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Thread: Suspension Bushings - Delrin, Rulon or Other

  1. #1
    Registered Member NickP's Avatar
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    Suspension Bushings - Delrin, Rulon or Other

    On more than one occasion, discussions regarding what bushing material should be considered versus stock replacement rubber units have arisen here so I thought for the sake of keeping it real, maybe a solid conversation might be in order. For starters, I am nor have I ever been a scientist, chemist or engineer so I am unable to unequivocally delineate data with any sort of authority so I'll leave that effort to others. I can however thanks to the internet, google and other sources, search for answers and draw some conclusions based upon white papers and other available data. So, what I'd like to open the floor with is real life experiences and other known facts - No name calling or insinuations allowed - Just the facts - opinions are great, but we all know the rest of the saying.

    Some reading of properties of plastics and their derivatives says there's a lot to choosing the right material. One material I found is Rulon. https://en.wikipedia.org/wiki/Rulon_(plastic). 142 seems to be a possibility. Others mixes are within the scope of the issue too. http://www.tstar.com/materials?__hst...view_32_page=1

    For mass production, cost may outweigh the complete exercise due to Rulon's cost but for the occasional use it might be good.

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    Registered Member chevynut's Avatar
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    http://www.boedeker.com/rulon_p.htm?...YvjBoCjRLw_wcB

    I personally think that stuff is way too hard to make a good bushing material that's somewhat compliant. It's 60-75 or so Shore D....

    Material Durometer Scale
    Bicycle gel seat 15–30 OO
    Chewing gum 20 OO
    Sorbothane 30–70 OO
    Rubber band 25 A
    Door seal 55 A
    Automotive tire tread 70 A
    Soft wheels of roller skates and skateboard 78 A
    Hydraulic O-ring 70–90 A
    Hard wheels of roller skates and skateboard 98 A
    Ebonite rubber 100 A
    Solid truck tires 50 D
    Hard hat (typically HDPE) 75 D
    56 Nomad, Ramjet 502, Viper 6-speed T56, C4 Corvette front and rear suspension


    Other vehicles:

    56 Chevy 2-door BelAir sedan
    56 Chevy 210 4-door sedan
    57 Chevy 210 4-door sedan
    1962 327/340HP Corvette
    1961 Willys CJ3B Jeep
    2001 Porsche Boxster S
    2003 Chevy Silverado 2500 HD Duramax
    2019 GMC Sierra Denali Duramax

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    Registered Member chevynut's Avatar
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    I think the best bushing material has to be relatively firm, not soft like rubber or hard like Delrin, and must have good lubrication properties. Solid bushings (like hard plastic or aluminum) work okay where there's only rotation, but they transmit the most NVH and need to be lubricated. Rubber allows too much flexing and movement of suspension components, but it's good as far as not transmitting NVH. Rubber tears and binds because the inner and outer sleeves are bonded to it so it's always in shear, restricting motion. Polyurethane is the plastic of choice because it can be made in different hardnesses, the inner sleeve slides on the polyurethane giving better motion without binding, and it can be impregnated with graphite (Polygraphite) to improve lubricity. Cost doesn't seem to be an issue with Polyurethane as it is with Teflon. IMO Delrin is too hard for most applications, and Teflon is too soft and easily deformable. Heims give good articulation but are bad at transferring NVH. The industry has chosen polyurethane, and I think there are good reasons behind it.
    56 Nomad, Ramjet 502, Viper 6-speed T56, C4 Corvette front and rear suspension


    Other vehicles:

    56 Chevy 2-door BelAir sedan
    56 Chevy 210 4-door sedan
    57 Chevy 210 4-door sedan
    1962 327/340HP Corvette
    1961 Willys CJ3B Jeep
    2001 Porsche Boxster S
    2003 Chevy Silverado 2500 HD Duramax
    2019 GMC Sierra Denali Duramax

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    Seems to me that the automotive industry in general has chosen rubber not PU.

    For performance applications, a harder rubber than OEM would be better, but pu is much easier to work with for short runs and does not require bonding, which often requires process tweeking.

