From: svoboda@rtsg.mot.com (David Svoboda)
Subject: Re: lane-splitting etiquette (& **** Harley questions ****)
Organization: Motorola Inc., Cellular Infrastructure Group
Date: Tue, 5 Jan 1993 06:07:49 GMT

In article <1993Jan4.184645.14034@megatek.com> tomw@megatek.com writes:
|In article <1992Dec30.204916.14840@rtsg.mot.com> svoboda@rtsg.mot.com (David Svoboda) writes:
|>
|>Chains are better now.  Even back then, I assume you neglected your chain to
|>have such a catastrophic failure.
|
|Not so. This was a well known problem for the first 2 years of the Honda 
|CB-750. The chain setup was inadequately engineered. This is not surprising.
|The bike had so many inovations (first of the new wave of multi's, first
|mass produced motocycle disk break, etc.) that it had to have a weak point. 
|The problem was so common that engine cases were unobtainable. Aftermarket
|duplex chain kits were even produced.

I'll give you that.  But that doesn't happen any more.  Unless a chain is
grossly neglected, it does not catastrophically fail.  That's a red herring,
based on data from 20 years ago.  Hell, Harley was using a chain then, too.

|It seems to me that you've made my point. Belts require *no* maintenance
|and even when totally neglected last longer that even the best cared for 
|chains. 

No.  Belts fail.  They get holes, they wear.  I have seen it.  I have
even helped someone replace a belt.  It sucks.

|And even with light oiling, chains still make a mess of the rear wheel.

That is undeniably an advantage that belts share with shafts.  Cleaning
a rear wheel is a pain.  If you object to it, use a non-sticky lube, and
it washes off as easy as any road grime.

|I've never heard of a chain lasting 50K miles. Have you personally achieved
|this? 

My personal best is 47K miles.

|And if you did, did you oil your chain 200 times and clean it 50 times?
|Even using your very optomistic 30 second figure for oiling only, that 1.5+ 
|hours of chain oiling. Myself, I'd rather be riding my bike.

Cute.  Careful who you compare mileage or hours with.  You might lose.

I lube a chain every 400 miles, and clean it monthly.  I ride in rain, and
some dust.  Rarely in a salt environment.  But dealing with a chain is a
pain, no doubt.  That is an advantage of belts and shafts.

|>Chains are required for situations of high stress and low clearance.  A belt
|>just cannot take that sort of stress.  
|
|I believe I've read that supercharger belts on top fuel dragsters transmit 
|roughly 300 hp. Clearly if chains were better for this, these people would 
|use chains. 

Now you are WAY in left field.  Steel is stronger than rubber.  It's not a
hard concept.  Have a look at hopped up Harley dragsters, and tell me how
many use belt drive.  For that matter, if a belt is so strong and reliable
in a hostile environment, why isn't Chris Carr using one?

In order to transfer the kind of power necessary for really strong performance,
a belt would have to be very wide.  Chains are smaller for similar strength.
Have you ever seen a supercharger belt?  It's BIG.

In any case, 300hp seems ludicrously high for a small compressor.  I would
like to see your reference, on that one.

|>And any environment that you subject
|>a chain to, I expect you subject the belt to.  Belts die, too, and are MUCH
|>more expensive (time and money) to replace.
|
|While belts are in the same hostile environment, they are not oiled and so
|road dirt does not stick to them. Once the dirt is stuck to the chain, it
|works its way into the innards and adds to the wear. 

Agreed, but the time you spend keeping them clean is easily offset by the
looser tolerences of a chain.  Working with a chain takes no special tools,
and is perfect for the backyard mechanic.  Isn't easy maintenance supposed to
be one of Harley's selling points?

|>Is it even possible to change the drive ratio, with a belt?
|
|Same as a chain: get alternative sprockets.

Please name a vendor for aftermarket pulleys.  I certainly haven't seen
them in catalogs.  And it's MUCH harder to change a pulley and adjust it
than a chain.  Most non-pros wouldn't even attempt it.

|>At least on my shaft drive bike, the oil can be changed very easily, and no
|>measuring is necessary.  The drain plug is right in plain sight, and you just
|>fill it until you can't any more.
|
|Still, you have to do it. Again, belts require *no* maintenance.

They should be checked occasionally.  A *slight* maladjustment can destroy
a belt.  But yes, it's less total maintenance.  But the maintainance is
such that the typical backyard mechanic can't do it.

Quibbling about a three minute job once a year is pretty silly.  Shafts are
close to belts in ease of maintenance.  And they last longer.

|There was a posting about a big twin with something like 150K miles that was
|still on the original belt. Because the belt is so much softer than the 
|sprockets, the sprockets almost never need to be replaced. I suspect that mile 
|for mile, by the time you wear out two sets of chain sprockets and two or more 
|chains, I would still be only on my second belt.

Of course, if you have sixty horsepower, and rarely use it, you don't wear
a final-drive much.  Most users of chains push them a little harder.  Hop up
the Harley to about 90hp at the rear wheel, do a lot of hard acceleration, and
see how long the belt lasts.  That would be a fair comparison to a Japanese
sport bike with chain.

|>|They're clean, tight, 
|>
|>Agree.  Those are the saving graces of belts.  I think a belt is just about
|>perfect for the Harley intent.
|
|Here we agree totally. I would say that yours is the best answer yet for the 
|orginal question, (paraphrased) why did Harley decide to put a belt on the 
|big twin?

Though I was just reading an article that showed how small out-of-round
conditions in wheel pulleys can destroy belts.  This is apparently a 
fairly common vendor problem at Harley.  They do not check the accuracy
of the pulleys at the factory.   And the accuracy of the pulleys only 
decreases with time, as sand and grit get between the belt and pulley
and wear it down.  Only four thousanths runout on that pulley puts the
belt tension out of spec.

Chains have no such critical measurements.  Hell, you can eyeball a
chain.  That's good enough.

I guess I should have said, "Perfect for the Harley intent of weaning
the Harley owner away from backyard maintenance, and into the shop."

Really, belts are well suited to the kind of use environment in a
Harley rear drive.  They are quiet and provide power-pulse damping.
They take little maintenance, usually just a check by the shop on
the yearly tuneup.  But they are NOT without problems, and they
are NOT suitable for many other applications.

I expect part of the reason they are on Harleys is they are just
a different way to accomplish the task, that sets them apart from
most of the competition.

			Dave Svoboda, Chicago