Author Topic: Swingarm bush fitting  (Read 2341 times)

Offline mark

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Swingarm bush fitting
« on: 15.03. 2010 05:05 »
I am getting ready to replace the swing arm bushes in my 55 road rocket. Are there any things to watch out for. I assume that I'll be using a press to push them in. The old ones have been removed.
Mark
55 road rocket




71 Norton Commando Roadster 750


Australia

Offline MikeN

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Re: Swingarm bush fitting
« Reply #1 on: 15.03. 2010 12:52 »
Yes,you will definately need a press to fit the new ones.Make sure you press on the outer part of the bush and not the centre tube or you will probably tear the bonded-in core out.
 Unless you can find a suitable drift or pusher to do this you will have to get something turned up on a lathe.
Mike

Online RichardL

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Re: Swingarm bush fitting
« Reply #2 on: 15.03. 2010 13:20 »
1. Confirm new bushes correct for your spindle. True '55 = solid spindle.  
2. Press can be all-thread rod with washers and nuts each end. (Use largest rod that will fit.)
3. Reports of some new bushes being a bit too large in O.D., making job grueling, like mine. I honed the inside of the swingarm and it was still one of the sweatiest, cuss and worryfilled jobs I can recall (and I don't just mean on motorcycles). Here would be a very good place for others to offer advice as to how to ease the way.
3. Inner sleeve sticks out a bit after installation to force a friction fit due to pressure from the frame plates. By so doing, the inner rubber absorbs vibration from the rotational movement of the swingarm. Personally I think this can be iffy or hit-or-miss, but I have come to accept this as the design intent.
4. Because the inner sleeve sticks out, be sure to protect it with oversized washers on your rod press.
5. Once in, it is possible for the left and right bushes not to align (my hand goes up, sheepishly). My solution was to buy a long expandable reamer to clear the way.

BTW, much of what I'm telling you I learned here from people far more experienced than I. I'm just trying to save you the research of finding it amongst our lengthy discussions.

Good luck,

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 mark

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Re: Swingarm bush fitting
« Reply #3 on: 15.03. 2010 22:15 »
Thanks for the advice. I've heard stories about bushes not fitting, does anyone know who can supply bushes that are known to fit correctly?
Regards
Mark
55 road rocket




71 Norton Commando Roadster 750


Australia

Offline a101960

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Re: Swingarm bush fitting
« Reply #4 on: 15.03. 2010 22:21 »
Possibly George Prew. His stuff is normally good but he can be an odd person to deal with. George specialises in BSA twins and Goldies.

Offline 1660bob

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Re: Swingarm bush fitting
« Reply #5 on: 16.03. 2010 08:15 »
Swingarm bushes eh? Hmm.. don`t get me started... well there you`ve gone and done it now... so here goes:
I am also "preparing" to refit bushes to my late a10 hollow spindle job.There are all sorts of pitfalls with this job, not least the fit and quality of the bushes available. For starters, as regards the problem of misalignment of the centre tube when pressed in, the bushes themselves are rarely (ever?) moulded together accurately and the inner/outer tubes not parallel to each other, hence the misalignment when fitted mentioned above... Bushes often come with the inner bore too small to fit over the swingarm spindle,(again i speak re the hollow spindle version) so my second set *sad2* came from Kidderminster who had them ready reamed out  slightly to fit the spindle, (a nice stiff fit by hand). This I regard as only the start!
I had looked at my swingarm (after a Titanic struggle to get the old bushes out) and saw that the bores were quite good and parallel.The O/D of the new bushes was far too big for the swingarm, with an interference of 15 thou. in places!. I decided remedial work was  necessary if there was any chance of success, so i bought a piece of 13/16 silver steel bar from the local engineering supplier,(same dia.as the spindle) & set it up in my lathe to run dead true, pushed each new bush over it and spun up the lathe- it was like watching a camshaft!!! I skimmed the ends of the inner tubes true and square- and FLAT-where they butt up together -the makers insist on ruining the inner tubes here by chamfering/de-burring the ends of the  tube at this most critical point- On the hol. spindle version there is precious little metal to butt up and take the clamping load when the spindle is tightened up-they soon come loose and dig into the frame, start to turn on the spindle instead of flexing the rubber, and burrow a great oval hole in the frame- believe me I know! I have also made up two small stepped stainless thrust collars to go between the tube ends and the frame to spread the load and protect the (repaired) frame plates.This means shortening the inner tubes by the same amount at their inner end (2mm) and pressing the bushes 2mm further in to accomodate, theres plenty of room to do it.To head off any centre tube misalignment, I have made a small collar to fit (tackweld)over the innermost  end of one inner tube with a "catch" taper to recieve the other inner tube as they come together inside the swingarm to automatically correct any misalignment on assembly.I have also trued up the O/D of the outer bushes by skimming a few thou off so ALL is now true to the spindle bore(as they should have been in the first place!!)This has lost some of the O/D inteference fit, but I think it was excessive anyway.I will lubricate with Loctite on assembly for a "belt and braces" job I will let you know if all is a success *eek* Bob.

Online RichardL

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Re: Swingarm bush fitting
« Reply #6 on: 16.03. 2010 13:07 »
Bob,

Very interesting and well thought out. My own work assumed, way too trustingly, that the parts came as a correct fit. Really dumb, I know. Also, at the time when I did the job I had no clue that the idea was for the frame to clamp the inner tubes together, and it took a lot of thick-skulled convincing before I understood and accepted it (after the fact). Finally, I often put myself in the position of conjuring ways to get around the fact that I don't own a lathe and a mill. If I decide to build another motorcycle, a combination benchtop turning and milling center may be the second expense (after the bike, of course).

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 chaterlea25

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Re: Swingarm bush fitting
« Reply #7 on: 16.03. 2010 18:36 »
Hi Bob,
Well written description of the work involved, I'm sure it will explain the antics involved to some of the owners here who havn't had to do this!!
My method of removing the bushes is this,
select a drillbit which will just fit betwen the inner and outer bushes (3/16 or so??)
drill as many holes as you can through the rubber until it starts to break up,
finish off the rubber with a narrow blade in a pad saw,
now the inner bush will come away, repeat on the otherside
now slit the outer bush with the pad saw and a hacksaw blade, this will loosen the outer bush
repeat on the other side or press out the remaining bush with a suitable mandrel
HTH
John O R
1961 Super Rocket
1963 RGS (ongoing)

Offline BSA_54A10

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Re: Swingarm bush fitting
« Reply #8 on: 17.03. 2010 07:18 »
Before you fit the bushes pop a grease nipple in the swing arm between the two bushes.
After fitting the bush, load the swingarm with rubber grease.
This will stop the spindle from rusting inside which makes subsequent bush removals much easier.
Bike Beesa
Trevor

Online trevinoz

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Re: Swingarm bush fitting
« Reply #9 on: 18.03. 2010 04:45 »
Wouldn't it be easier to use never seize or similar on the spindle?
  Trev.