Urethane suspension bushings - NOW READY!

[wwheeler]

I have a unique opportunity to buy tooling to produce urethane bushings for the W113. They also fit the W111, W108, W109 etc....These are tools that have been around for close to 20 years. Before I make that investment in the tooling, I was curious if there is any interest now. The bushings would mostly be for the trailing arm, subframe spring and sway bar.

These parts have not been available for a few years and mainly due to lack of interest in selling by the old vendor. I realize there will be a limited market for these, just curious how limited.

Thank you,

Wallace

[mazmonza]

I am using these at the moment but would like a spare set .

Maurice   

[pedrocamp]

Interested!

[Pawel66]

I am using these at the moment but would like a spare set .

Maurice   

I am curious: not experiencing more vibrations? The car should be "more stiff", they are quite durable, but my W463 experience was - a lot more vibrations transferred to body.

[dirkbalter]

Interested as well.

[Benz Dr.]

There was a guy in California that was making an entire set; trailing arms, sway bar, rear axle trailing arms, front suspension,and maybe more. I think the company was called Cox Racing Bushings. If they're not around anymore I'd say give it a try.

[wwheeler]

Cox isn’t around any more but I know where they are I realize the ride will be stiffer and most do not want that. But some do, which is why this product has been sold in the past in limited quantities. Thanks for the input.

[lreppond]

Interested. 

[Garry]

Am interested also

[mazmonza]

I haven't noticed vibration but the ride is firmer, I also have stiffer Olsen road springs.
With this combination I do get flatter roll free cornering but feel the road  more

Maurice

[Benz Dr.]

Ride is only a bit stiffer but the handling is much improved. I have a 22 mm sway bar on my car so it handles quite a bit better than a stock 230SL.

[Cees Klumper]

I bought the set from Cox Racing waaaaaaay back, probably around 2001. Fitted everything (mostly sway bar bushings I think) but for the 'donut' bushings under the rear trailing arms I quickly switched back to rubber because of the significant increase in vibrations.

[wwheeler]

Was that the front mount (frame) or rear mount (axle) for the rear training arm? I have been told that the front mount (frame) benefits greatly from urethane where as the rear (axle) doesn’t as much and can cause vibrations.

[JamesL]

Interested

[VincentR]

Interested

VincentR
280sl - France

[pedrocamp]

Wallace,

Do you know what durometer urethane was used in the original moldings? What durometer Cox used? Do you have various urethane durometers available from your proposed supplier? Compliance and transmitted vibration could vary according to selection. 

[russelljones48]

count me in.  can someone tell me why the rear bushings seem to generate NVH that is unacceptable?  I've used aluminum body mounts and urethane bushings in other vehicles of the same vintage with no detrimental effects.  I actually find it tightens up the car and reduces noises from body to frame flex..  urethane does need "special" grease - just a very sticky grease to avoid squeaks but I'm intrigued as to why it might change the NVH that much?

[wwheeler]

Thanks for the replies. I don't know now, but will be able to determine exactly what hardness was used in the past. I will actually be the one making the new parts from the original tools. So I can vary the hardness a bit if needed. I am still doing some background on the tools and such, but wanted to see if anybody has interest. I would say from the brief couple of days here, that there is sufficient demand.

[pedrocamp]

Good to hear you see a market and will proceed. It may be that the urethane durometer used could be application specific, a compromise of compliance and vibration transmission... and of course durability. For example a bit harder durometer for the forward joint of the trailing arm and softer at the rear joint? Or vice versa? In testing wide swings from 60 soft to 90 hard would be easier to feel than 70 to 80, especially in an un-instrumented road car. Manufacturers nowadays vary compliance and vibration isolation with holes or voids (sometimes fluid filled) in the mounts or joints. My Honda Odyssey has electronically controlled motor mounts that change their vibration isolation frequency range when the engine is either on 6 or 3 cylinder ECO mode. Most manufacturers use compliance as a tool to keep suspension geometry in check as Porsche famously did with the Weissach axle on the 928 to eliminate lift-throttle oversteer.

[FGN59]

Might this be a case of the more we learn, the less we know? as I believe a famous scientist once said (could have been François Jacob, or even A. Einstein, or some other bloke on par with those guys).

This thread, like many others, brings to the fore some truly fascinating aspects of mechanics and roadworthiness, all mixed and sometimes conflicting as they rightly should be (no true performance comes easily), but now I don’t know what to think anymore. At the beginning I thought I might be interested in those bushings, but the more I read, the less I understand... 

