Split Crank Pully

[my98gsx]

I ws just replacing my timing belt in my 1998 GSX and when i went to pull the crank pully off, i nowticed that the inside collar is split... I know i need to replace it thats a givin, but i run a speed shop in my town and have seen some difference off of running an underdriven crank pully. Unorthodox makes a crank pully for my car, and i did talk to them about the "crank-walk" problem and they said it should have no effect on it even though its un-dampened... has anyone ever had this problem? or does anyone run this setup on thier car and can give me feedback on if i should do this or not. - thanks.

 

[andytalon]

If your car is gonna walk its gonna walk, that may just give it a little more help to walk, not saying it will but it will most likely help it walk.

 

[jastermerrel]

You will get so many different answers to this question. I've been running a solid underdrive crank pulley for about 2 years, my pulley seperated on me and slung all of my belts. The car is my DD and I haven't run into any problems running it.

 

[TRBOBLU]

jastermerrel is right about you getting a bunch of different answers. Ive seen a lot of people do the solid underdrive pulley's with no "noticeable" problems. The engineer in me does not like the idea. The worst thing for any building, structure, engine or just about anything built is vibrations. The idea is that the factory crank pulley is there to help reduce vibrations. Ive also been told my numerous engine builder to just use the stock pulley or if you want to upgrade get one that works like the stock pulley. In all it is up to you, but my stage 3 buschur motor that I will be getting soon will run a new stock pulley.

 

[pinder91]

http://www.dsmtuners.com/forums/showthread.php?t=181105&highlight=undampened+pulley

That provides for a good argument for both sides. Although, I say stay dampened.

 

[andytalon]

A crank pully is not there to reduce vibration, that is what our balance shafts would do. Now some engines are balaced by this pully and it is called a Harmoic balancer. Our engines are Not balanced by the crank pully.

jastermerrel is right about you getting a bunch of different answers. Ive seen a lot of people do the solid underdrive pulley's with no "noticeable" problems. The engineer in me does not like the idea. The worst thing for any building, structure, engine or just about anything built is vibrations. The idea is that the factory crank pulley is there to help reduce vibrations. Ive also been told my numerous engine builder to just use the stock pulley or if you want to upgrade get one that works like the stock pulley. In all it is up to you, but my stage 3 buschur motor that I will be getting soon will run a new stock pulley.

 

[TRBOBLU]

So you are saying the stock dampener does nothing? I do not agree with your statement about it.

 

[andytalon]

First off lets get this straight, people get their crank pulleys confused with the harmonic dampers found on some V6/V8 engines. Harmonic balancer is a term that is 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 these applications deal with dsms and do not utilize a counterweight as part of the pulley as these engines are internally balanced.

 

[PieEyedPiper]

sooo... what are you actually saying then?
this device we're all contemplating on, doesn't exist? WTF

Since you seem to know about this maybe you could tell us what it IS for rather than what it is not?

I think we've established already that these devices do not balance anything, but rather, absorb vibrations or "dampen" them.

 

[TRBOBLU]

Exactly they dont balance anything. I never said it was a harmonic balancer. It is a harmonic dampener(hence the rubber and 2 piece design, its not one piece for a reason). A simple physics course or even engine building course will tell you about natural frequencies inherent in certain motors or structures. When an outside force, say the engine firing creates a frequency that matches the internal frequency the restults after a sustained period of time can be catastrophic. So in turn Mitsubishi for a very good reason put a harmonic dampener on the vehicile to reduce harmonic vibrations. And again, not just from my schooling but from talking to engine builders, they said if your vehicle came with it, leave it!. By removing it you are almost turning your crankshaft into a big tuning fork. You may not see bad results right away, but like I said eventually the vibrations will take their toll.

 

[andytalon]

First off we are not talking about vibration from the assembly, we were talking about engine vibration. Now if you want to talk about that, what you stated is correct.

 

[TRBOBLU]

I kinda thought that was a given but Ill be more clear in the future.

 

[IllEagl]

Exactly they dont balance anything. I never said it was a harmonic balancer. It is a harmonic dampener(hence the rubber and 2 piece design, its not one piece for a reason). A simple physics course or even engine building course will tell you about natural frequencies inherent in certain motors or structures. When an outside force, say the engine firing creates a frequency that matches the internal frequency the restults after a sustained period of time can be catastrophic. So in turn Mitsubishi for a very good reason put a harmonic dampener on the vehicile to reduce harmonic vibrations. And again, not just from my schooling but from talking to engine builders, they said if your vehicle came with it, leave it!. By removing it you are almost turning your crankshaft into a big tuning fork. You may not see bad results right away, but like I said eventually the vibrations will take their toll.

Do you still have your balance shafts? Should no one be doing that?

 

[Morphius]

Cripes.

It's there to dampen out torsional vibrations. Period. Causes of those vibrations are many, but it doesn't really matter.