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Why remove the balance shafts?

CO VR4

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Jul 13, 2002
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I'm not sure I'd like the vibration from one shaft not rotating and one that is...
 

G

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Feb 24, 2004
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zompton
Quote:
so here is my two cents on balance shaft removal...Don't do it its not worth it...I work at Mitsubishi and have seen too many things go wrong when you remove the shafts. Think about it this way...when the engineers designed the engine they put them in there for a reason...If they were not necessary they would not have spent the money on them. Engines are balanced primarily for high r.p.m.s...so when you approach anything over 6 grand and you got mods your pushing it to the limits..you want all the balance you can get to eliminate vibrations. the extra 10-20 horse some people say you can get is bogus when your engine blows up...lol i've seen it happen. Now you can argue with me but do your best! again engineers aren't stupid...and they get paid to save money!



on the subject of mitsubishi's Sirius engines, could you please explain the 4g61 please ?
 

atc250r

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Sep 11, 2003
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Orange County, NY
Quote:
I'm not sure I'd like the vibration from one shaft not rotating and one that is...



Actually when Mitsu sent me to their engine classes the instructor discussed how the balance shafts work and showed a teriffic video on it. One cancels out one set of harmonics and the other cancels another so by just running the back one you will still feel less vibrations than running none. I wish I could get that video and host it somewhere, it really makes sense of a lot of the mystery behind what the shafts do and how they do it. Like G said, if they are so necessary then why aren't they present in the 4G61?

John
 

i knew subject this would entail some strong opinions..and i'm glad to see both sides as well. BUT, don't dicriminate me for being a Mitsu tech! i don't go around and say other people are stupid" anyways..on another note..i can indeed hook local area people up with discount parts! PM me if you need somethin.
 

Quote:
If I want silky smooth, I'd own a Lexus. /ubbthreads/images/graemlins/rofl.gif



Life is too short to drive a Lexus
 

SDchargers

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May 26, 2004
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San Diego, Cali
Quote:
i knew subject this would entail some strong opinions..and i'm glad to see both sides as well. BUT, don't dicriminate me for being a Mitsu tech! i don't go around and say other people are stupid" anyways..on another note..i can indeed hook local area people up with discount parts! PM me if you need somethin.



I don't think anyone is discriminating you as a Mitsu tech myself included but maybe you should rename this thread "Balance Shafts, why you should or shouldn't remove them." instead of blurting something out like "Don't do it it's not worth it" like thats the only answer. You work at Mitsu so tell us some of the things that you've seen gone wrong removing them. I still have mine on but I plan to take it out soon not because I'm willing to sacrifice a comfort ride but because of everyone's first hand knowledge of what has happened when they were left on and seeing a couple of my friends cars that got taken out by them. Not everyone here has the money to throw at an engine everytime a belt breaks so explain to us in more detail any safety issues on why they should stay on other than the whole "the engineers aren't stupid" arguement. All the posts I've read about this topic have the majority people saying to remove them. Is it gonna save me money leaving them on?
 

Rausch

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Dec 21, 2004
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Cleveland, OH
experience tends to override most anything, even surmised "fact". i'm sure there is more experience here than one would need access to to make a decision...i too am an ASE master certified tech...presently unemployed in that field, but i would definitely take the general concensus here over any other...these guys know what they're doing, the primary reason i joined this board. i know my way around a host of vehicles, but i'm constantly learning things from the people on this board....that means something.
 

iceman69510

Turn Right Racing
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10,883
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Michigan
Quote:
Like G said, if they are so necessary then why aren't they present in the 4G61?

John



The vibrations worsen with increased displacement. The 1.6 surely did not suffer from it as much as a 2.0 liter. Porsche licensed the technology for the 2.5 l 944.
 
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mark95

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Joined
Jul 29, 2003
Messages
202
Location
Tea, SouthDakota
Quote:
so here is my two cents on balance shaft removal...Don't do it its not worth it...I work at Mitsubishi and have seen too many things go wrong when you remove the shafts. Think about it this way...when the engineers designed the engine they put them in there for a reason...If they were not necessary they would not have spent the money on them. Engines are balanced primarily for high r.p.m.s...so when you approach anything over 6 grand and you got mods your pushing it to the limits..you want all the balance you can get to eliminate vibrations. the extra 10-20 horse some people say you can get is bogus when your engine blows up...lol i've seen it happen. Now you can argue with me but do your best! again engineers aren't stupid...and they get paid to save money!



I dont work at Mistu. and I do know that if you run a modded car the BShafts will fail, not might but will.
The engines you have seen blow up from what?? An inproper BS removal? Or some fool running too lean at WOT?

And if you ask me the engineers didnt put too much thought into the design of the Balance Shafts. If for some reason your balance shaft bearings do seize up, even on a stock car that little belt gets caught in the timing belt and either A. You get lucky it doesnt do anything B. It throws your timing off and eats all the valves or C. It will spin the rear bearing on the front Balance shaft to where the block is no longer useable.

