Shimming?

[Frank211]

I ordered some new straight axles(Scx10), they came with shims(im guessing that's what they are), so where do they actually go on the axle ?
Do i really need them?
What's does shimming actually do, im guessing makes things tighter??
The new ebay axles i bought only had a rubberish shim that was pressed against the diff?


Sorry for the noob question, i gotta learn these things, and again, many thanks guy's.

[Voodoobrew]

The shims are used to maintain a proper mesh between the ring and pinion. They can either shift the ring or pinion depending on where you place them. Generally I think one or 2 on the pinion before the pinion is inserted into the housing should do it. This will tighten the mesh.

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[durok]

In some (fairly rare) situations you may not need them - they are provided to take up any slop that may exist when everything is assembled.

Generally speaking, when all the parts are assembled, any deviation from ideal tolerances can add up to play in-between the parts - which can increase wear and noise during use.

It's a good idea to assemble everything, check for play, then disassemble and install shims and lube everything up...

[rbronco21]

Are you shimming to minimize backlash? What's the goal? I've seen them check gear mesh in a 1:1 axle using paint or whatever it is, but how do you do that with a scale diff?

[Joshs4x4toyz]

Pinion depth, there is enough slop and with hypoid and spiral bevel types that they will bind if the pinion can ride back and forth too much. Honestly, I barely see the need anymore (atleast ar44 gearsets), they are getting very good tolerances in the housing it seems. I usually just take up the gap outside at the driveshaft and call it a day. They will bind if you let the pinion inward, so atleast do that. On the larger OG SCX and AR60 gearsets, I still shim the pinion on inside as they are typically too shallow and will eat the gears, especially OD sets.