    Everything is a compromise, what part of your specs do you allow to be deleted or degraded first?

  5. #5
    Registered Member chevynut's Avatar
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    Copied from my chassis assembly thread:

    Yesterday I decided to take a look at something I've long speculated about with regard to poly suspension bushings. RD has said that he doesn't like Poly bushings because they "bind" the suspension. Car Creations published a video showing how a rear C4 suspension supposedly "binds" and hangs up when poly bushings are used, limiting free suspension travel. I think that video was biased and assembled to help sell their products and not representative of a proper installation. Based on how the poly bushings are supposed to work, that "binding" shouldn't happen. The bushings should be pressed into the suspension part, and the steel sleeve in the center should be lubed and it should rotate within the bushing, and the bushing should not rotate within the suspension component. The diameter of the center sleeve is larger than the diameter of the hole, so there is preload on the bushing when installed.

    I had previously assembled my C4 dogbones with new Polygraphite bushings from P-S-T. They rotated fairly easily, but not as easily as I thought they should especially after sitting a while. So I took them back off and did some measuring. It turns out that the width of the front bushings when installed in the dogbones was around .020" or more WIDER than the length of the inner steel sleeve in all 4 locations. The inboard washers actually made an imprint in the bushings. The result of this is that the bushings were "pinched" between the frame parts as the bolts were torqued down. This causes a lot of friction in the assembly, which restricts free movement. It also forces the grease out from the sides of the bushing and eventually causes them to squeak.

    I pulled the bushings back out of the dogbones and faced them down on my lathe until the installed width was the same as the sleeve length. I didn't want any side to side movement so I tried not to make them too narrow. I found that 3 of the 4 rear dogbone bushings were the same width as the sleeve or slightly narrower, but one was significantly wider. So I faced that one down too, so now my bushings are "blueprinted" . I don't know why the manufacturers make them wider than they need to be, but it could be the tolerance in the width of the dogbones which isn't tightly controlled.

    After re-lubing everything and torquing the front bolts, the dogbones operate quite a bit more freely than before. I plan to do this with the lower front a-arms as well, to make sure they rotate freely. I think this problem is why some people don't like poly bushings and probably why they squeak so bad in some applications. You MUST lubricate the sides of the bushings too because they turn with the suspension movement.
    56 Nomad, Ramjet 502, Viper 6-speed T56, C4 Corvette front and rear suspension


    Other vehicles:

    56 Chevy 2-door BelAir sedan
    56 Chevy 210 4-door sedan
    57 Chevy 210 4-door sedan
    1962 327/340HP Corvette
    1961 Willys CJ3B Jeep
    2001 Porsche Boxster S
    2003 Chevy Silverado 2500 HD Duramax
    2019 GMC Sierra Denali Duramax

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    Registered Member NickP's Avatar
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    NVH - I would assume, relative to our slice of heaven, that each individual has their own threshold of tolerance relative to this condition within his/her own car and in this case, a 50+ year old one at that. Isolating noise in this instance, i.e. a C4 suspended vehicle shouldn't be that difficult especially due to the rear IRS essentially floating with only very few components transmitting a sound. Batwing - two mounting points isolated by either rubber or poly. The nose of the third member assembly attached with a form of a ladder or other form of extension typically with a poly rod end. Now, enter the anti-sway bar - isolated by rubber or poly at two points along with the connectors being anything from a rod end or a simple bolt with poly or rubber locators. If a stock spring is utilized there is a pretty good sounding board there but again, it's an integral component isolated by the three previously mentioned locations. If coil over shocks are utilized and each of the mount points have spherical bearings I suspect it might transmit some undesirable noise. The use of poly here will address that though.

    For the bulk of my past hotrods, I simply cranked up the stereo for the "street car" and for the most part the car had so many other detectable outpourings of noise and vibration I really never noticed them because I was having too much fun.

    I'm looking at a Delran "Acetal AF blend, supplied as a 2:1 blend of Acetyl AF-100 and Acetal 150 resins" now to play with for some new dogbone and camber rods. Newman had a huge price attached to their product but I think I have a solution that can be very competitive.

