Thank you for quoting this haha, I don't have the persistence to go back through my old posts to find that post.

But to reiterate what I've already said in the past, even after looking at thousands of hours of run data on an engine dyno, you're not sacrificing any mechanical components by removing the balance shafts.

Mitsubishi put them in the evo for the same reason that Aaron already said, people are pussies. But also, imagine dropping almost $40k (is what an evo would cost in today's money after inflation) and you get a car with a dash that vibrates, and the mirrors aren't usable at certain engine speeds... Mitsu would probably have a lot of unhappy customers if that were the case.

So for the last time, can we please let this topic die? I don't plan to talk about it anymore, I've given my input as a professional who's dealt with these systems for a living and have nothing more to say about them.

 

I have no balance shafts and my mirrors are fine :P.

 

Guys sorry for bringing this from the grave but I would like to share my experience. Around 5 years ago I put together my personal evo 8 engine and I used Ams racing balance shaft. After those 5 years and 30k miles on 700whp I decided to refresh it and open the engine to inspect it.
Bearings/crank/oil pump everything was in perfect condition and basically ready for another 30k miles. I also put together many engines with stub shaft around 95% of them and only couple of them had oil pump failure for some reason. So I am in the process of building another engine for myself and thinking that my old engine had ams racing balance shaft in and internals look awesome so I ordered gsc racing balance shaft for the second engine because ams is not making them anymore. But before I installed the gsc racing shaft I decided to test it for straightness on special fixture. To my surprise this gsc racing shaft had .003 runout which I was not feeling comfortable with. So to make sure I am measuring it right I put on the fixture old ams shaft from the old engine and runout is 0 so than I tested oem shaft runout very close to 0. So conclusion is that racing balance shaft might help only if its perfectly straight !! This shaft is spinning 2x faster than crank so with runout of .003 it would destroy bearing and oil pump very fast. I still think it is better to use stub shaft but I decided to share this with you guys anyway so it might help someone. I notice that kelford started making those racing shafts but I don't if I want to spend the time to test it. So far I am putting together another engine with stub shaft. Very interesting note was also from Andrei from Hp academy, he says that stub shaft does damage oil pump in 1 out of 6 engines that he build and since he started machining oem shafts and installing them he has no problems with oil pumps. Maybe those shafts does help if they are perfectly straight.

 

BS Question - If Rods & Pistons are replaced and weights change From OEM.

Then the resultant force of changing direction of the piston rod assemblies would change.

This would cause the balance shaft forces to mismatch with the balance requirements of a non stock engine.

Unmatched forces would create new vibrations.

Perhaps a built engine would be better off without balance shafts to avoid inducing new vibrations.

Race shafts / stub shafts would not have this problem since the balance feature is removed.

Thoughts?

 

The pump is already supported on that side with the stub shaft, adding a second support further away with a larger oil clearance makes no sense. The main thing that damages the pump is oil starvation.

 

Fixed that for ya

The stub shaft is an OEM mitsu parts from engines that did not use the balance shafts.

Also, the oil pump gear that sees side load from the timing belt tension is NOT the gear that goes on the stub shaft.