Distributor rattling

Bernie Benz b.benz at charter.net
Tue Jan 27 19:53:44 EST 2004

> From: Phil Rose <pjrose at frontiernet.net>
> Yes, to avoid confusing the easily confused, I ought to have said
> retightening so as to permit _less_ than a 1/4 turn twist.
>> I have never experienced the "distributor rattle" syndrome on either my 3B
>> nor 7A, always running tight belts so, No, I have never cured a nonexistent
>> problem.
> I wasn't expecting that you would have cured "a nonexistent
> problem"--just wondering if the _quantitative_ aspect of your
> "theory" (tighten somewhat beyond the 1/4-turn spec) was based on any
> BTDTexperiences.  I don't disagree with the belt-looseness
> theory--only question if there's any basis to assert that the  "1/4
> turn" (as opposed to 1/5 or 1/6) spec inherently fails to produce a
> properly tightened t-belt. It's just as easy to blame some weak
> fingers. Old Karl, the 300-lb Monkey Lad,, might bring the belt to
> much a different degree of tension (before reaching the same
> "1/4-turn" spec.) than does his new assistant, Gertrude (the 100-lb
> Monkey-Lass). So is the spec at fault? Well _yes_, but not because it
> needs to be changed to 1/5 turn instead of 1/4 turn. It needs to be
> something less subjective--especially for the DIY mechanic.
And just who would you rather have twist your belt?
> I suspect that the typical mechanic, wishing to avoid the rattle
> problem, might simply go much, much tighter than the 1/4-turn spec.
> But I've assumed that "overtightening" could have negative effects
> (i.e., excessive wear of bearings/bushings). Is this not the case
> with t-belts?
I've heard people claim that too tight a belt causes chirping noises, but
have never experienced same, using the Gertrude touch.
> Anyway, in my previous post I described a beneficial effect (i.e.,
> reduced rattling) after i installed a new belt which I adjusted to be
> tighter than the old belt had been (but still not more than the
> 1/4-turn "spec"). So you respond with the opinion that in _my_ case
> the tighter belt must've had nothing to do with reducing distributor
> rattle (see last line, quoted below). Well, Bernie, were you just
> joking, or are you asserting that anyone who tightens the t-belt to
> the 1/4 turn spec will definitely have a  belt that is too loose??
> Incredible!
>>> Of course the basic problem with Audi's (and most other)
>>> belt-tightening specs, is the lack of an objective means to establish
>>> the force--torque in this case--to be used. Over time...and many
>>> t-belt jobs...one presumably gets the required "feel" for belt
>>> tension, but otherwise...it's a pretty darn vague kind of spec.
Can't be very important then.
>> Also, there those DIYers among us insecure enough that they must use an
>> uncalibrated torque wrench on every nut and bolt.
> Oh, dear me, I guess your point is that I'm too "insecure" to
> believe my (1/X-turn) finger-twisting will necessarily result in
> optimum belt tightness?? Yep, guilty as charged. We don't all have
> those calibrated fingertips, Bernie...
It may be more the "Gertrude experience" at least she hasn't complained,
just a chirp.
>>> Ingolstadt's assembly line possibly has a specialist (Karl, the
>>> 300-lb Monkey Lad)  who does nothing all day but twist timing belts.
>>> Phil
>>> P.S. I used my own personal version of that  "1/4 turn spec" for the
>>> t-belt I replaced on the red car, last year; and there's been no
>>> significant distributor rattle. However it did rattle a lot before
>>> the belt change, and the old belt did seem quite loose.
>> IMO, had nothing to do with the belt change.
> I'd like to hear your "rationale" for that opinion.
A 100K TB is just as good as is a new one.


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