So after doing some research, this is the first time I have ever heard that you should not use helical gears and a stubby shaft. When I rebuilt my 97, I used an Autozone oil pump, slapped on the stub shaft, and went about my way. Still no issues with that after 35k miles of around 400 - 450hp.

I am currently rebuilding a 6 bolt for a 1993 GSX and plan on using a ACL oil pump that I bought from MAP on sale. I planned on using the helical gears that come with it and a OEM stubby shaft. I wanted some input on this, as the past threads seem to have some debate on if you can or can not do this. I did see that there was a bulletin stating that the covers are not interchangeable and that you should not use the straight cut gears in the helical gear covers. I have also seen some reported failures using the straight gears in a helical housing.

I figured that there may also be some more information on this in the present. I also was wondering if the ACL oil pump gears need to be deburred / detailed before using them as well. I just don't want to put this thing together and then have the gears lock up. Thanks.

Also this car will not be reving past like 7400. Not sure if that makes a huge difference or not.

I know tons of people eliminate the balance shaft, but is everyone really switching out for the straight cut gears?

I can't provide any technical proof either way but I have been using helical gears on the 1.6L stubby shaft and OEM case for the the past 30k without any negative issues but maybe it's just a ticking time bomb. Subscribed to see what factual data surfaces.

Just had my 6 bolt block built and used the stubby and acl pump. I used apex auto machine in il they are pretty well known out here for dsm builds they told me to buy that pump so I would think it’s fine. They really seemed to know the 4g63 in and out and were building dozens of them when I brought mine in.

No actual data, but my theory is the helical gears not only have thrust loads, but also an axial rotation due to the profile of the teeth and where they engage throughout their rotation.

Both of these effects could be mitigated some by the stock balance shaft, whereas the stubby shaft doesn't have the added weight or support to help either issue.

I had a stock BS turned down to a straight shaft and used that in my current setup (AMS style), and I don't think ill use anything else for my motors. Maybe if I hit baller status, I'll go for the FFWD oil pump at some point.

Biddy420 said:

Just had my 6 bolt block built and used the stubby and acl pump. I used apex auto machine in il they are pretty well known out here for dsm builds they told me to buy that pump so I would think it’s fine. They really seemed to know the 4g63 in and out and were building dozens of them when I brought mine in.

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Did you have the gears detailed / de-burred before installing it?

tametalon92 said:

No actual data, but my theory is the helical gears not only have thrust loads, but also an axial rotation due to the profile of the teeth and where they engage throughout their rotation.

Both of these effects could be mitigated some by the stock balance shaft, whereas the stubby shaft doesn't have the added weight or support to help either issue.

I had a stock BS turned down to a straight shaft and used that in my current setup (AMS style), and I don't think ill use anything else for my motors. Maybe if I hit baller status, I'll go for the FFWD oil pump at some point.

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I'm kind of following what your saying here. Wouldn't that matter a lot more for a high revving engine though? In my opinion that defeats the purpose of getting rid of the balance shafts to begin with. They still pose the rise of failure.

High rpm is one thing, but high oil film strength, pump load and timing belt tension will all play into it. I still think alot of timing belts are done just a bit too tight, and with a stubby shaft it could cock the shaft in the hole enough to lose oil film between the housing and shaft. Couple that with other factors, and it seems like a chance I don't want to take.

Keeping just the rear shaft as a turned-down unit should have little to no impact on reliability, or rotational weight, yet will provide support for the oil pump. I saw it as a win-win situation.
Though the rear shaft rides on a bearing, it's one of the first things to get oil supply, so as long as things are installed and not overly worn, there shouldn't be any issues.
The front shaft I have deleted.

Imo the stub shaft is questionable, and I know many people have zero issues with them, so it all comes down to personal preference.

I had the helical gears and stub shaft for a long time. Started racing/time trialing in more recent years. Took the motor apart over winter for a refresh and discovered my oil pump was just about ready to devastate my motor. You can see by the wear that it was loading with the tension of the belt. The belt was not over tightened. I do run a BLE solid tensioner, but it's set to the tension you'd find with the stock one. I had to hammer the pump gear out of the front case cause the bearing was that shot.

gsxitement said:

I had the helical gears and stub shaft for a long time. Started racing/time trialing in more recent years. Took the motor apart over winter for a refresh and discovered my oil pump was just about ready to devastate my motor. You can see by the wear that it was loading with the tension of the belt. The belt was not over tightened. I do run a BLE solid tensioner, but it's set to the tension you'd find with the stock one. I had to hammer the pump gear out of the front case cause the bearing was that shot.

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Maybe its just me, but judging by the marks on the case it kind of does seem like the timing belt tension was too tight at some point. Maybe even an oiling issue to the stub shaft. It looks similar to those stub shafts that used to be around with out the oiling grove. How often were you checking the tension? How many miles were on the motor? Which stub shaft was used?

Oh hi, @gsxitement , @tametalon92 !

Keep the balance shaft?!?!??

Removing a journal bearing on a shaft has zero to do with the thrust forces along the axis of the shaft.

