1973 Roadster swingarm

Previously Tony Ripley wrote:

Previously david_broadbent wrote:

In the midst of a major strip down of the back end of the old Norton and am in the process of removing the swing arm for rebushing. The book tells me that the front engine mount bolt is the correct size/thread to engage and thus remove the pinion. I t doesn't actually tell me what the thread is though? I vaguely recall 1/2" BSF from the dim and distant past. Can anyone confirm this thread size for me as I really dont want to dismantle the front engine mount as well as everything else I have going on at the moment! I would much make a dedicated threaded rod that also suits my slide hammer.

All advice greatly appreciated,

Dave

Hi Dave,

I may be looking at the wrong bolt but according to the andover norton site it is

BOLT 3/8" UNF x 4 1/8"

part-no: 06.3213

But if you look athttps://andover-norton.co.uk/en/shop-drawing/204/engine-mountings-head-steady-centre-stand

You should be able to confirm.

Regards

Tony

Tony,

thanks for the prompt response and the reference drawing. I think from that drawing, the bolt I am interested in is item 14, which is simply called Bolt - part number 06.0423. No thread size given. More helpfully though, the nut, item 16, quotes 1/2" UNF. Result!

Thanks again,

Dave

Thank you all for your advice - muc h appreciated. I was able to make a suitably threaded piece to attach to my slide hammer and now have the spindle in my hands.

I thought you might bew interested in the state of the spindle and particularly the bushes.

My decision to strip it all out was a marginal one as although there was play, I didn't think it excessive over the length of the swingarm - but look at the photos of the bushes! I have no idea how such deep scoring could have come about - unless it's as a result of the corrosion in the spindle? I know the bike had been stood for quite a few years following an accident prior to my buying it, which probably accounts for the corrosion?

Finally, somebody in the Roadholder mag years ago wrote about a mod to introduce a small tube into the swing arm - soldered in adjacent to the locking blot - to which a plastic pipe could be attached, run up under the seat and ever after topped up with the correct oil. The advantage of course is simplicity and also a sight glass of oil "content" in the bearings. Having got the thing apart with the intent of embodying this mod, I'm not sure how this oil would actually get to where it needs to be?

Any comments?

Yes, I had thought about that - brake bleed nipple through the endplate. It's pretty much set back from wandering boot theels so should be ok from that respect. It would mean that the "chamber " was never more than half full though - whereas the same bleed nipple, tapped in from above, would be much better able to keep the chamber full of the SAE140?

I attach another snap of rusted spindle.

Previously robert_percival wrote:

Previously ian_soady wrote:

Seems pretty well worn out to me....

If your plastic tube extended above the spindle level as you suggest then the head in it would keep the level within the spindle fairly high. In any case, the felt should help.

I have been trying, so far unsuccessfully, to achieve a tight dry iteration of the original elegant design and so avoid the complication of clamps etc tried elsewhere. see NYC Norton aftermarket offering for example.

Mechanisms to witness oil levels are redundant while oil leaks out. While there is oil to leak there will be oil to lubricate.

The quest to date...

Removed the Inner Primary and reamed the spindle tube for oversized spindle. ( With the Inner Primary off the Rear Engine Mount is more accessible for maintenance / upgrade.)

Polished cradle bearing faces / seal surface. Relieved cradle edges to avoid seals catching and getting cut on installation. ( Watch closely as the swing arm goes back in for pinching of the seals)

Rear Isolastic shims outside dust cover to eliminate any side clearance before fitting seals prior to final installation. Silicone to any potential location for oil leaks. If you are fettling this with the Inner Primary on then the LH End Cap needs to be fitted before the Swing Arm goes back in.

Trim a cone shape to a 1/4 UNF bolt to pickup the correct position for the spindle with a lock nut on your long 1/2 UNF spindle extractor / insertion bolt so you can rotate the spindle into position.

I marked the 1/4 UNF retaining bolt to be able to monitor that it doesn't start to vibrate off.

I laid the bike over, removed the nipple and put oil in with a syringe and tube to avoid pressurising the reservoir with the risk of blowing out the seals. Probably best to leave some space for air to expand and compress with changes of temperature.

This all stayed nice and dry for about 48 hours till I took the bike out for a ride..." A norton without oil leaks is a Norton without oil?" Don't you love them?

Next I will try tighter shimming and quad ring seals.

Robert, I can see you have put some real thought and effort into this - and certainly deserved a better result!

In my humble opinion I think the problem with the design is that as soon as the bike is ridden, the side loads from the swingarm will compress the O rings on one side of the arm, which relieves pressure at the other side and hey presto - a small leak. This is why your bike was leak free until you rode it. Multiply that by every bump and corner and the oil chamber will ultimately drain. To eliminate this would require a major redesign that doesn't leave it to an O ring to maintian the basic geometry of the suspension as well as preventing oil leaks! Alternatively - modify the bushes and swing arm to take grease nipples and just grease the thing! Think of all of those rear swing arm bushes on Mini's. I can't see there much of a difference in application - although access might be an issue - which is maybe why they went to oil in the first place??