    It's fun to try if for no other reason than to stay out of the bars at night.

  7. #7
    Registered Member chevynut's Avatar
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    If coil over shocks are utilized and each of the mount points have spherical bearings I suspect it might transmit some undesirable noise. The use of poly here will address that though.
    I just bought some spherical bearings from Aldan and noticed they have a steel bearing with a poly race. That was a little surprising. In front I'll be using bushings with the t-bar on bottom and probably the spherical bearings on top, although the poly bushings don't need to deflect much there. In the rear there's more movement so I may use the spherical bearings top and bottom.

    Quote Originally Posted by NickP View Post
    Newman had a huge price attached to their product but I think I have a solution that can be very competitive.
    You have no competition from Newman. He must have sold out all of his remaining parts because his site is totally shut down now.
    Last edited by chevynut; 11-18-2016 at 04:51 PM.
    56 Nomad, Ramjet 502, Viper 6-speed T56, C4 Corvette front and rear suspension


    Other vehicles:

    56 Chevy 2-door BelAir sedan
    56 Chevy 210 4-door sedan
    57 Chevy 210 4-door sedan
    1962 327/340HP Corvette
    1961 Willys CJ3B Jeep
    2001 Porsche Boxster S
    2003 Chevy Silverado 2500 HD Duramax
    2019 GMC Sierra Denali Duramax

  8. #8
    Registered Member NickP's Avatar
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    Quote Originally Posted by chevynut View Post
    I just bought some spherical bearings from Aldan and noticed they have a steel bearing with a poly race. That was a little surprising. In front I'll be using bushings with the t-bar on bottom and probably the spherical bearings on top, although the poly bushings don't need to deflect much there. In the rear there's more movement so I may use the spherical bearings top and bottom.

    I think that's just a PTFE liner

  9. #9
    Registered Member chevynut's Avatar
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    Quote Originally Posted by NickP View Post
    I think that's just a PTFE liner
    Here's what the Aldan website shows for the bearings I ordered from Summit, using the Aldan part number.




    However, on the ones I got the whole race is black. I found this pic on the QA-1 website and it looks like what I got...nylon/PTFE race. I wonder if this is strong enough for the coilovers.




    "QA1’s EMB Nylon Race Series spherical bearings feature an injection molded race for superior ball to race conformity. This race results in the bearing being completely self-sealing and self-lubricating, keeping dirt and debris out. EMB Series spherical bearings are ideal for low load, low oscillation applications."
    Last edited by chevynut; 11-19-2016 at 07:24 AM.
    56 Nomad, Ramjet 502, Viper 6-speed T56, C4 Corvette front and rear suspension


    Other vehicles:

    56 Chevy 2-door BelAir sedan
    56 Chevy 210 4-door sedan
    57 Chevy 210 4-door sedan
    1962 327/340HP Corvette
    1961 Willys CJ3B Jeep
    2001 Porsche Boxster S
    2003 Chevy Silverado 2500 HD Duramax
    2019 GMC Sierra Denali Duramax

  10. #10
    Registered Member NickP's Avatar
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    Quote Originally Posted by chevynut View Post
    Here's what the Aldan website shows for the bearings I ordered from Summit, using the Aldan part number.




    However, on the ones I got the whole race is black. I found this pic on the QA-1 website and it looks like what I got...nylon/PTFE race. I wonder if this is strong enough for the coilovers.




    "QA1’s EMB Nylon Race Series spherical bearings feature an injection molded race for superior ball to race conformity. This race results in the bearing being completely self-sealing and self-lubricating, keeping dirt and debris out. EMB Series spherical bearings are ideal for low load, low oscillation applications."
    Interesting; oddly enough, I was reviewing them last night also. Then, I too wondered about the "low load" and became submerged in trying to understand the imposed loads to them and that drifted to all joints within the suspension system, be it stock or poly etc. Once there, my confusion grew so I went to bed and didn't sleep due to calculating all night. I'm exhausted this morning. I still have no clue as to what kind, static or dynamic, loads the various points see and the selection of spherical bearings is way wide to add to my state of distress.

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