Balance shaft delete (better MPG observed)
 

I just removed the balance shafts from our 2006 rav4 2.5L and I wish I had done it sooner. The difference is amazing. More power, better response, less throttle needed, and quieter.

It used to down shift on the hills around here and the rpm's would go way up. Now it just rolls right up the hills like they're not even there. Night and day difference.

I hope we don't get a speeding ticket, because it takes barely any throttle to maintain speed. It's going to take some getting used to for sure.

The engine is much quieter now. There was some "clattering" that we attributed to engine wear, but it's gone now. It had to be the shafts making noise. We can now whisper with the engine running, both inside and outside the car. All you hear is the injectors clicking and the exhaust.

The mileage should go up some too.

Do you know the design intent of the balance shaft? Was it for idle vibration?

Yes, it was just for comfort, but you'd have a hard time even knowing it was there.

Such is the case for a lot of modern four cylinder engines... they’re fairly smooth even with the shafts deleted...

Did you physically remove yours or were they powered by their own chain which you could cut/remove?

I took them out. They were gear driven by the crank. They have plastic gears.:eek:

Plastic gears? WtF, Toyota?

I’ll have to buy a kit for my car, my balance shafts are ran on a chain that also runs the water pump...

I know, I was shocked as well.

The engine was making clattering noise and I figured it was just showing age.
It was the shafts! It's sooo quiet now.

Hmm... (looks over ZZP performance catalog)

I'm almost done putting a Honda 2.4L in my Insight. One of my first mods to the engine was to delete the balance shafts. These weight around 11lbs, are part of the oil pump assembly, and spin at twice engine RPM because their purpose is to minimize second order harmonics which would be transferred through the engine mounts. They don't do anything for engine longevity and add both friction and a lot of inertia to the engine.

I'll post a video of it when I'm done, looking like Thursday.

:turtle:

Counter argument:

https://www.jackstransmissions.com/b...balance-shafts

Since balance shafts spin at higher than crank speeds, it makes sense that they can wear out their bearings before the crank bearings, leading to noise etc. So removing worn balance shafts can 'improve' an engine.