Urethane suspension bushings - NOW READY!

[russelljones48]

OK, so according to Wikipedia here's the definition of a durometer - it's analogous to the Rockwell scale for metals...

The durometer is a device for measuring the hardness of a material, typically of polymers, elastomers, and rubbers. Higher numbers on the scale indicate a greater resistance to indentation and thus harder materials. Lower numbers indicate less resistance and softer materials.

[wwheeler]

I dealt with rubber and urethane for 35+ years so, I can help with some of the questions. I am still trying to get more info in regards to the existing tooling before I buy it.

Hardness of rubber is measured with a spring loaded pin. How deep it goes determines the hardness. The deeper the pin goes, the softer the material. There are at least 4 ranges of hardness and is measured with a durometer. Shore has A, B, C and D scales. Shore A and D are by far the most common ranges. They overlap and there is a reason for that. At the outer ends of the scale, the measurement becomes less accurate. So the optimum accuracy is in the middle of the range. You can google it and see what I am talking about. So a 70 Shore A rubber is a very common hardness and what most O-rings are.

But, when you squeeze and bend rubber, that is NOT the hardness you feel but rather Modulus. Modulus is very commonly mistaken for hardness. "An elastic modulus is a quantity that measures an object or substance's resistance to being deformed elastically when a stress is applied to it". Not my words but that is what it is.

A good example is that urethane has a much higher modulus than would common rubber. That is the property you are after for suspension bushings. Compare a 80 Shore A urethane to 80 Shore A rubber and you will find the rubber bends much more easily. Yes the harder the material the somewhat stiffer the material feels, but modulus is more important here.

That being said, I could see using a range of 85 Shore A to 95 Shore A urethane. Any softer than 85A, you aren't really gaining much over OEM rubber. 95A is hard as a rock and most would call a plastic. Plastic BTW, is usually measured in the Shore D range. 95A is equal to 55D as a reference.   

I am not however an expert in suspension systems and I could see experimenting with hardnesses. Yes, I think you could offer a mild upgrade and then the higher performance bushings. Each with its own pros and cons. That would not be an issue in production to do so.   

[russelljones48]

thanks for the explanation - it's helpful..  Can't wait to see what you come up with.  I think modern bushings would be a GREAT addition to what's available for our cars..  And they will not affect the car's originality if someone wants to revert to original rubber.  I've got the Koni adjustables and a set of aluminum rims and I'm quite happy with the results to the handing.  Can't wait to add to the tricks.. 

[Benz Dr.]

I can tell you that the Cox bushings were hard. Like hockey puck hard.

[jond907]

Interested!

[pedrocamp]

Even more interested, thanks! Glad to see you know the materials, hope the molds work out.

[wwheeler]

Cox bushings were 95 Shore A. If I had to start today, I probably wouldn't go above a 90 A. 5 points do not seem like much on paper, you you can feel the difference. I would like to experiment with both 80 A and 90 A. 80 A would give you a bit of an upgrade and 90 A even more. No two people are alike and want the same thing.     

[wwheeler]

The tools for the urethane suspension bushings are on the way!!! It looks as though I will be making these at some point soon. For the W113 Pagoda and W111 cars, the following will be available:
- front flat leaf spring
- Front sway bar (frame and end link)
- Rear axle trailing arm (frame and axle)

I have quite a bit to do and am looking at these being available in the summer or early fall. My initial plan is to make these ever so slightly softer. I think that will be a better fit for the Pagoda crowd, rather than the very hard compound used prior. But, we shall see.....

[pedrocamp]

Good news!

[russelljones48]

I agree - great news!!   Can't wait to get my set...

[wwheeler]

Getting closer. I have produced parts from each tool and they match the OEM in fit and dimension. The hardness is a bit softer than what Cox had. His was 93 to 95 Shore A and mine are 88 Shore A. Does not sound like much of a difference, but you can feel it being a bit softer. I think that hardness is a good compromise between performance and ride comfort. The last step in the process was to surface cut the "open pour" side flat. Sounds easier than it is, but that is now under my belt.

Shown is a rear sway bar bushing for the W112 and W109 cars with air suspension. For the W113, I have both front and rear trailing arm bushings for the rear axle, the front flat spring bushings and the front sway bar bushings.

Just a few more details to hammer out and they will be ready!   

[mrtzmd]

Just saw this thread. Interested.

[russelljones48]

Still interested.  Next big project on my car will probably be all the body/engine rubber.. 

[Rahul]

I might have interest in these!

[wwheeler]

They are coming along and I have a test bed scheduled on a 6.3 W112. Once that is done, they will be ready for sale. I have the full tooling for the W113 cars as well as anything made in the 60s. (not W100 though). I typically sell through one of the well known Mercedes parts suppliers to help simplify on my end. I am thinking by mid-November they should be ready to go. Thank you for your patience and want to make sure I get this right the first time.

Wallace

[russelljones48]

can't wait!!  a winter project 

[rwmastel]

It's been quite some time since I've been under my Pagoda.  What is this front flat leaf spring you talk of?  I don't remember it.

[wwheeler]

That is the "leaf spring" that mounts to the front of the chassis and then to the subframe. There are (4) bushings mounted there and this for the castor adjustment I believe.

BTW, getting close with production on these urethane bushings. I am taking great pains to make sure these are right the first time. I will post when they are ready to go.

[tedskeff@icloud.com]

Am very interested as it's time to change all of mine.

[wwheeler]

I have unfortunately been delayed on the start up for the bushings. 2020 has been a tough year to get loose ends tied. I am waiting on tooling that will allow me to finish the final production work. Once I get that, they are ready to go. Best date right now is mid January. So pretty close. I will post here when that happens. Thanks for your patience.

Wallace   

[wwheeler]

It has been a year since I started this project and now we are ready to go. I am selling these through Miller's. These are not currently set up on their website, but they have committed to stock parts for the Pagodas. Attached are a couple of pics of the parts that are available at the moment. To order sway bar parts, the diameter of the bar must be known. Other than that, it is pretty standard.

PM me if you have questions.

Wallace   

[russelljones48]

what's the price for a set?  I can't find anything on Miller's

[wwheeler]

PM sent.

[Rahul]

Curious, has anyone managed to try these out yet?

My bushings are up for replacement and I am debating whether to just stick with the OEM rubber, or try something different and longer-lasting. I am not going to have the time (or skill) to try out different setups for front/rear etc - so really looking for any recommendations on whether these are worth installing 'out the box'. If it purely comes down to experimentation or matter-of-taste I'll probably stick with OEM.

For ref, mine is a 1971 280SL, thanks.