Something to be aware of.

I have covered a few thousand kilometres now since I bought the bike, and love the lightness and the way that it handles. The suspension is adjustable for spring pre-load, rebound and compression damping both front and rear. I have dropped the front forks down a little through the top yoke to sharpen it a bit and enjoy the ride. It has a new Metzler Z6 tyre fitted to the back and a worn Bridgestone on the front.

There was always a slight niggle about the fast cornering which I put down to the part worn front tyre. It often felt like there was a very slight “step” when banking over so I have ordered a new Z6 front tyre, €74 from Oponeo.fr including delivery.

After a quick ride out today, the sun was still shining on our return, so Jude, my wife, set about cleaning her BMW F800ST. I decided to fit the new footrest rubbers that I had bought from the Ducati dealer this week. After fitting I thought that it might be a good idea to put a plank of wood under the rear tyre while on the centre stand, to see how hard the rear felt. To my amazement there was some play in the suspension. I could feel that there was about 5 to 10mm of movement at the tyre before the slack was taken up. After investigation it was located at the bottom of the rear shock tie-rod mount.

The bolt that holds this and the bottom of the rear shock can be reached through a hole in the right hand side of the swinging arm with a long 8mm allen key, on the other end of this (left side) there appeared to be a strange nut with two vertical flats. As I removed everything all became clear. The nut was in fact a bush with a thread in it. For the bush to work the flats had to be horizontal otherwise the bush part will not sit into the hole around the bolt! After correct reassembly all the play has gone.

Some pictures:

bush

Item 12 is the bush shown with the flats horizontal.

DSCF6097sThis is where the part is located and can be checked without dismantling anything.

DSCF6098sHere the flats are horizontal as it should be and the whole bush is sitting inside the recess in the swinging arm which ensures that the bush is in the bolt hole. As can be seen from the picture, if the flats are vertical then the bush will sit on the ridges on the swinging arm and not be seated correctly. The handling of the bike is now transformed.

I am not sure how this was fitted incorrectly, it could have been a previous owner or it could also have been some apprentice at a motorcycle workshop, but my advice is that any ST owner can look at this without getting their hand dirty and should do so if anyone else ever works on their bike!

 

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One thought on “Something to be aware of.

  1. brian May 8, 2015 / 8:35 am

    Hi Bob,
    I had a look at the spare ST2 swinging arm i have, the ‘nut’ is swaged in and even with a tap on the bolt head it does not move!!
    The ST3 is similar. I suppose that each time i removed the bolt it just screwed back up , and yes, was always torqued. So either it was always like that or something caused it to come loose in its mounting.

    Like

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