Swing arm question

Hi all
As part of my rebuild I plan a modification plate being welded the rear vertical face of the swing arm cross tube, this will be drilled & taped both sides with bolts positioned against the swing arm spindle.
So is that stupid 1/4 bolt in the centre still needed, as I'd like to construct an oiling tube/ dispenser into it??

Better not weld a plate to the swing arm cross tube. Instead use a set of Kegler clamps: strong durable all around spindle support and easy to fit. Top centre bolt can indeed then be used for an oil tube/dispenser.

What Nortonspeed said!

The Mk3 spindle doesn't have the center bolt.

http://www.oldbritts.com/1975_g16.html

This might be one of the Mk3 feature worth adding to an earlier bike, but it means modifying the cradle to accept those wedge bolt things. One could put Kegler Clamps at the locations for the wedges and tighten down the bolts onto the flats. This has been done and documented by members here.

Notice that the Mk3 does not have provisions for adding oil. This is because they did a better job of sealing it up and added felt wicks to hold the oil where it could do some good. There has been a fair amount of effort by various people adding oilers to this pivot point. I think it is overkill. When I got my Mk2, it had sat in one place for 35 years and was sunk up to its axles in mud. Basically everything on it was seized, except the swingarm, which came from the factory with the Mk3 style felts and seals, was in perfect condition. I found this interesting. When I reassembled it, I used those same types of felts and seals and used Amber Oil per a recommendation here. I guess in another 35 years I will find out if it held up.

I'm not sure what the current attitude is toward the needle bearing upgrade, but I might consider it if I was worried about this pivot. There is a lot of info on here about what various people have done to upgrade the swingarm tube on the cradle. Be careful welding stuff on to it as there isn't a lot of room and warping it would do more harm than good.

Russ

Many years ago I converted my gearbox cradle to the MK3 spec this has worked perfectly for many miles I'm not convinced needle rollers are necessary cheers

I realize that needle bearings are often used for this function but it is not an optimum use of needle bearings due to the very limited travel which tends to flat-spot them over time to some extent. Needle bearings are designed to roll, not to rock back and forth a few degrees. Oilite bronze bushings seem TO ME to be a much better choice for a swingarm. OTOH, if the needles are small enough diameter-wise and top quality, I suppose their life is probably beyond the average buyer's use/mileage on the bike before they sell or trade it.

I 3rd - recoil off welding or serious heating of small areas of swing arm unless robust jigged then heat stress relieved or may have a hot hell of a time with cradle, spindle and axle fitting. Its not great idea to weld nuts on either as weakens the thin tube the tiny nuts bare lots of load on to distort and make removal more hell, especially if area corroded by tire grit blast so threads fussed and nut edges crumbling or ugh head shears off...

Originals clamps were blued steel, which need long term watch. Use SS here and forgetaboutit. Think anti-seeze not loctite or re-read above.

olympus said:

Hi all
As part of my rebuild I plan a modification plate being welded the rear vertical face of the swing arm cross tube, this will be drilled & taped both sides with bolts positioned against the swing arm spindle.
So is that stupid 1/4 bolt in the centre still needed, as I'd like to construct an oiling tube/ dispenser into it??

Click to expand...

If you put two well placed flats (grind or mill) on the spindle for your push bolts, then, no, you can do away with the locating bolt.
No drama welding, just use a spreader bar at the axle area (original width +.060") before welding.

So is that stupid 1/4 bolt in the centre still needed,

The stupid bolt is in place to be removed to pour some oil in there to lube the swing arm bushings

if it goes in far enough it can make contact with the spindle to sort of stop it from rotating if it feels like it

On the right side of the swing arm, I remove the little threaded quasi grease thing and use a syringe to inject two cc's of oil annually

The way was designed was to inject oil in the zerk in one of the cover plates but looks so much like a grease zerk and grease makes more sense there any way, but spindle holes very small to slow oil weep, grease clogged, bushes grind dry and slack develops. So slow motion over short range only needs residual oil in bush texture not a bath. So realize if providing over head oil feed reservoir it will leak out at faster rate than when half empty leaked out, which makes as much or more mess than reason no one retains functional chain oiler, so must 1st get both ends sealed, which then eliminates need for reservoir so factory ease makes sense again. Oil injectors were traditionally the rear plunger type not lever arm or finger trigger, which would work too.

