Thinking About Buying Internal Gears for Your BMW SMG Pump? Read This First.

If you own a BMW WITH SMG SYSTEM, you already know how expensive the hydraulic pump can be. So when people see replacement internal gears being sold separately (instead of replacing the whole pump), it seems like a smart way to save money.

But we need to share something important.

Over the past while, we’ve had multiple customers contact us after buying internal gear sets from a German supplier (the ones sold online for the SMG pump). Unfortunately, many of them ran into serious problems after installation.

What’s Been Happening?

Here’s the pattern we keep seeing:

  • The gears don’t fit quite right.

  • Tolerances are off — either too tight or too loose.

  • The pump doesn’t operate smoothly after install.

  • In some cases, the pump ends up damaged.

And once that happens, you're no longer just replacing gears — you're replacing the entire hydraulic pump.

That turns a “money-saving repair” into a very expensive mistake.

Why This Matters

The SMG II pump runs at high pressure. These internal gears must be manufactured to extremely precise tolerances. Even small deviations can:

  • Cause abnormal wear

  • Create metal debris in the system

  • Reduce pressure output

  • Lead to complete pump failure

We’ve now seen enough cases to say this isn’t just a one-off issue.

Our Advice

If you're considering buying aftermarket internal gears for your SMG pump:

  • Be very cautious about the source.

  • Don’t assume “German-made” automatically means OEM-level quality.

  • Measure everything before installing.

  • Understand the risk to your pump.

Sometimes the cheaper route ends up costing far more.

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