G'day all ,
Just thought I might share with you some experience and information about
the baulk rings (or synchro rings) fitted to ribbed case gearboxes. Part
number 22G2033.
First a little history. The original baulk rings were machined steel,
and in 1983 (I think I have the right date) they cost around $38 Oz dollars.
Suddenly the price dropped to $3.50. "Why is this so" we all asked - but
not too loudly in case someone discovered a mistake and the price went
back up. Well the reason is simple - they weren't machined steel any more,
but made of sintered material. Imagine metal filings being stamped into
shape. A much simpler process. (Just as an aside, the rocker gear on BMC
engines changed to the square profile sintered ones at the same time.)
But there was another change, that we really didn't pay much notice of.
The steel baulk rings had flat contact surfaces where the ring sits against
the gear, with fine grooves to dispel the oil so you don't get the ring
"aquaplaning" on the gear. The sintered ones were much more pointed, not
unlike saw teeth.
Now to the point. Have any of you had trouble lately with baulk rings
that just don't last very long? We rebuilt two Mini gearboxes at Chrismas,
and within 1 month they were both back for new synchros. A customer mechanic
rebuilt his customer's Midget gearbox about 6 weeks ago, worked perfectly,
and within 500 miles his customer was back complaining of it crunching
in gears. On inspection, the baulk rings were not gripping any more, but
riding on the flat surface of the gear. I know three people, very good
mechanics with over 30 years of experience on BMC products, who simply
will not rebuild gearboxes any more. They give the job,the customer and
the problem, to someone else.
Why are we having this problem?
Two explanations.
1.. The points on the baulk rings wear much more quickly than the original
flat surface, and in a very short time the ring no longer grips.
2.. The baulk rings are expanding, with the same result. This isn't
conjecture - we have measured a few that have "grown" in diameter. I and
a few other people I know have tried to make a claim on Rover UK (the
supplier of these "original" baulk rings) through our suppliers, and Rover
is totally disinterested in the matter.
Is it co-incidence then that Rover has decided to discontinue manufacture
of baulk rings? Now I don't state this as a fact, but as what our two
largest importers and wholesalers have told me. It seems that BMW, who
bought Rover from the Brits for $1, are starting to discontiue some of
the older lines, and 22G2033 is now NLA.
But the good news. Another manufacturer (no I don't know who) has taken
up the mantle and is producing these baulk rings. And guess what - they
have flat contact surfaces, just like the pre-1983 ones.
So the moral of the story is: if you are about to rebuild a gearbox,
don't use baulk rings in the Rover packets. Use the new ones, which are
a brownish colour and easily identifiable by the flat profiles on the
inner surface.
avagoodday Colin
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