I agree mostly regarding passenger comfort, however there is something to be said about a car that vibrates enough that random bolts get loose.

 

I don't have this issue on any engines I've built, and it's been several.

 

My take on the BS delete was / has been this:

Sure, as a driver, one may not feel any noticeable increase in NVH, but what about the un-noticeable, high frequency, fretting damage being done to the journal bearings as noted in Jacks "White Paper"

By deleting the BS's are you trimming the engines life from a 100K motor to a 30K motor?

 

First: did you read the stuff I posted earlier?

Second: Aside from Jacks blog post, have you seen any evidence / data linking balance shaft removal with premature engine failure?

Third: I would like to think engine builders like English Racing, who offer balance shaft removal, aren't stupid.

Anecdotally I have half a decade of Daily driving (~50k miles) with no balance shafts and I have never experienced any bolts loosening. I wouldn't expect to because the additional vibration is hardly noticeable. I have also never seen any signs of bearing material in my oil.

What I have seen pop up plenty of times on this forum and elsewhere are engines being wiped out by failed balance shaft belts.

 

Balance shafts work for a small harmonic range of a stock motor doing stock stuff. Once you get more modded that junk goes right out the window. If you want to help vibration put a crank damper and a less light flywheel on and call it a day. In 20 years of 4g ownership, I've had maybe 4 years with balance shafts and the rest without. My experience is similar to Sean's, properly tightened bolts with loctite don't come out.

And 100k vs 30k motors? As soon as we started messing with them we're accepting they're reduced life, but the majority of people are going to kill a motor via tune/fuel/timing issues or oil starvation wear. If it was a DD and lightly modded I could see the argument to keep it but how many are still DD a near stock car?

 

Im ocd about torque specs, but again those specs are for a stock car. Once you remove balance shafts, stiff motor mounts, solid bushings, big cams, reving to 8k and beyond, stuff inevitably will still come loose. Which is why periodicly its a good idea to do a sanity/safety check on critical bolts. Im not talking bolts in the engine, but suspension, accessories etc. Adding loctite is a measure taken to prevent this, but in many cases if you're a Service manual purist its not called for in the documents.

 

I agree about the solid mounts, the amount of vibration they transmit to the chassis is insane. I've put billet mounts w/ stiff bushings on a 2g with balance shafts and that thing rattled my teeth at idle.