UIM · Driveline

Aftermarket pump/impeller housing, stator vane assembly, pump plate, pump shoe, UIM

The clean line between a stock pump and a race pump.

This page is UIM only, and the bodies do not agree. The same part under IHRA and IJSBA. Which one applies to you is decided by whoever sanctions the race you enter.

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This is one body's answer, not the sport's. You are bound by whichever body sanctions the event you enter. If you race more than one series, build to the stricter answer. The differences are set out in the rulebook comparison.

Where it stands, class by class

24 classes, grouped where the same rule gives the same answer rather than listed one by one, because an answer that holds for a class usually holds for every class that borrows its rules. 8 of them borrow another class’s rules and are marked below; for those, the link to the parent class is read from the categories table rather than stated in the rulebook. 8 publish no rule for this part and name no parent to borrow one from, and are grouped together at the end.

What each answer below means

Not legal

This comes off. The rules refuse it in this class.

Not permitted, not listed in the rules

Treat it as coming off. The class requires the craft to stay stock except where the rules allow otherwise, and this part is not on the list, so this is our reading rather than a rule we can quote at you.

Legal, with conditions

Keep it, but measure it: the rules permit this part only inside stated limits.

Legal

Keep it. The rules permit this part in this class.

No rule, this is an open class

Probably keep it. The class carries no stock clause at all, so anything unlisted appears to be open. The rulebook does not say so in terms, and this is our reading rather than a permission anybody wrote down.

No rule published for this class

Unanswerable here. This class publishes no rule for the part and names no parent class to borrow one from, which is an absence in the rulebook and not a permission.

Not legal 5 classes

ANY internal modification - grinding, surfacing, polishing, machining, shot blasting - of any transmission component, including the stator and exit cone, is prohibited.

• Runabout GP4 · 502.01.06-02
• Ski Division GP4 · 501.01.06.02
• Runabout Juniors GP4 · 502.01.06-02 · borrows another class
• Runabout Ladies GP4 · 502.01.06-02 · borrows another class
• Ski Juniors GP4 · 501.01.06.02 · borrows another class

Not permitted, not listed in the rules 3 classes

Nozzle, stator and pump housing are not listed as modifiable, so under the closed-list rule they must stay OEM.

• Ski Division GP3 · 501.02
• Ski Juniors GP3.2 · 302.01 · borrows another class
• Ski Juniors GP3.3 · 302.01 · borrows another class

Not permitted, not listed in the rules 1 class

Pump, stator, nozzle and driveshaft modification is not granted in GP3.

• Runabout GP3 · 502.02

Legal, with conditions 1 class

TWO-STROKE only. Four-stroke retains the prohibition on any transmission modification. · 502.03.09, 502.03.10

• Runabout GP2

Legal 1 class

Impeller housing, stator vane assembly, pump mounting plate and pump shoe may be modified or aftermarket. · 501.03.09.01

• Ski Division GP2

No rule, this is an open class 3 classes

No driveline article.

• Ski Division GP1 · 501.04
• Ski Ladies GP1 · 314 · borrows another class
• Ski Veterans GP1 · 302.01.05 · borrows another class

No rule, this is an open class 2 classes

No article covering this part. Free under the open-list reading of GP1.

• Runabout GP1 · 502.04
• Runabout Veterans GP1 · 302.01.05 · borrows another class

No rule published for this class 8 classes

No component rules are published for this class and no single parent class is named, so this part cannot be answered for it. That is an absence in the rulebook, not a permission.

• Endurance · 317.03
• Freestyle Amateur · 312
• Freestyle Free · 312
• Jet Raid · 317.01
• Offshore · 317.02
• Parallel Slalom · 313
• Ski Future Electric (SFE) · 302.01
• UIM Hydro-Fly · 900

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Aftermarket pump/impeller housing, stator vane assembly, pump plate, pump shoe: if the rule your class applies reads differently to you, or the rulebook has changed since this was read, ask. We answer with the section we read it from, or that we have not read it. Ask a rules question.

Every UIM class · where the rulebooks differ · checks on parts the shop sells · how this site reads a rulebook.