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Balance Shaft myth debunked!!

Discussion in 'Modified 1995-2001 Explorers' started by Hunz, September 27, 2009.

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    1. Hunz

      Hunz New Member

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      ok guys, many of us have pondered whether or not a 4.0l SOHC 2wd engine could swap in place of a 4wd SOHC engine w/ a balance shaft. I have heard of many rumors running around this forum of how swapping a 2wd SOHC in a 4wd engine's place that had a balance shaft will cause some vibration in the 2,000-3,000 RPm range......FALSE

      This weekend I finished my my long project. After pulling the seized engine out of my 4wd ex and the one out of my donor 2wd ex, I finally got the 2wd motor in and running. I drove the car for a good while(looking for any signs of vibration or anything out of the ordinary) and she ran like a dream.

      If anyone has questions about the engine swap just hit me up, I'll be more than happy to let you pick my brain
       
      Last edited: August 14, 2010
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    3. gijoecam

      gijoecam Village Idiot Elite Explorer

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      Did you try it in low range? IIRC, that's when the vibration could occur, and the reason for the balance shaft.
       
    4. Hunz

      Hunz New Member

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      No sure haven't, but the balance shaft is in no way shape or form connected to the transmission or transfercase anyhow, so the engine isn't going react different during 2wd vs 4lo when around 2,000-3,000 RPM range. The myth of vibration would technically occur all the time the car was running in the 2,000-3,000 RPM range regardless of gear selection, however in the case I have witnessed no irregular vibration occurs at all.
       
    5. techieman33

      techieman33 Explorer Addict

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      That's cool that you don't have any vibration, but I don't think that one instance of it debunks the need for a balance shaft.
       
    6. Hunz

      Hunz New Member

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      Well first off, the "myth" about the balance shaft is that when a 2wd SOHC(no balance shaft) is placed in a 4wd SOHCs place that had a balance shaft, a vibration in a certain RPM range will be noticeable(or possibly other damaging side effects). I took on this project and busted the myth. Many members want to know if the swap could be done, and have been told that adverse effects or complications such as our "vibration" can occur, by members with no experience(not knowledge, experience). I know and have heard of many members who have seen great deals on donor engines but were 2wd SOHCs when they supposedly needed a SOHC with a BALANCE SHAFT or else!!!!!!!!! I am just giving those members who are skeptical or nervous some proof. As for "I don't think one instance of no vibration means that others may not have this occur".....Facts are instances that have been proven and leave no room for error, and I am proof. This myth remains debunked
       
    7. SuRrEaLNJ

      SuRrEaLNJ hail to the king, baby! Elite Explorer

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      the ballance shaft is really not necessary. they actually make balance shaft delete kits to remove them out of the focus 2.3 to free up some hp from reduced rotational mass
       
    8. gijoecam

      gijoecam Village Idiot Elite Explorer

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      Well, except for the fact that they ARE bolted to one another....

      Not true. Harmonic vibrations can occur under a whole host of operating conditions, not just a specific RPM.

      The engineers that developed the engine spent tens of thousands of hours doing NVH testing under a whole lot more widely varied operating conditions than your 2000-3000 RPM test, and determined that the balance shaft was necessary for some specific reason. It's likely that the extra weight/inertia/shape/polar moment of the transfer case added to the driveline, or possibly the front half of the driveline adversely affects the vibration of the engine, or the engine itself transmits vibrations in some undesirable way to some component (be it the engine itself, the mounts, the passenger compartment, or any of a thousand places) and tha undesirable vibration is unique to the 4x4 drivetrain in some way. At any rate, it was installed there for a reason, so unless you know something the engineers don't, I don't think you can call it a 'myth' in the first place, let alone 'debunk' it based on one instance.

      The question was never whether or not it was possible to bolt a 2wd engine into a 4x4 truck. They are the same engine, aside from the balance shaft. The question is whether or not doing so would have any negative side effects. One can only infer from the original design that there was some specific reason the engineers opted to install the balance shaft on ONLY the 4x4 vehicles, and one can logically infer that the engineers would not have insisted on installing it if there wasn't a need for it. Should you choose to do otherwise, then it must mean you are much wiser than all the engineers that designed, tested, and developed that engine.... And that's a pretty bold claim, IMHO. I guess nearly 20 years of powertrain development must be wrong....

      Let's not overlook the fact that it would appear that now ALL of the SOHC motors include the balance shaft, regardless of whether it's a 2wd or a 4x4. I didn't check to see exactly when that change occurred, but the service manuals for the '09 no longer specify the balance shaft for 4x4s only.... Again, if there was no benefit derived from it, they would have gone the other way and removed it from all the engines.
       
    9. Hunz

      Hunz New Member

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      Well the myth was one of irregular vibrations in the 2,000-3,000 rpm range, that myth is busted. Many folks were worried about negative side effects, I am just here to show them that I have done the swap and experienced none. It is not to say that it may be better to have it, because clearly the Ford engineers proved that. You don't need it contrary to the myth!
       
      Last edited: August 14, 2010
    10. gmanpaint

      gmanpaint Torsion Bar Free Elite Explorer

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    11. techieman33

      techieman33 Explorer Addict

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      Just because yours doesn't have a vibration at those rpms, and doesn't appear to have any problems doesn't mean others won't. There are a million variables that could have changed and led to you not getting it. One vehicle out of hundreds of thousands just isn't enough to prove anything.
       
    12. gijoecam

      gijoecam Village Idiot Elite Explorer

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      Looks like the show's been canceled... ;)



      Hunz,

      I don't know where the 2000-3000 rpm 'myth' originated from... All I do know is that a half-million balance-shaft-equipped engines per year over 13 model years shows there must be some need for it. Automakers don't just arbitrarily bolt things to the engines.