Donnie for the win. Oil pumps die because your motor is shit and full of garbage, or you starve it for oil. No other reason at all.

I'm just going off the information that I was given when I posted about this on my build journal. Just trying to help. Post 182. A couple links I found informative. The stub shaft that I have is not eBay one or junk. It's a mirage stub shaft. The stub shaft showed no signs of wear or lack of oil. This motor was together since 2013, had six track days on it at about 360whp. Just trying g to help out with my experience.

http://www.dsmtuners.com/threads/98-gsx-time-trial-build.510081/page-8

Not really familiar with de burring they sent me this pic during assembly maybe they did they didn’t charge or say anything about it to me

jakk220 said:

Maybe its just me, but judging by the marks on the case it kind of does seem like the timing belt tension was too tight at some point. Maybe even an oiling issue to the stub shaft. It looks similar to those stub shafts that used to be around with out the oiling grove. How often were you checking the tension? How many miles were on the motor? Which stub shaft was used?

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The belt tension was checked before every race weekend/track day.

Post #3


http://www.dsmtuners.com/threads/2g-oil-pump-staight-cut-or-helical-gears.464223/

19Eclipse90 said:

Oh hi, @gsxitement , @tametalon92 !

Keep the balance shaft?!?!??

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Not sure how I missed this thread

donniekak said:

Removing a journal bearing on a shaft has zero to do with the thrust forces along the axis of the shaft.

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Well that was very simply put haha. I was having trouble picturing how using the stub shaft would affect the cover and gears negatively. Timing belt tension I can totally see being an issue. Which is the first thing that comes to mind when I see a lot of these failures.


My goal wasn't to bring up the age old argument of "Should the balance shafts be deleted" but more of if there was proof (other than pictures of failures) that there is a negative effect on the axial forces when using helical gears and a stub shaft. I would think you would see abnormal wear on the gears as well. But I'm no engineer .

I will always delete my balance shafts. I have had one take my engine out and its no fun.

gsxitement said:

Post #3


http://www.dsmtuners.com/threads/2g-oil-pump-staight-cut-or-helical-gears.464223/

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The problem with that is that there was a bulletin out from Mitsubishi stating not to use straight cut gears in a helical housing (post 33 in your link). I am sure that they had some reasoning behind this. What the reasoning is I am not sure.

And I don't think post 3 in that thread is entirely true. My car has seen Track days, drag strips, autocross, and daily driving. My stub shaft has not given me any issues yet. Not saying its impossible that it wont. But I feel most people do not swap to straight cut gears when doing a BSD and you do not hear about a ton of failures. Just a few.

jakk220 said:

The problem with that is that there was a bulletin out from Mitsubishi stating not to use straight cut gears in a helical housing (post 33 in your link). I am sure that they had some reasoning behind this. What the reasoning is I am not sure.

And I don't think post 3 in that thread is entirely true. My car has seen Track days, drag strips, autocross, and daily driving. My stub shaft has not given me any issues yet. Not saying its impossible that it wont. But I feel most people do not swap to straight cut gears when doing a BSD and you do not hear about a ton of failures. Just a few.

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I never said to use helical gears in a straight case or vice versa . I didn't have a failure for years with helicals and stub shaft, and I've had that setup since 2004. In several builds. I'm just trying to give my experience. Take from it what you will. And if people like Tim Zimmer said that straight gears and a stub shaft is the more reliable way to go, I'm ok with going that route.

gsxitement said:

I never said to use helical gears in a straight case or vice versa . I didn't have a failure for years with helicals and stub shaft, and I've had that setup since 2004. In several builds. I'm just trying to give my experience. Take from it what you will. And if people like Tim Zimmer said that straight gears and a stub shaft is the more reliable way to go, I'm ok with going that route.

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Believe me, I trust Tim 100%. I appreciate the input from your experience. It really is valuable information. I am just looking for the experience from others as well. Both good and bad. Just to throw in other possible variables. You are one of the few to actually report the failure and share the information.

Its just I was looking for more factual, tested data rather than theories and carnage is all. A more controlled study. I believe the straight cut gears would have to be for sure used in an OEM housing at the very least, and not an ACL. So I think im just going to throw the stub shaft on, leave the gears however they are, and see what it does.

If my 7 bolt ever goes kaput, which I'm sure someday it will, I will be sure to analyze everything carefully and report everything to everyone.

19Eclipse90 said:

Oh hi, @gsxitement , @tametalon92 !

Keep the balance shaft?!?!??

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Tottally agree with you, i realize now I didn't clarify my thought on the axial comment. It probably has zero effect, but I was thinking the small amount of extra mass attached to the oil pump drive may "dampen" those axial movements fore and aft.
It probably has zero effect tho.

I also agree that most oil pump failures likely come from poor maintenance and isht in the oil.

