Author Topic: Swinging arm  (Read 7598 times)

Offline riflegreen

  • Moving Up
  • **
  • Join Date: Jun 2009
  • Posts: 14
  • Karma: 0
Re: Swinging arm
« Reply #30 on: 11.06. 2009 21:17 »
The inner sleeves pass right through the rubber & abut to each other in the middle , the outer sleeve is a press fit in the swinging arm .

The outer ends of the inner sleeves are tight to the frame and are clamped tight by the spindle . Before tightening the spindle the swinging arm should be moved to roughly half travel and then tightened to clamp the bushes , this gives the correct torsion to the metalastic bushes .

If this is not done and the bushes move round the spindle you will get wear in the frame and wear in the bush ends .

Eventually makes a very wobbly ride .

Chris

Online bsa-bill

  • Wise & Enlightened
  • *
  • Join Date: Mar 2006
  • Posts: 5456
  • Karma: 62
Re: Swinging arm
« Reply #31 on: 11.06. 2009 22:14 »
see what you mean Richard but I'm sure the sw/a tube is stepped, however my memory is suspect since I had heart op last September, this forum does help though

All the best - Bill
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Online RichardL

  • Outside Chicago, IL
  • Wise & Enlightened
  • *
  • Join Date: Nov 2007
  • Posts: 5062
  • Karma: 48
Re: Swinging arm
« Reply #32 on: 11.06. 2009 22:30 »
Riflegreen,

Great comment and welcome to the forum. The aspect of tightening at the half-travel point is not one I considered when assembling my bike (given the fact that I thought it was just free pivoting) and has not been mentioned here previoulsy, as far as I can recall.  

Since I am newly brainwashed into the torsion rubber theory, two questions come to mind, springing from your comments.

1. Would it be better to loosen the spindle nut and sit on the bike with the shock absorbers attached, then, use that as the tightening point for the spindle? Would this not provide a better half-travel point?

2. Is it possible that the squeezed-tight friction fit, either intentionally or fortunately, has limitied friction where the outside portion of the inner sleeves makes contact with the frame plates? It seems this would result in slippage under duress and might serve to protect the, as you say, "melalastic bushes." Then, when back closer to the half-travel point, the friction is still enough to afford normal short-arc movement.

Any comments are welcome and will certainly be an education for me.

Richard L.

Plan on signing up for the world-wide 2020 DISTINGUISHED GENTLEMAN'S RIDEon September 27, 2020 (if it's not cancelled and we are free to move about by then). Watch website at https://www.gentlemansride.com for details.

Online RichardL

  • Outside Chicago, IL
  • Wise & Enlightened
  • *
  • Join Date: Nov 2007
  • Posts: 5062
  • Karma: 48
Re: Swinging arm
« Reply #33 on: 11.06. 2009 22:32 »
Bill,

I find that riding does require a lot of attention to the ride itself, but destresses me because I don't think of things like work, home improvement, family squabbles, et cetera.

Richard L.

Plan on signing up for the world-wide 2020 DISTINGUISHED GENTLEMAN'S RIDEon September 27, 2020 (if it's not cancelled and we are free to move about by then). Watch website at https://www.gentlemansride.com for details.

Online trevinoz

  • Newcastle, N.S.W. Australia.
  • Wise & Enlightened
  • *
  • Join Date: Jul 2006
  • Posts: 2903
  • Karma: 67
Re: Swinging arm
« Reply #34 on: 11.06. 2009 23:37 »
Richard, have a look at your shocks and see how little they actually move.
When fitting the swinging arm, I leave the spindle loose and fit the shocks then tighten the spindle. Works for me.
Aren't you lucky there are so many people willing to correct your misguided ideas?
Trev.

Offline coater87

  • Wise & Enlightened
  • *
  • Join Date: Jul 2008
  • Posts: 1181
  • Karma: 6
Re: Swinging arm
« Reply #35 on: 12.06. 2009 03:11 »
 OK,

 So the bush just gets crushed up against the frame plates? Should the hole in the plate be the same size as the pin, or bigger?

 Looking at mine, the frame plate hole is quite a bit bigger, and this is whats giving me the slop. Do I need to weld this shut then re-drill to the correct size- or maybe that little bit of slop is supposed to be there to line up the swing arm and the nut is what keeps everything in place?

 I have no idea.

