Lightweight pulley+bse kit bad or good?

[sugarfree]

Hey guys fairly new to the forum but not to the import scene just had a quick question regarding lightweight pulley's. Its always been my understanding that the stock pulley soaks up all the vibrations from the crank and that since aftermarket pulley's don't do this it's hell on the crank bearings. I have both a underdrive pulley and balance shaft eliminator kit on my 2g. Am I adding insult to injury to a car that is prone to crank walk in the first place and is the combo I have a"double whammy" per say? I just recently found out the po installed the pulley so please no flaming thanks for the help

 

[talonDSMerr]

Harmonic dampers and "balance" shafts AKA silent shafts do different things. While silent shafts use eccentric weights to counteract natural imbalances that are apparent in inline 4 cylinder engines, harmonic dampers act to absorb and dissipate torsional vibrations that are caused by the actual combustion process creating torque spikes that twist the crankshaft ever so slightly.

So, balance shafts counter the vibrations caused by the asymmetrical design of inline 4's, while harmonic dampers absorb torsional vibrations caused by the explosions in the combustion chambers.

Getting rid of your balance shafts with a BSE kit won't harm your motor. It will, however, increase vibration at certain RPMs. Getting rid of your harmonic damper and having a lightweight underdrive pulley in its place means those torsional vibrations in the crankshaft will not have anywhere to dissipate and will continue to oscillate within the crank. Eventually, something will give, and in most cases, the crankshaft will fail.

So, in my opinion, its still just a "single whammy," but do yourself a favor and replace the underdrive pulley with either a stock damper or an aftermarket damper such as ATI or Fluidampr.

 

[sugarfree]

Thanks man i appreciate the reply, i've actually got a stock harmonic balancer on the way i'm almost curious if this car had crankwalk before because in the po's paperwork i found that the engine was replaced at 45k so who knows Thanks again for the help though

 

[9!'clipseDOHC]

Harmonic dampers and "balance" shafts AKA silent shafts do different things. While silent shafts use eccentric weights to counteract natural imbalances that are apparent in inline 4 cylinder engines, harmonic dampers act to absorb and dissipate torsional vibrations that are caused by the actual combustion process creating torque spikes that twist the crankshaft ever so slightly.

So, balance shafts counter the vibrations caused by the asymmetrical design of inline 4's, while harmonic dampers absorb torsional vibrations caused by the explosions in the combustion chambers.

Getting rid of your balance shafts with a BSE kit won't harm your motor. It will, however, increase vibration at certain RPMs. Getting rid of your harmonic damper and having a lightweight underdrive pulley in its place means those torsional vibrations in the crankshaft will not have anywhere to dissipate and will continue to oscillate within the crank. Eventually, something will give, and in most cases, the crankshaft will fail.

So, in my opinion, its still just a "single whammy," but do yourself a favor and replace the underdrive pulley with either a stock damper or an aftermarket damper such as ATI or Fluidampr.

Great post, very well written! Rep points awarded.

 

[crash89]

Great post, very well written! Rep points awarded.

Agreed! I had a slight idea as to what these did and knew they did their job. But now, Great read!!!

 

[talonDSMerr]

Thanks guys, glad I could help!

 

[burkgonzo]

Thanks guys, glad I could help!

Nice write up! Light weight pulleys FTL!