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Author Topic: A7 Swing arm Bushes - fitting to Swing Arm  (Read 2478 times)

Offline gpo746

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A7 Swing arm Bushes - fitting to Swing Arm
« on: 27.02. 2018 21:33 »
Pic 1 .This is my Swing arm from (I assume !) my 1954 A7 SS .
Pic 2 I just bought these bushes from Southern Division (via eBay) and looking at the measurements there seems to be a 0.75mm difference. Seems to be abit much of a difference.
These bushes are Part No. 42-4115 , (they are the smaller diameter ones) .
Pic 3 Swing arm inside diameter (with wifey being the hand model..I don't have nails that long !)
I realise these bushes have to be pressed in with so many tons of pressure. However with 0.75mm difference I would be worried someting would jam , split or go crack crunch  *eek*... I would appreciate your thoughts guys .
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Offline bsa-bill

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Re: A7 Swing arm Bushes - fitting to Swing Arm
« Reply #1 on: 27.02. 2018 21:42 »
I'd send them back, some years ago I bought a set from a well known BSA dealer and they were just to thick I pressed one in a little and it was obvious it was wrong, apparently you had to put them in a lathe and turn them down a bit (not mentioned at all), not having a lathe I bit the bullet and bought another set from  C&D autos (fitted perfectly).
Also wondered about putting them  in a lathe when there is rubber in there, would it not squeeze up ??
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Offline coater87

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Re: A7 Swing arm Bushes - fitting to Swing Arm
« Reply #2 on: 27.02. 2018 23:03 »
 I had to turn my new set down too.

 They are made incorrectly, and can be corrected as Bill says with a lathe.

 Lee
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Offline duTch

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Re: A7 Swing arm Bushes - fitting to Swing Arm
« Reply #3 on: 27.02. 2018 23:04 »
 
Quote
....apparently you had to put them in a lathe and turn them down a bit (not mentioned at all),.....

Maybe I'm being eccentric,  but I suggest there'd be no guarantee that the outer sleeve be concentric with the inner, and any bit eccentric would magnify with speed *dunno*

 Do you have the old bushes for comparison ?
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Offline gpo746

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Re: A7 Swing arm Bushes - fitting to Swing Arm
« Reply #4 on: 27.02. 2018 23:23 »
Sadly, no..I got the bike in a pile of parts and the swingarm was naked without the bushes , this is the first time I have seen the bushes in the flesh ..what is wrong with the manufacturers?  *conf* Why can they not make things that ACTUALLY fit....!
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Offline Greybeard

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Re: A7 Swing arm Bushes - fitting to Swing Arm
« Reply #5 on: 27.02. 2018 23:26 »
My guess is they are made for a different application or motorcycle and are readily available and cheap.
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Offline gpo746

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Re: A7 Swing arm Bushes - fitting to Swing Arm
« Reply #6 on: 27.02. 2018 23:31 »
Quote from: bsa-bill on 27.02. 2018 21:42
I'd send them back, some years ago I bought a set from a well known BSA dealer and they were just to thick I pressed one in a little and it was obvious it was wrong, apparently you had to put them in a lathe and turn them down a bit (not mentioned at all), not having a lathe I bit the bullet and bought another set from  C&D autos (fitted perfectly).
Also wondered about putting them  in a lathe when there is rubber in there, would it not squeeze up ??
Hi Bill,
        A bit costly to send them back as these people are in Germany . The thickness of the outside tube wall is a shade over 2mm . I am worried that shaving them down will only leave 1.25mm of meat of wall thickness. I am curious to know what the factory BSA or C and D autos repros wall thickness is? . It may seem silly but , I am concerned that the walls will either collapse or ripple under pressure of fitting them. .. am I right to worry?
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Offline KiwiGF

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Re: A7 Swing arm Bushes - fitting to Swing Arm
« Reply #7 on: 28.02. 2018 00:54 »
This thread has some info from my experience with silent blocs aka bushes, and some pics I found 010 interference fit was ok when it came to pressing them in without a large press etc

https://www.a7a10.net/forum/index.php?topic=4293.msg31755#msg31755
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Offline Tomcat

