Author Topic: renewing unusual swing arm bushes on 61 super rocket - what to do?  (Read 1298 times)

Online mikeb

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Musky i was thinking: the spindle has a step just before the thread (on the right hand side). the step sits against the back of the right hand frame plate, so then the nut clamps the spindle to the frame plate. So its won't squish the frame together as the nut is not pulling across the length of those spindle. so it doesn't compress and lock the swingarm...??
 If that's correct the spindle will act like a distance tube... so I don't need one....?
while the spindle fits snug to the inner of the silent bloc, on this setup the bronze bushes rotate around the spindle
does this make sense or wishful thinking???
New Zealand
'61 Super Rocket  - '47 B33 -  '18 Triumph Street Triple RS

Online KiwiGF

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yes Kiwi - we met in the 'naki - good rally that was.
and dutch I agree those spacers/rings look too puny for the job. That may explain the groove in the end of one bush (where the fibre washer was mangled)

actually the spindle has a step in it at the RH/threaded end, inside of the RH frame plate! So i guess that's what stops the plates getting bent in (when the locking plate isn't broken off at the left end). So maybe I don't need a distance tube through the bushes??? Just need some better end spacers rather than those tiny rings in the fibre washers? maybe some large washer-like spacers of the right thickness..?? tho not sure how to keep water out, other than grease.

if so this just got easier! comments?

Just my opinion but I don’t think the current design will work well at all, and worse has caused the frame hole to be enlarged, so it’s either fit blocs, or spend some money getting a “distance tube” made up. The easiest way of doing that would be to get a piece of thin wall tube with an internal diameter the same as the frame holes, and machine the o.d. to suit the bushes as required. The bushes will also need drilling/reaming out.

The “distance tube” needs to be slightly shorter than the distance between the frame plates such that the spindle bolt will clamp it tight. Bronze washers will also need to be made up to fit between the bronze bushes and frame, to remove endfloat. A grease nipple for maintenance would be good.

I think it would be easier to fit blocs.
New Zealand

1956 A10 Golden Flash (1st finished project)

1949 B31 rigid “400cc hot rod” (2nd finished project, + favourite bike)

GL1800 Goldwing, well, the wife likes it

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G'day Mike.
Is yours a hollow spindle? 42-4340 used from 56 to 68 A7/10/50/65 has no step *ex*
Without the clamping action of the spindle original silentbloc's wouldn't work either.
Something other than the bushes has been modified, the spindle.
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
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Offline wortluck

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Incidentally, my original Silentblocs were fine, I only replaced them due to the swingarm being enamelled.

Thanks for the Karma, feeling the love already  *smile*
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Offline edboy

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some swing arms inner bores are stepped. if not its lathe work to make a outer shaft and i pegged my one with a grease nipple fitting from under the swing arm. i pump grease into mine until it  comes out the sides regularly and the bushes do not rotate in their housing but around a slave hollow spindle which is tightened to meet the frame .the bushes are shimed to minimise end float. the design is used on triumph twins o.i.f and late tridents i believe. its a lot of work , the old girl will handle like a gsxr and when you sell it someone will want to back to silentbloc bushes.

Online bsa-bill

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Quote
some swing arms inner bores are stepped.

yep one of mine is
All the best - Bill
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Online mikeb

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Musky I'm thinking it should be 42-4340 too. would you call the attached photo stepped? it only goes through the hole in the frame plate up to the small step behind the threaded section.

it also looks pretty similar to the one shown eg here (third pic): https://www.feked.com/swinging-arm-spindle-bsa.html so I assume it the correct part.

?
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Online KiwiGF

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Musky I'm thinking it should be 42-4340 too. would you call the attached photo stepped? it only goes through the hole in the frame plate up to the small step behind the threaded section.

it also looks pretty similar to the one shown eg here (third pic): https://www.feked.com/swinging-arm-spindle-bsa.html so I assume it the correct part.

?


Whilst we await muskys wisdom, the more I’ve thought about this, I don’t think there is any getting away from having a “distance piece” which is clamped tight against both of the frame plates by the spindle bolt. This is the only practical way I can think of that will ensure the spindle cannot (shouldn’t!) move, and thus enlarge/damage the frame plate holes, the std design is effectively done this way albeit the “distance piece” comprises the silent blocs and the stepped swing arm tube.

As per previous post, there is also an argument that the clamping of the plates together via a tube, provides some extra strength to the frame *dunno*

If I’m right this is not good news should you wish to continue with bronze bushes (sorry)
New Zealand

1956 A10 Golden Flash (1st finished project)

1949 B31 rigid “400cc hot rod” (2nd finished project, + favourite bike)

GL1800 Goldwing, well, the wife likes it

KTM 950 ADV, cos it’s 100% nuts

1952 Armstrong Siddeley Whitley for rainy days (with wife)

Offline duTch

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 How about this from the first paragraph of the original post ??

 
Quote
..... Inside the swing arm there’s something loose between the two bushes (I can’t see it or get to it yet).......

Started building in about 1977/8 a on average '52 A10 -built from bits 'n pieces never resto intended -maybe 'personalised'
Have a '74 850T Moto Guzzi since '92-best thing I ever bought doesn't need a kickstart 'cos it bump starts sooooooooo(mostly) easy
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G'day Mike.
Google 42-4340, none of the pictures have a shaft with a step.
https://tinyurl.com/y999zqby and here https://tinyurl.com/y9wgyqeh mine is also stainless.
I would imagine if the makers wanted a step in the shaft to stop it going through the frame plate it would be substantially bigger.
Could your spindle be home made to suit the bush design?
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
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Online mikeb

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I get your point Musky - that's a puny step on my spindle. (? *eek* that sounds all wrong  *eek*?)
and yours Kiwi: a distance piece looks required to make this durable.
So maybe back to silent blocs would be more reliable. I might have another careful look at this tomorrow.

and BTW I really appreciate all the thoughts and comments you guys are offering. This forum rocks! *smile* *smile* *smile*
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'61 Super Rocket  - '47 B33 -  '18 Triumph Street Triple RS

Offline edboy

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the swing arm spindle looks knackered and having the bushes floating on that spindle is not what i thought your conversion consisted of.you need to bore the bushes for a hollow spindle to run between the frame that the bushes rotate on and minimal clearance on the s.a. spindle. look up the honda 750 sohc arrangement for the idea. i use b50 needle rollers instead of bushes . off the shelf and fit the s.a. inner bore. i have the drawings and bearing sizes somewhere and if you message me i ll reply monday  or tuesday

Offline morris

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Converted my SA to bronze bushes a while ago. Still very happy about it
https://www.a7a10.net/forum/index.php?topic=11767.msg90309#msg90309
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Offline wortluck

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Made me smile when I saw the Silentbloc set up on the A10 and how hard the sods were to remove.  When I restored a 1959 BMW R60 back in early 1980s, BMW were already using taper needle rollers!
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Offline edboy

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hi morris. if he was to use top hat bushes he would have to make new ones. i m suggesting  boring out his existing bushes and using a hollow spacer between the shaft and bushes. add a grease nipple, saw and file hollow spindle to width and off you go.