I put grease zerks in Peel spindle after closing spindle holes and grooving bushes, worked a treat but discovered chain will snatch bottom zerk out on rough surfaces/leaps/landings. Work around was grease up then remove zerk leaving a grease plug. Now I just slather Cornhead grease in and forgetaboutit.

Here's a link for graphite-impregnated bushings https://quakercitymotorworks.com/norton-swing-arm-bush/. No worries about grease/oil after that. Add the Kegler clamps like Russ suggested; they do help tighten-up the rear end.

Nathan

Totally agree re swingarm clamps - one of the best things you can do for the bike! I've never used graphite bushings but after reading the link and doing some additional research, I'd definitely use them if/when it became time for new bushings. OTOH, I installed new Oillites/swingarm clamps in '08 and there is still absolutely no play so I suspect the bike will never need it's bushings renewed, at least by me!

The bushings simply don't wear. The support spindle tube sure does. Crush the tube to the spindle or use locator bolts or whatever to secure it. Thick Oil, never grease. Enjoy.

Torontonian said:

The bushings simply don't wear. The support spindle tube sure does. Crush the tube to the spindle or use locator bolts or whatever to secure it. Thick Oil, never grease. Enjoy.

Click to expand...

Yes to the above. On the pre-Mk3, you can have brand new spindle, bushings, swingarm, and the whole business can still wallow around if (when) the tube gets egged out, which is what I found on my bike. Had to ream the tube (and bushings) and fit an oversize spindle. According to Phil Radford, not uncommon at all.
Now I have the NYC Norton Kegler clamps, shd be good for life.
IMO, that tube shd have been 2 or 3 times as thick and hardened somehow.

Thanks Gents some great ideas flowing here... sorry I have a couple more questions
Looking at the AN swing arm spindle it has two flats milled into it... I have to assume these are for Kegler or similar clamps to be fitted.... The site shows a extra gusseted swing arm but makes no reference to modifying your existing arm or where to purchase Kegler or similar clamps??

Does any one have the site where Kegler clamps can be obtained please??

Appreciate a lot has changed in the 50 years since my 72 Mk 4 was built, but what is the thought process in not using grease to lube the swing arm bushes then ...... or now??

Thank you

olympus said:

Looking at the AN swing arm spindle it has two flats milled into it... I have to assume these are for Kegler or similar clamps to be fitted....

Click to expand...

Originally, the flats were machined in the shorter Mk3 spindles to accept the Mk3 cotter pins (no central bolt, see link, below).

https://andover-norton.co.uk/en/shop-drawing/137/swinging-arm-suspension-units-chainguard#


Current production 'long' spindles have the hole for the original pre-Mk3 cradle and flats to suit the AN 'cotter pin' conversion cradle for pre-Mk3 models.

https://andover-norton.co.uk/en/shop-details/16872

The current 'short' Mk3 spindle also has the bolt hole as it then fits the late Mk2/2A cradle with the 'sealed' pivot as well as the Mk3 'cotter pin' cradle.

http://www.britishmotorcycleparts.c...arm/06-4699-swing-arm-spindle-850-mk3-06-5053

When I built my basket case 750 in 1983, I was underwhelmed by the way the spindle was located. At the age of 30, this was my first bike restoration job. I dreamed up a way of improving it as shown in the photo. I doubt that the Kegler clamps had been invented at that time, not that I would have known about them anyway. The bolts don't push on the spindle, they are threaded into it. I had the spindle made up out of silver steel by a toolmaker at my workplace. A few years ago I tore the bike down to do a few upgrades, including adding an oiling tube where the old 1/4" bolt used to be.

I always have the swingarm spindle hard chromed. I also add a small tube to fill with gear oil in place of the zerk. Never see any wear, although I agree the support of that area is lacking. MFB, that looks like a nice rigid addition.

NYC Norton has the clamps. Alloy w SS fasteners.
Broken link removed
Their instructions don't tell you to remove the spindle, as I recall, but IMO, that wd be mandatory to clear any swarf from having drillled the tube.

And "bill" on this forum (signs his posts "Windy") makes and sells them himself.
In response to my inquiry last June, he sent me this:
the ones i do are carbon steel at $50.00 including post in the US. I might be talked in to doing a set in stainless at an increase in cost to be determined.also it is hard to work with stainless. there is no need as you all but cant see them.

https://www.ruland.com/SP-17-F.html...ource=yotpo&utm_medium=email&utm_campaign=map
me, I put this