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lets talk balance shafts for a second.


gsxconvert
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Galant VR-4 org Post #: 1062005 posted 04/13/12 12:22 AM     Remind Me!  Send Private Message   Edit Post      
this is widely discussed but i want to make sure i did the right thing so affirm me for a minute.

I like balance shafts. i like the smoothness..

so i took a block with already perfectly non worn shafts and bearings.. and put all new ACL bearings in it and had the balance shafts micropolished. with a gates kevlar belt do you think im ok for about 400hp. the rest of the block is built well too im just 2nd guessing myself.. i know AMS says to keep them or at least the one on the oil pump beacuse the stub not being braced can cause the oil pump gears to separate.. but im kinda on the fence.. its not to late to delete since the engine isnt in the car yet.

thoughts?

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turbowop
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Galant VR-4 org Post #: 1062013 posted 04/13/12 01:20 AM     Remind Me!  Send Private Message   Edit Post      
Lose them. The spin at twice the RPM as the crank. They are a liability on any car making any decent amount of power. And any "smoothness" they provide is negligible, IMO. Also, using a stub shaft isn't an issue. Thousands of people using them with no problems, including me on two different GVR4's.



-Mark

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1051


Edited by turbowop (04/13/12 01:22 AM)

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cheekychimp Galant VR4.org Moderator
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Galant VR-4 org Post #: 1062016 posted 04/13/12 01:51 AM     Remind Me!  Send Private Message   Edit Post      
Mark,

I buy that and I realize that in most cases, owners of VR4s tend to modify their vehicles to make them significantly more powerful than stock, but are there that many recorded instances of catastrophic balance shaft failure? And technically, weren't thousands of VR4 and DSM owners using them without problems before they started modifying the engines?

Again I'm not saying you are wrong, I'm just trying to get a grip on how many instances of failure we are talking about in terms of percentages and whether failure was attributable to poor design or just stressing the engine way beyond the manufacturer's recommendations. If the failure was noticeable at high rpms for example, wouldn't there be a case for saying that the shafts are perfectly safe in a car with a stock red line?

Paul.

Edit: Personally, I had the balance shafts removed during my 'ultimate' Galant build but left them in on the stock daily driver car. I do think the stock car is smoother, but then again it's kind of hard to tell because (a) I've done other things to the project car which obviously increase vibration anyway (like fitting harder polyurethane engine mounts) and (b) I've done very little fettling and tuning on the project car whilst I've had a ton of work done on the daily driver getting it to run nicely!



Getting old sucks ... but it sure beats the alternative !!!


Edited by cheekychimp (04/13/12 01:58 AM)

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gsxconvert
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Galant VR-4 org Post #: 1062017 posted 04/13/12 01:57 AM     Remind Me!  Send Private Message   Edit Post      
this is what kinda threw me off for a bit

From the AMS website

The AMS Race Balance Shaft Eliminator Kit is the only “no compromise” way of removing the factory balance shafts. Eliminating the balance shaft not only frees up horsepower, it also reduces the chance of belt failures ending up in catastrophic damage to your motor. In our experience, replacing the front balance shaft with a stub shaft will increase the chances of oil pump failures. This is likely caused by eliminating the support provided by the rear bearing journal. A stub shaft allows the oil pump gears to push apart and wear into the aluminum pump. Aluminum that is being worn away will enter the clean oil stream and contaminate the engine bearings. Eventually this can result in the oil pump seizing. The AMS shaft is machined to eliminate the counterweight while leaving the bearing journal in place to keep the factory engineered support for the oil pump gears.

I just really do not like the vibrations in my last engine from them being gone at low RPM, and having avid mounts its 2x as bad. ive done research on Japanese and Australian evo sites and they tend to NOT remove them. and ive had odd info from various old rally sites about the fact the rally GVR4's kept them too and that was pure race car.

i know there a liability but i think i have done and replaced them correctly. I know the typical arguments about oil pressure and whatnot but in my old car i didint see any increase on my mechanical gauge with them in or out. and i had a 7 bolt with a failed stub and the pump was chewed up.

