Savage X diff shimming?

[Jmacca]

Hi guys,

My savage x diffs like to click while braking and my LHS said to shim them but I forgot to ask on what side of the diff should I put the extra shim

Can anyone tell me what side to put the shim so the diffs will stop clicking under braking?

Thanks.

 

[TGL]

Either side of the diff or the bevel (input) gear could require shimming.
It really depends on whether the mesh is too tight or too loose and where the slop is or isn't.
It's kind of a black art until you fiddle with it a time or two.
Place the diff in the bulkhead and spin it around and play with it and get a feel.
I made enough mistakes before I finally figured it out.

 

[olds97_lss]

Usually you shim behind the pinion (but not much or the cup won't go on) and behind the ring gear side of the diff itself.

If yours has already started hopping teeth... I'd be ordering a new set of ring and pinion or complete diffs off ebay. The newer X/XL gears do hold up to abuse pretty well though. Far better than the older cast gears.

 

[Jmacca]

well, my pinion is missing about 3 or 4 teeth so I'm waiting on a new one before I try to shim it. Is there any method you can suggest to make sure I get it right? its getting expensive been through 3 pinions and 2 crowns in a couple of weeks >.<

EDIT: it is a new savage X so they aren't old gears.

 

[TGL]

As Olds stated, you usually shim behind the pinion and/or behind the ring gear side of the diff itself.
I think of it as trial and error meets Goldielocks.
It's either too loose, too tight, or just right.
If it's too loose, you add a shim.
If it's too tight, you remove a shim.
If it's just right, you put it together and have a beer.

 

[Jmacca]

As Olds stated, you usually shim behind the pinion and/or behind the ring gear side of the diff itself.
I think of it as trial and error meets Goldielocks.
It's either too loose, too tight, or just right.
If it's too loose, you add a shim.
If it's too tight, you remove a shim.
If it's just right, you put it together and have a beer.

will using that red lead stuff that they use on 1:1 cars work to identify whether it is correct or not?

 

[olds97_lss]

Never tried it. I adjust mine by feel. I'll hold the pinion stationary and rock the diff itself forward/back (slightly rotating) to feel the gear lash. When you have just a "tick" of play, that's good. Then you bolt it all together dry (no grease/oil) and spin the diff to feel for tight/loose spots. Then shim/adjust accordingly. Once you have it feeling good, lube it up and break it in. Usually a tank or two of figure 8's wear the gears in.

You may also want to look at your bearings. Any slop/looseness at all in the bearings will pretty much make shimming pointless. You really have to keep a close eye on diff bearings as they take a lot of abuse keeping the gears together. It causes a lot of side load on the bearings that the diffs spin in. If RC makers were smarter, they would use tapered roller bearings (like many 1:1 autos do on wheel bearings) vs flat bearings. They would handle the side load a lot better and hold their tolerances much longer.

Like these:

Every time you get on the gas or jam on the brakes, the gears are trying to push themselves away from each other. This creates a ton of load on the sides of our bearings.