10/20/2000

SONIC TECH NOTE SERIES:

SONiC TECH NOTE SERIES:

After market Light weight crankshaft pulleys

Condition: 
Flywheel/harmonic dampener and crank bolts coming loose, engine 
bearing problems

Never remove the factory crank pulley on any engine to replace it with a 
performance pulley or light weight performance pulley.  To replace the 
factory engineered pulley with something made by a person or company that 
does not understand the complete engine design will hurt the 
performance/reliability of your engine not help it.

Toyota and many other manufactures such as BMW, Porsche, Mercedes all use 
dual mode damper pulley designs in all their engines.  I have also received 
a similar tech note on crank pulley's from Dinan Engineering (BMW 
performance).

The factory stock pulley is designed to absorb both torsion and bending 
lateral vibration from the crankshaft.  This helps the crankshaft deal with 
high vibration in the 400 Hz range after the #1 piston fires.  Overall this 
has many benefits on the bottom end.  It helps the crank deal with high 
continuous loads as well as overall bearing life, not to mention overall 
engine life.  Also the drive-line will have a more pleasing sound with very 
little 400Hz vibe's setting up.

See the following jpeg pictures from a Toyota engineering book discussing this!!


 

Also see:
http://suprasonic.org/public_html/sonictech/dinantech/dinan.html

A number of times I have personally seen bad side effects on street and 
track cars using these after market crank pulleys.  Avoid them, there are 
other good performance upgrades that will not hamper the reliability of your 
nice engine.

I understand that this topic has seen many flame war's back and forth on all 
of our supra club mail lists and other car lists around the country. 
I personally don't mind this at all, I feel it is my responsibility to tell our members
about correct and documented information such as this topic regardless of the flame
wars it could result.

Please send any flame comments with regard to this directly to 
regr@me.com e-mail address so as not to bog down the list servers with 
this type of email. 

There has been too much disregard the past year on all of our club web sites 
with regard to erroneous information being given to many car club members around 
the world. 

Our sites should only offer good upgrades for Toyotas.  Upgrades that will not hurt the 
reliability of the car.
 

Regards
 

Reg Riemer

Written by Reg Riemer Copyright Sonic 1997 (free to distribute and copy in this original format)


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