Is a 1 3/8 gearbox/swingarm spindle tube normal?

Hi all,
big thanks to everyone who posts articles on this site as its helped me heaps. I'm about a year in on a rebuild of an 850 commando I inherited off my dad. The bike was in a bunch of tool boxes and seems to be a mix of at least two different bikes. Anyhow, most of the prep work is done and I was just fitting the swing arm to the gearbox cradle and I noticed there is no screw hole to locate/hold the spindle in place. The OD of the spindle tube also measures in at 35.16mm which I think might be 1 3/8" if you took the powder coat off. Can someone help me out and tell me if this is perhaps a modified cradle or one off an earlier model Norton? from what I understand the tube the spindle goes through should be 1 1/8 od? The swing arm I have seems to be the welch plug type but the spindle I have has no flats on it and I think is the longer version (just shy of 7 inch). I was going to buy a swing arm service kit from RGM and some of those split clamps from NYC but I don't think the clamps will fit (ive emailed NYC and I will await their answer). I figure what I may have to do if the split clamps wont fit is buy the RGM kit, remove the cradle drill and tap a central hole for the spindle drill holes for the spindle flats, weld nuts on and put some bolts through, I'm not real flash with a welder though and i'm a bit hesitant to do this. Any info from the collective wisdom of the forum would be great, sorry if the explanation is a bit vague, thanks.
p.s i have tried to upload some images to illustrate my explanation but cant seem to make it work

Re: Is a 1 3/8 gearbox/swingarm spindle bore normal?

morton said:

p.s i have tried to upload some images to illustrate my explanation but cant seem to make it work

Click to expand...

You need to first load the pics on one of the many free photo hosting sites - photobucket, flickr etc
and then post the links here, using the img button (above).

I have no memory whatsoever of what size the pin is, will watch with interest.

Re: Is a 1 3/8 gearbox/swingarm spindle bore normal?

Thanks Rohan,
Hopefully this works, the first two links are photos of the swing arm spindle tube in question. The second two if anyone's interested are my bike when i first got it and where I am now with the build (until I pull it all apart again to fix the swing arm situation).



http://i1126.photobucket.com/albums/l60 ... 2ffvjk.jpg

http://s1126.photobucket.com/user/morto ... m.jpg.html

http://s1126.photobucket.com/user/morto ... i.jpg.html

http://s1126.photobucket.com/user/morto ... y.jpg.html

Re: Is a 1 3/8 gearbox/swingarm spindle bore normal?

morton said:

Thanks Rohan,
Hopefully this works, the first two links are photos of the swing arm spindle tube in question. The second two if anyone's interested are my bike when i first got it and where I am now with the build (until I pull it all apart again to fix the swing arm situation).

Click to expand...

Added image tags to your link, but can't even find the last three shots. You need to copy-and-paste the image address (URL) to get the image on your post.

This photo may also be useful, if anyone can help with the identification. The swing arm spindle tube seems to be welded while the isolastic tube is brazed, not sure if this means anything?

http://s1126.photobucket.com/user/morto ... sort=3&o=4

morton said:

This photo may also be useful, if anyone can help with the identification. The swing arm spindle tube seems to be welded while the isolastic tube is brazed, not sure if this means anything?

http://s1126.photobucket.com/user/morto ... sort=3&o=4

Click to expand...

You need to use the photobucket IMG code.
The spindle tube looks as if it has been repaired. The holes for the oil filter body are missing (although they are there in your previous photo so I assume you drilled them?) which suggests it's not the original cradle.


The spindle bore also looks oversize compared to the standard cradle. What diameter is the spindle?

Thanks for the reply,
yep I drilled the cradle for the oil filter, I actually had to change the angle and position of the holes a bit from a template I found on the net so the oil lines would clear the spindle tube. This probably should have given me the first warning something wasn't right but I didn't think much of it. The id of the bore measured 22.23 mm (7/8" I'm guessing) with verniers and seems to be about the same as the swing arm bushes so I don't think this has been done to take an oversized spindle maybe. The bush which goes through the tube is actually 2 bushes, one on either side of the tube with probably a 20mm gap between each. I think perhaps the original tube was damaged or for whatever reason someone has just fixed it wit what's at hand, to their credit its actually a pretty good job, I just wish I picked up on it earlier before everything was powder coated and ready for assembly

Is it possible that your swingarm has been converted to pivot back to front. I.e. that the swingarm is locked to the spindle and it turns inside the cradle bushes. Is the spindle od now the same ID as the eyes on the swingarm without their bushes.
When I had to rebuild my cradle with a new spindle carrier ( which I machined oversize and tapped for two bolts to brace the spindle) I contemplated whether reversing the bushes would be a better option.

Cheers for the suggestion tyborg,
The swing arm has not been modified so it seems as though its set up for standard operations, I do understand what you were proposing though. I have been able to get some feed back from Kenny at NYC who I have to say is a top bloke, without me being a paying customer he has taken the time to send me several emails to help explain the situation. The verdict... my gearbox cradle is a modified 750 cradle, someone has taken the time and effort to weld and re-bush an oversized spindle tube. The though is that this should eliminate the play which seems to be common with norton rear ends. I'm going to drill a hole for the spindle locating nut, buy a new spindle kit with welch plugs etc and fit it all up.

Instead of the one central spindle lock it would be wise to use two, drilled so they contact the flats on the later spindle. A lot of the wear on the spindle and carrier was due to pivoting of the spindle on the centrally mounted lock. This is what the Keller clamps are designed to try and do with a thin wall tube.

So is the central spindle locating hole usually threaded, or is it just a hole that the bolt goes through to be threaded into the spindle? Because the flats on the modern spindles are not threaded I assume I would have to weld some nuts onto tue spindle for tue bolts to screw into. Would this be correct?

morton said:

So is the central spindle locating hole usually threaded, or is it just a hole that the bolt goes through to be threaded into the spindle?

Click to expand...

It should be just the spindle.

morton said:

Because the flats on the modern spindles are not threaded I assume I would have to weld some nuts onto tue spindle for tue bolts to screw into. Would this be correct?

Click to expand...

Here are some examples our members have posted. It might not be absolutely necessary to weld the nuts, only cut threads in the tube and use locknuts, however, clearance is limited and as the tube in your cradle is a larger diameter it could pose even more of a problem.

Snorton74 said:

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MexicoMike said:

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xbacksideslider said:

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Thanks for posting those pictures and for the advice L.A.B. I was a bit hesitant to drill and tap straight into the tube in case it chewed it out. If its something that's been done before by you guys with experience I'll definitely suss it out. I figure seeing as though there is no central hole drilled I might even be able to offset the holes if there are clearance issues; drill the central hole at 2 o clock and the locking nuts at 5 o clock. I'm really just having a stab saying this though as I haven't had a look if it would help at all. I think I may have enough room though if I use the right bolts.

I drilled the holes, welded 2- 1/4" unf nuts and use socket set screws to hold the shaft in place... you can slip a 3/4" long bolt into the tube, stick it out through the hole and have it centre the nut over the hole, then weld

There are 15 videos on YouTube about the swingarm. They helped me to understand the problem and solution. https://youtu.be/5WnLsyxkrm0

Thanks for the info and the link to the youtube it was really helpful. I have ordered the MK3 type spindle kit, drilled the locating hole for the centre spindle, built a jig and I'm going to drill and tap some studs in the tube to lock onto the flats of the new spindle. Ill post some pictures after I'm done