Good balance shaft removal walkthrough
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I don't think there's really a limit or a power/torque threshold at which the balance shafts are 'unusable' man.
Most people just remove them to improve reliability (avoid having a broken balance belt tie itself around the timing belt and cause slipping i.e collision of valves into pistons).
Either that or they think that removing them will give them a much faster throttle response i.e weight saving.
Having said that, they do operate a twice crankshaft speed so I'm not sure if MMC designed the bearings to withstand the service requirements of a high revving engine (aftermarket camshafts) but I highly doubt it would be an issue seeing as motorbike engines rev. twice as much and they use similar bearings.
The only other thing you would consider for a high HP build is having a machined oil pump drive which is basically the stock shaft with only the weights machined off of it so that the shaft is still supported in the engine block, preventing yaw movements which could result in damage to the oil pump housing.
Most people just remove them to improve reliability (avoid having a broken balance belt tie itself around the timing belt and cause slipping i.e collision of valves into pistons).
Either that or they think that removing them will give them a much faster throttle response i.e weight saving.
Having said that, they do operate a twice crankshaft speed so I'm not sure if MMC designed the bearings to withstand the service requirements of a high revving engine (aftermarket camshafts) but I highly doubt it would be an issue seeing as motorbike engines rev. twice as much and they use similar bearings.
The only other thing you would consider for a high HP build is having a machined oil pump drive which is basically the stock shaft with only the weights machined off of it so that the shaft is still supported in the engine block, preventing yaw movements which could result in damage to the oil pump housing.
Not so much how much power you will be making but how much $$ you're willing to risk by keeping them in - it's a reliability issue.
Ive seen way to many engines over the years prematurely fail due to balance shaft failure. Whether from wear, excessive heat, lack of lubrication, tight tolerances, bent shaft, poor assembly doesnt matter, they're a link in the chain and another component at risk of failing when included as part of the entire bottom end rotating assembly.
Let's face it, we have known these buggars to spin bearings or sieze and break the balance shaft belt which in turn gets caught in the timing belt and causes complete engine failure - nobody wants to see that happen! . Its one of those things that 'could go wrong' so in all honesty when I build performance engines now I tend not to put them back in unless someone specifically wants to keep them (never). I simply dont trust an item spinning at twice the rotation speed of the engine to maintain a sufficient enough oil supply for long bearing life over time. For the amount of $$ going into forged internals, machine work etc and from a general risk assessment point of view, elimination offers some piece of mind.
There are benefits with removing them: frees some extra horsepwoer, frees up some extra oil pressure, less rotating mass, less things to go wrong, but the downside is some extra vibrations throughout the engine and consequently the vehicle... very little that could be noticed unless you're running some hard compound engine mounts anyway. Less face it, with most of the cars being built for power/competition use with stiff suspension, low profile tyres, racing seats, big cams with rough idle and everything else to make your ride uncomfortable, that isnt going to matter much to the occupant is it? And if used for competition purposes engines usually get driven to extreme and rebuilt a lot more often, depending on the type of use it gets.
On the otherhand, the argument for keeping them in place has its own merits as well as they help offset the harmonic inbalances through the rotating assembly and.... umm.... and.... fark, cant think of much more? If you have ever had the pleasure to speak to someone who has had complete engine failure due to balance shaft failure ask them if they put them back in after their new engine build?
Either way as long as the engine has a regular maintenance regime in place you shouldnt have to be driving it to a point where anything fails. But then again shit happens doesnt it?
Also, if anyone tries to feed you bullshit about the short stubs causing oil pump failure they're full of it. The short stubs are OEM parts from 4G61 engines and there is no common problem of the oil pump gear twisting from the belt loading up against them. IMO the problem happens when people re-use tired and worn oil pumps in engine rebuilds. When rebuilding a new engine and fitting a balance shaft removal kit you should be installing a new oil pump at the same time.
Ive seen way to many engines over the years prematurely fail due to balance shaft failure. Whether from wear, excessive heat, lack of lubrication, tight tolerances, bent shaft, poor assembly doesnt matter, they're a link in the chain and another component at risk of failing when included as part of the entire bottom end rotating assembly.
Let's face it, we have known these buggars to spin bearings or sieze and break the balance shaft belt which in turn gets caught in the timing belt and causes complete engine failure - nobody wants to see that happen! . Its one of those things that 'could go wrong' so in all honesty when I build performance engines now I tend not to put them back in unless someone specifically wants to keep them (never). I simply dont trust an item spinning at twice the rotation speed of the engine to maintain a sufficient enough oil supply for long bearing life over time. For the amount of $$ going into forged internals, machine work etc and from a general risk assessment point of view, elimination offers some piece of mind.
There are benefits with removing them: frees some extra horsepwoer, frees up some extra oil pressure, less rotating mass, less things to go wrong, but the downside is some extra vibrations throughout the engine and consequently the vehicle... very little that could be noticed unless you're running some hard compound engine mounts anyway. Less face it, with most of the cars being built for power/competition use with stiff suspension, low profile tyres, racing seats, big cams with rough idle and everything else to make your ride uncomfortable, that isnt going to matter much to the occupant is it? And if used for competition purposes engines usually get driven to extreme and rebuilt a lot more often, depending on the type of use it gets.
