UD crank pulley harmful?!

[97t4mitsu]

i've got an underdrive crank pulley from the guys over at Unorthodox...but i've just been told by one of my good friends who builds and races honda's and mitsu's and even neons that the Underdrive pulleys on the 420A's are actually bad for them, since they don't have a balance shaft, and there is nothing there to absorb the vibration.

it makes plenty of sense to me, but i have never heard this before. should i replace it with a stock pulley or is there one out there that has a damper in it? what are you're guys' thoughts on this?

 

[VelocitàPaola]

The stock one doesn't have a damper in it either... That thin ring of elastomer doesn't do much at all; it's not like a real dampener at all.

When/if you rebuild your engine, get your rotating assembly balanced. If you don't plan on pushing your car, and you're not going to rebuild, don't worry about it.

 

[dr1665]

No worries. At. All.

In a decade of 2GNT ownership, I've never heard a single case of engine failure linked to UDP balance issues. It's not like a first rate outfit like Unorthodox, who is known for specializing in pullies, is going to be offer an unbalanced pulley. Mine's been on for well over 60,000 miles. Purchase a quality unit (no Ebay shit) and install with confidence.

 

[WarSaw]

Please read this from Unorthodox Racing website.
It explains the confusion about what the rubber ring on the stock 420A crank is there for.

Be sure to click on the link as there is much more there to read about UDPs.

http://www.unorthodoxracing.com/faq_pulleys.html

Cut and pasted from their site:
People are getting their crank pulleys confused with the harmonic dampers found on some V6 / V8 engines. "Harmonic Balancer" is a term used loosely in the automotive industry. Technically, this type of device does not exist. The "balancer" part comes from engines that are externally balanced and have a counterweight cast into the damper, hence the merging of the two terms. None of the applications we offer use a counterweight as part of the pulley, as these engines are all internally balanced.

The pulleys on most of the new import and smaller domestic engines have an elastomer (rubber ring) incorporated into the pulley that makes them look similar to a harmonic damper. The elastomer in the OEM pulley serves as an isolator, which is there to suppress natural vibration and noise from the engine itself, the A/C compressor, P/S pump, and alternator. This is what the manufacturers call NVH (Noise Vibration & Harshness) when referring to noticeable noise and vibration in the passenger compartment. It is important to note in these applications, the elastomer is inadequate in size and durability to act as an effective torsional damper. If you look at the pulleys on some imports there is no rubber to be found at all. We have samples of these, mostly from Acura/Honda, the Nissan Altima, 1.8L Eclipse, 2.3L Fords, Chrysler 2.2L's, and 1.8L VW's, to mention a few. This is not to say with our pulleys you will hear a ton of noise or feel more vibration from your engine compartment. Most owners who have installed our pulleys notice the engine actually feels smoother. This is result of replacing the heavy crank pulley with our crank pulley. NVH is variable and unique to every car. NVH will increase with the installation of an aftermarket intake and/or exhaust, for example. Think of OEM intake systems in newer cars, they use baffles and resonators in the intake to quiet all the intake noise. Aftermarket intakes eliminate these resonators and create dramatic increases in engine noise from the throttle opening and closing. So to most tuners, certain types of NVH can make the driving experience more enjoyable.

The purpose of a traditional harmonic damper is to protect against crank failure from torsional movement. This is not necessary in most modern engines because of the many advances in engine design and materials. Factors such as stroke length, displacement, inline, V configurations, piston dwell time, piston pin off-set, power output, etc., do determine when and how these harmonics and torsional movements occur.

Copied from another thread in the 420 turbo section. Hope it helps.

 

[97t4mitsu]

nice! well that's definitely good news for me, i don't know why i didn't check their website for anything. but that's what i come here for anyways. thanks for the help dudes.