Swing arm lubricant

I am rebuilding a 1971 Commando Roadster. Apparently a PO had filled the swing arm cavity with grease. I understand the recommendation is to fill the swing arm with heavyweight gear oil, but I'm worried about the effect of gear oil on the rubber O-ring seals. Has anyone tried a lighter oil like ATF? ...although I can guess about the warning on leaks. Dana

As near as I can make out, the sintered bronze bushes need to soak up some lube and then give it back when needed. The O-rings are really more to keep dirt and dust out. When you look at a parts list they are called dust covers until 1975 when they changed some of the components and they became oil seals in the process. My bike came with Mk3 style "oil seals" and I was not highly impressed. So I guess the point of this ramble is that you use something in there that works well with the bronze bushes, so lighter oil probably isn't going to provide what you want.

Russ

I use 140 weight oil .
I have drilled out the centre of the spindle locating bolt, added an extended length grease nipple with the centre ball and spring removed(drill out) secure a Tygon tube over this grease nipple and secured, run the tubing up the left inside frame tube to under the seat and filled the tube with 140 oil. (I use an old plastic syringe)
This way there is a constant supply and the yellow tubing allows you to check the oil level from time to time. The open end is secured with a zip tie on the breather tube running back to the oil tank. (I tie this tight to partially block the open end )
Just a matter of topping up here if necessary.
What I have found it leaks down to a nominal level, once the bronze bushes are staturated the leak down stops.
Regards Mike

I use 140wt oil also, installed with a grease gun through the fitting on the side of the SA. BUT be careful with a grease gun, it can apply enough pressure to blow the opposite side cap right off the swing arm, stripping the long thin "bolt" and blasting oil all over the place. It should not be necessary to explain how I learned this!

Loosen the centre bolt and turn the grease fitting to the top.Take the grease fitting out and with the bike on the sidestand use an oil gun and put 140 wt oil in until it it filled and overflowing and then put the grease fitting back in.Saves using a greasegun and then putting pressure on the small centre shaft and breaking it.Guess how I know about that.Goes back to my new 71 commando,8 commandos ago.
Bruce Chessell

As for O-rings presumably even pedants understand that an o-ring is an o-ring regardless of composition? And synthetics can easily be degraded when exposed to certain petroleum products. More to the point is mike996's comment. I thought the idea of the small central bolt which locates the swing arm spindle in the engine mount/carrier was additionally to provide an 'overflow' indicator upon removal of the bolt to determine when the reservoir is full when filling via the grease nipple? Dana Twin

ATF will leak right back out very quickly and I can see no advantage to use something that thin. I use 80W90 gear oil and Bruce Chessell's method and it mostly stays in there. I shoot a bunch in at the start of every season with a large syringe hooked to a length of Tygon tubing. A few squirts is all you need. You don't need a lot of oil to keep the bushes lubricated.

manxmangp said:

As for O-rings presumably even pedants understand that an o-ring is an o-ring regardless of composition? And synthetics can easily be degraded when exposed to certain petroleum products.

Click to expand...

Can think of literally billions of o-rings exposed to petroleum products - oils and greases, etc - if it caused rapid deterioration, someone would have noticed by now ??
They were developed for that application....
Get real.

Fuels, solvents and brake fluids may be a different issue.

"I thought the idea of the small central bolt which locates the swing arm spindle in the engine mount/carrier was additionally to provide an 'overflow' indicator upon removal of the bolt to determine when the reservoir is full when filling via the grease "

I don't know if it was designed with that thought (overflow) in mind but when I blew out the caps, I had removed that bolt. I was too energetic with the gun, expecting to see oil coming up out of that hole but the tiny passages in the swing arm shaft couldn't flow the 140 oil fast enough to relieve the pressure before popping the caps.

I have to say that since replacing the orings/caps/long, thin screw after that experience and refilling with 140 (carefully!) I have had no leakage at all from the swing arm. At most you can collect a faint smear or oil if you run a finger around the bottom half of the fitting.

Hmm...in the old days I had an original 71 back when they made then and the standard saying with Commandos was, "If it's not leaking oil, it's out of oil!" Maybe I'd better check that swing arm!

Funny, I always thought the center bolt was to fix the spindle in place. I do find it handy for adding oil, as I remove the nipple from the end cap and then inject oil into the center bolt hole until it comes out the end!

FWIW, Jewell Amber Oil has come highly recommended for swingarms. I have a tube here but I have not "topped" up the bike with it as I have been thinking I would like to pull the swingarm and clean it first. So I have no report on its effectiveness.

