IHRA · Driveline

Aftermarket driveshaft and couplers, IHRA

IHRA answers this part for 29 of its classes. 9 of those answers permit the part outright and 4 permit it with stated conditions, leaving 16 that do not. 3 of the ones that do not are classes we read as open rather than as refusing it. 11 are inferred from how the class is written rather than quoted from a rule naming this part.

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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

29 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.

What each answer below means

OEM part required

This comes off. Only the part the manufacturer fitted is allowed here.

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.

OEM part required 5 classes

Must remain OEM.

• Drag, Sea-Doo vs Sea-Doo · DD.11
• Drag, Yamaha Pro Stock · DD.1
• Drag, Sea-Doo Pro Stock · DD.2
• Drag, Yamaha Spec · DD.3
• Drag, Sea-Doo Spec · DD.4

Not permitted, not listed in the rules 8 classes

On a closed list an unlisted modification is not permitted. · A.2.2, J.1

• Runabout Lites
• Four-Stroke Ski Lites
• Runabout GP2
• Runabout GP3
• Ski GP2
• Ski Lites
• Ski GP3
• Drag, Turbo No Nitrous

Legal, with conditions 1 class

Model-dependent. Aftermarket couplers and dampeners are permitted. W.5 Aftermarket permitted. · W.5

• Runabout Endurance

Legal, with conditions 1 class

1:1 ratio. TITANIUM DRIVESHAFTS PROHIBITED. · U.5.2

• Sport Spec

Legal, with conditions 1 class

Model-dependent. Nothing in Four Stroke Ski Lites opens the driveline, so a four-stroke entry keeps it as supplied. On a two-stroke entry P.2.6 allows modified couplers and other pump-area changes provided the original engine-to-pump drive ratio is kept, and an aftermarket shaft is not named. · P.1, P.2.6, J.1

• Ski Limited

Legal, with conditions 1 class

1:1 drive ratio required. · CC.4.1

• Freestyle

Legal 4 classes

1:1 ratio.

• Runabout Limited · BB.9.4
• X2 Vintage · T.5.2
• Sport GP · V.8.2
• Runabout GP · X.6.3

Legal 2 classes

1:1 ratio required.

• Ski 1100 Modified · R.5.4
• Ski 1500 Modified · Q.5.4

Legal 1 class

1:1 ratio. TITANIUM DRIVESHAFTS ALLOWED in this class. · S.5.1

• Ski Vintage

Legal 1 class

Aftermarket drive shafts are allowed, where the other stock-based drag classes keep the shaft stock, and no ratio or material limit is stated. · DD.5

• Drag, Super Stock

Legal 1 class

1:1 drive ratio required. · K.7.3

• Ski GP

No rule, this is an open class 3 classes

The class states only what it bans and calls itself run what you brung, against a section DD preamble that says anything unlisted is illegal.

• Drag, 2 Stroke Unlimited · DD.12
• Drag, Stand Up Unlimited · DD.10
• Drag, Unlimited · DD.6

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Aftermarket driveshaft and couplers: 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.

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