Cutting the balance shaft?

[_97tsiawd_]

Ok so I was getting ready to get a stub sahft to install, then I read on DSM.org to just tap the the shaft for a 25mm bolt to seal the oil holes and CUT the rear shaft off. Is this something I should do? Is it going to hurt anything?



Edit: Its a 6bolt block.

 

[SBR Joe]

Ok so I was getting ready to get a stub sahft to install, then I read on DSM.org to just tap the the shaft for a 25mm bolt to seal the oil holes and CUT the rear shaft off. Is this something I should do? Is it going to hurt anything?

Thats as ghetto as it gets...just spend the few bucks on a stub shaft and give yourself some peace of mind.


Joe

 

[Lonnie gandee]

You can buy the kit for like $30 on parts dinosaur...

 

[_97tsiawd_]

I know its ghetto, thats not what I asked. Does it work?

 

[_97tsiawd_]

I know how much a kit costs, I'm not saying I cant/wont get one. I just want to know if cutting it works? If there are any SERIOUS things that could happen from doing it.

 

[SBR Joe]

I know how much a kit costs, I'm not saying I cant/wont get one. I just want to know if cutting it works? If there are any SERIOUS things that could happen from doing it.

Well it wont be balanced correctly by just "hacking it" which can result in oil pump failure...


Joe

 

[_97tsiawd_]

Thats all I needed to know. Ive already got the kit on the way.

Thanks
Ryan

 

[Nvisabl]

Well it wont be balanced correctly by just "hacking it" which can result in oil pump failure...


Joe

I ran a hacked BSE kit for 8 years. This was before most people new what a bse was, (Circa 1992) never had a problem. However they do call me OCB "OLD CHEAP bAS----" I am not advocating not using the kit. I did remove both shafts and flipped bearings also used red lock tight and a plug not a bolt.

Good luck
DJ

 

[_97tsiawd_]

You used the plug on the rear shaft? Or to plug where the front shaft used to be?

 

[Lonnie gandee]

The plug is meant for the front shaft... The rear uses the stubby,,,



If you want to be cheap, just cut your ####in belt.

 

[SBR Joe]

The plug is meant for the front shaft... The rear uses the stubby,,,



If you want to be cheap, just cut your ####in belt.

DO NOT!! This is an even worse idea, i know this from first hand experience....


Joe

 

[Nvisabl]

You used the plug on the rear shaft? Or to plug where the front shaft used to be?

I plug the oil pump side removed the front shaft and spun the bearings 180 degrees. work for over 8 years. I pulled the motor before anything happened just a mild rebuild.

DJ

 

[_97tsiawd_]

I plan on leaving the front shaft in with no belt. Either way, kit or no kit. I've got the motor pulled now and doing a slight rebuild.

 

[J-speed99]

I cut the rear shaft and tapped and lock tighted a bolt in both my 1g and 2g. I don't know why SBR Joe thinks it is ghetto. I just don't see why I would want to buy a part and wait for it to show up when I could do it myself in 20min. for free.

 

[SBR Joe]

I cut the rear shaft and tapped and lock tighted a bolt in both my 1g and 2g. I don't know why SBR Joe thinks it is ghetto. I just don't see why I would want to buy a part and wait for it to show up when I could do it myself in 20min. for free.

Its kinda like putting zip ties on your wg actuator line to increase boost instead of buying a boost controller. .... it just doesnt sound like a good idea, and for the price it costs to do it "right" i dont see the sense in it.

Joe

 

[dsm-onster]

It's not wrong or ghetto to cut a balance shaft. There is no balance issues. There is no other differences vs. purchasing your kit. Other than paying you .

There are several threads on this forum about simply removing the BS belt leading to no issues other than a little more vibration. I've removed the BS belt on 3 dsms personally and had no issues other than SLIGHTLY more vibration. I've ridden in 7 total with no bs belt but w/ a rear shaft. All have zero issues for 10s of thousands of miles.

BTW, They all exhibit the proper oil pressure vs. running a stubby shaft kit.

 

[SBR Joe]

It's not wrong or ghetto to cut a balance shaft. There is no balance issues. There is no other differences vs. purchasing your kit. Other than paying you .

There are several threads on this forum about simply removing the BS belt leading to no issues other than a little more vibration. I've removed the BS belt on 3 dsms personally and had no issues other than SLIGHTLY more vibration. I've ridden in 7 total with no bs belt but w/ a rear shaft. All have zero issues for 10s of thousands of miles.

BTW, They all exhibit the proper oil pressure vs. running a stubby shaft kit.

Well i had an oil pump fail when the BS belt was removed with BS still in and had helacious vibrations at 5k and up.

Joe

 

[dsm-onster]

+8500rpms no terrible vibrations.

How does removing the belt put more stress on the oil pump? In fact, how does it have any more stress on it when running the shafts of phase? The BS is "wobbly" or has imbalance purposefully, with or with out the other BS in phase or even rotating.

 

[SBR Joe]

+8500rpms no terrible vibrations.