      I don't know that anyone here (myself included) has ever told someone that they CAN't use a 2wd engine in a 4x4. We simply point out the fact that the balance shaft is a distinguising difference between the two motors, and leave it at that. The choice is ultimately up to the installer whether they want to try it or not.

      I'm happy you were successful at using it, but that's not to say there isn't some as-yet-unidentified need for it that you simply haven't come across yet. As has already been mentioned several times, one example does not debunk a 'myth' (or 15 years of engineering).
       
    13. Turdle

      Turdle Step-buddy Staff Member Moderator Elite Explorer

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      Until Mythbusters prooves the "Myth" or " Fact" I think it is safe to believe the engineers.

      :p::D

      Maybe the OP also drives a Harley Davidson, and therefore doesn't notice the vibration?
       
    14. Hunz

      Hunz New Member

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      point taken fellas, I talked to a guy who has had (2) 2wd engines go south on him in a 4wd; I am now eating my words. he said the first one had no vibration but had the timing chain go. The second engine started out with a little vibration and then two months later it felt like a washing machine on the spin cycle. Do any of you guys have any clue as to why this problem would get progressively worse??? I haven't noticed anything so far but have only driven it a small distance. The engine I have in it has only 45k on it and not really wanting to risk messing up the engine. Anyone think this guy just had used engines prone to failure regardless of the fact that they were in a 4wd?
       
    15. gijoecam

      gijoecam Village Idiot Elite Explorer

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      It's possible that they just happened to be 2wd angines and they just happened to fail... But by the same token, it's possible that the lack of the balance shaft causes a vibration that (and I'm just making this up) causes the oil around the pickup to cavitate at a certain speed, causing it to lose oil pressure, or maybe the vibration causes excessive wear on the cylinder walls from the vibration causing the pistons to rattle around.... Who knows? Maybe one day I'll attempt to track down the powertrain guys that work on the Explorers...

      As for the vibration getting worse and worse over time, maybe the vibration accelerates the degradation of the motor mounts, allowing more vibration, which makes the mounts (or whatever's causing it) worse... I have no idea. I just have to assume they installed it there on all the 4x4s for some {more-than-arbitrary} reason.
       
    16. gijoecam

      gijoecam Village Idiot Elite Explorer

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      Yeah, because there's a reliable source of analytical scientific data for ya'?!!?
       
    17. Hunz

      Hunz New Member

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      Well said gijoe. I just talked to a ford tech at a dealership, and he said it sounds like the guy with two bad 2wd donors had the common timing chain issue with the first engine ,and that the second engine had the motor mounts coming loose. His opinion is that I should have nothing to worry about, but anything can happen we all know that.


      I'll keep everyone posted on the future outcome of this swap, and we'll see where the wind decides to take me
       
      Last edited: August 14, 2010
    18. tomj1102

      tomj1102 New Member

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      Hi I have just purchased an explorer that had a damaged wheel bearing. After repairing that i went for a test drive and found to my horror the motor has a bad vibration at around 2.3 k/rpm especialy when accelerating. What can cause this? Is it possibly the balance shaft out of time or the chain not connected etc.
      Any help would be appreciated.
      cheers Tom
       
    19. 2000StreetRod

      2000StreetRod Staff Member Moderator Elite Explorer

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      torque reaction

      Does the balance shaft rotate in the opposite direction as the front drive shaft? If so, it might partially counter the torque reaction of the drive shaft reducing vibration. Although, it seems like the effect would be minimal.
       
    20. Hunz

      Hunz New Member

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      Well I have put a engine without a balance shaft in a 4wd ex and I get a vibration between 2.3k to 2.5k rpms. it only happens when under load, but I wouldn't say that it is a bad vibration at all, most passengers wouldn't even notice it unless I had told them.

      I talked to one guy who told me that it could be the drive/flex plate
       
    21. Kris Guilbeaux

      Kris Guilbeaux Elite Demon Secretary Staff Member Moderator Elite Explorer

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      Well I have some more balance shaft info for you as well. You can take a balance shaft motor and remove it and the chain plug the oiling holes and the motor will run completely normal. The balance shaft is not needed. I have a installed a 2002 SOHC balance shaft motor (with it removed) into a 99 Sport no vibrations. I want to know what is really does. because it sure doesn't cut down on vibrations.
       
    22. Hunz

      Hunz New Member

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      Well fellow xplorers, it seems as if we have finally put this myth to bed about negative side effects of 2wd engines in 4wd xplorers. I have been driving my 98' xplorer for 3,000+ miles now with a non-balance shaft motor in a 4wd X and no negative side effects
       
    23. Hunz

      Hunz New Member

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      Just wanted to post an update on the 4wd ex with a 2wd sohc engine. 11,000 miles after install and she still runs like a dream
       
    24. 99SportX

      99SportX Well-Known Member

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      Good to hear. I wonder if one could remove the balance shaft from the SOHC? It seems to me that these motors have enough parts already so the less parts the better IMO. I could care less if I have a minor vibration. There are already plenty of other vibrations. One of my friends did a balance shaft delete in his saab motor to rid of a little rotating mass. Plenty of folks do it to 4cyl motors. I don't think a 6 would be much different.
       
    25. hazmat456

      hazmat456 Active Member

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      kind of like a harmonic balancer,I guess you could run a motor without one but for how long?
       
    26. Kris Guilbeaux

      Kris Guilbeaux Elite Demon Secretary Staff Member Moderator Elite Explorer

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      Yes, a few posts up you would see I removed a balance shaft from an SOHC motor and is running fine in a 99 Sport.

       

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