Swinging arm spindle query.

Tell me about drastic, Phil
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Yes - as others have inferred this involves cutting the top tube and welding a lump in - there was a massive thread ages ago - cant find it but maybe someone can/ - have done one or two and known of others - stops all that wobbling. Other drastic way is to eat like you're eating for 3 people, and the extra weight will soon damp those nasty wobs down - have you tried it 2 up yet? - Regards - Phil
 
Have a look here,one of the Sydney blokes found this,do a seach on this thread

Jugs_S
Guest
Swing arm side play
? on: March 30, 2008, 10:52 ?
 
Putting a bigger bolt in won't guarantee the swing arm sits dead horizontal, the only way to do that is to set the frame on a mill and ensure the spindle holes are machined in line at 90 degrees to the headstock axis. In real life the fact that the ends of the bobbins are square to their diameter pretty much enures that when everything is pulled up tight the axle assembly sits square and won't budge, the swing arm plates do bend a bit under duress, I have boxed out the swing arm pivot plates and fitted a 16mm spindle to stiffen that area of the frame up which works well. Pinching bearings and spacers through a frame to form an axle is pretty much standard procedure on chain driven bikes and is a system that works very well across many different marques.
  Try tucking down behind the clocks and sliding your arse back on the seat and getting hold if it that normally calms them down a bit if they start to sway.
 
Hi Vince.  Can't find the thread, searched all the keywords but just get 'computer says no'.
As to swingarm location, its been a long time since I dealt with '70's tech.  All the fairly recent (as in post 80's) stuff seem to use a positive tension system on the bearing inners, as in a frame mounted hollow screw that buts up to the inner with the through bolt then clamping the lot in the frame.  BTW pivot bolts are at least 22mm and some quite a bit fatter, oh, and they are ALL as near an interference fit as makes no difference in the bearing inners. 
At least it gives me a little hope untill Monday when I can get to the engineers shop!
 
I found it by searching under
Jugs swingarm
Jugs is Will S,one of the Sydney blokes,he was having handling issues with his 120 Jota.I lent him my swingarm bearing replacement kit and he went in.He is an ex Aussie Navy Fitter and very close to the best Laverda Tech I have struck,very very anal at getting things right.What he found and corrected went over my head.He explained it a couple of times but I just couldn't get the gist.Worth a read and maybe applicable.
 
Thats the tread but there is nothing very technical about that,I am sure there was another issue
Will was looking at as well.I will ask and pass it on.
 
when a bloke was 20-something & bulletproof, that flex & weave stuff could be an issue at times.
so i got meself one of these.    problem solved !!  it was a great investment.
spondon-101.jpg


now, i just deal with the factory frames again.  they're 'ok',,  sort of.
yea,, i guess i'm more a 'senior' kinda bloke now.  oh dear, when did that happen!  ???
Mark
 
Pure sex Mark!

Rotten weather today so can't go riding and the 'blades just been treated to a full fettle too
Anyhoo.  Been delving trough the Google and after trawling the Harley threads, and then the Triumph threads all of which detail a very similar situation I came across an interesting paper on this phenomenon.  To give the bullet point, it concludes that:-
Wobble BELOW 45mph, problems in front of the steering stem, wobbles ABOVE 45mph, problems behind the steering stem.
This does somewhat, concur with my reasoning. 
Further input.  When in the wobble, shutting off the power calms it all down, applying power brings the wobble back.  At 90 per, the engine is starting into the fatter part of the torque / power curve, so will start to heavily load anything a bit suspect. 
I also had a long talk with he previous owner and he absolutely confirms that this has had no accident or drop damage.  More annoyingly, he also says he never noticed any particular handling foibles, but, in his day he was a well built chap and strong as an ox, maybe he could muscle it a bit better than me!?  ( Sad to see what time can do to the human body). 
He still takes a propriety interest in it and is as concerned as I am to sort it out properly, (so I am very sure I've not been sold a wrecked pup). 
Ah well, a day of Le Mans and BSB to enjoy, battle resumes tomorrow.
 
jdugen said:
I also had a long talk with he previous owner and he absolutely confirms that this has had no accident or drop damage.  More annoyingly, he also says he never noticed any particular handling foibles, but, in his day he was a well built chap and strong as an ox, maybe he could muscle it a bit better than me!?
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Your not riding side-saddle by any chance?

On a serious point, I have read through your posts and notice that you haven't changed your rear tyre! Considering the grief you are getting from the handling and that pretty much everything else checks out ok, then changing the tyre is a comparatively easy experiment - same type as front perhaps?.
 
phil37 said:
In the old days we fitted a smaller width rear tyre to stop the weaving - Regards - Phil
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I did just that about a year ago and went to a 120 profile rear tyre from 130 - albeit for a different reason.
The handling in general did improve.
 
My Jota tends to get a high speed wobble if the back tyre is worn. Anything past about 50% wear and it becomes noticeable, then gets worse as the tyre wears further.
Same thing happens with my Ducati, except it doesn't start until the tyre is about 75% worn out.
 
So....  Whats on today's menu.  Ah, Humble pie! Lovely, I'll have a large helping please.

Yes, you were all perfectly correct, a new Bridgestone in the back, stable as you like right through to Go to Jail speed. 
In my defense, the tyre fitter had a long careful look at the TT100 and could see nothing at all wrong with it.  He did say that he thought the inner tube was a size too large and did show some evidence of being wrinkled, so maybe that had a bearing on the issue?
So, it seems I have a nice, rorty, 'good' handling example of the breed, at last.  Isle of Man here we come!

BTW, just as a feeler.  I'll be looking to sell her after the Manx if anyone is interested, and, I'm not a greedy person.

Cheers and really, thanks for all the input.  I was starting to pull tufts of fast diminishing hair from my scalp over this one.
 
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