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2G Machine OEM Balance Shaft?

Posted by AlmightySo, Dec 10, 2018

  1. Stubby

    5 vote(s)
    83.3%
  2. Straight Shaft

    1 vote(s)
    16.7%
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  1. AlmightySo

    AlmightySo Proven Member

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    Has anyone done this? I have a buddy that works for a machine shop, so figured this wouldn't be to bad of an idea rather then getting the stubby for $70.


    47688457_199363971010486_121454919147323392_n.jpg
     

    Street Build 773  0

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  2. bastarddsm

    bastarddsm Supporting Vendor

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    Where are you paying $70 for a stubby shaft? It's $18 from mitsu.

    The machined down rear shaft is a bad idea. I've seen far more spun rear BS bearings than broken bs belts and junk oil pumps caused by stubby shaft combined.
     

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  3. ThunderChild

    ThunderChild Supporting VIP

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    I disagree that the machined shaft is bad, I run one and had one done for another member. Gives me more confidence in the oil pumps stability.
    There alot of debate on each pieces pros and cons, but I will only be using machined, full length shafts on my motors, unless I go with an FFAB oil pump setup.
    Now paying for a cut down shaft kit I wouldn't do, they're not hardened and any machinist worth their salt can cut one down, polish it and if needed/wanted balance it. FWIW I had mine trimmed with no extra balancing and it's had no issues in 30k miles.
     

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  4. jakk220

    jakk220 Proven Member

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    ^^^ I was the other member Tametalon had the shaft cut down for (thanks again LOL). It has only been in the car for about a thousand miles but its working just fine. But then again so is my 7 bolt that has an Autozone oil pump with a stub shaft which has been like that for 30k pretty decently hard miles.

    I think the key is proper installation of the new balance shaft bearing and making sure oil pressure is good. The shaft is pretty much just floating in there so if it somehow fails then I would guess there was another factor that played into the failure. Same with the destroyed oil pump gears. I feel like the stub shaft alone is not enough to kill them. Just my opinion.
     

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  5. jinscho

    jinscho Proven Member

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  6. bastarddsm

    bastarddsm Supporting Vendor

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    Lets look at some real world hard use examples:

    My talon, same OEM oil pump since 2012, and it might even have helical gears in it still. It goes 10k on routine, and made a couple trips to 11.5k this year when I broke the trans. (fuel cut rev limit isn't quick enough) It lived through breaking a cylinder wall, and putting 2gal of water in the oil for the last half of a 10.50@140 pass. I knocked a headgasket out and it blew the freeze plug out of the end of the head, and jammed up the timing belt. Oil pump keeps on ticking. Has close to 40k mi on it since 2012, and all of that with an oem stub shaft.

    My beater galant gsx, it's had 30k put on it. It was a well used pump I put a new oem stub shaft in about 2010. It gets the sh** kicked out of it, 30k and maybe 3 oil changes. Always high dollar Rotella T 10e30, LOL. It's been really high rpm too. I had a couple 2-3-2's at 7500, from not being used to it. It get beat on when cold, when hot, when low on oil, when it has a dead fuel pump, ect. Still kicking.


    Then we go to the other side:

    When I bought my Talon it was a N/T auto, 120k and owned by a little old lady, religious maintenance. I bought it for $400 because they thought it had a rod knock. It was a spun BS bearing.

    Then I just picked up an AWD Summit Van. 140K on it with a rod knock.... Nope spun BS bearing. I've taken several stock 6 bolts apart with spun BS bearing and all else is great.

    So tell me again how that shaft that spins at 2x engine speed (that's 20k if you have a high revver) is a good idea.

    If you are killing oil pumps and are not a crazy auto cross guy pulling high lateral G's or a drag racer going consistent 1.4s 60's, it is operator error. And still it's not the stub shafts fault.
     

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  7. jakk220

    jakk220 Proven Member

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    I feel like a straight shaft and a stock shaft could yield different results. I could be wrong I guess.
     

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  8. bastarddsm

    bastarddsm Supporting Vendor

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    Possibly. Someone should figure out the force due to imbalance with rpm, and compare it to the load on a rod bearing.
     

