Rear disc conversion

[Bryanj]

Does that swing arm have taper roller brgs or does the arm pivot on the bolt? If it pivots on the bolt you need to modify it!
PM me for why

[allankelly1]

I would have thought if you are running plain bushes you should never pivot directly on the bolt but there should be a sleeve that is a slide fit in the plain bushes is the width of the frame and the bolt then passes thru this assembly and tighten up using the sleeve to keep the frame width right?

Also this sleeve should be wide enough to allow a slight side float of the arm
In the frame with the bolt fully tight?

Best wishes Al


Sent from my iPhone using Tapatalk

[allankelly1]

Mine is running needle rollers, as should the Dresda arm of yours.

Thanks Oddjob for the info

Looking forward to adding this little tweak to the bike even if it needs a tweak

Also offer is still there if I can help you with any 3d project

Best wishes Al


Sent from my iPhone using Tapatalk

[Bryanj]

Thats the problem Ken and all as if it pivots on the bolt without a collar or spacer to get trapped in the frame you cant do the bolt up tight without restricting swing arm movement and if you leave it loose enough for arm to move the holes in the frame wear.
 Have a box arm that is fitted with bushes that pivot on the bolt, its crap and useless unless i get them bored to fit a standard collar and narrowed enough for the collar to be trapped with clearance for arm.
Thats what the phenolic thrusts in original arms and flanges on brass replacements are for.

[allankelly1]

Thats the problem Ken and all as if it pivots on the bolt without a collar or spacer to get trapped in the frame you cant do the bolt up tight without restricting swing arm movement and if you leave it loose enough for arm to move the holes in the frame wear.
 Have a box arm that is fitted with bushes that pivot on the bolt, its crap and useless unless i get them bored to fit a standard collar and narrowed enough for the collar to be trapped with clearance for arm.
Thats what the phenolic thrusts in original arms and flanges on brass replacements are for.

Sounds like a easy engineering fix

I will see what I receive and then if require modify so the the pivot bolt can be tightened but still maintain some slight side float no matter if it is a taper / needle bearings or a plain push set up

Can’t be any harder than the rear disc conversion


Sent from my iPhone using Tapatalk

[Bryanj]

Having read all this i have no doubt as to your capability to fx it. Look at how the standard arm pivot works and it should be easy, just need to know its necessary!

[allankelly1]

To be honest a simple plain p,bronze bush that fits either end of the swing arm pivot tube ( like the ones Julie supplies for the standard arm) and hollow shaft that is a slide fit on the bushes which the swing arm bolt can pass thru should be more than sufficient

All you then you need is the correct sideways float that can be adjusted on shims and some dust covers

Lastly you can alway add a grease nipple

But thank you for the advanced warning on what to expect

Best wishes always Al


Sent from my iPhone using Tapatalk

[allankelly1]

Hi

Got Dresda swing arm today

Very happy so far and it’s the taper roller bearing type so happy days



Will need some TLC like the bearings regreasing and a powder coat or paint but things are on the up

Also sorted my brake  line feed and bleed the system



 





And as predicted pedal movement is much less with the system filled and bleed

Just need to sort  out all the rearsets parts in aluminium etc and the system should be up and running


Sent from my iPhone using Tapatalk

[Bryanj]

I notice the swingarm bolt has a castle nut so the tightness must adjust the tapers play, hope the bolt is a good fit in the frame holes.

[allankelly1]

Hi

The bolt supplied “looks” the same diameter as the original swing arm frame bolt holes but without removing the arm I cannot confirm

So I have please a couple of questions

Why diameter is the original swing arm spindle please?

Also what is the frame internal distance please
between the two mounting holes  / plates

That way I can dummy up the assembly on the bench first  as rather than setting the preload  in the tapers via the castle nut I will make an internal precision length spacer tube that sets the inner race distance (like a internal wheel bearing Spacer) so the pivot bolt can be just tightened up fully (rather than tightened just to set the taper roller preload) without overloading side preload on the taper bearings if that makes sense?

Many thanks in advance

Best wishes Al


Sent from my iPhone using Tapatalk

[Bryanj]

Cant tell you the bolt size, might be able to measure a collar if its the same as a 500 one

[allankelly1]

No worries

I will strip it out this  weekend and put a plan together as bike is now drained down for the winter

Al least it at taper bearing that in my mind  is the best set up as the bearing cope with both axial and radial loads



Sent from my iPhone using Tapatalk

[allankelly1]

Original is 14mm.

Sent from my iPhone using Tapatalk

[K2-K6]

I can't see a problem running them without a spacer (the taper roller Dresda design) it's as he designed it with significant background and real testing of those design in competition.

If the arm and bearings are a tight fit in the frame (you may have to undo the rear engine mounts if they pull the frame in) then the spindle can be torqued to 25lb/ft with them free floating.  They are designed to take axial load in that way without any problems at all, generally people have been squeamish about torqing them as such which may lead to problems. 

They are not like a wheel bearing joint in that the load is mostly radial on those, with very little pure axial demand.  A internal spacer would be used if you wanted to put much higher torque load on the threads, such as a differential pinion assembly in which the bearing preload is high to prevent axial shunt, also the securing threads high torque demand such that it doesn't loosen in service life.

The swing arm bearings have a comparatively easy life and some preloading will help maintain positional accuracy under road conditions.

The design does a very clever balance of forces in that location, being very able to resist the expected input while remaining so very simple.
He placed the bearings right out by the frame, giving them the easiest task possible to resist frame torsion load (if you look from the back of the bike and tried to rotate the top of the wheel one way, with the bottom across the other way) but by using roller bearings if the arms move such that it twists the main pivot tube in it's own torsion, then it can't lock up as plain bearings risk doing from that tube twisting.

[K2-K6]

Interestingly, there's some information about standard 400 swing arm in FEA program on this link http://www.denoonsp.com/bimota-7.htm along with some other modifications on a 400 on the site.

Hasn't got a disc conversion like yours though Alsn