Racing Balance Shaft

[BrokenTsi]

A few years ago I destroyed an oil pump. I believe it was due to the fact that I rev my engine to 9k+ on a daily basis. I replaced the front case and everything was good to go.

Im doing a new engine build, 2.0l. I sent out my balance shaft to JacksTransmissions to have it machined. I believe the race shaft will add stability to the oil pump and it wont cause that wrenching "lever" stress on the drive gears from the timing belt.

I installed it and now I have second thoughts. I just dont like the fact that I added a bearing that could possibly fail, and it seems like the balance shaft is too tight in that bearing. I just have bad thoughts about it.

For those of you who rev high like me, do you use the stub shaft? Im sure most of us do. Has anyone ever had the oil pump gears eat their way into the front case?

Alot of race cars use this shaft. I know AMS does on most of their Evo's. The shaft itself, after its machined, weighs hardly 1lb. Think I should just put the stub shaft back in and hope for the best? In all of my years, this is the only time Ive ever ruined a front case.

 

[pneumo]

Follow your instincts- if something doesn't feel right take a closer look at it. You might have to take it apart and look closely.

It's not easy to install balance shaft bearings without pounding a ridge on the side of the bearing as you press it in. Maybe you're feeling a ridge rubbing on the shaft?

Non- OEM oil pumps are sometimes made with a softer grade of aluminum which can wear quicker. I wore out a new Topline oil pump in two years of weekend use and 8500 rpm rev limit. When I say 'I wore it out' I really mean it had as much wear as an OEM pump with 100k miles on it, and I didn't want to put it on my racecar.

I use the Mitsu stub shaft that has the groove in it. I don't recomend the budget shaft that doesn't have the groove since it reduces lubrication to the oil pump shafts. BTW, neither the stub shaft nor the balance shaft sees any force from the timing belt. It just spins in the oil pump while being pushed by the other gear in the oil pump.

 

[JusMX141]

A few years ago I destroyed an oil pump. I believe it was due to the fact that I rev my engine to 9k+ on a daily basis. I replaced the front case and everything was good to go.

Just out of curiosity, when this happened were you running straight-cut or helical pump gears?

 

[BrokenTsi]

After it broke, I put in straight cut gears on the new case. I dont remember what gears were in it to be honest.

You dont think the timing belt "pulls" on the oil pump gear? That was the only explanation for me as to why the gears ate theselves into the oil pump. Could you elaborate on that more and help me understand why it doesnt?

 

[pneumo]

There's two gears in the oil pump. The T belt pulls on one gear. The other gear is connected to the balance shaft, so that gear doesn't carry any tension, load, force, whatever from the T belt.

 

[TSIfreek]

I have one in my new motor and I am going to be swaping it our for the stuby. Main reason why is I have 15 psi at idle on my new motor hot and I should see 25 with 15/40 regular oil.
I checked my 1st motors front case that used the stuby and helical gears and I found no wear in the stuby shafts bore or on the shaft itself. I did find wear on the main gear that the timing belt drives but not to bad.
I also dont like the added bearing that needs to be oiled its just another thing that can fail.
I have asked alot of high HP guys running in the 9s what they run and they all run the stuby.
I just wanted to try it on this new motor but I just dont like the slight loss of oil pressure I got from it.
Pluging the bearing should bring the idle oil pressure were im happy.

There's two gears in the oil pump. The T belt pulls on one gear. The other gear is connected to the balance shaft, so that gear doesn't carry any tension, load, force, whatever from the T belt.

You got it!

 

[BrokenTsi]

Im sold. At first I thought it was a good idea, but after installing it (on the engine stand), I really didnt like the idea of adding a part that COULD fail. My case and new gears only have a few thousand miles on em, so I'll just reuse it.

So I left the bearing in there and I'll just reuse the stub. Thanks guys.

 

[4gsx63]

Im sold. At first I thought it was a good idea, but after installing it (on the engine stand), I really didnt like the idea of adding a part that COULD fail. My case and new gears only have a few thousand miles on em, so I'll just reuse it.

So I left the bearing in there and I'll just reuse the stub. Thanks guys.

I hope this message isn't too late. I initially bought a "race/machined" balance shaft for my motor build. Like one of the member said, it is difficult to install the balance shaft bearings without deform the ridge slightly. So after I installed the BS bearings and try to test fit the machined shaft, it didn't want to go in. I put some assembly lubes on it and it finally went in. However, when I try to rotate it, it didn't feel smooth at all. At this point, I said forget about it. I would just stick with the stubby shaft. Make sure you pack the gears with lubes and prime it. Also don't forget to properly tension the timing belt to the proper spec.

I had to knock the BS bearing out and reinstall it so the oil holes aren't lining up. I hope you did the same because you will be loosing oil pressure if you didn't.