Topic: Understanding swingarms

[HondaMan]

Sometimes, the terms and names for the swingarm parts become confused. This is because of guys like me, who have worked on lots more than just Hondas, and the terms I came to use from working with other machines besides motorcycles. (Sorry    )  So, to help fix up the issue, here's a picture and some descriptors. Double-click the picture to make it bigger.

In the pivoting area, Honda calls the pivot journal a "Collar". That's #10 here.
In the bearing area, Honda calls the bearings a "bush, RR swingarm". That's #7 here.
In the grease seal area, Honda calls the seal a "Ring". That's #12 here.
On the ends of the pivoting assembly, Honda calls the end cap a "bush" again: #8 here.
Inside the frame, Honda calls the dust cap washers "Dust Cap Seal", #11 here.

Most generic machine terms for these are (and can be found in catalogs like McMaster-Carr, Grainger, etc., industry standards):
"Collar" = Pivot Shaft.
"Bush" = Bearing or Bushing.
"Ring" = Felt Seal or Felt Washer.
"Bush" (on the ends) = End Cap or Seal Retainer.
"Dust Cap Seal" = Cupped Washer or Dust Cover.

The bushings (#7) in this picture must be inserted into the swingarm's tube until they are recessed by the same distance as the stackup of the (End Cap #8 + Felt Washer #12). This distance varies from one bike to the next, as Honda's parts were all over in tolerances here (still are). Typical setback to the end of the bushing inside is in the range of .210"-.250". Too much setback causes poor sealing, end cap stress, and faster wear: too little causes broken end caps and destroyed felt washers. Either one of these will make for poor handling on the bike.

Hope this helps!

[coyotecowboy]

Thanks for the tips!!!

Here's a swingarm-related question;  Are those cute (but totally useless) Japan spec grease zirks pressed into the ends of the pivot bolt, or are they threaded?  I havent popped mine out yet, but they look to be pressed in to me

[754]

Pretty sure they push in, you may have to drill them to tap to  regular zerks..

[HondaMan]

The "K" models used push-in ones (that often fell out!), and the later ones had little ribs on them, if on the big bolt. The ones in the middle of the arm's pivot all thread in.

I have replaced the Japanese ones with both push-in, ribbed brass fittings, and installed threads (1/4-28) and threaded in "real" ones. I much prefer the threaded ones, especially with power grease guns.

[bubbafun101]

I dont mean to hijack this thread, but since we are on the subject.... I read from time to time questions about fitting a longer swing arn to our beloved bike. Usually the swing arm from a Dohc. I dont need you to explains why they do. Got that figured out since I suffer from the same. But rather what is the "ring" advantage to this longer swing arm?? Is it high speed stability? Ability to run a wider variety of rims? I have just never read a reason for the longer arm.

[754]

You can usually get off the line quicker... no wheelie..less ticket, plus you dont win drag races by backing off the throttle to control a wheelie...

A bit more stabilty at speed as well.

[dusterdude]

also you can put in a bigger tire to help you get off the line quickly.

[ceruzziracing]

I'm in the process of rebuilding mine right now. Found the needle bearing setup from old bike barn, what's the thoughts about that setup? Sounds to me like an improvement----should I be looking at this setup since the bike will be seeing some track time? Thanks in advance. FWIW, I'm having to grind out the factory steel bushings. Was unable to get them out with a drift and small sledge...

[Terry in Australia]

I wouldn't use the steel needle roller bearing kits, they are easily damaged, and extremely prone to rust, so one trip to the pressure washer can kill them dead. I converted a neighbors RM250 Motocross bike's swingarm and suspension linkages to bronze a few years ago after he nearly fainted, when he found out what the needle roller replacements cost.

I installed a new old stock needle roller kit in my F2 because I had it for years (it came with a heap of parts I got with 2 bikes I bought in 1999) and I couldn't be bothered machining up a pair of bronze bushes at the time, but otherwise, I really wouldn't have bothered. One of the "frame tuning" tips of the 1970's for the Suzuki GS750 was to dump the needle rollers and replace them with bronze bushes. Cheers, Terry.

[ceruzziracing]

Am I correct in thinking that if you use the bronze bushings, you eliminate the felt rings? Also, do you still retain the "dust cover" or does the total assembly then just consist of the pivot shaft and bronze bushings?

[754]

Pressure washers are not your bikes friend..

[HondaMan]

Am I correct in thinking that if you use the bronze bushings, you eliminate the felt rings? Also, do you still retain the "dust cover" or does the total assembly then just consist of the pivot shaft and bronze bushings?

For best results, the felt washers must be retained, if they were there. On the K6-later frames, the bushings were a "Top Hat" flanged design, as Honda cheapened the parts. These often freeze up with rusted pivot collars, since water finds its way easily into this seal-less design unless greasing becomes a religion. The dust caps are missing on this later design, requiring a bead of grease around the inside of the cupped washers to make a "seal" against water. Doesn't work as well. If your bike is this later design, I recommend cutting grease-spreading grooves across the bearing surfaces of the pivot collar so grease can find its way out there and make the seal: I do this on rebuilds of these types of arms.