 Lee
Central Wisconsin in the U.S.

Online trevinoz

  • Newcastle, N.S.W. Australia.
  • Wise & Enlightened
  • *
  • Join Date: Jul 2006
  • Posts: 2903
  • Karma: 67
Re: Swinging arm
« Reply #36 on: 12.06. 2009 05:38 »
Lee, it should be a close fit. Weld and drill or file.
Trev.

Offline MikeN

  • A's Best Friend
  • ***
  • Join Date: Mar 2009
  • Posts: 220
  • Karma: 0
Re: Swinging arm
« Reply #37 on: 12.06. 2009 08:49 »
Lee,
  Just to complicate it a little.
   There are 2 diameters of pins available(and silentbloc bushes to match).The first s/arm models had rod operated rear brakes.When they chaged to cable operation BSA introduced the cross-over shaft which required a larger diameter pin.When the Rocket Goldstar came out it reverted to the smaller pin.
  You say your frame hole is quite a lot bigger so you may not have the correct pin . If you dont wish to purchase a new pin the best way to rectify is to have some reducing bushes made up to make sure the holes stay concentric.
 However, If the oversize hole is due to wear in the frame then it might be better to repair, as you say with welding and re-drilling.
 Mike

Online bsa-bill

  • Wise & Enlightened
  • *
  • Join Date: Mar 2006
  • Posts: 5456
  • Karma: 62
Re: Swinging arm
« Reply #38 on: 12.06. 2009 11:08 »
Hi Richard - yes up here the procedure was to get a prospective girlfriend to sit on the bike ( bike off the stand) and tighten the spindle at that pint, of course at a later date you may have to repeat the procedure with nieghbourhood fat lass to get it right *lol*

and on the other point re stress the more I get at this project ( and rob bits of my was roadgoing bike ) the further I get from riding, now the gearbox does'nt want to shift properley, I'm at a standstiil now due to pains in my legs and thighs Doc talks about muscular something or another also got three screaming grandkids staying, cant find a way to make them unhappy, tell them to be quit and they just smile and continue - why me

never mind there's a better day coming

All the best - Bill ( sorry for the downer you got me on a bad day)

All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Offline riflegreen

  • Moving Up
  • **
  • Join Date: Jun 2009
  • Posts: 14
  • Karma: 0
Re: Swinging arm
« Reply #39 on: 12.06. 2009 11:15 »
Hi All ,

Spose I should have introduced my self , ex Greeves Comp Dept , Guzzi , Ducati , Suzuki , MZ , CCM , Yamaha & and anything else that came into the dealers .

Currently have two Goldstars , an A7 and a pre war single .

The idea of metalastics is to give torsion to the swinging arm etc that they are fitted to , yes, sitting on the bike then tightening the spindle will give the same effect and is probably not far from half movement . Preloading the bushes applies to any make of bike that has them .

Don't forget that the swinging arm pivot being the pivot point has very little movement compared to the wheel/damper end .

The spindle should be a sliding fit in the frame mounts , too much slop can make the wheel/swinging  lay at an angle relative to the frame .

The same applies to the solid spindle arm & the hollow spindle later frames .

It is not uncommon to see large washers brazed on the outside of the frame mounts to repair worn holes but drilling oversize and fitting spacers looks much neater .  

Far as I recall the tube that the bushes fit into is parallel right through .

I think most of the Goldstar parts suppliers sell spacers to convert the hollow spindle frames to solid type , these could be used to repair damaged arm mounts .

The only danger when drilling out the frame mounts to repair them is not getting them in line bit like repairing the center stand lugs when they wear out through lack of grease or the nuts being loose .

Chris

Offline LJ.

  • Peterborough UK.
  • Wise & Enlightened
  • *
  • Join Date: Jun 2006
  • Posts: 1403
  • Karma: 15
  • The Red A10!
    • LJ's Website!
Re: Swinging arm
« Reply #40 on: 12.06. 2009 14:22 »
Hiya Chris! Nice to have you join us, I should have recognised 'riflegreen' Thanks again for the tool box... We must catch up again soon eh? mean while... I'm outta this thread, dont wanna get into doing swinging arm bushes yet.  *eek*

