enriquez2000 said:

I've run both pump gears and never had an issue either way. I still have a straight cut set in my bin just sitting there

But to your question the back bearing where the big end sits gets oil so line that hole up. The other 2 turn 180 degrees and block the holes in the block.

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pauleyman said:

That's not true. The oil pump driven shaft does not have holes. The shaft is oiled through itself. The oem bearing has no holes. That is the ops concern as he was provided with bearings and all 3 have holes when one shouldn't.

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AustinGST98 said:

Well if it was that straightforward then the straight cut gears wouldn’t be so sought-after. I’ve seen a lot of claims such as “On most “High” power builds people delete the balance shafts, the helical gears have “axial/side loading” issues at high rpm without the balance shaft where as the straight gears don’t have that issue with an OEM stub shaft” so typically when going with helical (as is the only available type of gears available oem) you can resolve this with the dummy shaft and bearing on the oil pump driven side.

You see this type of configuration as well with a lot of electric motors in industrial complexes, where the shaft goes from the motor, to the driven item (pump or fan) and the end rests in a bearing. Why would they not just keep the end of the shaft floating and save money on each pump or blower assembly if it makes no difference?

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DSMPT said:

This would be a personal preference.

This is just my opinion, I think it's true that it may make some difference on wear with or without the balance shaft in long term or in a high rev build. But it seems it spread out a bit exaggeratedly. This is not like something happens immediately. And by seeing things from a different perspective, the dummy shaft would possibly cause some collateral damage. For instance, in case if you would break rods and if the broken rods would hit the shaft, that impact will kill the front case or/and gears for sure, wouldn't be reusable. In that case if you would't have the shaft, you may be able to reuse the front case and pump gears. So I think there is pros and cons.

Here is some info that is little known, 4g6 series 1.6/1.8L, like 4g61 or 4g67, they come with the same front case and oil pump gears as 4g63, just without the balance shafts. We know that the stub shaft we are using is from those engine. They also switched to the helical gears after 91, like 4g63. Which means the helical gears with a stub shaft was by default from factory in 91+ 4g61/4g67.

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donniekak said:

There is no thrust bearing on the shaft. That’s the only thing that takes an axial load. A stub shaft is just as likely to move axially as a whole shaft.


We ran stub shafts in 1300+ hp builds with a fuel pump driven off the timing belt. Zero pump issues.

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