Another option is something like the GSC race balance shaft delete kit. I have one installed on my current motor and have all the confidence in the world. I do plan to take a peak after this race reason so we will see how it holds up for another year. Here is what I am talking about:

https://www.power-division.com/gsc-power-division-race-balance-shaft-for-all-4g63-evo-s-and-dsm.html

Boomdeeze said:

Another option is something like the GSC race balance shaft delete kit. I have one installed on my current motor and have all the confidence in the world. I do plan to take a peak after this race reason so we will see how it holds up for another year. Here is what I am talking about:

https://www.power-division.com/gsc-power-division-race-balance-shaft-for-all-4g63-evo-s-and-dsm.html

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Same thing I was mentioning before, AMS had them back in the day, may still. I just copied them and had a stock shaft machined down since it was far cheaper.

I had a Topline oil pump seize up on me, on a fresh 2.3L stroker build... it had helical cut gears, along with the stubby shaft (OEM 1.6L Mirage) BSEK in this build. I found similar wear markings, that (to me anyways) indicated a large amount of side loading of these gears was responsible for taking out the cover. Pics below:

https://www.dropbox.com/sh/n8so02ge9nmctw8/AAAdXev_BHNRFlLU9s9P_15Pa?dl=0

My solution was to rock a 1990 style straight cut gear set & OEM cover on my 4g64 build. -Although they're a bit more noisy, they have been solid for about a decade now. I tend to hear them make the most noisy ~3k, under light load & on deceleration. -I can only suspect that they don't have the same side load characteristics as the helical cut gear sets do & that's helped them last longer. Both sets were deburred prior to assembly.

BoostedTalonTS said:

I had a Topline oil pump seize up on me, on a fresh 2.3L stroker build... it had helical cut gears, along with the stubby shaft (OEM 1.6L Mirage) BSEK in this build. I found similar wear markings, that (to me anyways) indicated a large amount of side loading of these gears was responsible for taking out the cover. Pics below:

https://www.dropbox.com/sh/n8so02ge9nmctw8/AAAdXev_BHNRFlLU9s9P_15Pa?dl=0

My solution was to rock a 1990 style straight cut gear set & OEM cover on my 4g64 build. -Although they're a bit more noisy, they have been solid for about a decade now. I tend to hear them make the most noisy ~3k, under light load & on deceleration. -I can only suspect that they don't have the same side load characteristics as the helical cut gear sets do & that's helped them last longer. Both sets were deburred prior to assembly.

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That wasn’t axial loading, if it were the wear would be equal 360* of the thrust surface. That was side loading that cocked the stub shaft. A second journal bearing at the end of a shaft will help with this loading.

However, these failures are most often seen with aftermarket cases.
The type of gear in them doesn’t matter as it’s the force trying to shove the gears away from each other that does this. The bearing surface area of a stub shaft is enough to support this, but dirty, or bad oil can cause it to wipe the bore. Sometimes the machine work on aftermarket cases is off, or the metal is to soft as well.

gsxitement said:

I had the helical gears and stub shaft for a long time. Started racing/time trialing in more recent years. Took the motor apart over winter for a refresh and discovered my oil pump was just about ready to devastate my motor. You can see by the wear that it was loading with the tension of the belt. The belt was not over tightened. I do run a BLE solid tensioner, but it's set to the tension you'd find with the stock one. I had to hammer the pump gear out of the front case cause the bearing was that shot

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I had a failure on a fresh 6bolt G4CS. Topline case and helical gears with OEM stub. Looked identical to gsxitement, but mine ovaled out the shaft bore and crank walked the motor.

I'm Running OEM case and straight cuts with OEM stub shaft now, but only have a few thousand K on it so far.

I think proper tension is also key, probably something I didn't pay much attention to, back then.

donniekak said:

That wasn’t axial loading, if it were the wear would be equal 360* of the thrust surface. That was side loading that cocked the stub shaft. A second journal bearing at the end of a shaft will help with this loading.

However, these failures are most often seen with aftermarket cases.
The type of gear in them doesn’t matter as it’s the force trying to shove the gears away from each other that does this. The bearing surface area of a stub shaft is enough to support this, but dirty, or bad oil can cause it to wipe the bore. Sometimes the machine work on aftermarket cases is off, or the metal is to soft as well.

Click to expand...

Well the ACL pumps are at least known to be decent quality. So maybe it's the topline / AutoZone covers that are prone to failure. A a $400 oem cover isn't in the budget right now, so the ACL will have to do.

And while a second journal bearing would help, wouldn't it eventually just wear into the bearing at the far end of the shaft just at a different rate? I feel as though if there is a clearance issue from the get go even with straight cut gears or a full shaft there will still eventually be an issue.

jakk220 said:

Well the ACL pumps are at least known to be decent quality. So maybe it's the topline / AutoZone covers that are prone to failure. A a $400 oem cover isn't in the budget right now, so the ACL will have to do.

And while a second journal bearing would help, wouldn't it eventually just wear into the bearing at the far end of the shaft just at a different rate? I feel as though if there is a clearance issue from the get go even with straight cut gears or a full shaft there will still eventually be an issue.

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If you're using a race style shaft for the oil pump drive that rides on its two original bearing surfaces (front cover AND rear journal), then no. It will have far more support keeping it square in the bore.