Great BXA 5.2L read

Great read. The most curious section for me is the balance shaft section:

Balance shaft and vibration damper

The BXA engine had a nodular cast iron balance shaft that was located in the ‘V’ section of the upper crankcase housing between the cylinder banks. The balance shaft rotated in the opposite direction to the crankshaft and at the same speed to offset first order inertia forces.

A vibration damper was fitted at the front of the engine to absorb crankshaft torsional vibrations created during the power stroke. The damper had three main components:

  • A counterweight to the crankshaft;
  • An accessory drive pulley; and,
  • A bonded element (elastomer rubber) that joins the two pieces together.

Viscous oil was used to dampen the relative movement between the elastomer rubber element and the accessory drive pulley – this reduced torsional stress on the crankshaft during combustion and reduces stress to the crankshaft from accessory components driven by the poly-V belt.

I question if long term use of a light weight crank pulley would be determinate and counterintuitive to what the engineers at Audi were trying to prevent? Thinking about my broken crank as I’m trying to give the car away.

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If it’s your gut telling ya this. Took me 40 years to starting listening to it. 95% right. Be fun to test this somehow…??

There are a few ways you can look at this.

There are other motors that have a balance shaft that also run the LWCP and they don’t have any issues

You also have a fluid filled TQ converter basically bolted to the back of the motor Via a flywheel that would absorb some of the same dampening

And lastly one of the many reasons people replace their crank pulley is that the OEM unit breaks down and brakes apart almost all of them fail over time. This is a disaster when they fail

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I did nor know this. Great chuck of knowledge. Thank you.

So I should probably swamp mine out.?104,500.

My car was literally shaking bad from it and I assumed it was other things until I finally changed it and all that shake was gone.

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If I recall right. Your flywheel might have had damage from a front ender as well?? Some lady or something? I saw your old wheel in photos. If by chance you got a rundown of any specific type of tools needed? Any tips or advice on how to do the R/I on my flywheel. Would be appreciated very much.

That damaged I inflicted myself trying to remove the stripped fly wheel bolts. Like when I removed them with my impact literally all of them stripped so I had to a get a remover kit to hammer over it and remove it

That never made the shake come. I assume the shake is from my accident I got into because ever since after that slowly started getting worse with the shake until I noticed a oil spot directly below the damper which I assume that was the oil from it.

After my accident I fixed the entire car and then a month later the starter died and I pulled the engine and screwed with all that craziness

When you mean r/I you mean remove it?

I assumed R/I = remove/install

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Remove install like bro said

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Oh gotcha. If I remember correctly you need a tool that holds the flywheel in place and then the triple square bits I think they are called to remove them

You need that counter hold tool

Yeah man! More toys. Much appreciated.

I think that brings up a good point about replacing the OEM dampener at a certain number of miles (60-75k range?)

The Audi design engineers must have seen the need to dampen both ends of the crank. I’m sure they saw the low hanging fruit (and cheaper) solution of using a solid metal unit, but something in their assessment directed them to go with the solution they came up with. Just my $.02

I’ve seen a lot of 5.2 motors will front dampener issues. Everything from torn or dissolving rubber to just almost split unit. The 3.0T guys saw this early on and it can be a huge issue.

Since the 5.2 motor has the dampener that seems to degrade over time you never know what stage it’s in. So with that in mind. It almost make sense to just upgrade to the JHM LW solid unit. The counter balance is still there it just has less weight. The result is a nice noticeable ability for the motor to feel more free to spin IMO

Surely won’t argue with the performance improvement.