Posted by Banker@teranews.com on April 20, 2010, 10:43 am
Why are tensioners needed?
Inquisitive Banker
Posted by big_piper on April 20, 2010, 11:46 am
Banker@teranews.com wrote:
> Why are tensioners needed?
>
> Inquisitive Banker
A mechanical chain running on cogs or gears needs just the right
amount of "lash" to drive the gears. If the chain is too tight the
mechanism will bind. If it's too loose, it will slam back and forth as
one gear drives the other, linked by the chain. Chains will wear over
time. So will the gears. They also change with temperature. The longer
the chain but more variation there is int he system.
The chain tensioner adjusts for the wear of the system over time.
Gear drive cams have to be fit to tighter tolerances, and they make
more noise. The economics of the assembly line indicate a chain drive
and mechanical tensioner system to be better for the MoFoMoCo. A gear
drive setup is better from a longevity point of view bit it costs more
to fit and it makes more noise.
Personally, I think a better compromise would be a gear follower
instead of the sacrificial shoe. That would be more expensive but not
as expensive as a gear drive system.
--
BigPiper
AH#138
BS#246
Posted by Paul Harwood on April 20, 2010, 12:46 pm
big_piper wrote:
> Banker@teranews.com wrote:
>
>> Why are tensioners needed?
>>
>> Inquisitive Banker
>
>
> A mechanical chain running on cogs or gears needs just the right amount
> of "lash" to drive the gears. If the chain is too tight the mechanism
> will bind. If it's too loose, it will slam back and forth as one gear
> drives the other, linked by the chain. Chains will wear over time. So
> will the gears. They also change with temperature. The longer the chain
> but more variation there is int he system.
> The chain tensioner adjusts for the wear of the system over time.
> Gear drive cams have to be fit to tighter tolerances, and they make more
> noise. The economics of the assembly line indicate a chain drive and
> mechanical tensioner system to be better for the MoFoMoCo. A gear drive
> setup is better from a longevity point of view bit it costs more to fit
> and it makes more noise.
> Personally, I think a better compromise would be a gear follower
> instead of the sacrificial shoe. That would be more expensive but not as
> expensive as a gear drive system.
I agree!
Posted by Phil Boutros on April 21, 2010, 3:00 pm
> A gear
> drive setup is better from a longevity point of view bit it costs more
> to fit and it makes more noise.
AFAIK (from Oh-fish-yul H-D sources), the noise issue is the
only reason they went to chains. They simply couldn't meet EPA noise
requirements with the gears.
Phil...the used-to-be-in-the-loop Asshole(tm)...
--
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Posted by Paul Harwood on April 20, 2010, 12:43 pm
Banker@teranews.com wrote:
> Why are tensioners needed?
>
> Inquisitive Banker
Chains/belts stretch after long hard use, and must be kept taught before
they start slappin around with too much play, from throttle on and off.
That explains why gear/direct drive is so, FAR superior.
That is why, when I rebuilt my 1970 Oldsmobile W-30, I used Joe
Mondello's parts, that included his TWO PIECE timing chain cover, so
that I could replace the cam, chain, and gears, without removing the oil
pan(and consequently the engine) to replace those parts!
Had a gear drive been available at the time, it would have been GRAND!
Straight Cut Gears sound cool, too!
That's why I loved that Muncie M-22 "Rock Crusher!" What a whine!
And no, the Old's Engine had no " Cam Chain tensioner".
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> Inquisitive Banker