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  9. ThunderChild

    ThunderChild Supporting VIP

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    Glad to hear!

    I'm not trying to say one is better than the other, but the design made sense to me.
    Biggest thing I see is it gives a larger margin of error when setting up the timing belt tension vs the stub shaft, but we should all be able to set up a t-belt with 0 issue.
    Used engines with uncomfirmed history of maintenance I don't think qualify as worthy examples. I have however seen many threads with stub shafts and pump housings absolutely destroyed after stub shaft installation, and also many that have had no issues with stub shafts.

    It's a preference thing I guess, but the machined shaft seems more logical to me :idontknow:
     

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    1990 Plymouth Laser N/T
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    1987 Toyota Pickup/Hilux
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    1997 Mitsubishi Eclipse Spyder GST
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    1992 Eagle Talon TSi AWD
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  10. bastarddsm

    bastarddsm Supporting Vendor

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    Repeat after me. Timing belt tension has nothing to do with oil pump stub shaft failure. In general, oil pump failure is USER ERROR. Say this out loud and write it on a black board 1000X. Mother mitsu wouldn't have sent the 1.6's out the door with a stub shaft if it was a problem. Eliminating warranty dollars is like the #2 mission of a major manufacturer, followed closely behind #1 making money.
     

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  11. ThunderChild

    ThunderChild Supporting VIP

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    I understand your stance and generally agree that manufacturers will try to eliminate warranty work. Though I have seen a number of things over the years that makes me wonder if they really give a rats-a$$ about any of that.
    Though I will still politely disagree with you about the stress applied to the oil pump shaft by the belt, ESPECIALLY when a belt is over tensioned (which may not necessarily lead to a timing related failure, at least before an oil related failure has it's chance, depending on how over tensioned it is).

    Once again tho, you are correct it is completely in the users hands to ensure things are done correctly!

    @bastarddsm out of curiosity, I know you did a lot of stress analyzing for your 4 spider CD. I'm wondering how hard it would be to calculate the (radial?) load the timing belt applies to the oil pump drive pulley and shaft?
     

    Street Build 99  3

    1990 Plymouth Laser N/T
    fwd · manual · 1G DSM

    228  8

    1987 Toyota Pickup/Hilux
    awd · manual · Misc Vehicles

    Street Build 742  7

    1997 Mitsubishi Eclipse Spyder GST
    fwd · manual · 2G DSM

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    1992 Eagle Talon TSi AWD
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  12. JusMX141

    JusMX141 Moderator

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    These shafts seem to be popular in the Evo platform with the understanding that the OEM helical pump gears can thrust-load at high RPM. I'm not sure how many shops actually found this to be a problem before they began producing the machined shaft or if it's just a theory, but I'm sure there are far more cars out there driving around with this shaft installed than actually need it.

    In the race car we have OEM straight cut gears and the same used OEM oil pump/case that's been on three different blocks, currently revving to 10,000+ and not one issue. Use good oil (Penngrade1, VR1, or similar), tension the belt properly, and use an OEM stub shaft and you'll be just fine. I'd much rather have the shaft missing altogether than spinning around in the block at 20,000 rpms as the smooth shaft can seize in the rear bearing just like a normal balance shaft if you have oiling issues.

    Others, including the current owner of Buschur Racing, seem to agree. Shaft.jpg
     

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  13. brian9397gsx

    brian9397gsx Proven Member

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    I also don't think it has a place. I've had my dsm since 2003 and the first engine failure I had was a spun balance shaft bearing. Then a few years later a friend of mine, his motor developed a knock. I tore it down and found the balance shaft bearing spun. In all my years and countless friends with 4gs I've only seen 1 pump failure and it was because the timing belt was way to tight. The balance shaft bearings just seem to have spun randomly possibly from over rev or the fact it's a heavy mass that's not balanced on a shaft spinning 2x the engine crank speed. They are not there to balance the rotating assembly just to remove 2nd order nvh in 4cy engines. They are not there to support the oil pump if they were the 1.6 that we all buy OEM stub shafts that were made for them would've had them also.
     
    brian9397gsx

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  14. bastarddsm

    bastarddsm Supporting Vendor

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    Clearly you've never worked inside the engineering offices of an automaker, eliminating warranty dollars is #2 only behind making money.