[Terry in Australia]

What about O rings Mark? or would they trap water?

[HondaMan]

What about O rings Mark? or would they trap water?

They probably would: they'd have to have these dimensions for an SOHC4 bike:

1.044" OD x 0.845" ID x 0.060" thick, rectangular cross-section.

The ID could go as high as 0.850", but not smaller with the 1.044" OD, or;
the OD could go to 1.032" with and ID of 0.842 to 0.835".
This is due to the ring needing to rotate if the ID is less than the pivot collar diameter, or the clearance FROM the pivot collar if the OD is larger than the ID of the tube. Either way, though, it will be a less-effective seal than grease-impregnated felt or wool in this particular design.

[mustangcar]

Am I correct in thinking that if you use the bronze bushings, you eliminate the felt rings? Also, do you still retain the "dust cover" or does the total assembly then just consist of the pivot shaft and bronze bushings?

For best results, the felt washers must be retained, if they were there. On the K6-later frames, the bushings were a "Top Hat" flanged design, as Honda cheapened the parts. These often freeze up with rusted pivot collars, since water finds its way easily into this seal-less design unless greasing becomes a religion. The dust caps are missing on this later design, requiring a bead of grease around the inside of the cupped washers to make a "seal" against water. Doesn't work as well. If your bike is this later design, I recommend cutting grease-spreading grooves across the bearing surfaces of the pivot collar so grease can find its way out there and make the seal: I do this on rebuilds of these types of arms.

i removed the swingarm on my 78k removed the cupped washers ,now i see some pressed in caps that look like phenolic/plastic how do i remove them?,they seam to chip if i try to pry them off,tried to pump grease in the center grease zerk like crazy but grease won't come out at ends ???is the center collar shaft suppose to rotate? cause mine seems seized, i want to make sure its not rusty inside thanks for any replies

[HondaMan]

Am I correct in thinking that if you use the bronze bushings, you eliminate the felt rings? Also, do you still retain the "dust cover" or does the total assembly then just consist of the pivot shaft and bronze bushings?

For best results, the felt washers must be retained, if they were there. On the K6-later frames, the bushings were a "Top Hat" flanged design, as Honda cheapened the parts. These often freeze up with rusted pivot collars, since water finds its way easily into this seal-less design unless greasing becomes a religion. The dust caps are missing on this later design, requiring a bead of grease around the inside of the cupped washers to make a "seal" against water. Doesn't work as well. If your bike is this later design, I recommend cutting grease-spreading grooves across the bearing surfaces of the pivot collar so grease can find its way out there and make the seal: I do this on rebuilds of these types of arms.

i removed the swingarm on my 78k removed the cupped washers ,now i see some pressed in caps that look like phenolic/plastic how do i remove them?,they seam to chip if i try to pry them off,tried to pump grease in the center grease zerk like crazy but grease won't come out at ends ???is the center collar shaft suppose to rotate? cause mine seems seized, i want to make sure its not rusty inside thanks for any replies

Uh, oh...yours is suffering from the "seized F design" problem. The single zerk in the center of the swingarm never would grease the outer halves of the bushing surfaces. This makes them seize, which then beats up the bushings.

You might try this: soak penetrating oil into one end of the holes by setting the arm up on one side overnite. Then, do it again, from the other side. Then insert a (sacrificial) 3/8" rachet extension into the hole, and beat it out. You might find the bushing comes out with the pivot collar, while it flattens the 3/8" extension's head. You'll also find the grease pathways plugged with a gritty combination of ground-off phenolic bushing and dried out grease, which makes an effective epoxy. That's what kills this design.

You can change the design to the better "K" type: see above.

[mustangcar]

Thanks Hondaman,i did manage to pound out the collar last night,boy was it tough to get it out,messed up one of the outer bushing ends,will have to get the bushings out,maybe  using an expanding concrete bolt then tap from opposite side, i had read some time ago these type bolts are helpful in removing bearings, i tried tapping with screwdriver but they are just too skinny to catch,was thinking about replacing them with the bronze afterrmarket from oldbikebarn.com,,,i will try to replace with earlier design someday,

[HondaMan]

Thanks Hondaman,i did manage to pound out the collar last night,boy was it tough to get it out,messed up one of the outer bushing ends,will have to get the bushings out,maybe  using an expanding concrete bolt then tap from opposite side, i had read some time ago these type bolts are helpful in removing bearings, i tried tapping with screwdriver but they are just too skinny to catch,was thinking about replacing them with the bronze afterrmarket from oldbikebarn.com,,,i will try to replace with earlier design someday,

I haven't thought of that removal tool: I'll have to try it. Thanks for the tip!