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Just curious as to why you are doing that.Originally Posted by oscarmayer
Sorry about the long post below but I wrote most of it for some people that are on another site so I just pasted some of it for here to save some time.
I have used Delrin and other non metal bushings in many apps, however, I wouldnt use them for swing arm bearings because they are a bit soft and wont take as much abuse and I really dont know were this fad started . . The bronze bushings are pretty hard to beat, and even with the old style bronze bushings, worked fine providing they were greased every few years . . The main problem with them comes from getting water in them and never servicing them . . A set of the old style bronze bushings will last a very long time . . The 954 bronze is far stronger than the old school bearings and will likely outlast a few generations of family . . These are military spec, and are similar to the ones used in the landing gear of airplanes and huge earth movers . . Irregardless, I would make any bushing as long as possible up to a maximum length of 1 1/2, because the longer they are, the longer it will take for them to wear out.
It is common for the rubber bushings in suspension parts on cars and trucks which will be used in high performance apps, to be replaced with more rigid parts like, Urethane, Delrin, Heim joints, Needle bearings and/or spherical bearings, to reduce friction and flex . . Most, motorcycles, and all ATVs use bushings or needle bearings in the swing arm . . This is because, on these types of vehicles, especially the high performance ones, it is important to keep the swingarm, and hence, the rear wheel, or wheels, from moving independently of the bike as much as possible . . Imagine if Jeff Wards bike or Wayne Raineys 165 mph road race bike had a rear wheel that moved from side to side even the slightest amount . . Obviously this is not as critical on a recreational ATV etc, but I still see no point in intentionally using bushings that not only cause the swingarm and rear wheels to do this, but in most, if not all cases, will wear much faster, not to mention increasing friction.
If a bushing has to be made, it requires the exact same process to make one out of a plastic, as it does to make one out of a metal, therefore, other than possibly a slightly higher cost, and slightly longer machining time, therefore I cant think of a good reason not use metal for swing arm bushings . . In fact, in many cases, one could use aftermarket needle bearings instead of bushings even if their bike didn't come with them.
The following is a chart I made comparing some of the commonly used materials for bushings . . The Delrin AF and NYLUBE are both self lubricating, however, since the bearings will be greased anyway, and these wont be going in an F1 car, the coefficient of friction number is less important.
I listed these in order of my preference and strength against compression . . I would dot use Nylon or the Acetal POM-C.
.....TYPE ... Compressive strength Dynamic CF .Hardness Tensile . Wear .. ME
SAE 954 BRONZE 22,000 psi* .. 0.37* . B17/RB83/R156 .. 70,000 .. N/A .. 14,000,000*
KETRON CM CA30 .. 29,000 psi .. 0.20 . D93/M102 .. 9,000 .. 150 .. 1,250,000
NYLUBE MO . .. 14,500 psi . ... 0.12 . D85 . 12,300 . 32? .. . 508,000
DELRIN AF [BLEND] .. 16,000 psi .. 0.05 . M85/R115 . 8,000 . 57 .. 485,000
DELRIN [POM-H] . 16,000 psi .. 0.25 .. D86/R122 . 11,000 .. 200 .. 450,000
ACETAL [POM-C] 11,000 psi .. 0.21 . NA/R86 8,800 .. 200 .. 400,000
LEGEND
Asterisk * = Approximate value.
Compressive strength = The point at which a material breaks or permanently deforms by a fixed percentage . . The amount of deformation noted in the materials above is 10%.
CF = Coefficient of dynamic [moving] friction without additional lubricant . . The NYLUBE has oil impregnated into the material.
ME = Modulus of elasticity . . This is the amount of force required to compress a material a fixed percentage . . The higher the number, the more rigid [less compressible] it is.
NOTES
Some of the specs above may vary slightly depending on who the mfg of the material is, however, the chart is a good, overall representation and comparison of them.
SAE 954 BRONZE This is Military spec and has good corrosion resistance . . The CF number is against mild steel . . It will be lower if the bearing is used against Hardened steel . . With grease, the CF of the will be approximately 0.16 against mild steel and slightly lower against hardened steel.
ASM 4640 Bronze, also known as C630, or CDA 630, or C6300 - This is also Military spec, and is superior to SAE 954, and would work xlnt, and will possibly outlast several generations of family, however, it is a little more difficult to machine and a bit of overkill which is why I posted the 954 instead . . Also, the ASM 4640 should be run against a hardened shaft . . The 954 should be run against a shaft that is as smooth, or smoother, than sanding with 2000 grit paper and water or WD40 for the last cut will produce.
KETRON CM CA30, also called CM CA30 PEEK This contains 30% Carbon . . The compressive strength is equal to that of the 954 Bronze, and twice that of any of the other materials . . Its ME is more than twice that of any other material except for the Bronze.
NYLUBE MO This contains some Moly.
DELRIN AF This contains 13% Teflon [PTFE] . . Military spec is 20% Teflon.
AVERAGE COSTS FOR 1 1/4 DIAMETER BAR/ROD . . Approximately 6 bearings per ft.
SAE 954 $45.00 per 12 ... 6 bearings ...... $9.00 per bearing.
KETRON CM CA30 PEEK . $414.00 per 30 . 17 bearings .... $24.15 per bearing.
NYLUBE MO . $130.00 per 96 . 55 bearings ...... $2.36 per bearing.
DELRIN AF [BLEND] . $50.00 per 12 . 6 bearings ...... $8.33 per bearing.
DELRIN [POM-H] $10.00 PER 12 6 bearings ....... $1.66 per bearing.
ACETAL [POM-C] . $9.00 per 12 . 6 bearings ...... $1.50 per bearing.
LUBRICATION
I would use an extreme pressure grease for any of these bearings in this particular app.
BRONZE Lithium based grease is best for these types of bushings . . Lithium with Moly is even better . . Two of the best Lithium greases are made by Shell Oil for Aviation purposes and are Military spec . . The straight Lithium is called AeroShell 33 and the second is AeroShell 33M which is the same as the 33 with the exception of the Moly.
Dont use grease with Graphite or ZDDP because these can eventually damage the bearing,
NYLUBE Contact mfg for recommendation, although the Lithium greases should be fine . . It is also possible that this material can be run without grease in this app but I would be hesitant to do that, and since this material has Moly in it, I would use a grease with Moly in it as opposed to one with Graphite or Teflon etc . . Silicon base grease may also be ok.
DELRIN AF Since this material has Teflon in it, I would use a grease with Teflon in it as opposed to one with Graphite or Teflon etc . . Silicone based grease may also be ok.
POM-H AND POM-C Any of the above greases should be fine.
Mineral oil based grease can damage Polycarbonate bushings.
Heres small quantities of the AeroShell 33M . . 3 1/4 oz for $4.70
http://www.ebay.com/itm/AeroShell-Gr...061a1e&vxp=mtr
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