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Re: A7 Swing arm Bushes - fitting to Swing Arm
« Reply #8 on: 28.02. 2018 06:29 »
Yep, the set I bought were too big, so skimmed them in the lathe. I machined them till they felt like they would just about go in by hand. But given the length of the bushes they were tight by the time I pressed the last of them in. This is typical of pattern parts  *eek* and some original parts also need to be custom fitted too. I believe that's called 'fettled' in the UK, LOL
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Offline bsa-bill

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Re: A7 Swing arm Bushes - fitting to Swing Arm
« Reply #9 on: 28.02. 2018 09:10 »
Quote
Why can they not make things that ACTUALLY fit....!

Well they do (often) but nothing to stop dealers buying bushes made for 1 application and selling them for something else (like BSA swinging arms)

Agree with Dutch that turning on a lathe may bring about some eccentricity (helped by the rubber bit), but would think once pressed in it might not matter too much.
Welcome to the wonderful world of after market parts Dom
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Offline gpo746

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Re: A7 Swing arm Bushes - fitting to Swing Arm
« Reply #10 on: 28.02. 2018 11:02 »
Quote from: bsa-bill on 28.02. 2018 09:10
Quote
Why can they not make things that ACTUALLY fit....!

Well they do (often) but nothing to stop dealers buying bushes made for 1 application and selling them for something else (like BSA swinging arms)

Agree with Dutch that turning on a lathe may bring about some eccentricity (helped by the rubber bit), but would think once pressed in it might not matter too much.
Welcome to the wonderful world of after market parts Dom

Hello Bill, I am no stranger to aftermarket parts believe me !  *lol* ..It has just been nearly a decade since I last laid my hands on a Brit bike . Took your advice and contacted C&D autos but sadly NONE IN STOCK !and looks that way for the foreseeable future. So, I am stuffed and looks like I will have to machine the ones I have down.
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Offline gpo746

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Re: A7 Swing arm Bushes - fitting to Swing Arm
« Reply #11 on: 28.02. 2018 11:12 »
Quote from: kiwgf on 28.02. 2018 00:54
This thread has some info from my experience with silent blocs aka bushes, and some pics I found 010 interference fit was ok when it came to pressing them in without a large press etc

https://www.a7a10.net/forum/index.php?topic=4293.msg31755#msg31755

Good Rig you have there ! exactly how I would do it ! Thanks that has confirmed that you should not need a mega ton press to shove them in . I will re-read your thread when it comes to getting mine done . Shame C&D have not got any bushes as I would have bought a set from them .
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Offline gpo746

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Re: A7 Swing arm Bushes - fitting to Swing Arm
« Reply #12 on: 28.02. 2018 14:16 »
Been thinking...   *conf*
Weighing up the pros and cons I think I will return these as they are sub-standard . They are slack on the swing arm shaft to a point where I can "rattle " them side to side on the shaft. They are badly reamed out, not smooth , looks like someone has jiggled a small drillbit inside to get somewhere near the size as they are badly scored inside all over the place . Even If I turned the OD down to fit the swing arm the ID for the shaft will be no good, I will end up with a rickety swing arm .  *eek*
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Offline Greybeard

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Re: A7 Swing arm Bushes - fitting to Swing Arm
« Reply #13 on: 28.02. 2018 15:10 »
Has anyone tried fitting bearings in the swing arm? Would need internal spacer(s). Does the rubber serve a purpose or was it a cheapskate idea?

What are the required sizes: OD 32mm? Internal?
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Greybeard (Neil)
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Offline bsa-bill

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Re: A7 Swing arm Bushes - fitting to Swing Arm
« Reply #14 on: 28.02. 2018 15:48 »
Quote
Does the rubber serve a purpose or was it a cheapskate idea?

I read, heard , or was told the S/A should be tightened up somewhere about the riding position, the rubber then provided some damping/ resistance to the movement, whether that is the case I have no idea but I have yet to see a bush where the rubber has torn away from the rest of the bush.
Could be the S/A moves within the frame (inner sleeve not tightened enough) I don't know it is a funny set up
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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
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