Anyone know anything about unbalance shafts in an engine? (New Car Question)

[Josh Langel]

So, I was searching for a new car and stumbled upon the all new 2008 Mitsubishi Lancer GTS. It's really a nice car (under $19,000 loaded) and it looks hot. So, I figure I may buy a new car.. get the MPG I want and then invest another 9-10k in a 01-02 Sport Trac as a truck (total spending around 29-30k, much less than the XC90 from Volvo). I was gathering some information (mostly positive) about the new Lancer and came across something interesting...



The Lancer has unbalance shafts in the engines. Is this because it's a cheaper car? Performance? It's an Inline 4 Cylinder engine.



Thanks for your help.





[Broken External Image]:

 

[Travis Munday]

It acts like a harmonic balancer or vibration dampener. Since the motor is an inline type, it tends to want to get a bit wobbly at the extremes of the crankshaft when the RPMs get high. An unbalance shaft will counteract/limit this wobbliness so you don't wear out bearings, belts, and components premature.



Some makers like the balance shaft more as it is a bit easier to work on the motor and doesn't require special tools to do an overhaul, whereas harmonic balancers do. They are also lighterweight, rather, the weight is spread out over a larger area, so the front bearings of the motor wear at about the same rate as the others. Harmonic balancers tend to wear the bottom front main bearings faster then the other main bearings.

 

[Josh Langel]

Thanks for the information, Tiger.



So, basically is only a design element? Meaning, it really doesn't effect longevity of engine?

 

[Travis Munday]

Well, it does, yes. Without it or any other vibration reducer, the engine would tear itself apart rather quickly.



It's not there because it's an economy car. It's not there for performance (or lack thereof). It's there to protect the engine from itself.

 

[Kevin Palmer]

A better name is "Balance Shaft". Why, because you would know exactly what it does...



As Tiger stated, it basically helps keep things in balance to itself...

 

[Ryan D]

That new lancer is nice . .

 

[Josh Langel]

Ryan,



For what you get for the price, it isn't bad at all. I only wish it was AWD...that's the only thing right now keeping me from jumping on it. But, then again, I gassed the ol'Tundra up today and it was $3.04 a gal.. so that 4 banger with 27MPG sounded even better.



But, I do want AWD, so I may go with a Volvo. Not sure yet

 

[Travis Munday]

You can get AWD for much cheaper then an XC90.

 

[Josh Langel]

 

[Ryan D]

You want the AWD? Sounds like a good excuse to talk to wife into an EVO =) or WRX wagon . .

 

[Tom Schindler]

Ryan,



I don't think Mud has to convince anyone else except his wallet.





Tom

 

[Josh Langel]

Not married.