Author Topic: B40T swinging arm bushes...  (Read 274 times)

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griffo

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B40T swinging arm bushes...
« on: 21 May, 2018, 15:00:42 »
  I have to change the bushes in my B40 swinging arm. Quite a bit of movement laterally so it must be done to use on roads between sections, Having never tackled this before is there any easy way to do this job ? Yes I have no doubt parentage, stress and big hammers come into a job last done 57 years ago.. All tips heeded unless a trapped finger is involved.. Thanks   ::)   Griff
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AdrianS

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Re: B40T swinging arm bushes...
« Reply #1 on: 21 May, 2018, 16:58:54 »
If they are the same as my 1961 B40, they will be a bit of a pig to do!

My spindle had seized and the bike had to be stripped ( it was during a rebuild) for the frame to be put into a big press.

Several tons later the spindle came out. The bushes in the swinging arm were cut out and new ones pressed in. They had to be reamed in situ for the pivot pin to be refitted. I didn't leave mine as an interference fit in the bushes - just a very snug fit so a gentle tap with a mallet would remove the pivot. Make sure everything is greased up very well! There was also a shim that had to be fitted between the swing arm and the frame to take up lateral movement - cant remember which side without looking but it is important. I think also the handbook says the swing arm should be greased every 500 miles.

AWJDThumper

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Re: B40T swinging arm bushes...
« Reply #2 on: 21 May, 2018, 17:27:04 »
They can be a pig to shift even with an otherwise bare frame. I found that with a 12T hydraulic press it can be very difficult to move the spindle even after a lot of heat has been applied. With the last one I did I found the most effective way of removing the spindle was with a suitable large drift and a club hammer - the impulsive force generated is surprisingly greater than the 12T generated by my press. I'm about to remove a spindle from a Bantam and will let you know how I get on. Once you've overcome the initial stiction, its then easier to get it moving.

griffo

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Re: B40T swinging arm bushes...
« Reply #3 on: 21 May, 2018, 20:53:02 »
Thanks lads , just as I thought , a pig. Got a big 'ammer but not too much energy now-a-days as age is creeping up. I'll have a go and if Mabel does not give the money (age tester) I'll batter the bugger out....  ;D   Griff
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AWJDThumper

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Re: B40T swinging arm bushes...
« Reply #4 on: 22 May, 2018, 07:48:47 »
Use as much heat as you can on the frame around the swinging arm pivot. My frame is going to be powdered coated and so I can use a blow torch. If you want to protect the paintwork, use a hot air gun to raise the temperature as much as possible. As said, the main problem is breaking the initial stiction due to the pivot rusting in the frame. Once you start to get it moving, the job will become much easier.

AWJDThumper

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Re: B40T swinging arm bushes...
« Reply #5 on: 22 May, 2018, 12:03:37 »
Just removed the spindle which drifted out quite easily with the minimum of heat needed. In my case, I needed to remove take the swinging arm apart in order to get the frame powder coated otherwise the trapped grease will cause a problem in the baking oven. Fortunately, the bushes don't need replacing although this is normally straightforward if you have the correct size reamer to use afterwards.

hock79

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Re: B40T swinging arm bushes...
« Reply #6 on: 05 June, 2018, 06:30:03 »
Hi, I have to do the same for my C15.

Iíve never used a drift before (which may lead to me breaking either myself or the bike).

Can anyone recommend one to buy? Size, shape etc

There seems to be a few options out there and I just want to make sure I use the right one for the job.

Thanks

AWJDThumper

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Re: B40T swinging arm bushes...
« Reply #7 on: 05 June, 2018, 06:40:22 »
The C15/B40 swinging arm spindle is drilled through from either end about 1.5" or so and then tapped. I think the Bantam spindle is exactly the same and so when I drifted one of these out recently I simply inserted a long 3/8" bolt (I believe) into the bottom of the drilled hole and used a club hammer to drift out the spindle. The alternative is to use a ~3/4" bar of metal against the end of the spindle but you risk damaging it this way.

griffo

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Re: B40T swinging arm bushes...
« Reply #8 on: 09 June, 2018, 21:54:52 »
 Had a lucky day. Hit the spindle with a lump hammer and drift and the thing flew out. Second hit.... Question.. Is it worth putting in roller bearings to replace the bronze bushes ? If using the bushes would it need a reamer to fit them to the new  spindle.... Griff
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AdrianS

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Re: B40T swinging arm bushes...
« Reply #9 on: 10 June, 2018, 08:15:49 »
 Not sure about roller bearings. The bushes are not very thick and I would assume the swing arm would need machining to take any available roller bearings. I think a properly set up original arrangement if looked after will last many years!

griffo

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Re: B40T swinging arm bushes...
« Reply #10 on: 10 June, 2018, 08:25:17 »
Yes , thought the same myself as these have lasted best part of 60 years. Will not be around for that amount of time myself .. 135 and riding a trialer.... Griff
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JulianS

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Re: B40T swinging arm bushes...
« Reply #11 on: 10 June, 2018, 09:58:14 »
If your bushes are steel backed ( like used in the 1969/1970 A50 and A65) I would expect them to be pre sized because the bronze alloy is quite thin and would not really be suitable for reaming. The supplier should be able to advise if they are pre sized.

They need to be pressed in squarely then you can check the fit of the new pin.

If bushes are all bronze alloy they will more than likely need to be line reamed after pressing into swinging arm.

Below is an article from 1966 showing reaming the bushes.

griffo

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Re: B40T swinging arm bushes...
« Reply #12 on: 15 June, 2018, 19:41:28 »
Bushes in and reamed. A few delicate taps with a lump hammer and all is home and greased. Back wheel in again to-morrow then dirty again on Sunday. Grand week as all flowed (so far) to plan. Griff
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