Sunday, 30 October 2011

Broken bottom bracket spindle!

Last week I suffered a broken bottom bracket spindle on my Viscount Pro bike, which dates from about 1978.  Like some other Lambert and Viscount components, the spindle has had a bad press, but I reckon around 33 years is not a bad service life for such a highly stressed part.  The break was not at the circlip grooves, which have been suggested as bad features of the design by acting as stress concentrators, but right against the left hand (non-drive side) crank - possibly where the taper starts.  I think the break may have begun a couple of weeks ago - there had been some creaking from the crank.  Before that the crank had worked loose a couple of times - so perhaps the unusual stresses had initiated the crack that began the break.
Not having a spare Viscount spindle handy, I took one from another of my bikes - a Viscount Aerospace Sport, also dating from the late 1970s.  The bottom bracket bearings on the Sport were almost seized and needed replacing anyway.  
Unfortunately, unlike when I replaced the bearings in the Pro a few blogs ago, the replacement spindle was very difficult to remove from the donor bike.  I had to bash it hard with a big hammer and consequently I had to file the tapers back into shape afterwards.  It proved to be quite rusty in the middle part.  Eventually I got the new spindle into place on the Pro (the earlier blog has more details of the process and photos).  I hope the bad treatment with the hammer has not started any micro cracks that will limit the life of the replacement.
In the blog about bottom bracket bearings (4 February 2011) I was a bit vague about the length of the spindle.  In fact the Viscount bottom bracket shell is the British standard 68mm, so there is 68mm between the circlip grooves.  On the drive side there is 29mm to the end of the spindle, on the left it is 24mm, making 121mm total length.  The asymmetry is to do with getting the right chain line, but it is a bit of a mystery why it was done that way and replacement with non-Viscount symmetrical 124 or 125mm spindles seems to work as well as, if not better than the original.
There has been a long gap in these blogs but I hope to get going again.  Thanks for the interesting comments.  I will be answering questions raised and discussing other Viscount & Lambert issues.  Subjects that have occurred to me include: model names and specifications; decals (transfers) and stickers; brakes; saddles; other unique parts; and frame numbering.  Perhaps we could start a register of Lambert & Viscount bikes?