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DynastyLCD
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Galant VR-4 org Post #: 1062058 posted 04/13/12 11:02 AM     Remind Me!  Send Private Message   Edit Post      
Quoting cheekychimp:

Mark,

I buy that and I realize that in most cases, owners of VR4s tend to modify their vehicles to make them significantly more powerful than stock, but are there that many recorded instances of catastrophic balance shaft failure? And technically, weren't thousands of VR4 and DSM owners using them without problems before they started modifying the engines?

Again I'm not saying you are wrong, I'm just trying to get a grip on how many instances of failure we are talking about in terms of percentages and whether failure was attributable to poor design or just stressing the engine way beyond the manufacturer's recommendations. If the failure was noticeable at high rpms for example, wouldn't there be a case for saying that the shafts are perfectly safe in a car with a stock red line?

Paul.

Edit: Personally, I had the balance shafts removed during my 'ultimate' Galant build but left them in on the stock daily driver car. I do think the stock car is smoother, but then again it's kind of hard to tell because (a) I've done other things to the project car which obviously increase vibration anyway (like fitting harder polyurethane engine mounts) and (b) I've done very little fettling and tuning on the project car whilst I've had a ton of work done on the daily driver getting it to run nicely!





Paul, i have to chime in on this, because i just bought a running and driving 1g with a bad balance shaft bearing. it did enough damage to destroy the bearings, oil pump, throw metal everywhere, just cause a real mess. the lower shaft bearing i found in the oil pan, and the one closest to the case had welded itself to the upper shaft. the owner originally said the car had something "scored in the head" as his CL ad stated. i went to see the car, listened to it, and heard what he had to say. sounded like a stuck lifter for about 2 seconds, then it was quiet. he said he ran it, drove it around, etc, and it never made any more noise than upon initial start up.

mind you, this car is bone stock. no modifications at all, just maintenance. down to the heatshields, MAF silencer and airbox, and the darth vader BOV cap. nobody screwed with this thing, at all. the car has 150k, and judging by the rest of the car, nobody really beat on it. i think about how much damage this caused, saying that to save this engine will cost a very good amount of cleaning everything thoroughly, along with a set of bearings, new oil pump, and very possibly a crank, including all the gaskets and everything else. so a full rebuild, basically.

its just not worth it.

you want comfort, don't put poly mounts in your car. get nice new rubber ones. don't put cams in it. and turn the idle up a little to combat the vibrations. ditch the balance shafts, and take 3 bearings out of the equation that could potentially spin and damage the rest of your engine. not to mention removing the risk of that belt somehow letting go, and causing the timing belt to jump time. i just see the balance shaft removal as a necessary procedure at this point as long as the engine is apart. its added insurance and peace of mind, plain and simple.



- Phil

'92 Galant VR4 - 881/1000 - 2.0/FPgreen daily
'92 Eagle Talon TSi - 2.3/3052/1600's/killmode.
'05 Honda TRX450r - pack-a-punched woods weapon
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cheekychimp Galant VR4.org Moderator
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Galant VR-4 org Post #: 1062067 posted 04/13/12 12:09 PM     Remind Me!  Send Private Message   Edit Post      
Phil,

That's fair enough and thanks for chiming in with genuine first hand experience, it is exactly this sort of information that helps everyone make informed decisions. So for my stock car, when it comes time for a rebuild or the engine is opened up enough to warrant doing the BSE, you and Mark would recommend removing them but retain the majority of other stock OEM or OEM ugrade (read later EVO) parts for reliability/driveability?



Getting old sucks ... but it sure beats the alternative !!!

