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Online Illustrated Assembly Instructions
As soon as you buy your Micro RS4 kit, be sure to see our latest website feature, Micro RS4 Assembly Instructions. These step-by-step written, fully illustrated instructions show you exactly how the "pros" at HPI built their Micro RS4 kits.

Front Diff Gear Update
The small brass gears (#73403a) that fit into the front diff case may need to be slightymodified to fit onto the silver pin (#73403b). If the brass gears won't slide easily onto the pin, use a sharp hobby knife to gently ream out the inside of the gear so the pin will slide in. See the picture below for an illustration of how to modify the gear. The gear is made of softer metal than the hobby knife blade so it is easy to cut away too much - make a few passes at both ends of the gear with the knife (you should have some brass shavings) and test-fit the diff shaft. If it is still tight, make a couple more passes and try it again.

You can also send your gears to us (see the Contact page at left) for free replacements.