captiveis1

iTrader: (1)

DontStopMe, there was no audible noise until the car was started cold, then i heard a sort of whirring noise from the timing cover area. I didnt notice anything at idle (i do have cams though so idle is bumpy anyways) but when shifting around 3.3-3.5k i felt like there was a lot of vibration in the shifter.
From Clermont->Lake Mary->Tallahassee and then around town in Tallahassee was probably ~350 miles. But with the exception of those few pulls initially, the car didnt see more than 4k rpms or 2psi throughout that time because those pulls/spool did not feel right at all haha

EDIT: i realize you weren't asking me those questions

DontStopMe

iTrader: (19)

Interesting read. Thanks for posting.

MinusPrevious

iTrader: (3)

Hi Paul. Was hoping you would read it. You have a good mechanical mind

Joe

six40

You are extremely lucky. Having a timing belt failure immediately after purchasing my last 4G63 DSM which took out more than half the valves, I can tell you it's not fun. Mine wasn't caused by the BS belt, but my friend lost an engine due to it. I immediately pulled the engine out, did the BSE as one should and I have in almost all my other 4G63's, all new seals and gaskets, and all new OEM timing components.


The balance shafts spin opposite of eachother, to cancel out vibrations, at twice the engine speed. So if you're buzzing on the highway at 3,500 RPM those things are spinning at 7,000. If you're revving the engine out to 8,000 they're spinning at 16,000 RPM. I for one, despite what Jacks says, agree with almost all the other engine builders and owners of 4G63's and always remove them. Jack's Transmissions specializes in transmissions - so take that article with a grain of salt. There are plenty of engines that do not utilize balance shafts.


A balance shaft delete should be properly done with proper OEM parts. Ideally machining the oil pump shaft down to take the weight off but keep the stock length, next best solution is the OEM mirage stubby with the oiling groove. At no time is simply removing the BS belt acceptable, as you have now stopped one balance shaft from spinning while the one driven by the oil pump gears is still spinning at twice the engine speed with nothing to counteract it.


BSE vibrations are not bad at all. Barely noticeable at idle and again around 3k rpm. If you have stock mounts and cams, there's basically no difference to you.


After 10+ years of owning, driving and wrenching on the 4G63 I always vote to toss the balance shafts. High mileage on these deteles without issues. I enjoy future timing belt change simplicity, less rotating mass, and a nice increase in engine oil pressure. If that is not in the cards with your scenario OP, a complete timing belt service with new OEM parts is the way to go

Biggiesacks

+1 for shaftless. While maybe vibration does have some long term effect on durability, balance shaft belts kill these engines all the time. I have never come across any information about an engine failure being caused by removing the shafts (properly).

LetsGetThisDone

iTrader: (1)

You certainly can not run without just one shaft, they do spin opposite direction now that I think about it. Running just one would be bad.


The second order vibration is due to when the pistons are all at the same height in the bore, they are below the mid-height of the bore, so it creates a harmonic.


OP, you are VERY lucky that the balance shaft belt didn't take out your timing belt.


I would also take what Jack's says with a LARGE grain of salt. He is the only Evo trans build that ever even mentions that.

barneyb

I had a new bbelt on hand but the crank bolt proved impossible to remove. So, I bought a new 1/2 inch impact. No joy. Next I ordered a special type of socket advertised as being made for this application. With that and my tired old air wrench the bolt came out like it was finger tight. So, whatever time that fooling around consumed is how long I drove without a bbelt. Yes, a daily driver.

There was a roar noise in the 4500 rpm and above range like I'd blown the guts out of the muffler. People with loud exhaust systems maybe never hear his, don't know, but it didn't sound happy to me.

DontStopMe

iTrader: (19)

Thank you.

I pined it to my video comments. Now i just wish i could easily update the video.

This makes a lot of sense to me. Thanks for posting.

I've heard of people just removing the rear belt and not doing anything else and not having issues. However, i guess this does not mean it should be recommend or is the best solution.

