domi swing arm

Hi Giles

You can get the outer part of the bush out either with a press and press them all the way through.

The tube is paralell so no problem there or you can get a small grinder and grind them until they split.

Be aware though you will need a good press to get them back in they are very tight and a peice of stud bar with 2 nuts does not work.

Also the spindle should be a nice snug fit in the bushes if its not I would suggest you replace it.

Hope that helps.

I have always though that Norton had it wrong with 'Silentbloc' S/A bushes. There is a parallel on old cars where some used to have many 'Metalastik' mounts thatoperate on the sameprinciple- isolate vibration from the chassis. In the case of rubber-mounted bushes I would expect the spindle to rotate freely (with an engineering clearance) in the bushes and be well greased in the space between as they are effectively "sealed-for-life". The problem is that they seem to be a tight, interference fit with no rotation in the inner bush at all - this puts the rubber in rotational shear. Not ideal in my opinion as its diameter is too small.

Before I got my frame and S/A stove enamelled I was worried about getting the old bushes out first. A nameless NOC member (Don't want to name him in case it doesn't work out!) suggested I just leave them as stoving doesn't usually damage them. It seems to have been right as they are still tight - too tight in my thinking, as I said! Dunno if they'll ride OK but I think it was wiorth trying just to avoid the aggro of getting the old ones out. Burning them is just butchery! Not a sound engineering method either!

Cheers, Lionel

Hi Giles.

Perhaps you could cut a slot through the outer remaining part of the bearing with a hacksaw blade. You could then prise along the slot to get some freedom from the tight fit inside the swing arm.

As you have already set fire to the bearing you can always reheat the outer swingarm area so there is some expansion to aid the clearance. I would also soak the outer bearing with penetrating oil for several hours or longer.

After the above you can select a heavy rod to fit through and with a slight angle you can make contact with the inner edge of the other bearing outer and with a hammer it out. As soon it starts to shift it become easier very quickly.

It doesn't matter about the loose fit of the spindle as the inner part of the SilenBloc bearings push internally against a spacer so the whole lot is pinched up tight when you tighten the spindle nuts. The spindle then does not move in relation to the inner part of the bearing so no wear can take place. All swingarm movemt is derived via the rubber being distorted.

Picking up some points that Lionel makes, the angular distortion of the rubber isquite small and has proved to last nearly for ever.

You must remember that when you tighten the spindle to trap the bearings you must apply a riders weight to the machine or position the swingarm that replicates that of a loaded machine. This will mean the rubber only has to flex 50% downwards of the TOTALswing arm movement and 50%upwards thus keeping any distortion to around 10 degrees of rotation in any direction(my guestimate)

Hope this helps

Les

Hi Giles

Les is not quite right to say that the spindle does not need to be a good fit in the bushes.

If the spindle is loose in the bore of the bushes that will allow the swing arm to move from side to side.

This will cause more wear and will put excess strain on the pivot points in the frame.

The spindle needs to be a good fit and if its not then a new one should be fitted.

Just clamping it all tight will not be enough to take up the play in the spaindle and hold it in place.

As for heating the swingarm to force out the bushes that will be difficult as both the bush and swingarm are steel so will expand at the same rate, if you saw through them though that should free them enough to get them out.

If your raelly struggling send me the swinging arm and I will do it for you.

Hope that helps.

Nigel.

Previously wrote:

Hi Giles

Les is not quite right to say that the spindle does not need to be a good fit in the bushes.

If the spindle is loose in the bore of the bushes that will allow the swing arm to move from side to side.

This will cause more wear and will put excess strain on the pivot points in the frame.

The spindle needs to be a good fit and if its not then a new one should be fitted.

Just clamping it all tight will not be enough to take up the play in the spaindle and hold it in place.

As for heating the swingarm to force out the bushes that will be difficult as both the bush and swingarm are steel so will expand at the same rate, if you saw through them though that should free them enough to get them out.

If your raelly struggling send me the swinging arm and I will do it for you.

Hope that helps.

Nigel.

Hi Nigel. Yes I agree that there should not be radial play on the spindle to bearing. I just pictured that Giles meant that the looseness was free rotary movement rather than anactualsloppiness. I thought he was concerned that the spindle was turning in the bearing, but tightening the spindle locks it all up. If he did mean it wasso loose it was rocking then this is not right.

As far as heating goes, I would also agree that if everything was heated tothe same temperature thenthe loosening would be very slight if anything at all, but I pictured the heat would be applied to the external surface oftheswingarm tube endsrather than the hole set including the bearing thusleaving the inner bearing shielded and somewhat cooler. This method will create a temperature gradient (through conduction) accentuated byany rust orcorrosion around the outer skin of the bush whichacts as an insulator to the heat conduction tosome extent so heating this way does produce a temperature diference between bush material and swingarmwhich can aid removal just a little, and a good thumping with suitable drifts will see it moving out. Personally, I would not have heated it up in the first place though and just relied on a long soak of penetrating oil before attempted removal.

Regards

Les