5 cyl interference

[Lawrence C Leung]

Chain drives and gear drives are considerably noiser than their belt
counterparts (ask a SAAB owner). And, due to the need to lubricate the
chain or gear drive, the block has to be longer, consequentially heavier,
and more expensive, especially when one now must cast a galley for the
timing drive system. With belts capable of going the equivalent of an
average of 5 to 10 years, and chain drive systems generally going just
about as long, what is the loss using a belt drive?

LL - NY

BTW - the very argument above is what delayed the implementation and
marketing of 16V version of the VW 1.8 liter 4 for almost 3 years. They
finally ended up with a belt to the exhaust cam and a smaller, quieter
(than a long chain) chain from the exhaust cam to the intake cam. And the
engine is most definitely noiser than the 8V. BUT the short chain (vs a
long one, with many more wearing links) does have a much longer life than
a belt. 

On Tue, 30 Jan 2001 00:31:10 -0500 cobram at juno.com writes:
>JanDebL at aol.com writes:
>
>> should design a camshaft drive that doesn't fail instead of the 
>> current belt design that looks like it was stolen from a sewing
>machine.  
>
>Oh, they have them.  Mercedes has always used the tried and true 
>chain
>driven cam system, and their engines rev pretty high and perform 
>pretty
>well too.  The only "problem" they ever had was when they went to the
>single row chain in the early V8 380 engines-which they corrected for
>free by replacing with a double row setup.  The single row chain 
>STILL
>lasts about 100K miles though.  
>There are kits that replace GM style V8 chain/sprocket setups with 
>solid
>gearing,  very simple systems, one gear on top, one on bottom and two 
>in
>the middle-chain eliminated.
>With the new alloys and space age polymers out there, it is rather
>surprising (and dissapointing) that all the less 
>engineering/maintenance
>intensive systems are not put into production cars.  I guess their
>rational is that they only have to worry about the new car purchaser, 
>and
>his warranty service.  After warranties expire,  timing belt 
>replacements
>(and damage thereafter) becomes a cash cow to keep the dealers 
>service
>dept in the black.  So why bother?
>
>BCNU,
>Cobram at Juno.Com
>http://www.geocities.com/MotorCity/Flats/1469/
>
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