Swingarm service

Headed for the "Kegler clamp" mod on my 74 850.
Looking at the bike and the group 15 parts plate, it occurs to me that after pulling the wheel and hub, I cd loosen the RH silencer clamp, pull off #9,the 3/4" iso stud nut 063598, the 2 #3 bolts 060858, and take the the whole sub-assy of muffler, z-plate, and foot rest away from the right side to open things up and get at the swingarm, save a lot of disassembly of the various components.
Anybody ever try this? Any reason it shd not work?
Too much nonsense to reassemble all those spacers and washers, maybe? It is pretty tight behind that support plate, I see.

One more thing: Can someone tell me the size and threadform for the central bolt 060327 that goes through the tube and into the top of the SA pivot spindle?
Going for that 1800's steampunk railroad look, I plan to replace that bolt with something like this:
http://www.ebay.com/itm/Gits-01450-Oil- ... SwdGFYp9Uw
Thanks in advance!

Mr. Rick said:

Can someone tell me the size and threadform for the central bolt 060327 that goes through the tube and into the top of the SA pivot spindle?

Click to expand...

1/4 UNF
https://andover-norton.co.uk/en/shop-de ... 7-06-8075-

Doesn't the '74 cradle swingarm tube have the 2 wedge bolts, rather than a single bolt swingarm tube??

I have a '70 model so I don't know if my bike is different than yours, but all I did was:

put the bike on the centerstand
remove the back wheel
undo the shocks to lower the swingarm to the ground to expose the swingarm tube from the rear of the bike
mount the premade clamps temporarily to mark the place where to drill the swingarm tube
Remove the clamps and drill the tube until I touched the axle, then remove the single axle bolt and remove the axle
Finish drilling and deburring the swingarm tube
grind 2 flat spots on the axle where the drill has marked them
reinstall the axle, install the clamps and tension their set screws
reinstall the wheel, shocks and stuff... done

The only issue I recall was the axle passes very close to the frame, so I used a tire iron to flex the cradle upward on the isolastic play to pull the axle clear of the frame

Doesn't the '74 cradle swingarm tube have the 2 wedge bolts

Click to expand...

No, it was added for the 850 MK3's, the MK2A's did get some MK3 parts but never seen the cotter pins on a MK2A until the aftermarket added them well after production finished to cradles with slots for adjustable gearbox position.

My April 74 mk2 does have the shorter MK3 bushings, welch plugs and oil wicks in its swing arm. So you should verify what your configuration is if you plan to replace these before you order - they may not match the Mk2 parts list.

When I built my 1970 Commando from a basket case in 1983, I was underwhelmed by the way the swingarm spindle was located in the tube. I devised a "pre-Kegler" modification to improve it. I got a toolmaker at my workplace to make a new spindle out of silver steel, with tapped holes to hold the spindle more securely.
Much later, I added a gravity fed oiling system. The hose goes up under the seat. It holds quite a bit of oil. ( too much, as I discovered)

Thanks you guys, for the feedback and info. Yes, mine has the old-style single 1/4 top bolt, hence the "need" for the Kegler mod.
MFB: I like that tube feed arrangement, not sure where you found that brass piece, or if you made it yourself?
If this bolt was larger than 1/4, my job wd be a Lot easier! Either way, I'm on my second try at making an adapter to take the 1/8 NPT from the cup oiler on top, to 1/4-28 for the bolt hole, using a pc of 1/2" brass hex bar and an ancient Shopsmith. I've end-bored a small (2mm, .079) pilot hole through the hex (not easy to start and keep it centered!).
The 1/8 npt tapping (bored first to 11/32") went off center but worked okay, but my first piece failed on the last step as I finished threading the 1/4 UNF. It was weak because my pilot was too large and off center. I have to keep the pilot as small as possible for strength , but large enough to pass that 85/140 oil.
So here's a question for those machinist types who (unlike me) actually know what their drill bits do in brass: How big a step can I take with successively larger bits, and still keep the hole centered?
Or is this even possible?

How big a step can I take with successively larger bits, and still keep the hole centered?

Click to expand...

The pilot hole must be bigger than the chisel point on the next larger drill, that means the larger drill is cutting only on the taper and so self centralises. Always use new drills in case the resharpening has created an off centre taper.

I've always found mcmaster carr to be a good resource. I found this adaptor in 1/4 x 28tpi, but it might be a little too short to get many turns in the axle hole.

https://www.mcmaster.com/#2684k33/=19anpum



then you can add this adaptor linked below to attach the cup to the first adaptor.. (pictured below)

https://www.mcmaster.com/#2684k19/=19anwns



it's all stainless, so it's stronger than brass fittings. The only real issue I can see is the first adaptor's 1/4 x 28tpi is kind of short... but since you are now carrying the force on the axle with the new clamps and set screws, maybe it will work... HTH

*I'm going to do a better search for a hollow stainless stud in 1/4 x 28tpi. I like the idea of gravity fed oiling though the old swing arm bolt hole.

