but I am a 928 owner and I drive 928's every day and they are my passion. Just because I am a vendor does not mean I do not have an opinion.
I use all sorts of products on my cars just as you do and feel that feedback to the community is worthwhile. I comment with appropriate information when it is needed. I try and put right misleading comments when I can.

When I have a RHD customer asking for an expansion tank I send them to Carl. When someone does not want a complete rebuilt upper A arm but just the ball joint I send them to Carl. If these parts work as they should I will gladly point them out to customers that do not want to pay $98 for the part.

I have learnt a lot from this thread - differing opinions about the use of Poly. I will just watch and learn more 8>)

FreedP

Both materials were available when our cars were engineered and built.
Why did Porsche select rubber?

I suspect they believed it to be the better solution.

Carl Fausett

I agree. While Colin is entitled to his opinion (like everybody else) he does nt seem happy with "they're not for me" or "I won't use them". It seems he insists NOBODY use them. That suggests that he has a hidden agenda that he is actually working on.

Colin, its arrogant to think you should make the decision what to use or not use on everybody's car. These are intelligent adults, and they will each make their own purchasing decision based on their beliefs.

Example: we make supercharger kits for the 928. Many look at them, the page has many hits, but relative to the traffic on those pages, only a few buy. No problem - that's the way it is. They aren't interested in it. Fair enough. But those that don't buy do not log in to a forum and post "nobody should ever supercharge their car!" This is sort of what your doing, Colin.

You're welcome to your opinion, and you have stated it. I believe without any supporting data to it, but whatever.

Carl Fausett

Roger -

If you sold the Suspension restoration sway bar bushings right out of the box, it could be the hardware that caused them to squeak. The hardware supplied is pretty thin and some have even broken it when they were installed as-is. We supply different hardware to keep the brackets from twisting, and I have no complaints that they squeak at all.

To all: if you have a set of our front sway bar bushings installed with our supplied hardware, would you please post whether yours squeak or not? Mine don't, buyt I want to hear from YOU.

I'm putting forth a theory that, if they are allowed to twist in their mounts, they may squeak. And if held correctly in position, they do not. I'd like some others with experience with them on their cars to tell us what they have found.

Carl Fausett

Reading Hacker's comments - I can see he'd like more automotive comparisons, not industrial comparisons. Fair enough.

How about the 928 International replacement polyurethane front upper a-arm bushings? I've been selling them for years - no complaints of "short life" or "squeaking" from any of my customers.

To all: if you have installed a set of polyurethane upper a-arm bushings from me or 928 International, would you please post your results? Do they squeak? Did they wear out quickly?

Carl Fausett

I'm not sure that's true that they had both materials available to them. These suspension bits were laid down in about 1976 from what I can tell from "Projekt 928" for their lengthy real-world driving tests through Africa. The 1978-1995 lower rear suspension bushings are all the same, this original design was never modified.

And I don't know that the current quality of graphite-impregnated polyurethane was available in 1976. 37 years ago!

If I set that aside, I think I can also understand why Porsche would go "rubber" and not "poly". The 928 was designed more as a touring car than a performance car. We have ample examples where they went to great lengths to isolate vibration and noise from the occupants, even to the detriment of performance. After all, it was their luxury car. So it is clear to me they valued quite, vibration-free driving above performance in some aspects of this car. And the rubber parts would tend to favor that.

Also, the rubber parts would likely last longer under all road conditions, where grit/sand from a gravel road can get into a polyurethane part and gall it up.

Now we come along, years later, and we may be a little more performance-oriented and want better cornering and control of our camber settings than the rubber provided, and we service our own 928 so we don't mind the occasional inspection of the bushings to see how they are wearing. Or perhaps we don't plan on keeping the car forever - so as long as they last 10 years, that's "good enough" where it would not have been "good enough" for Porsche.

These are just a couple reasons I can think of that Porsche went with rubber.

RKD in OKC

When I was upgrading the suspension on my 951 for better performance in street/track use in 1998, I asked about going to poly bushings. My mechanic said he would have no problems doing it and it would increase the accuracy of the suspension, BUT most the street/track use cars he had put them on to date, the owners had them removed after a couple of months due to the harsher ride on the street. No mention of any noise or wear issues on the street or track customers that kept them in.

huskeric

I think I installed my first set of poly bushings in '86 on my 69 4-4-2 front sway bar and rear lower control arms - they performed very well. Then installed in 1992 on my Chevy pickup truck (with 40" tires) on my 93/96 (in the same years) Trans Am through out, in 2007 on my '05 Vette, last year on my 89 944T, and soon to be on my '89 928 - and perhaps a few cars in between that I missed. Throughout all these installs, I do acknowledge some squeaking, but this has been reduced greatly over the past 15 years. And, all my cars are driven 100% on the street, as I don't track them. I have never had one failure - and have put many miles on several of them. I have also done before/after testing (within my limited non-engineering ability) and have found them to perform better than the OEM parts.

I am not claiming to be an expert by any means, but I do discount the claim that urethane should not be used and have no place on the road.

SMTCapeCod

I dislike resurrecting sour threads, but am wondering whether there are some folks with additional experience with the subject bushings? Or to respond to the inquiry about those previously in-play for the front a arms?