How does removing the belt put more stress on the oil pump? In fact, how does it have any more stress on it when running the shafts of phase? The BS is "wobbly" or has imbalance purposefully, with or with out the other BS in phase or even rotating.

I dont know how it happened... I too have removed BS belts because they either broke or were about to break and had no problems, but the last time i did it (go figure it was to my own car) about a week later it spun the BS bearing and soon there after locked up the oil pump with it bouncing around in there. And the vibrations were crazy immediately upon removing it. I couldnt figure out how and why that happened...just my luck i guess but after that event i wont suggest it.

Joe

 

[TunaTalon]

+8500rpms no terrible vibrations.

How does removing the belt put more stress on the oil pump? In fact, how does it have any more stress on it when running the shafts of phase? The BS is "wobbly" or has imbalance purposefully, with or with out the other BS in phase or even rotating.

The two balance shafts cancel each others horizontal vibrations because they rotate in opposite directions and are in phase. When the balance shaft belt is cut the other shaft (driven by the oil pump) transfers it’s full imbalance load to the engine right at the oil pump.

See the FAQ at:
http://www.dsmtuners.com/forums/new...6-7-cutting-belts-remove-3.html#post151314501

 

[dsm-onster]

I dont know how it happened... I too have removed BS belts because they either broke or were about to break and had no problems, but the last time i did it (go figure it was to my own car) about a week later it spun the BS bearing and soon there after locked up the oil pump with it bouncing around in there. And the vibrations were crazy immediately upon removing it. I couldnt figure out how and why that happened...just my luck i guess but after that event i wont suggest it.

Joe

I agree that the Balance Shaft is a factory placed liability for the sake of the driver's butt. It revs at 2 times the rpms of your engine. If we take out engines to 8500rpms then the BS is seeing 17000rpms!!! So those bearings are a liability.

BUT! they seam to do fine in my case and several others. Removing the BS is great. Cutting the bs is fine. If done correctly . Also, shaving the bs down to a round rod at least removes the counterweight that causes high rpm bearing failure. This would be like balancing your engines rotating assembly as that benefits the main bearings the most. Taking off the bs belt atleast halfs the likelyhood of spinning a BS bearing. Cutting or removing the bs reduces that likelyhood to zero.

 

[dsm-onster]

The two balance shafts cancel each others horizontal vibrations because they rotate in opposite directions and are in phase. When the balance shaft belt is cut the other shaft (driven by the oil pump) transfers it's full imbalance load to the engine right at the oil pump.

See the FAQ at:
http://www.dsmtuners.com/forums/new...6-7-cutting-belts-remove-3.html#post151314501

Yea, they cancel out the engine vibrations. And that is very understandable for a car manufacturer to do considering the market at the time. (of course a better setup like small gears that toyota does would be better). But No there is no cancellation of momentum in the individual assemblies even when tied together by a rubber belt. The BS is "wobbly" or has imbalance purposefully, with or with out the other BS in phase or even rotating.

But the purposeful off balance of each shaft contribute to canceling the shock "waves" coming from the engine. They both still rotate off balance, right? That link you posted tells us that the bs assemblies cancel out the vibrations the engine exerts on the unibody. The balance shafts run unbalanced to cancel out the engines vibrations that otherwize would reach your arse.

The counterweight of each shaft is biased completely to one side. It center of mass is NOT the shaft center of rotation. Therefore, there is inertia subtracted out of the rotational inertia and converted to translational inertia. If you spin one around in a block, you will see that they stop alot quicker than spinning something of equal weight but more balance. Even when bound together with a rubber belt, the assembly stops quickly and has an oscilitory rotation just before coming to rest. That is because the total inertia stays the same but are broken in to two vectors for each shaft; one acting at a tangent to the rotation (rotational inertia) and one acting perpendicular to the rotation. Thus, this translational inertia is encouraging the shaft journal side w/ the weight bias to strike the bs bearing.

Because of this same tendency, an engine crank is built w/ counter weights. And is the reason we all spend so much money and time ensuring our rotating assemblies are balanced when we plan on taking our engines beyond the rev limit. But, these buggers are spinning at TWICE the rpms of the engine. And they are purposefully and severely unbalanced even when coupled w/ a rubber belt. . . Just to keep our butts still.

 

[99gst_racer]

To back up the original question: Yes, you can just cut the shaft. Before it became known that the stubby shaft was available, many people just cut the shaft. I had a 6-bolt in my garage a couple years back that had a cut shaft.

 

[TunaTalon]

Yea, they cancel out the engine vibrations. And that is very understandable for a car manufacturer to do considering the market at the time.

Canceling engine vibrations is always a good thing, even today.

(of course a better setup like small gears that toyota does would be better).

Gear size has no effect on second order harmonic imbalance.

But No there is no cancellation of momentum in the individual assemblies even when tied together by a rubber belt.

But yes the horizontal forces from one eccentric shaft do cancel the horizontal forces of the other. When the off-center weight on one shaft is pointing left, the other is pointing right. When the forces from the two shafts are horizontal, the two forces are equal and opposite, canceling each other.