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DynastyLCD
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Galant VR-4 org Post #: 1062073 posted 04/13/12 12:26 PM     Remind Me!  Send Private Message   Edit Post      
in my personal setup, i run stock rods, pistons, block, crank, and front case. ACL tri-metal for main and rod bearings, always use Mitsubishi stub shafts and gears, if the case is at all worn down where the oil pump sits, buy a Mitsubishi front case. don't screw around with topline or parts store crap..... evar. ARP headstuds and a Mitsubishi MLS are holdin down 35 psi through the 3052 right now without an issue, HKS 272's seem to be a great all around cam, and they do wonderfully, and if you have the money to spend, Evo rockers are stronger/lighter, all the valve train stuff is lighter and better, and thankfully interchangeable with our heads.

people do big things on stock blocks these days. Fonz's talon is dumb fast for what it is, on the brink of a 10 sec 16g car, being daily driven. Ostar went 9.30s or around there, taking the record. Mike Rizzotti went faster on his stock block than his built motor, if i remember right. i feel like a fresh 6 bolt does wonders. who cares if it doesn't have high compression. it will take a lot of boost and a great amount of timing too.

sorry, totally steering this post in the wrong direction.

balance shafts suck. /thread



- Phil

'92 Galant VR4 - 881/1000 - 2.0/FPgreen daily
'92 Eagle Talon TSi - 2.3/3052/1600's/killmode.
'05 Honda TRX450r - pack-a-punched woods weapon
You call down the thunder, and i'll reap the whirlwind.

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Whoodoo
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Galant VR-4 org Post #: 1062078 posted 04/13/12 01:04 PM     Remind Me!  Send Private Message   Edit Post      
I had the balance shaft belt fail a couple summers ago. The car had 130k on it and all the balance shaft bearings were in good condition (this motor was stock and well-treated its whole life). I chose to eliminate the shafts by turning down the eccentric weight of the rear shaft and simply leaving the front in without installing a new BS belt. So, essentially I made my own AMS race balance shaft kit. Even with the original rubber motor mounts, there was slightly more vibration felt in the cabin. If I were in your position, I would get new bearings and keep the shafts, making sure to install a new Mitsu BS belt only because I prefer a more refined feeling car. I agree that bearings have the potential to fail, but really the larger risk is in a belt failure.



62/2k

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turbowop
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Galant VR-4 org Post #: 1062084 posted 04/13/12 01:42 PM     Remind Me!  Send Private Message   Edit Post      
Quoting cheekychimp:

So for my stock car, when it comes time for a rebuild or the engine is opened up enough to warrant doing the BSE, you and Mark would recommend removing them but retain the majority of other stock OEM or OEM ugrade (read later EVO) parts for reliability/driveability?




That's what I recommend. I have 1051 for power and speed and I am willing to deal with the vibrations and harshness that come with some of the mods done to it. 503 is my grocery getter and ski car. I like it to be smoother, so I retain rubber motor mounts, stock cams, etc. Even without the balance shafts, it's smooth as butter.



-Mark

A face only a grocery shopper could love.
1051

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TRBODSM
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Galant VR-4 org Post #: 1062091 posted 04/13/12 02:07 PM     Remind Me!  Send Private Message   Edit Post      
For a stock revving motor I would use a stub shaft. If you are revving higher than stock rev limiter I would do the "race balance shaft".

I have rode in a handful of fully built 4g6x's and have had no vibrations at all with solid bushings all around. The motors were fully balanced and that is a huge reason why there is no vibrations.
Is your rotating assembly balanced? If not have you rode in a car that has a balanced rotating assembly?

That is something to think about when building a motor.

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turbowop
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Galant VR-4 org Post #: 1062095 posted 04/13/12 02:20 PM     Remind Me!  Send Private Message   Edit Post      
Both my rotating assemblies are bone stock. I can't say I've ever ridden in a car with a fully balanced assembly, but I have a hard time believing that there would be zero vibrations with poly mounts, especially in a car with cams more aggressive than stock.



-Mark

A face only a grocery shopper could love.
1051

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mitsuturbo
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Galant VR-4 org Post #: 1062146 posted 04/13/12 06:07 PM     Remind Me!  Send Private Message   Edit Post      
If the OP gears separating is a concern, try to get your hands on the older style straight cut, as opposed to the helical gears. Straight cut gears will not have the tendency to push apart.

