Yokomo S4-503R17A 40T Ring Gear for YZ-4S Race Differential Gear  [S4-503R17A]

Yokomo S4-503R17A 40T Ring Gear[Use w/17T D Gear] for YZ-4S Gear diff
Price:
NZD$47.84
Brand:
Yokomo
Model:
S4-503R17A
GTIN:
0639342210398
Condition:
Brand New
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Fine tune your YZ-4S differential with the Yokomo 40T ring

The Yokomo S4-503R17A 40T ring gear brings improved tooth alignment to your YZ-4S gear differential. Built to work with a 17T drive gear, it helps reduce drivetrain lash and supports consistent torque delivery during cornering. Its precise manufacture gives dependable service for regular track use.

Compatibility and practical benefits

This 40T ring gear is made for the YZ-4S chassis and fits B-YZ4SF, B-YZ4SF2-1, MOR-010, and MOR-020 models. The accurate tooth profile encourages better meshing with the 17T drive gear, which helps reduce noise and uneven wear.
Remark :
Due to limited stock availability, please notice that some Yokomo items may have to order from the factory and the ready time is around 4-6 weeks. Customer purchases the item is assumed to accept the waiting time which allows us to order directly from the manufacturer if the item is out of our warehouse.

Will this ring gear change my gear ratio?

No, the tooth counts define the ratio. Using a 40T ring with a 17T pinion gives the same ratio as other 40T/17T pairings, but mesh quality will affect efficiency.

Is any machining required to fit it?

In most cases it is a direct swap. Confirm the mounting holes and bearing seats match your differential case before final assembly.

How do I check gear mesh properly?

Apply a thin smear of gear marking compound, rotate the gears, and inspect contact pattern. Adjust pinion height or shims until contact is centred on the tooth face.

Can I use different oils with this ring gear?

Yes, oil choice affects differential behavior but not gear fit. Use a viscosity suited to your driving style and check for slippage or binding after filling.

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