LetsGetThisDone

iTrader: (1)

To keep oil pressure more in check, you can delete the front shaft, but leave the rear shaft in place with no belt on it. This way you don't have to block to the oil passages off for the rear shaft, which causes a big increase in oil pressure that these engine don't really need..

MinusPrevious

iTrader: (3)

Good report^^^

Seems like every thread Ive read reports "expect vibration" w/the BS delete. Can you imagine what that vibration is doing to all metal to metal bearing surfaces

This "white paper" done by Jacks should be given a level of respect, as he is an expert in the field of re-building drivetrain components

The Mitsu engineers spent a lot time, effort & money to develop the BS system. Theres some serious reasons why they are there

BluEVOIX

iTrader: (69)

After finding out and mentioned earlier in this thread both shafts spin opposite directions etc.. I believe removing one would throw things off balance.

I might need to read Jacks article again as it's been a long time since I read through it but I don't recall if he specified removing both shafts or maybe his findings were for only removing the rear ?

I removed the BS on my 2003 Sentra SER years back. The only Vibration felt which was ever so slight was at a certain rpm range around 3.5k-4.5k . I was running oem motor mounts when removed. The balance shaft setup was different compared to the Evo. The Sentra motor QR25DE had a cartridge containing two opposite spinning shafts in the oil pan area. So removing the bs , you removed both shafts at once and added windage tray to prevent oil slushing around away from the pickup tube.

Now some things to note in general . There are cars with 4 cylinder motors that don't have balance shafts. Mazda CX-5 with the 2.0 four cylinder doesn't have bs but the 2.5 motor does. If I remember correctly it was because the larger motor created more unwanted vibrations resulting the need. It was a video I saw a while back engineer explaining the difference between the two on the new skyactiv motors.

I understand that different motors are engineered and designed differently . But from everything everywhere mentioned, modern car motors are internally balanced and bs are only there for luxury purposes to reduce those "secondary" vibrations created by inline 4 motors.

These secondary vibrations or forces might be throughout the rpms but are probably more pronounced at certain rpms. Maybe that's why I only felt it at certain rpms on the Sentra. So if that is true then it's probably also true that bs's are designed to be most effective for certain rpm window not equally effective throughout all rpms range.

Didn't Dave Buschur run the bs stubby delete on his Evo and from his observations he did not see or notice any negative motor damaging signs to removing the bs ?

barneyb

Any time you lose an engine bearing, unless you caught it at the instant of infant knock, metal has spread throughout the engine and ruined it. I date to the time of the first DSMs and even the revered 6-bolt liked to toss balance shaft bearings. Two different 7-bolt engines followed, each worse than the previous. Balance shafts got a bad reputation that goes back to 1990.

Mitsubishi finally cleaned up the design and gave us an engine without balance shaft and crank walk problems.

The second order vibration has nothing to do with the internal balance of the engine and it occurs at all rpms. However, it increases to the forth power of rpm. In other words, double the rpm and increase the vibration by16.

I have no idea whether balance shafts are a ‘luxury item’ or have real engine benefits but their use or benefit will be related to displacement and the red line of the engine. Maybe they are an odd ball item in a car with few other luxuries.

An old car requires the same maintenance as a new car and maintenance on an Evo is expensive. Some people will always try to skimp. My wife’s WRX is over time for a timing belt. Sigh.

Biggiesacks

pretty sure if there was some big issue with pulling the balance shafts we would know about it by now, and the pro engine builders wouldn't be recommending it. The delete parts are mitsubishi parts, so at least in some form or another they produced an engine without them.

2006EvoIXer

iTrader: (1)

You beat me to it. Keep balance shaft for DD.

Biggiesacks

I would love to see some data on how many of these failures are caused by people not doing the proper maintenance on the balance shaft belt vs belts that are just prematurely failing. I guess you would also want to know what kind of mods and vehicle usage too.