The properties of the rubber belt play no part in balancing the engine, it just drives one shaft.

The BS is "wobbly" or has imbalance purposefully, with or with out the other BS in phase or even rotating.

Yes one is as “wobbly” as the other. But the effect of the system consisting of the engine and both balance shafts is affected by phasing. As designed, both shafts have upward forces that are additive when the engine’s second order harmonic forces are downward. Both shafts have downward forces that are additive when the engine’s second order harmonic forces are upward. Because the shafts rotate in opposite directions their left and right forces cancel each others.

If the shafts are both 180 degrees out of phase they would add to the engines natural vibrations. If they both rotated the same direction their horizontal forces would be additive.

With only one shaft, it will add horizontal vibrations to the engine whether in phase or not. This is the point that was intended to answer the OPs post.

But the purposeful off balance of each shaft contribute to canceling the shock "waves" coming from the engine. They both still rotate off balance, right?

No, the purpose of the balance shafts is to cancel the second order harmonics that are inherent with four cylinder in-line engines. In-line fours like the 4G63 engine have two pairs of pistons 180 degrees apart on the crankshaft. One pair goes up while the other pair goes down. If the speeds and acceleration rates of the two pairs of pistons were the same, the engine would be perfectly balanced. However, because the rod angle changes, the velocity of the piston changes throughout the stroke. With any reasonable rod length the piston velocity is higher near TDC than at BDC.

Please see Balance shaft - Wikipedia, the free encyclopedia for the Wikipedia article on balance shafts.

That link you posted tells us that the bs assemblies cancel out the vibrations the engine exerts on the unibody.

Actually that link was to my post in the FAQ that discussed the effect of balance shafts out of phase or missing.

The balance shafts run unbalanced to cancel out the engines vibrations that otherwize would reach your arse.

I know I’m an annoying old man but not old enough to discuss my arse in a public forum.

In my stroker Talon most of the vibrations seem to go the steering wheel.

The counterweight of each shaft is biased completely to one side. It center of mass is NOT the shaft center of rotation. Therefore, there is inertia subtracted out of the rotational inertia and converted to translational inertia. If you spin one around in a block, you will see that they stop alot quicker than spinning something of equal weight but more balance. Even when bound together with a rubber belt, the assembly stops quickly and has an oscilitory rotation just before coming to rest. That is because the total inertia stays the same but are broken in to two vectors for each shaft; one acting at a tangent to the rotation (rotational inertia) and one acting perpendicular to the rotation.

We agree that the balance shafts are eccentric, maybe that’s why I like them.

Thus, this translational inertia is encouraging the shaft journal side w/ the weight bias to strike the bs bearing.

Good point. This is the essence of the 1977 Mitsubishi patent on balance shafts. (
Engine balancer - United States Patent 4,028,963) That Mitsubishi patent called for a bearing on each side of the eccentric weight instead of being cantilevered in order to decrease the wear on the balance shaft bearings. Those bearings are heavily loaded due to the imbalance of the shafts. The main bearings on my Talon were “like new” after 183,000 miles bathed in Mobile One while the balance shaft bearings were in bad condition.

Because of this same tendency, an engine crank is built w/ counter weights.

The crankshaft can/should be balanced by adjusting the counter-weights for static balance. Static being the key word. An in-line four cannot be statically balanced to eliminate second order harmonics.

And is the reason we all spend so much money and time ensuring our rotating assemblies are balanced when we plan on taking our engines beyond the rev limit.

This bit of lore has been promoted to myth. When I started the calculations for the StrokeOrNot document I expected to find that the vibration forces from mismatched piston weights would be much more than the forces from second order harmonics. Boy was I wrong. The imbalance forces exerted on the crankshaft from second order harmonics is about ten times the force on the crankshaft from pistons that are mismatched by 20 grams.

I still hold my olde cherished belief that piston weights in a performance engine should be matched. Closely matched. But now that I know that second order harmonics are applied to the crank in the same manner as static imbalance, and are ten times as great, I have to re-think just ignoring the harmonic imbalance.

But, these buggers are spinning at TWICE the rpms of the engine. And they are purposefully and severely unbalanced even when coupled w/ a rubber belt. . . Just to keep our butts still.

[sarc on]I know something about being unbalanced but have never been very good about keeping still. Oh, you mean the balance shafts? [/sarc off] The concept of balance shafts in four cylinder engines is over 100 years old. It’s a real consideration is basic engine technology.

If static balance is important to keep from vibrating the valve train then I just can’t ignore the effect of second order harmonic vibrations on the valve train. The balance shaft loads are coupled to the block. The vibrations from the second order harmonics are coupled to the block. With the balance shafts in place the block will vibrate less.

That was a lot of words for a single post. Please see http://www.kidzuku.com/StrokeOrNot.pdf for even more words and pretty charts on this topic.

 

[Lonnie gandee]

I say it revs faster though, when there are no balance shafts...Which is why i like them gone..

Coupled with a lighter flywheel, its almost N/A feeling..