Cheers
LJ.
Ride Safely Lads! LJ.
**********************
1940 BSA M20 500cc Girder/Rigid- (SOLD)
1947 BSA M21 600cc Girder/Rigid-Green
1949 BSA A7   500cc Girder/Plunger Star Twin-(SOLD)
1953 BSA B33  500cc Teles/Plunger-Maroon
1961 BSA A10  650cc Golden Flash-Blue
1961 BSA A10  650cc Golden Flash-Red

Offline 69Bonni

  • A's Best Friend
  • ***
  • Join Date: Apr 2009
  • Posts: 109
  • Karma: 0
  • '67 A65T, '58 Roadrocket, '69 Bonnie, '60 350 AJS
Swinging arm ... RGS more Questions
« Reply #41 on: 12.06. 2009 15:19 »
Hi and Welcome Chris!

Blast!!! i just as i thought! the solid spindle is a different dia to the hollow type. Now wouldnt it just have been easier to have the same holes in the frame and and use a bigger Dia solid spindle.

All this buillding RGS is getting to be a pain! So i have my single sided hub, and my chain guard, my brake pedal and although the single sided hub will fit the swing arm, the swing arm doesnt have the right chainguard mounting or the Torque arm mounting. Im begining to think it may be easier to Modify the swingarm than change it for a B31 / SS hub type.

Quandry, if i fit a B31 swing arm i have to mod the frame too and it have bigger holes for the hollow tube.
Maybe i just machine up a solid spindle the Dia of a Hollow spindle or Machine up a dummy spindle the same Dia as the brake cross shaft with some end plats on to look like a solid, and Modify the swing arm.

Does the Board think i could use a clamp on Torque arm mounting on the swing arm obviously a substantial one. Sounds tacky doesnt it dont like the idea maybe i will change that swing arm after all.

Any views appreciated

Steve
Kind Regards
Steve Rickman

Offline riflegreen

  • Moving Up
  • **
  • Join Date: Jun 2009
  • Posts: 14
  • Karma: 0
Re: Swinging arm
« Reply #42 on: 12.06. 2009 15:36 »
Hi Steve ,

You have to remember that the RGS used a lot of GS cycle parts and these were all based on the first s/arm frames of 1954 .

If you alter your s/arm to GS/RGS type and fit a solid spindle you need to fit the rducing spacers in the frame. Have you got the rear set rest mounts in the frame loops ? , if so then Eddie Dow recommended using the footrest as the brake pedal fulcrum - saves welding a brake mount on .

Lots of the replica RGS have the full width swing arms with all the bits cut of and the single sided hub brackets welded on .

Takes dedication to make even a proper replica RGS ( and a deep pocket ) *smile*

I've just sold an A10 frame with all the right bits on ( 1954 ) and was suprised to get £500 for it .

Chris

Online RichardL

  • Outside Chicago, IL
  • Wise & Enlightened
  • *
  • Join Date: Nov 2007
  • Posts: 5062
  • Karma: 48
Re: Swinging arm
« Reply #43 on: 12.06. 2009 15:46 »
Steve,

In adpating my post-'55, hollow-spindle-type frame to work with my left-side-pull half-width brake, I bought a hollow spindle and the associated bushings with the larger diameter. That is from whence my tale of bushing replacemnt woes originated. I plan to put rubber plugs in the spindle openings when I remember to do so.  

Further torturing the twisting rubber topic, it just occured to me that the metalasitic bush was designed well-prior to the design of the hollow spindle. The bushes for solid spindles had thicker rubber to stretch than those for the hollow spindles. Does anyone believe or know for certain that BSA did the math or the tests to determine that less rubber would stretch adequately? Does anyone care, or am I just an obscessed frustrated, wanna-be motorcycle engineer?

Richard L.
Plan on signing up for the world-wide 2020 DISTINGUISHED GENTLEMAN'S RIDEon September 27, 2020 (if it's not cancelled and we are free to move about by then). Watch website at https://www.gentlemansride.com for details.

Offline riflegreen

  • Moving Up
  • **
  • Join Date: Jun 2009
  • Posts: 14
  • Karma: 0
Re: Swinging arm
« Reply #44 on: 12.06. 2009 15:52 »
Richard ,

I suspect BSA looked at all aspects of the different size metalastics , they certainly did at Greeves when they went fron a 3/8" spindle to a 1/2" and then 5/8" .

Metalastics are also available in different grades of rubber , there were four different grades for Greeves front forks for road , trials , mot cross and r'racing .

Chris