Mr. Rick said:

not sure where you found that brass piece, or if you made it yourself?

Click to expand...

Yes I made it out of a piece of hex bar.

I hit on gravity feed for the swinging arm pivot too, sort of by accident. Trying to pump oil through the oil nipple on the end always made a mess, and I was never even sure that any oil got in there. The manual calls for 'sufficient to fill the cavity every 5,000 miles'. There was no way I was ever achieving that, and how much is that anyway?! I'd appreciate an answer to that btw, if anyone knows! So I took the ball and spring out of the nipple and lockwired on a length of hose that goes up and over the top frame tube so the end hangs down, under the saddle, with a bit of foam in the end to keep out muck etc. I use a syringe to put maybe 20ml of oil in the hose every now and then. But I learned straight off that it wasn't worth putting very much in, as it just leaked out. This was very soon after I had the Mk3 upgrade done so I thought, well, that's it then. And so it seems. No problems yet. Just thought I'd pass it on.

nortonmkiia850: That sounds rather ingenious. Sorry, no idea how much is the required amount of oil...

kommando: Thanks for the advice. I think I can see what you're talking about, although if the pilot hole is bigger, I'm not sure how much enlargement cd take place?

oOnorton Oo: Thanks for taking so much time to provide the McMaster references. I agree that the 1/4" engagement length is too little. By the time we get 2 adapters and the oil cup attached, there wd be a good deal of leverage on that short stem, and given the amount of shaking going on, I fear it wd snap off, leaving an extractor job in an awkward place.
I've now decided that the 1/4 bolt hole is just too small for this job. Minor dia for external 1/4-28 is about 0.206, and min dia to pass the oil is on the order of .09"
Subtract one from the other and divide by 2, we get (best case and perfect machining)a wall thickness of about .058, too thin in my opinion.
I'm either gonna scrap the project altogether, or drill & re-tap the tube/spindle to 5/16-24, or maybe 1/16 npt, the latter of which I can find a ready-made adapter for.
Thanks again!

I did a similar mod, removed the centre of the grease/oil nipple and fitted a piece of plastic tube that runs up next to the oil tank filler (1970 Fastback) there is no dipstick on the fastback, well not on mine so my home made dipstick lives in the plastic tube and doesn't get a wipe before it is stowed. So the residue oil finds it's way to somewhere useful.

Here's a little follow up:
This is my first attempt to post pictures, so forgive me if I get it wrong...

I enlarged the top hole in the pivot tube after removing and tapping the spindle 5/6-24 to take the (2nd) adapter which I made to accept the 1/8" NPT cup oiler.
I gotta say, this whole effort was something of a fool's errand. I embarked on this because the lube had to be added too often, and that was because I could not seem to seal up the tube. Now that I have (or think I have) succeeded in sealing it up, an ordinary bolt wd have been sufficient. But it looks cool, right? :roll:


Here's the machine, almost as old as I am, used to "machine" the adapter from 1/2 hex bar.


Here is the NYC Norton version of the Kegler clamps installed. It was necessary to make some longer (7/8") set screws (parts supplied are just under 3/4 long) and it was easier to tighten the locknuts using "socket head" bolts, rather than the hex-head pcs supplied with the kit. Also, if you are working (as I am) with a spindle that has flats, the inside edge of the RH clamp has to relieved on the back side to clear the oil line from the filter (if you have one). If I had it to do again, I'd have tapped the tube 1/4-28, instead of just drilling through. Also, IMO, there is no good reason to try and do this (drilling or tappiing the tube) without removing the SA and the spiindle.


Here is a little drilling jig I made to help me get the proper spacing before drilling the tube. 3.33" wide and relieved on the inside edges to stay off the welds. Holes are 1" (+/- 0.1") off center, (2" apart) to permit the set screws to land in the flats on the spindle. And if you have the flats, ya hafta drill at the "9:00" position, of course. The tube is pretty close to 1.125" OD, so the holes are 9/16" from the inside edge of the jig.


So I had some fun, got the result I wanted, and learned something: use grease and not oil, to lube up the spindle as you re-insert it. Mine is very tight and must be slide-hammered out.

Grease is bad for the bronze bushes - it plugs up the pores.

Grease is bad for the bronze bushes - it plugs up the pores.

Hey Thanks! So much I don't know...