My previous ‘oldie’ was a 1963 Jaguar Mk2 (albeit with a 4.2L, 270HP engine), a kind of a beast, really fun to drive but requiring you to really pay attention to the road, and a bit of a ‘hard’ ride. The softness of the 280SL is a surprise (a nice one, sort of), but I wouldn’t mind a bit of a tighter (stiffer) ride, as long as the car remains as homogeneous as it is now (front/rear balance), for it is quite remarkable as it is. What to do? Stiffer bushings, thicker sway bar?

[pedrocamp]

I would hazard to guess you won't see a detectable balance change switching to urethane bushings on both ends of the car. You will improve the efficiency of the front anti roll bar with a hard durometer urethane by reducing the compliance which could increase understeer by a small amount but you may need to be Rene Arnoux, Alain Prost or, in the modern age, Charles LeClerc to feel the difference... but of course I am not questioning your driving skill! I am sure there are those on this forum more knowledgeable than me but you may only notice increased responsiveness, a bit "crisper' handling, due to the reduced compliance in the suspension (depending on durometers chosen... harder more, softer less) but you may feel increased transmission of vibration - sharper frequencies as the softer durometers of the OE rubber bits are not there to absorb or dampen it. Urethane bushings can be noisy, squeaky, as Russell mentioned and should be greased if used in rotational joints.
A stiffer front anti roll bar will change the balance of the car (usually towards more understeer or push) unless coupled with the addition of a proportionally sized rear bar. If balanced the bars will flatten out the ride, less weight transfer to the outside tires, but increase the chance that you compromise traction in a bumpy corner since you are increasing spring rate in roll. Spring rate changes, proportional or not front to rear, can change balance and responsiveness. Reducing compliance in any of the system will make the car less "cushy"... usually, but more controlled. For a race car the engineers try to reduce compliance as much as possible to increase suspension and chassis control unless that compliance is beneficial. Of course a dedicated race car will rattle out your dental work compared to a road car.
In the end its a compromise on how you want the car to feel, one driver may like the balance of a particular car where another finds it unbalanced for his style. Again I don't want to try to appear as an expert on these cars or suspension setups in general, I am sure there are those on this forum that could recommend specific modifications to the suspension and chassis to improve responsiveness without losing too much of the comfort that Mercedes engineered in.

[russelljones48]

Don't let Pedro fool us with his modesty - he's been around performance cars for quite a while now and extends his job as his hobby..  His advice is good and changing out the various "Rubber bushings" in our cars will ultimately be a personal choice of preference.  Here's what I remember of the history of "Rubber" suspension/chassis bushings.  I believe they came to the forefront in post-war cars and were used by engineers to eliminate NVH issues in part because they believed the public wanted a "smooth" riding car..  for us Americans , remember those 60's land yachts whose steering and suspension was so isolated from road feel that it was hard to tell for a while if you were actually going to turn?  They were also "Rubber" because it was one of the few readily available materials.  I remember the choices in the late 70's for my autocross car - solid aluminum, maybe brass or nylon, or actual bearings.  Now we have far more choices and engineerable urethane.  I will choose to eliminate the "slop" from Rubber bushings which delay response until they're sufficiently compressed (I.e. mechanically hardened) to respond.  So, I'm a buyer 

[FGN59]

Well, driving skills left out of this, when I had to replace the worn bushings on the front anti roll bar on my Jaguar, I immediately felt a much improved, more precise and responsive handling, so I’m with you on all this. My concern was with the different grades of urethane (what is called durometer in this thread as I understand it), and how to chose which grade for which part of the suspension without buying a trainload of different grades for each different bushing...

[pedrocamp]

I've stolen knowledge from a lot of well qualified people! Even an average driver like myself would feel the difference with a package of less compliant urethane bushings installed compared to the stock rubber bushings. FGN59's experience sounds logical in that he felt the handling sharpen but may have still felt the car was still balanced... correct? Not to speak for Wallace but likely one or two grades of urethane likely enough choice for this application. It may be he finds that one material works fine in all the locations or substitutes a softer or harder grade in one or two. Given the option I'd buy a couple different durometers for some of the joints to see how it affects my car. I'd be most interested in possibly two different grades for the cone bushings at the rear trailing arm to axle location. These joints by my estimation seem to take forces from all different directions with longitudinal and lateral rotation thrown in. Not to mention the rubber ones seem to constantly squeeze out!
Russell reminds me of the distinct difference I experienced when I drove a Mercedes for the first time as a teen in the 70's, smooth ride but precise compared to the Stateside sedan competition. The Mercedes engineers had managed to find a nice balance of compliance control and vibration isolation. I was sold. That said a sportier, slightly less cushy ride can be fun on a mountain road.

[doitwright]

Over the past several years I have heard from a few people that Mercedes suspension rubber for our cars is not the same as it used to be tending to lean more toward the softer side. If you could produce a couple of variations like “original” and “performance” I suspect you will have a market for these parts.