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1966 Honda super 90 swing arm bushing material

C

Cmachine84

Plastic
Joined
May 10, 2018
I have a 1966 Honda super 90 that I have recently got back from the powder coaters and am readyish to begin assembly.

I am not necessarily a motorbike guy but I believe I remember hearing that swing arm bushings and the like are made out of Delrin from time to time as an upgrade.

The current bushings in the swing arm and forks, shocks etc are old and I’ve got tons of black acetal.

Bad material choice? Good choice? Please advise. I have read a few posts including the high impact bushings post for off-road bikes but keep in mind this is a 90cc cruiser for me around Southern California, not even the trail 90 version which may see harder use :)

I may have some UHMW too or some nylatron rolling around but Delrin turns so nice and easy. Ideas?

Thanks
 
Member " ArtRacing " is deeply immersed and competent with the specifics of these and can give you input specifically regarding OEM and upgrading. Try PMing him. Tell him I say hello.
 
Small and super fun to ride, cruising along the cliffs and ocean here in San Diego. Tough winter days, sunny and 74.

I think I have maxed the bike out flat at about 50mph before I tore it down for paint. My favorite is easy Sunday afternoon rides at 35 mph. Safe is is still very important even at those speeds.
 
It has been a very long time, but if we are talking about a Honda S90 they did not have a real journal bearing for the swinging arm. The 'bearings' were actually a rubber bushing where the inner part of the bushing was tightly clamped by the swing arm through bolt and the outer was a press fit into the swinging arm. The torsional stiffness of the rubber bushing contributes a bit to the stiffness of the suspension. The clamping force of the through bolt ties the frame together to some extent. I do not think that acetal could be used in the same way (i.e. a torsional bushing) - it would be far too stiff. Perhaps you could make a replacement journal bearing from acetal, but you would need to ensure that you did not lose stiffness because you could not torque the bolt up tightly.

It is possible that the US version of the S90 was different to UK, but you should get better than 50mph out of if the engine is good. I remember it as a fun bike to ride and pretty much unbreakable.
 
Delrin is nice if lubricated if not then any moisture will cause rust.Nylatron is graphite mix,Nyloil is oil mix and Nylon with oil and Moly sulfide is available.Any will work just fine my pick is oil/moly s mix.
Since you have Delrin and can add grease fittings use that.
 
Ment to add that you will have to use an inner sleeve and end thrust washers to set lateral clearance and bolt clamp pressure with any of the non metal bushings.
 
Cmachine84 said:
...I think I have maxed the bike out flat at about 50mph before I tore it down for paint...
Click to expand...

billmac said:
...It is possible that the US version of the S90 was different to UK, but you should get better than 50mph out of if the engine is good. I remember it as a fun bike to ride and pretty much unbreakable...
Click to expand...

In the summer of '67 I worked at Port Alberni on Vancouver Island. I bought a brand new S90 to get around on. Over the course of the
summer I saw just about every part of the island and left myself with a ton of memories. Thanks for rekindling them.

I could get 60 mph out of mine but I had to have a helmet on and have my chin resting firmly on the handlebars--I didn't hit 60 very often...:D
 
Delrin is a good material-- when it comes to anything exposed to sunlight-- I like to get material with added uv inhibitor in it. My go to material for exterior applications that are exposed to sunlight and need great impact properties is UHMW(ultra high molecular weight). Machines like delrin and takes some punishment.
 
I used to have a good little side business going upgrading swing arm bushings. My son raced hare scrambles for years and I rode for team fat ass briefly. The problem with the bushings is that dirt and mud get into the needle bearings and tears them up. The other problem is that there is no way to lube the bearing other then take it apart which would almost have to be done after every race in muddy conditions ( I'm talking almost up to the tank mud slurry conditions). I just knocked out the bearing and made bushings out of nylon. I tried PEEK because I had some but they did not hold up well. The key is to add a grease fitting between the bushings in the top of the swing arm just forward of the shock mount so you can drive out the crud and re-lube them between races. It's kind of like Buddy bearings on your trailer.
 
The bushings are metal rubber metal . one of the reasons is swing arm bearings do not to perfectly in line it is a weldment , though's steel backed bearings can be fun to remove . If they are not failing I would leave them be it it not a racer .
 
The rubber/metal bushing has proven to be the most reliable all weather combo in automotive suspension for the last 70 years.
I used to make delrin bushings for Corvettes & Vipers.It makes quite a difference in the handling and feel.The reason is that the compliance of rubber bushings induces unwanted steering effects in high loaded cornering.

On a Honda 90 the frame & swing arm is a bunch of spaghetti to begin with so going with stiffer bushings is not going to do much.99% of them probably go to the junk yard with the original bushings.So unless they are not available or affordable for standard use that is what I would use.
 
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