On the otherhand, the argument for keeping them in place has its own merits as well as they help offset the harmonic inbalances through the rotating assembly and.... umm.... and.... fark, cant think of much more? If you have ever had the pleasure to speak to someone who has had complete engine failure due to balance shaft failure ask them if they put them back in after their new engine build?
Either way as long as the engine has a regular maintenance regime in place you shouldnt have to be driving it to a point where anything fails. But then again shit happens doesnt it?
Also, if anyone tries to feed you bullshit about the short stubs causing oil pump failure they're full of it. The short stubs are OEM parts from 4G61 engines and there is no common problem of the oil pump gear twisting from the belt loading up against them. IMO the problem happens when people re-use tired and worn oil pumps in engine rebuilds. When rebuilding a new engine and fitting a balance shaft removal kit you should be installing a new oil pump at the same time.
VR-4Squid
Well-Known Member
Yes and no. In a "normal" application the stub shaft is fine. The issue comes when the rev limit is raised dramatically - big horse power engines turning 9-10,000rpm + Basically anything you intend to be streetable probably won't have a problem with the 4G61 stub shaft.
Lol, that makes me feel more comfortable about the 4G61 stub shaft I used when eliminating the balance shafts.
I too have had a 4g63 fail due to balance shaft related issues.
In the past I have built a few 4G63's, some with and some without balance shafts and have never had a problem, ever! Not even with vibrations. Though with every build where I removed them I have only ever used genuine Mitsubishi eliminator parts and have always had the rotating assembly fully balanced.
In the past I have built a few 4G63's, some with and some without balance shafts and have never had a problem, ever! Not even with vibrations. Though with every build where I removed them I have only ever used genuine Mitsubishi eliminator parts and have always had the rotating assembly fully balanced.
That's a seperate ball game again.
What do you mean, I'm not sure I follow? Balancing the rotating assembly removes many of the small vibrations caused by removing the balance shafts.
uh oh, here we go again.
I’m not here to argue with anyone mate, I just stated my experiences with and without them
VR-4Squid
Well-Known Member
No it doesn't.
It seems like alot of people, you fail to understand what the balance shaft does.
Balance shafts are most common in inline four cylinder engines which, due to the asymmetry of their design, have an inherent second order vibration (vibrating at twice the engine RPM) which cannot be eliminated no matter how well the internal components are balanced. This is because all four pistons are at tdc or bdc simultaneously (slowest piston speed is at this point) and again are all at mid stroke (highest piston speed) at the same time.
A well respected tuner once told me Mitsubishi used balance shafts on 4G63 engines to save them having to balance the rotating assembly
As I understand it, balancing a rotating assembly is much like balancing a wheel, thought instead of putting more counterweights on it, the components are progressily shaved until they reach as little 'wobble' as possible.
Balancing a rotating assembly is simply that, balancing the parts that comprise the rotating assembly.
As you could imagine it would be hard to get the counterweights cast perfectly each time on the stock crankshaft from factory (well it's further than what the manufacturer is willing to go/pay, and is not really neccessary for stock standard cars).
Balancing the rotating assembly is basically to perfect the 'rough' weighting that is innate in the cast item.
Balance shafts were introduced to overcome a seperate vibration caused simply by the operation of an inline engine. The horizontally opposed Subaru engine does not have this problem, simply due to it's configuration, it's a flat four engine, not and inline four. It is not only Mitsubishi who tried using balance shafts in the inline engines, Mitsubishi only coined the name 'Silent Shaft'.
Dude, read the link in the first post, this is an extract from it - "Balance shafts are commonly found in inline four cylinder engines such as the Mitsubishi 4G63 which, due to the asymmetry of their design, have an inherent second order vibration (vibrating at twice the engine RPM) which, contrary to popular belief, cannot be eliminated no matter how well the internal components are balanced."
"cannot be eliminated no matter how well the internal components are balanced" Fair enough I understand this but this doesn't mean they cannot be reduced. Why is it that many members like myself don't notice these vibrations and some wine about how bad it shakes the whole car?
Because it depends on what their car was like before the mods took place. If it was a smooth running stocker and they went from one extreme to the other then they will complain about the extra noise and vibrations as a result of the worked engine, big cams, solid engine mounts, balance shafts removed, stiff suspension, h/duty clutch etc. But if they already had a few forms of these modifications done prior to balance shaft removal then chances are they wouldnt even notice much, if any extra vibrations at all. You do come across a few hypocrites now and then who complain about the extra noise/vibrations after modifying their cars now and then :lol: If they want a smooth and quiet drive then they should buy a second car, perhaps a Camry or something :lol:
LWNSLW
tits and arse man
mitsu have been using (SILENT SHAFTS) for nearly 25 years, they are still used up till the ch lancer/evo 9. If they thought it was a bad thing to have in there stock cars they wouldnt have them. Remove them if you think they are going to fail, i for one will be leaving mine in. If the they can spin to potentially 20k+rpm i don't think they will mind a extra 5k.....
an interesting thing to note about balance shafts is that group n ralliart cars used to run balance shafts
Group A cars did not.
My car being race only I have removed them to get rid of some weight and get rid of the risk of belt failure, for me its a no brainer.
I have solid mounts etc and i dont find it harsh at all.
Group A cars did not.
My car being race only I have removed them to get rid of some weight and get rid of the risk of belt failure, for me its a no brainer.
I have solid mounts etc and i dont find it harsh at all.
