[DeTomaso] Damper balance problem ???

[John Bentley (jab)]

Patrick,

There are two things to consider when talking about balancers...

1) The fixed, first-order balance.  This balance you can feel when the
engine is running if the balance is wrong.  If it was wrong, in addition
to vibrations you can feel, the front crank bearing would have a strange
wear pattern (IMO).  I'd want to know what type of balancer came off the
engine and what type was put on.

2) The outer ring of the balancer is connected to the inner portion by a
rubber or elastomer that damps 2nd-order (or higher) torsional moments.
You cannot feel this "balance".  If it isn't working properly, it can
cause severe damage to the crank.  There will be one or more resonances
at a particular rpm where that load is high enough to break the crank.
Since you can't "feel" it, there is no way to predict that particular
rpm and avoid it.  Yes, there are other aftermarket fluid dampers, but
I'm assuming you are talking about stock-type dampers.

Without knowing the internal/external balance of each engine, it's a
crap-shoot when swapping dampeners from one engine to another and I
would avoid it.  I'd talk to whoever balanced the engine in question and
get his thoughts.  One of my engines is internally balanced and uses a
fluidamper and the other is externally balanced and uses a stock
dampener.  Both work fine.

JB


 

-----Original Message-----
From: detomaso-bounces at realbig.com [mailto:detomaso-bounces at realbig.com]
On Behalf Of Patrick Hals
Sent: Wednesday, December 06, 2006 5:28 AM
To: detomaso at realbig.com
Subject: [DeTomaso] Damper balance problem ???

Hi All
This question is for a friend of mine, new Pantera owner,  who
experiences a problematic situation with a brand new 351 C longblock:
Does it make sense to you that a damper, coming from a 351 C engine,
once properly installed on another new 351C engine, could cause major
crank and bearings problems after 1000 miles only, while carefully
driven at no more than 4500 RPM ? ( Oil pressure significantly drops,
crank's bearings in poor condition...)
I must precise that the new engine is a 2 bolts high performance
longblock, with a remanufactured standard crank, new Arias pistons and
Crower rods, all properly balanced, but that the damper and final
assembly was made by another careful workshop. The engine , after final
assembly,  was not finetuned on the dyno, before being put in the
enginebay.
Many thanks
Patrick - Candy 2862
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