Russ

The only issue I can think of by just adding oil via the spindle cover is it may not cover the top of spindle which can then rust up where most the load wear occurs. If Norton intended to add oil via the center trap bolt why would the cheap ass factory bother to add an oil zerk in spindle cover? As reported the spindle oil holes don't allow much oil flow to fill up from below to cover over spindle top. If I was to re-do Peel's center bolt tube reservoir I'd stuff the tube full of cotton to stifle the oil flow to slow wicking action as very very few of us can get factory set up to really seal messy dripping flow through.

I use STP oil treatment. It is about the right weight and seems to stay in the right place. Quad O-rings help keep it all in place.
Mike

STP and Lucas oil treatment are dang close in thickness but not nearly as thick as oil some special assembly oils that won't drip off a knife blade in summer for like 12 hrs vertical. I thought it was grease till set straight by engine shop that gave me some. Still leaked out new Al indexed cradle with perfect condition 850 swing arm and new bushes - oil rings >just hanging still from rafters over cold oil thickening winter season. I thought I was going to be able snear at those with mere 190 grade oil honey drool, but ugh just meaner cement mess to clean up before working to finish past Peel project. Gave up and became a greaser convert modifier.



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STP (or anything else that thick) is extremely heavy for this application. I doubt it would move through those tiny spindle holes at all.

140 gear oil viscosity is 460 cSt at 40 degrees C; STP Viscosity at the same temp is 5200-6340 cSt, over 10 times thicker.

Duh the bushes pores holding oil is the lube principle here not oil bath and STP is not nearly thick enough to not flow through the tiny even partially rust clogged spindle holes too fast over time not to still check in seasonally or so to keep top of spindle rust free. The thicker the oil up to real grease the better the set up works long term. I now see this area as mainly needed oil to prevent rust and flush grit out more than friction wear protection.

"I now see this area as mainly needed oil to prevent rust and flush grit out more than friction wear protection."

I don't agree - sorry.

Bushings use oil, not grease for lubricant. STP/Assembly lube/grease are the wrong lubricant for the application. None of them will flow/absorb into the brass/bronze in the proper manner. Any oil is better, regardless of weight. Obviously the thinner oils are more prone to leak but if the seals/and sealing surfaces, including the small washer for the retaining screw are in good condition, very little leakage will result.

Its really about a total non issue of what ever lube you can keep in wet-ish in spaces between top offs. Your corrective attitude-advice is a tad mislead on this swing arm application as if these bushes needed as much oil in them as if they was a spinning shaft application rather than tractor implement like rocking grinding loading with nil heat to carry off nor any oil wedge to surf on. One can only get away with grease if the area is modifed for it so not just clogging the spindle tiny holes if fed from side plate zerk. Vintage British shop tools includes an hand push oil gun that looks like small grease tube gun but pumps oil not grease through zerk. I sold mine off when I became a greaser.

Veteran British motorcycle hand operated reproduction oil pump BSA Triumph Norton Matchless Ajs Ariel Royal Enfield [Norton not listed so takes ya chances]

"advice is a tad mislead on this swing arm application as if these bushes needed as much oil in them as if they was a spinning shaft application "

I completely agree with you on that. But my concern is that those thicker lubes will not manage to get where they need to be with out some sort of forced "injection" capability and even at that there is no way to really tell if the lubricant got to where it needs to go. Oil will definitely migrate to the bushing surface without any problem...other than potential leakage.

Swing arm spindle protection is one of my sore-est sorriest subjects having had two now that were essentially impossible to remove w/o destructive measures swing arms simply can not survive. The spindle lives kind of tipped in the bushes so opposite faces of spindle wear into ~1/3rd around lips that can't be turned to clear both at once or even one at a time. The other thing is dry spindle area rusts with both acts like some grit but mostly swells up crumble then piles up trying to extract spinde that may still spin freely in its bore and bushes. From what I've seen the rust hazard dissolving hardened surface is way more the wear worry than actual friction rubbing is but rust rubs off rather easy don't I know. I can't fault an oil bath as would be best practice spun or rocked - as long as the frame-floor stains don't bother ya and ya can stay ahead of spindle non bush areas drying out.

Funny hobot maintenance lesson that flys in face of civilized reasoning, Trixie's chain side swing arm zerk clears chain flop as long as I stay ahead of sloppy tension til new chain installed so can skip a 1000 miles+ before checking but inhaled grit wore rings out for blow by that oiled chain before I got to rings and dang chain collected grit and wore out so loose it snatched the zerk out of its hole. But I'd pumped it two times to over flow grease so good to go a few seasons till sticking another zerk in but removing it this time and just tape or set screw the hole from grime. Chain must strike it off center to spin out as prior lost one didn't injure threads. Pure luck out by eye ball measures on drilling/tapping. If i did a grease job again I'd open up and add some more spindle shaft holes, more so at far DS end and feed grease in the old taboo way so no exposed swing arm bush zerks needed. Maybe melted wax would stick around.