Re: hydraulic t-belt tensioner rebuild

["Daegrigg (Don)" <daegrigg@xxxxxxxxxxx>]

Joe,

There was a very thorough discussion of the various tensioner options back
in April.  Search the archives for more info.  Also the 164 discussion page
has some excellent information.

Don

----- Original Message -----
From: Joe Elliott <jee@domain.elided>
To: <hmdecampo@domain.elided>
Cc: <alfa@domain.elided>
Sent: Monday, July 28, 2003 12:53 PM
Subject: RE: hydraulic t-belt tensioner rebuild


> --On Monday, July 28, 2003 9:36 AM -0700 "H. Martin de'Campo"
> <humanatek@domain.elided> wrote:
>
> > Joe Elliott wrote regarding belt detensioners:
> >
> >
> > "the Zat detensioner has no accomodation for
> > the thermal expansion of an all-aluminum engine.  Don't other
> > manufacturers just use a spring?  It seems to me that that would work
> > beautifully, because the engine doesn't expand enough for delta x in
> > Hooke's law to be appreciable, so the force exerted by the spring would
> > remain rougly constant as the motor expanded, and consequently belt
> > tension would remain roughly constant.  At least a lot more  constant
> > than with the scary (albeit reliable, thus far, knock wood) Zat device.
> > And a big ol' spring probably won't leak or break either.   Joe Elliott
> > '82 GTV-6"
> >
> > JOE:  YOU'RE BEATING A DEAD HORSE, YOUR ZAT DETENSIONER IS THE BEST AND
> > MOST RELIABLE RESOURCE TO RESOLVE THE DETENSIONER ISSUE.  MOREOVER, AS
> > MANY OF US KNOW THERE IS A BAD BATCH OF SPRINGS IN MANY OF THE
> > DETENSIONERS BEING SOLD BY MANY OF THE ALFA PARTS SHOPS...  I'VE DONE
> > SOME CALCULATIONS ON THE MOTORS THERMAL EXPANSION AND THE TRUTH IS ALFA
> > NEVER NEEDED TO PLACE AN "ADJUSTABLE" DETENSIONER BECAUSE THE ALLOY
> > EXPANSION IS THE EQUIVALENT OF THE THICKNESS OF A SHEET OF PAPER!  IN
> > TODAY'S MODERN ALL ALLOY BLOCKED MOTORS LIKE HONDA, ACURA, NISSAN, FORD,
> > ETC... NO ONE USES A DETENSIONER ANYMORE DESPITE THEY'RE ALL ALUMINUM
> > BLOCK.  WHY?  BECAUSE MOST MANUFACTURERS NOW KNOW THAT THE SO-CALLED
> > THERMAL EXPANSION IS NEAR NIL OR NEGLIGIBLE AT BEST.  SO... MY
> > RECOMMENDATION IS WORRY ABOUT SOMETHING ELSE, B/C IF YOU'RE USING THE
ZAT
> > DEVICE YOU'LL BE FINE.  THAT'S WHAT I'M USING IN MY CALLAWAY. AND THAT'S
> > WHAT MODERN MANUFACTURERS ARE DOING TODAY...
> >
> > My 2 cents.
> >
> > H. Martin de'Campo
> >
> >
>
> I agree that the dynamic aspect of Alfa's tensioners was silly, but do
> other manufacturers really use a fixed mechanism like Zat's?  I could have
> sworn that BMW used a spring so that tension would remain roughly constant
> even if the engine did expand.  And the expansion must be more than the
> thickness of a sheet of paper--just feel the tension in the belt on a
> Zat-equipped car when it's cold, and again when hot--it gets appreciably
> tighter.
>
> Joe Elliott
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