If you have seen too many thing go wrong from removing the Balance Shafts the procedure wasnt done properly.
 

turbowop

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Apr 29, 2001
Messages
11,971
Location
Yakima, WA
I swear we get two of these guys a year now on the board that try to go off about how removal of the balance shafts will ruin your engine. /ubbthreads/images/graemlins/rolleyes.gif Where is this mysterious rock you guys crawl out from under? /ubbthreads/images/graemlins/dunno.gif

People have been pulling the balance shafts out of 4g63's for how many years now? Find me even *one* example of an engine that was destroyed after the balance shafts were removed correctly. Please. /ubbthreads/images/graemlins/uhh.gif

Keep your two cents. /ubbthreads/images/graemlins/banghead.gif
 

Barnes

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Feb 9, 2003
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6,249
Location
Richland, WA
Didn't someone on here have severe bearing erosion from super high oil pressure after they removed the balance shafts? Although that is easily fixable and not really related to the kind of failures people seem to imply that could happen without b-shafts.
 

Ok.. guys. I'm gonna play both sides of the fence here. First keep in mind that I own a 2.3 Magnus that vibrates pretty good and losens bolts continously. This occurs with new flywheel/clutch/fluidampr/stockmotor mounts.

Is it fair to say?

1. Stock 4g63 motors have gone on average >100k miles without balance shaft failure.
2. As long as normal periodic belt changes are done (every 60k) chances are slim BS's will fail
3. As long as you stick to the factory rev limit of 7k you shouldn't stress the BS bearings more than designed for.
4. Additional Horsepower should not cause additional BS bearing stress.
5. Balance shafts remove 2 order harmonics which run rampant in strokers (2.3's)


Is it also fair to say?
1. Spining the balance shafts does require a certain amount of power.
2. Spining the balance shafts past the crank rpm or 7k does produce accelerated wear of the Bs bearing.
3. Removing them requires less maintance and less to go wrong.
4. Removing/blocking oil passages produces high oil pressure.


SO my point is If your going to run a stock rev limit, and are willing to do the 50-60k maintance intervals, and change oil regularly, you shouldn't have much issue. In fact, those of us with the bastard 2.3 stroker could possible benefit greatly with a much pronounced vibration.

Let me know if I'm wrong on anything here.
James
 

atc250r

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Quote:
2. As long as normal periodic belt changes are done (every 60k) chances are slim BS's will fail



That is the only thing I really have to take exception to. Both of my BS failures were not related to the belt at all. In fact, the belts never broke either time but rather the bearings that the shafts ride on failed. When one goes it causes a chain reaction since the oil pressure now drops the rest of the BS bearings fail, then all the material from those bearings is pumped through the motor and end up ruining all the bearings in the bottom end. If its bad enough it will damage the cam journals or seize the short block and cause the crank to be damaged.

John
 

intresting... how many miles were on thos bs bearings? oil changed regularly? rev past 7k often?

James
 

atc250r

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I don't have the history from the previous owners but the second one had fresh oil in it and the records that I had seemed to indicate the owner took good care of the car. Whether the failure was due to poor maintenance (oil changes) or a poor design really doesn't matter when your stuck on the side of the road with a toasted motor /ubbthreads/images/graemlins/grin.gif. As I've stated before I won't own a 4G63 with the shafts in it anymore but what others choose to do with their motor is OK with me. The larger the motor is the worse the problem so that is why the 1.6's didn't have them and the 2.3's are a mother f'er without them. Did you try the locking bolts for the flywheel? The problems you are having are the main reason that I'm going to stick with a 2.0 if/when I build a good short block. Edit: Oh, and both cars were right around 165,000 miles when it happened.

John
 
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JOhn,

That kind of makes my point. they were well over 100k when they failed.. see that's ok with me. I don't expect a race motor to last over 100k anyway.
 

atc250r

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Yeah but they weren't race motors. One was my car and it happened to the previous owner who was a 40 something college professor who used it as a commuter and the other was my wife's daily driver, again not an aggressive driver. Both of those motors would still be alive and well if not for the shafts. For those of us that have the eqipment and skill to repair such a catastrophic failure it's merely an inconvenience but for others who are not so lucky it could mean the difference between sending the car the the junkyard or not. No one has come up with a failure caused by them being removed on a non race engine and IMHO the failures that you are experiencing are due to the fact that its a stroker motor. Please don't take this as me trying to be a jerk about it because I'm not, this is a great discussion IMHO but can you name one instance like I mentioned above?

John
 

I agree it's great discussion. I agree that removing them makes a high mileage motor more reliable. But a new stock or race motor kept within the 7k rpm limit and maintained properly should not experience any BS issues until AFTER 100k. Which to ME is acceptable. Hell, I don't mind swapping bearings every 100k miles.

I agree that no one has reported any motor failures directly related to the removal of the BS's. But there are so many other ways to kill a motor as well. Yes my problems are from a 2.3 stroker. and I intend to one day, get off my ass and reinstall the Balance shafts and see exactly how much of a difference it will make. Hell I rarely go over 7k rpms.

I do wonder how the removal of the shafts have contributed to broken cranks and flywheel/clutches because of the various bolts that work loose though.

I guess there should be a compromise then.

I believe that a motor with Balance shafts kept withing 7k rpms, with regular maintenance performed, should perform flawlessly/reliable upto 100k miles. After that you need to replace all bearings. especially the BS bearings.

Does anyone know of any properly maintained motors, redlining at 7k with balance shafts that have failed before the 100k miles mark?
 
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atc250r

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I agree and the BS problem is nothing compared to the crankwalk of the 2G's. Oh, and if you ask me 7000rpm is where the fun has just begun, my new motor will see 9000rpm reliably /ubbthreads/images/graemlins/devil.gif. Hell, my shortblock is basically a stock rebuild and it sees 1-2 shifts at 8500 regularly /ubbthreads/images/graemlins/grin.gif.

John
 
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