Traction Avant

Sir,
Although we are only a comparatively small B.M.C. garage we repair a lot of Minis and 1100s and think that our experience (from the other side) may be of interest.

The failure of the constant velocity joint in many cases can be put down to manufacturing tolerances or to mis-sizing when assembling (Birfield make the ball cages in three sizes, i.e. standard, plus .004 in. and plus .010 in.). This is usually the case when the failure occurs early in the joint’s life.

The ingress of water into the joint causes the grease to solidify and lose its lubricating properties, then starts “the knock.” This happens even though the boot and crimped on aluminium band may appear perfect. A split boot is also a common cause. The centrifugal motion of the shaft seems to throw the grease out but lets water or grit in. Some c.v. joints have to be replaced due to wear and tear, 60,000 miles is the normal life, but this can go up to 100,000 miles and over on joints that have been checked regularly and where split boots have been discovered and replaced early.

The repair costs some of your readers mention seem rather high; perhaps they have been having complete shafts fitted instead of replacing only the c.v. joint. A fair price for changing a c.v. joint would be £2 10s, labour plus parts (c.v. joint, grease, boot and circlip) £8, or slightly less, should cover the complete job. It may console some of your readers to know that we have had no trouble at all with cars which have been made in the last 18 months.

Better quality control during manufacture and modified boots seem to be making this a reliable unit. The troubles apparently coincided with the introduction of the 1100s when production figures had to be doubled. The coupling (hooke joint) which is also complained about has several reasons for failure too: oil leaking on the coupling, poor bonding of the rubber to the steel cross; fierce or juddering clutch; over-tightening of “U”-bolts; and brutal driving techniques. The current coupling is now made of harder rubber and only the “S”-types seem able to break them, and this only when being driven hard.

We like Mr. Issigonis’s Minis and 1100s which are now benefiting from a long production run. Given another 20 years they may have a reputation better than Volkswagen’s ! !

Birmingham. N.N. Bailey.
[Letters have been pouring in but we think sufficient have been published to clarify the position, so this correspondence is now closed.—E.d.