I don't understand the BS being turned down to alleviate some lateral push on the gears anyhow. The balance shaft doesn't ride against anything at the back end. There's plenty of room for it move and to allow the gears to exert lateral force on the case. I honestly think it's a marketing gimmick for AMS to make more money. It's completely unnecessary, but they've sold a bunch of them.



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Galant VR-4 org Post #: 1062187 posted 04/13/12 10:22 PM     Remind Me!  Send Private Message   Edit Post      
My car had balance shaft issues when I purchased it. I wish I had been able to drive with and without out them, but I wasn't. I was a Porsche mechanic for a number of years and I do know that 944 do not run smooth without them at all. I know they are a different bread, but the same concept. There are problems with them, but if I could have reinstalled I would have. One of the bearings had spun in the block and the bore was to big to install a new bearing's.

For a daily driver I would keep them! My .02 worth!



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gsxconvert
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Galant VR-4 org Post #: 1062249 posted 04/14/12 02:13 AM     Remind Me!  Send Private Message   Edit Post      
see this is where im on the fence.. yes its a daily driver.. and i think that i kept them and did the work to put them back in correctly.

i completely agree about the marketing gimmick from AMS now that i think about it. it may prevent side to side but not lateral.

I dunno i think im just going to keep them.. its a 16g car with evo valvetrain. 2g pistons and all arp and a port job. i even had the cams micropolished.. i went a little anal because i dont want it to break. (fat chance)

thanks for everyones input i think ill keep my shafts.

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GSTwithPSI
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Galant VR-4 org Post #: 1062259 posted 04/14/12 07:08 AM     Remind Me!  Send Private Message   Edit Post      
My GST has the stock motor with around 160k on it. It is my daily driver and it is lightly modded click . I have never had any issues with the balance shafts themselves, only with the balance shaft belt. To me, the balance shaft belt is the weakest link in regards to balance shafts. Much of the time when the balance shaft belt goes, it can take the timing belt with it.

They absolutely do make a difference with how smooth the motor feels though. It is probably up to each individual how much of a difference this is and how it is perceived, but it would be wrong to say the don't make the engine operation smoother and reduce vibrations some. It could be argued that the difference balance shafts make are negligible, especially depending on how your car is modded, but there's a difference none the less. I would say the reasons to eliminate them far outweigh the reasons to keep them, but I like the smoothness they provide on my current setup, and have opted not to eliminate them.

I will end with a story. I was driving my GST a few years ago when the engine all of a sudden started feeling like it was running rough. It wasn't all the time, but while accelerating through the gears I could definitely feel a vibration which randomly got better and worse through the RPM range. I started to troubleshoot for all sorts of problems. At idle the car hardly seemed different, but as soon as you would rev the engine there was no doubt something was broken and it was running rougher than before. The worst thing was the car ran great still, it just vibrated and felt like shit. It felt like a misfire almost, but the car ran too good for that to be the case. After tons of work and troubleshooting, I finally figured out the vibration was caused by a bad balance shaft belt. The timing gears had cleaned all the teeth off the belt, and it was just chillin under the timing cover not doing anything. Luckily it didn't break off and destroy my timing belt. I replaced both belts and called it a day. I tell you this story only to point out, that I could instantly feel the difference in the car without the balance shafts in action. It felt foreign, and without the shafts doing what I was used to them doing, the car felt like crap. I would have never thought they would have made such a difference had this not happened to me. Since that happened, I've always like the idea of keeping them because of the smooth operation they provide. Just my 2 cents.


Edited by GSTwithPSI (04/14/12 07:18 AM)

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grocery_getter
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Galant VR-4 org Post #: 1062261 posted 04/14/12 07:45 AM     Remind Me!  Send Private Message   Edit Post      
Take them "oh shit!" shaft out. The wear in the oil pump assembly is with the *drive* gear shaft pressing onto the drive gear shaft bore on the 9~10 o'clock position as caused by the timing belt tension pulling the shaft sideways. Basic physic and geometry. Seen this all over many many times. Always the same wear, always the same position. Its a marketing gimmick. There is no force acting on the driven shaft. Nothing at all. And if there is a wear mark on the driven shaft inside the oil pump housing it is always circular and spread 360deg and not just at one spot, indicating a widespread oiling problem be it debris or insufficient oil film. I have analyze many many many to know the truth... or the lies, depending on how you look at it.



