RE: timing chains and sprockets

[James Montebello <jamesm@domain.elided>]

The rarity should be a clue about how often they're replaced.  Timing
chains are commonly available, but the sprockets aren't.  This tells
me there's no ready market for the sprockets, but obviously a healthy
market for the chains.

Still, I'm a bit puzzled by the apparent need for chains to be replaced
all that often.  My primary experience with drive chain wear and
replacement is with motorcycle drive chains, which most commonly wear
out because of dirt and misalignment (not to mention having to transmit
80-120hp).  Sprockets wear quickly, too.  However, I've had well-cared
for drive chains last 35-40K miles.  Timing chains, by comparison, live
in a relatively dirt-free environment, don't suffer from misalignment,
have a constant bath of fresh oil, and are even double-row, which I would
think would improve strength and durability.  Given all that, I'd expect
a timing chain to last the life of the car (or at least over 100K miles).

james montebello

On Wed, 4 Dec 2002, White Anthony wrote:

> Kind Alfisti,
>
> So the prices I was quoted for parts snapped me swiftly and unpleasantly from any illusions about replacing timing sprockets.  Particularly the intermediate sprocket, which was priced at $900.  This, for the record, is what I paid for my entire car.
>
> And why does the parts department explain what the price would be if a part were available?  "A crankshaft timing sprocket would be priced at $126, but they haven't been available for a long time now."  Sure, good, I'll take two of them, then.
>
> Ah well.
> So it goes.
>
> Regards,
> Anthony
> .
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