In the past I used a bulk product made of Nylon/Teflon material of some sort, surplus from the aircraft industry.  I think I used Delrin, too, it's been a long time.  All worked for a time but all eventually need replacement.  My applications were for  dirt bikes  so perhaps street use would be less severe and therefore last longer. The OEM nylon type guides would only last a few hours.

Rod

You might want to look into one of the grades of UHMW. (ultra high molecular weight polyethylene) This material is frequently used for chain guides in non MC applications.

I used to use the tensioner pad out of a 4 spd evo sportster when we did 883 racing.Professional Plastics sell nylon 66 in sheet stock if you were going to make several.
 Dman # 93

Nylatron MD

Good Stuff,

Steve

It depends on the mode of failure. Possible materials with pros and cons are:-

1)Ultra High Molecular Weight Poly Ethylene. This is soft tough an slippery, but has a very low melting point. It is good for low load or low speed bearings in a hostile and dirty environment. It is ductile and has quite a lot of compliance for a plastic. It is very similar to the High Molecular Weight Polyethylene used in cutting boards

2) Acetal (Delrin, Celcon, Ultraform, Tenax etc). This makes a hard stable very high load bearing bearing. It does not tolerate dirt well due to its lack of ductility, and it only has a moderate melting point. It responds well to silicone oil and PTFE (Teflon, Fluon Hostaflon etc) additives. Silicone and PTFE are synergistic in their actions as additives to Acetal.

3) Polyurethanes have extremely good ductility, and moderate bearing properties. Probably not for this application.

4) Nylon 6.6 (Nylatron, Zytel, Ultramid, Vydene, Maranyl etc etc etc) Nylon 6.6 is used extensivly as barstock for the higher load or speed sector of the plastic bearing market, often graphite and Molibdimum DiSulphide filled. These molly filled nylon 6.6s are also used almost exclusivly as original equipment timeing chain guides and tensioners. Other Nylon options are Bronze filled nylon 12 and nylon 4.6 (Stanly). Nylon 4.6 gives generally 3 times t6he life of molly filled 6.6 in timeing chain tensioner applications as it has the same frictional properties, but substantially higher softening and melting points.

I would use Nylon 4.6 for this application, if "burning" or melting is the mode of failure.

Regards
pat

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