Andre
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Edited by grocery_getter (04/14/12 07:46 AM)

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Galant VR-4 org Post #: 1062266 posted 04/14/12 09:10 AM     Remind Me!  Send Private Message   Edit Post      
I realize this isn't the case for you, but I bought a car with a bad head. Had the head fixed, put all new timing components on it. I checked all of the balance shaft bearings by spinning them by hand; everything seemed fine. First start up, however, there was a loud "GRRRRR" sound and the balance shaft belt shot out of the timing cover like a snake missile. For all I know, it was the balance shafts that caused the bad head on the car to begin with and I was lucky that it didn't snap the timing belt on exit.

I promptly removed the balance shafts in all of my other cars.



-Jeff
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gvr4ever
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Galant VR-4 org Post #: 1062279 posted 04/14/12 10:01 AM     Remind Me!  Send Private Message   Edit Post      
I'm reading some of the post on how smooth the engine is or isn't. Unless I got really lucky and have a really balanced engine, I hardly noticed any change. With standard motor mounts anyway.

I was a tad worried about it, but I was more worried about having a older car and knowing what leaving them in could do.

I'm actually kind of picky about how my car drives and keeping it smooth. I hated the clutch chatter of a ACT 2600 to give you an ideal of how smooth and stock I like having the car drive and feel.

Idle might have a slight vibration in it, but driving, I really can't tell that I removed them. It's also about a 15HP gain too, so slight power gain and a longer lasting engine.



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gsxconvert
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Galant VR-4 org Post #: 1062317 posted 04/14/12 02:25 PM     Remind Me!  Send Private Message   Edit Post      
thats what im after is a very smooth car.. ive take just about everything into account to make it that way i was just 2ng guessing myself.

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Gombos
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Galant VR-4 org Post #: 1063615 posted 04/21/12 08:48 PM     Remind Me!  Send Private Message   Edit Post      
I've owned cars with and without balance shafts and really couldn't tell a difference in vibration. Stub shaft is fine too, most, if not all of the high power cars I know of run the stub shaft with no issues. Most oil pump failures are due to oil starvation.



Mike Gombos
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Galant VR-4 org Post #: 1063663 posted 04/22/12 01:55 AM     Remind Me!  Send Private Message   Edit Post      
As far as balanced assemblies. I think I had +- 1g on each rod/piston combo. It still vibrates. Eliminating balance shafts just seems like the right thing to do. If you don't like vibrations don't put the urethane motor mounts in.



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Galant VR-4 org Post #: 1063667 posted 04/22/12 02:07 AM     Remind Me!  Send Private Message   Edit Post      
+1 on elimination the balance shaft.

Heres a pic of my b-shaft bearing. Idk what caused it, but this was after a couple runs at the track. Found my balance shaft seized and then snapped the belt.




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Galant VR-4 org Post #: 1063677 posted 04/22/12 08:59 AM     Remind Me!  Send Private Message   Edit Post      
Quoting GSTwithPSI:

My GST has the stock motor with around 160k on it. It is my daily driver and it is lightly modded click . I have never had any issues with the balance shafts themselves, only with the balance shaft belt. To me, the balance shaft belt is the weakest link in regards to balance shafts. Much of the time when the balance shaft belt goes, it can take the timing belt with it.

They absolutely do make a difference with how smooth the motor feels though. It is probably up to each individual how much of a difference this is and how it is perceived, but it would be wrong to say the don't make the engine operation smoother and reduce vibrations some. It could be argued that the difference balance shafts make are negligible, especially depending on how your car is modded, but there's a difference none the less. I would say the reasons to eliminate them far outweigh the reasons to keep them, but I like the smoothness they provide on my current setup, and have opted not to eliminate them.

