Stub shaft BSEK vs GSC/AMS style BSEK

[awdtalon4451]

I've been reading up on both methods of deleting the balance shaft recently because I recently bought a built shortblock with a BSEK. But I ran across this while doing a little research which has me a little paranoid. http://www.amsperformance.com/cart/AMS-4G63-Race-Balance-Shaft-Eliminator-Kit.html

If what AMS says is true about stub shafts increasing oil pump failures by lack of support on the rear bearing journal and premature rod and main bearing failure from metal contaminated oil (material from gears rubbing the pump housing). Not trying to discredit AMS on their claims but wouldn't we be seeing a lot of oil pump failures from people running the stub shaft?

Both claim to be true and tried but what about proven? Maybe I'm trying to convince my self into buying the kit but I'd like to know if anyone else has any input on this.

 

[bryanwheat]

In my opinion they are full of it. The OEM stubby shaft was used in hundreds of thousands of cars that don't have premature pump failure. Look at all the Mirages still on the road today.

With the AMS style shaft you have one more point of possible failure at the balance shaft bearing. With a stubby shaft you don't have to worry about that, and you have WAY less mass being driven by the oil pump. In my opinion less mass on the oil pump will mean less wear over time.

 

[BogusSVO]

I think the logic of it is sound.

Look at the number of oil pump shaft seal leaks.
It is another support point to keep the gears from shifting in the oil pump housing.

That's one of the reasons timing belt tension is so carefully checked.

 

[Fiascoxl]

I agree with them, just don't think it is necessary on any motors turning under 9k rpms.

 

[Cdc1221]

Hahaha Dale, I SWEAR I had nothing to do with this subject popping up.

 

[BogusSVO]

I agree with them, just don't think it is necessary on any motors turning under 9k rpms.

Maybe not necessary, but for that little bit of support it provides, it falls into that "it would be nice to have parts"

 

[My1GLaser]

Here is my experience. I have a Mirage stub shaft with 20k miles on it. 9k redline. I beat the piss out of my car every time I drive it!!!

I had the front case apart last year and the pump looked fine and was still in spec. It was a used OEM pump with new helical gears when I built the motor 5 years ago. I looked at the mains and there were no abnormal signs of wear either. My rod bearings looked great a few months ago when I had the oil pan off to change a rod (broken wrist pin). I do change my oil every 500-700 miles though

 

[brian9397gsx]

I agree. I've only seen one pump fail personally and that timing belt was way to tight.

 

[dsmspick]

I think the response to the shorts being bad was when a ton of people were using the stubby that had no oil groove in it which was causing major issues.

If you use the OEM kit with the oil groove I see no point in using the long BSEK. Tons of people run the OEM kit with no issues. So basically it comes down to a preference.

 

[BogusSVO]

I agree. I've only seen one pump fail personally and that timing belt was way to tight.

This is the main reason, I like the idea of long shaft to the stubby shaft.

Here is my experience. I have a Mirage stub shaft with 20k miles on it. 9k redline. I beat the piss out of my car every time I drive it!!!

I had the front case apart last year and the pump looked fine and was still in spec. It was a used OEM pump with new helical gears when I built the motor 5 years ago. I looked at the mains and there were no abnormal signs of wear either. My rod bearings looked great a few months ago when I had the oil pan off to change a rod (broken wrist pin). I do change my oil every 500-700 miles though

20k Miles, 5 years, 9000RPM Sounds like you are doing it right.
Run the stubby.

Either method will work.

 

[JacksonAuto]

The common argument against balance shafts has been bearing failures. If you're still using a shaft, then what's the point? Weight loss is negligible. Use the stubby shaft if you must remove the shafts.

 

[JusMX141]

The point behind a balance shaft elimination kit is to actually eliminate the shafts....derp.

OEM front case and OEM straight-cut gears have been proven to the point where I feel comfortable using that setup in any of my high-RPM builds.

 

[delta448]

OEM front case and OEM straight-cut gears

^This.

If you're concerned about gear/housing wear and contamination using the stub shaft, run the 1990 oil pump gears that are straight cut instead of the later helical ones. Debur/detail before installing. They make a little bit more noise, but won't load themselves against the pump housing.

 

[92nolatist]

I am currently running the AMS style shaft in my car, only because of the the myth of oil pump failure and strain, blah blah blah. Its been in my car for 2 years and 24K miles, no issues. However, when its time to rebuild again, I'll be going with OEM stub shaft (which I've actually had in my possession for 5 years ) because I don't want to risk having balance shaft bearing failure.

Plus, I have straight cut oil gears, so I don't need to worry about side load wear into the housing and all that jazz.

 

[donniekak]

The straight cut gears do not prevent side loading, they prevent thrust loading. The timing belt tension is what causes the side loading.

I have seen a couple oil pumps fail with a stubby. Excessive side play, not in and out thrust play causes the oil pump shaft seal to leak. The further away from the belt the side load is supported, the less leverage the belt tension has on bearing load.

 

[awdtalon4451]

Dale is the individual that mentioned both methods when I had some machine work done. I just wanted to hear others thoughts before I went ahead and decided.

^This.

If you're concerned about gear/housing wear and contamination using the stub shaft, run the 1990 oil pump gears that are straight cut instead of the later helical ones. Debur/detail before installing. They make a little bit more noise, but won't load themselves against the pump housing.

I guess im gonna pull my oil pump out and see what gears are in it when I get home today. Is there a vendor/website that sells the 90 pump gears in case I need them?

 

[92nolatist]

Thats what I meant when I said side load, meaning thrusting into the housing, sorry.

 

[awdtalon4451]

The timing belt tension is what causes the side loading.The further away from the belt the side load is supported, the less leverage the belt tension has on bearing load.

Could you explain this a little more? So too much TB tension will cause the pump to side load and wear into the housing?

 

[My1GLaser]

I have a question: Are you guaranteed to have proper belt tension with a properly set tensioner pulley if you have the correct plunger protrusion? All OEM timing components.

 

[donniekak]

Could you explain this a little more? So too much TB tension will cause the pump to side load and wear into the housing?

Yes.
Just like tightening your alternator belt until its ready to snap will kill your alternator, and waterpump bearings,

 

[bryanwheat]

The straight cut gears do not prevent side loading, they prevent thrust loading. The timing belt tension is what causes the side loading. I have seen a couple oil pumps fail with a stubby. Excessive side play, not in and out thrust play causes the oil pump shaft seal to leak. The further away from the belt the side load is supported, the less leverage the belt tension has on bearing load.

The shaft that the sprocket and seal are on has nothing to do with the balance shaft. Both sides of that shaft are supported in the pump housing.

Having the OEM stubby, AMS shaft or an OEM lower balance shaft will not in any way have anything to do with the pump wearing out with too tight of tension, or cause the seal to leak.