To have done all you have and still not cracked the problem is disappointing - but no worse than your rear chain I suppose - It's just something you oil periodically. What you will have achieved is minimising the rate at which the oil leaks!

I think your point about not pressurising the oil chamber is a very valid one though - which is actually why I first considered the plastic tube sight glass/filler idea.

Finally, regarding the comment Ian made about felt washers - I think that only applies to later Commandos - there were certainly none on my Mk2A when I dismantled it?

Previously robert_percival wrote:

Previously ian_soady wrote:

Seems pretty well worn out to me....

If your plastic tube extended above the spindle level as you suggest then the head in it would keep the level within the spindle fairly high. In any case, the felt should help.

I have been trying, so far unsuccessfully, to achieve a tight dry iteration of the original elegant design and so avoid the complication of clamps etc tried elsewhere. see NYC Norton aftermarket offering for example.

Mechanisms to witness oil levels are redundant while oil leaks out. While there is oil to leak there will be oil to lubricate.

The quest to date...

Removed the Inner Primary and reamed the spindle tube for oversized spindle. ( With the Inner Primary off the Rear Engine Mount is more accessible for maintenance / upgrade.)

Polished cradle bearing faces / seal surface. Relieved cradle edges to avoid seals catching and getting cut on installation. ( Watch closely as the swing arm goes back in for pinching of the seals)

Rear Isolastic shims outside dust cover to eliminate any side clearance before fitting seals prior to final installation. Silicone to any potential location for oil leaks. If you are fettling this with the Inner Primary on then the LH End Cap needs to be fitted before the Swing Arm goes back in.

Trim a cone shape to a 1/4 UNF bolt to pickup the correct position for the spindle with a lock nut on your long 1/2 UNF spindle extractor / insertion bolt so you can rotate the spindle into position.

I marked the 1/4 UNF retaining bolt to be able to monitor that it doesn't start to vibrate off.

I laid the bike over, removed the nipple and put oil in with a syringe and tube to avoid pressurising the reservoir with the risk of blowing out the seals. Probably best to leave some space for air to expand and compress with changes of temperature.

This all stayed nice and dry for about 48 hours till I took the bike out for a ride..." A norton without oil leaks is a Norton without oil?" Don't you love them?

Next I will try tighter shimming and quad ring seals.

Robert,

what do you mean by quad ring seals? Sounds like a simple inprovement whilst I have the thing in bits. I also think the shimming is a great idea.

Dave

Thank you for that. I had never heard of quad rings but I'm all over them now!

I have just been talking to one of the main UK suppliers - Eastern Seals. Very helpful young lady. They needed the inner diam and the cross section. I've taken the o/d of the bush flange at 41.26 as the guide here. They can do a 41.28 or a 42.8. I have gone with the latter. They also do that diameter with a cross section of 3.53, which compares well with 3.46 diam, which was what I got from measuring the standard o ring.

The result is quad ring BS826.

Unfortunately they have none on the shelf so they need to get a quote from their supplier. I await the quote with some interest and let you know what they offer.

Dave

Just heard back from Eastern Seals. A pair of BS826 quad seals is - wait for it £29 plus VAT! The thick end of £18 each. However, for an order of 10 off, the price drops to £7.50 each. No idea what 100 off would cost!

Is there enough interest out there in the club membership to warrant putting my hand up for ten off?

Previously ronald_proctor wrote:

Previously Dave Broadbent wrote:

In the midst of a major strip down of the back end of the old Norton and am in the process of removing the swing arm for rebushing. The book tells me that the front engine mount bolt is the correct size/thread to engage and thus remove the pinion. I t doesn't actually tell me what the thread is though? I vaguely recall 1/2" BSF from the dim and distant past. Can anyone confirm this thread size for me as I really dont want to dismantle the front engine mount as well as everything else I have going on at the moment! I would much make a dedicated threaded rod that also suits my slide hammer.

All advice greatly appreciated,

Dave

I made a permanent oiler for the swingarm on my 71 Commando,by cutting the head off a 2" x 1/4 unf bolt,drilling it carefully 1/8" right through in a lathe and using a locknut ,screw it into the swingarm pin a few turns,then nip up the locknut. A small diameter clear plastic tube can then be pushed over the plain shank and secured in place with a small clip.The tube is run up under the seat ,cable tied in place and is then filled with SAE 140 oil- Slowly!!. The bushes will then never run dry,and the tube rarely need stopping up.I must get some of the quad ring seals, 'cos the only oil leak on the bike is the occasional drip from the swingarm!! You can't have everything!

Ronald,

I'm just at that point now and intend to follow a similar line - but how the hell do you drill/tap the swing arm spindle - or did you just utilise the original single anchor bolt?