I will end with a story. I was driving my GST a few years ago when the engine all of a sudden started feeling like it was running rough. It wasn't all the time, but while accelerating through the gears I could definitely feel a vibration which randomly got better and worse through the RPM range. I started to troubleshoot for all sorts of problems. At idle the car hardly seemed different, but as soon as you would rev the engine there was no doubt something was broken and it was running rougher than before. The worst thing was the car ran great still, it just vibrated and felt like shit. It felt like a misfire almost, but the car ran too good for that to be the case. After tons of work and troubleshooting, I finally figured out the vibration was caused by a bad balance shaft belt. The timing gears had cleaned all the teeth off the belt, and it was just chillin under the timing cover not doing anything. Luckily it didn't break off and destroy my timing belt. I replaced both belts and called it a day. I tell you this story only to point out, that I could instantly feel the difference in the car without the balance shafts in action. It felt foreign, and without the shafts doing what I was used to them doing, the car felt like crap. I would have never thought they would have made such a difference had this not happened to me. Since that happened, I've always like the idea of keeping them because of the smooth operation they provide. Just my 2 cents.





This is actually misinformation. The reason your car vibrated harshly and felt like shit, as you described it, is because you had ONE balance shaft still rotating with the weight spinning.

"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. This vibration is generated because the movement of the connecting rods in an inline engine is not symmetrical throughout the crankshaft rotation; thus during a given period of crankshaft rotation, the descending and ascending pistons are not always completely opposed in their acceleration, giving rise to a net vertical inertial force twice in each revolution whose intensity increases quadratically with RPM, no matter how closely the components are matched for weight."

This is a quote from someone much smarter than me. Having built several engines though, I understand it and the very small side effect of removing the balance compared to the risk you take of leaving them in. The balance shafts rotate at twice the speed of the engine and yet rely on bearings smaller than either the rod or main bearings. In theory, with good oil pressure, this wouldn't be a problem. But the belt being smaller is a weak link and the tendency for oil pressure to "momentarily" be a little on the low side effects these more than the rods and mains.

I won't build an engine without removing them. The absolutely minimal noticeable vibration is far outweighed by the piece of mind gained from there absence.

Josh



A veteran is someone who, at one point in his life, wrote a blank check made payable to 'The U S of A 'for an amount of 'up to and including my life.' That is Honor, and there are way too many people in this country who no longer understand it.

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LILEVO
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Galant VR-4 org Post #: 1064305 posted 04/25/12 01:30 PM     Remind Me!  Send Private Message   Edit Post      
I've always run an "AMS style" rear shaft in my engines and never had any issues.


Any vibrations are really non existent with exhaust drone and poly mounts.




90 Mirage - "LIL EVO" 770awhp/580tq, [email protected]
04 Lexus LS430 - "WNTR BTR"
96 Land Cruiser - GT35R
93 Stealth RT/TT
91 GVR4 1958/2000


Edited by LILEVO (04/25/12 01:31 PM)

Posts: 195 | From: Wisconsin | Member Since: 09/20/03 | IP: (184.59.39.71) | Report this post to a Moderator

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Galant VR-4 org Post #: 1064312 posted 04/25/12 02:05 PM     Remind Me!  Send Private Message   Edit Post   
Quoting AMS:

In our experience, replacing the front balance shaft with a stub shaft will increase the chances of oil pump failures.



The stub shaft in question is an OE part from a 4G61. That engine, from the factory, has this setup. What I don't like about the AMS shaft is that there is still a shaft that is spinning at twice engine speed, as well as having a bearing that can fail. We had a car in our shop just last week that spun the rear shaft bearing when the customer grabbed 2nd in stead of 4th.

In my opinion, anything more than a daily driven street car must eliminate the balance shafts, but is highly recommended even on the daily driven street car.

Posts: 292 | From: Phoenixville, PA | Member Since: 01/18/05 | IP: (68.80.78.92) | Report this post to a Moderator


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