Friday, 4 February 2011

Replacing Viscount bottom bracket bearings

Over last weekend I dismantled the bottom bracket on my 1978 Viscount Aerospace bike and replaced the bearings.  This turned out to be quite straightforward - surprising considering all that has been written about these components, but it is fair to say that, according to a friend with more experience of Viscount bottom brackets, I was lucky with this one.  It wasn’t too stuck and not rusty.

First I took off the cranks.  The spindle wobbled in one of the bearings, showing that replacement was overdue.  It was then necessary to remove the circlips, in theory there to stop the spindle sliding through the bearings but probably not doing anything.  A proper pair of circlip pliers helps, but you can improvise with little screwdrivers or some such.  

To remove the spindle I sized up various tools but picked up a hefty hammer.  I tried putting a bit of wood between the hammer and the end of the spindle, but that didn’t work so I just bashed away.  Should anyone be following this, put the crank screw in the spindle and hit that.  It saves distorting the end of the spindle. However, it might damage the screw, although I was lucky.  I had to file the spindle back into shape.  It slid quite easily out of the bearings although one of them fell apart.  Getting the bearings out required a narrow cold chisel (a six-inch nail might have worked) and the hammer.  There are ‘pullers’ for extracting bearings.  I have one, but the hammer method is fine when the bearings are shot anyway.  The pictures show the shell and the spindle together with an old bearing and a new one (the new one on the left) and the circlips.

I cleaned up the spindle and the seats for the bearings carefully.  I was advised to ‘polish’ the spindle (thanks Steve) and I did that.  I put one bearing on to the spindle, using an old adjustable spanner to convey the taps of my hammer to the inner ring of the bearing.  I thought whether I should put Loctite or anti-seize compound on the spindle and bearing housings and went for the anti-seize, thinking that nothing was likely to move once assembled.  Then I just needed to tap the bearings in, opening up the adjustable spanner to strike their outer rings until they were flush with the shell.  Here’s a picture of this.

After adjusting the position of the spindle and fitting the circlips, the job was done.  The cranks went on nice and square and the result is great - sm-o-o-o-th.

If your bb spindle is damaged or lost there are replacements around.  The length is 122mm or 123mm, depending on who you read.  To my shame, I forgot to measure mine.  Anything from 120 - 123mm would probably work as well.  Phil Wood at one time made a stainless steel spindle that would be bomb-proof.  This one on eBay would probably be ok.  YST made a similar spindle.  There are other options for replacing Viscount bottom brackets, which I will describe another day.

The bearings are numbered ‘6003’, measuring 35mm outside diameter x 17mm inside diameter x 10mm thick.  The ‘6’ gives the type of bearing (single row deep groove) and shows it is a metric size.  The first zero is the series, which indicates the thickness and outside diameter.  The ‘03’ at the end shows that the bore is 17mm.  I found this out from the Gizmology site.  If you are buying bearings for your Viscount or Lambert, you will want 6003-2RS ones.  The 2RS means that both sides have rubbers seals to keep out dirt and grit.