Metal Distributor gear

Bernie Benz b.benz at
Tue Nov 20 15:25:40 PST 2007


Its not just the miles, not just the age, but also the health of the  
valve gear drive train that are important factors in the life or  
early failure of the distributor drive gear. An improperly (low)  
tensioned timing belt can lower the torsional resonant frequency and  
thus increase the vibration amplitude of the valve drive resonant  
system. Not a problem on the 10V engines, but the 20V engine‘s valve  
drive has twice the inertia of the 10V, thus a lower resonant  
frequency and higher resonant amplitude, marginal at best. A design  
poorly carried forward without appropriately increasing torsional  
stiffness, from the bullet proof 10V design. Self destructive at its  
worst. With poor maintaince, even with a poor factory TB adjustment,  
new engines have been known to exhibit the dreaded “distributor gear  
rattle” resulting in early timing chain wear and distributor gear  
failure. So, keep your TB tight!


On Nov 20, 2007, at 2:28 PM, Peter Schulz wrote:

> Mike:
> Its not just the miles, its also the age.
> Ask Paul Royal who was left stranded when his gear shattered with
> less than 100k miles on his Avant...
> -Peter
> At 05:18 PM 11/20/2007 -0500, mike claire wrote:
>> I think I'll find a gear, or a used metal gear distributor and I'll
>> replace it next summer.
>> My car barely has 100K easy miles on it so I'm not too worried.
>> Thanks
>> Mike
>> On 11/20/07, PeterBergin at <PeterBergin at> wrote:
>>> I got a gear on the last group buy and installed it with 218k on  
>>> the  car.
>>> The old gear was still intact, however there were fine stress  
>>> crack  lines
>>> from
>>> the center spreading out toward's the gear teeth.  Glad I did it   
>>> now.
>>> Pete
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> -Peter Schulz
> Chelmsford Ma, USA
> 1995.5 S6 Avant Emerald/Ecru
> 1995.5 S6 Avant Silver/Platinum
> 1991 200 20v Q Avant Titan Grey (for sale)
> 1991 90 20v Q Red
> 1991 CQ silver  (eS2 recipient)
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