    I can do the analysis on anything, the problem is, I'm not going to waste time on something that's not an issue. I can shoot from the hip, and say with the amount of bearing area it has, the oil pump can support way more load than the strength of the belt.

    As for 'Over Tensioned Belt' - the only possible way you can over tension the timing belt is by bottoming out the tensioner, or running a solid adjustable one like the BLE one. The tensoner is a hydraulic shock absorber - it has no appreciable change in force over it's entire range of travel. It can't be over tensioned unless you bottom it out. Go look at your timing belt, chances are there is slack between the cam gears. If not it doesn't really matter, we've all experienced it. The closing ramp on the exhaust cam has enough force to compress the tensioner slightly. So tell me how can the tensioner over tension the belt, and how is the 'race shaft' going to save the oil pump.
     

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  15. bastarddsm

    bastarddsm Supporting Vendor

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    It's like us OG's that have been around for 20 years haven't battled this and solved the problem already. How many of us owned the cars before the shops selling these race shafts even existed?

    Keep a good supply of clean air free oil of the right viscosity and additive package, and the factory oilpump/stub shaft doesn't fail.
     

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  16. ThunderChild

    ThunderChild Supporting VIP

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    That's fair, and I'm not trying to say I know more than anyone else, I'm just stating my view on the piece and asking the questions I'm still curious about.

    The warranty work thing is subjective I believe, as I worked at a dealership (Lexus) about 10 years ago, as well as a few freinds that work at various dealers around the area, and most of them never gave a squat about warranty work. That's not to say that they don't want whatever work being done, done right, but they didn't seem to care how much warranty work was actually being performed. A lot of that will also depend on the manager as well, and I sure didnt and still don't like doing warranty work for a variety of reasons.
     

    Street Build 99  3

    1990 Plymouth Laser N/T
    fwd · manual · 1G DSM

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    1987 Toyota Pickup/Hilux
    awd · manual · Misc Vehicles

    Street Build 742  7

    1997 Mitsubishi Eclipse Spyder GST
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  17. 95GSXracer

    95GSXracer DSM Wiseman

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    All you need to do to understand why balance shafts are such a liability is to do the math on what RPM they are turning. It's scary. A turned down shaft would be subject to the same rpm. Personally, I won't risk it. I run your basic stub shaft on my car and have never hurt an oil pump in the 10 years I've been racing it. I agree that timing belt tension is a nonissue. Same for gear style. From what I've found over the last 18 years, the biggest killers of oil pumps are poor oil selection and picking up air.

    That said, I don't like to discourage people from doing their own thing. If a race shaft makes you feel better, by all means try it out.
     

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  18. Strm Trpr

    Strm Trpr Proven Member

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  19. motomattx

    motomattx Proven Member

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    ^^^ Both of you guys are right on the money on this, oil quality and oil level are what will keep your stub shaft going, also using good quality parts and not China knockoff parts.
     

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  20. AlmightySo

    AlmightySo Proven Member

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    48369966_2066464643441627_7794664059332198400_n.jpg 48380941_2066464673441624_3594841541752913920_n.jpg 48383912_2066464713441620_7662836016775954432_n.jpg 48405701_2066464760108282_7445029068325519360_n.jpg 0505091353a.jpg
     

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  21. ThunderChild

    ThunderChild Supporting VIP

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    Looks great! :thumb:
     

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    1990 Plymouth Laser N/T
    fwd · manual · 1G DSM

    228  8

    1987 Toyota Pickup/Hilux
    awd · manual · Misc Vehicles

    Street Build 742  7

    1997 Mitsubishi Eclipse Spyder GST
    fwd · manual · 2G DSM

    Street Build 940  1

    1992 Eagle Talon TSi AWD
    manual · 1G DSM

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    1992 Eagle Talon TSi AWD
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  22. GST with PSI

    GST with PSI DSM Wiseman

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    /thread
     

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