Balance Shaft Removal

Ford Focus ZX4 ST Modifications - Balance Shaft Removal - Phil Usher - June 2006

$19.00 2.3L Ford/Mazda Balance Shaft Removal

$ 7.00 USPS Shipping

$26.00 - Total

To reduce in cabin vibration the Duratec 2.3L engine can be fitted with a balance shaft.  "The BS spins at 4x crankshaft speed to cancel out the centrifugal forces of the rotating assembly: pistons, rods, crankshaft. The basic idea is that if you move something in X direction at X speed, then suddenly reverse that direction, this sudden change causes a vibration because the object wants to continue moving in X direction, not -X. Now, the idea of the balance shaft is to apply an equal amount of force in the opposite direction at the precise moment X shifts to -X in order to cancel out the vibration." - whynotthinkwhynot April 15th, 2005"

The Ford Ranger uses the same 2.3L engine and comes without a balance shaft.
 

I bought a Balance Shaft Delete kit from Marcy Motorsport and it arrived quickly.

Removing the Balance Shaft serves 3 useful purposes:

  1. Removes ~15lbs of physical weight. (Not terribly important)
  2. Removes several lbs of rotating weight. (Slightly faster rev response - perhaps 1hp gain)
  3. Increases oil capacity of the engine. (Very desirable)

Install Instructions: http://www.marcymotorsport.com/html/tech/mm-bsrk-23d.htm

June 15th - Kit arrived. I'll try installing sometime in the week of June 26th.  I will need to buy 6 quarts of oil - Think I'll go with 0-30W Mobil One or any other synthetic close to that spec (0-30W to 10-40W).  It should be noted that the thicker oil (40W) will require that I allow the oil to warm up some prior to running the car hard.  For a racecar application 50W would not be unreasonable.

June 27th - Balance Shaft was removed and the oil and oil filter were changed today.  The vehicle now holds six quarts of Mobil One 0-30W.

Driving home from NPR I notice that things which previously were a murmurs are now shudders.  For example I had previously noted that the car had (at ~3,200 revs) a hesitation which is now presents as definite shudder.  This is probably a tuning error which needs to be addressed at some point.  I also notice that unloading the throttle does transmit the change much more forcefully into the cabin.  Personally I don't have a problem with this, it will lead me to be gentler when coming off the throttle which is a good thing.

Do I notice any increase in performance?  No. The car perhaps feels a bit more "free" but the fresh oil could be as much a reason as the balance shaft removal.

Conclusion

If there is performance gain to be had for the removal of the balance shaft it's a very small one.  The factory fitted balance shaft is designed to reduce vibration transmitted into to the cabin when you lift off the throttle (think creeping around a parking lot) and having removed it from the car I can tell that it met its design goal very well.  With the balance shaft gone I find the oil capacity has risen to almost six quarts, a huge capacity gain and is the true value of this modification.

Pictures:

Josh - NPR - Studies Balance Shaft Removal Documentation.

Oil Pan removed shows balance shaft assembly.  The black thing is the oil pick up arm.

Balance Shaft has been removed.  Note the oil pickup arm was also removed to allow the balance shaft to be removed.

Josh taps in plug using provided rod bar.

This is the removed balance shaft.

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