What type of bronze for swingarm bushes?

[LWC82PE]

What type of bronze would be best for swingarm bushes?

932 (SAE 660)
954 (Aluminium Bronze)
SAE 841 graphite filled bearing bronze
SAE 840 or 841 oil filled (Oillite)

Or something else?

I plan to fit grease nipples if I can but not 100% sure if I have room/access yet.

[Momus]

932. All the bearing suppliers carry it as hollow bar.

[Lozza]

They are all pretty good (aluminium not as good as the others) if you can't fit a grease nipple reliefs in the bore will hold grease for ages if sealed at either end

[LWC82PE]

Ok thanks i was on the right track then and was close to grabbing the 932/SAE660 anyway. Will have seals at each end and request grease grooves inside bush. Its a brand new arm and nothing currently in it so i need to design all these parts in this area myself.

[sleepy]

I have always used LG2 bronze which is 836. I have never seen the 932 available from any of the metal suppliers or bearing shops in Qld.

[80-85 husky]

too small for a set of needle rollers??

[Mike52]

Have drilled up the centre of the swingarm bolt and tapped with 6mm thread , when not greasing they are  blocked with 6mm grub screws.
Works well for me.

[LWC82PE]

I will get 932 from USA if i have to.
Yeah i plan to have needle bearings on the inside and bushes on the outside like the Suzuki s/arms but yeah i am a bit limited with space both in OD and for length as its  its one of those s/arms that has a gap in the middle too . Have to use 24mm OD bearings with 18mm ID  for spacers with 2mm wall which leaves 14mm for the pivot bolt. Probably Koyo 18BM2416 which is what some Kawasakis use, its a full compliment roller, but there is also an IKO 18x24x16 that is a caged type too. Have not decided on which sort to use yet. . Its one of those s/arms that has a gap in the middle too. Would have preferred if i could use 14x 20 spacers as they re easy to get but it would mean going to a bigger than 24mm OD bearing which i don't want to do as it leaves the housing wall too thin like the 78 RM swingarms., so i got to get 14x18 hardened spacers made too If i cant get 14x20 suzuki ones ground down to 18mm OD. Got a 12 x 18 spacer from All Balls to test out but the guy i asked to drill it out to 14mm ID said it was too hard material wise.

[Momus]

Diverging slightly I reckon the best swingarm pivot arrangement is a sealed tapered roller in the frame either side. The SA construction and maintenance would be much easier and with the wider straddle a lot stronger. I think Suzuki may have used this method on some of their early works mx bikes. I am tempted to try it on my Pre 70 TS250. Penalty would be slightly increased bulk ànd perhaps weight.

[Frank M]

Taper roller bearings as swingarm bearings have the disadvantage that the bearing clearance must also be adjusted with the swingarm axle. When the bearing clearance is correctly set, the swingarm axle sits loosely in the frame and works out the frame bores. With a distance tube between the inner bearing shells in exactly the right length, the bearing clearance can be set to 0 and the swingarm axle can be tightened to required torque.

[LWC82PE]

BMW's have tapered roller bearings in the swing arms like you would use in steering heads.

[sleepy]

The swingarm Harely's used tapered rollers and we all know how well they handle.
If it's a repo or home made swingarm that is welded together after the pivot bores are machined the only choice is to use bronze bushes and line reem them to size.

[Frank M]

jepp, thats also my choise. Flanged bronze bushes and reaming to perfect size.

[Momus]

Taper roller bearings as swingarm bearings have the disadvantage that the bearing clearance must also be adjusted with the swingarm axle. When the bearing clearance is correctly set, the swingarm axle sits loosely in the frame and works out the frame bores. With a distance tube between the inner bearing shells in exactly the right length, the bearing clearance can be set to 0 and the swingarm axle can be tightened to required torque.

If you have the tapers in the swingarm there has to be a correct length crush
spacer between them that gives 002 to 004" of preload. Set up correctly like this, not like in a head stem, or like old school car front hub assembly, the pivot bolt can be done up full tight to give you as strong, or stronger, depending on diameters/sizes etc, assembly as a flanged bush or NR setup.

I'm not suggesting taper rollers in the arm itself on a dirt bike; pretty obvious that the required housing diameter immediately causes chain clearance issues. The bearings are housed in the frame, well sealed and protected and readily accesible for maintenance from either side with no more disassembly than removing the pivot bolt- or even a nut on either side if using a stud type of pivot. The swing arm itself is greatly simplified; the pivot bolt merely has to go through a hole in a glorified bush. This setup required that the frame has required stiffness but could result in a very satisfactory set up.