Pictures of how to shim a diff.

[yzf128r]

This is a brief description of how to shim your diffs. I'll do my best to give you a step by step description of each picture.

Here is a picture of the diff. and the shims I use.


Remove the 4 screws shown in this picture


Separate the cases


Remove this gear


Place shims on the shaft as shown. I usually start with 1 or 2 shims.


Slide the shims all the way down until they are against the gear.


Insert the gear back into the housing


Put the cases back together and insert the 4 screws


Check for slop by trying to move the shaft on the left in and out. If it feels snug, check for binding by rotating it. If it all feels good, your done. If it feels sloppy, add another shim. You want it to move as little as possible in and out, while still rotating freely.


Hopefull this post helps those of you with questions on how to shim the diff. I'm not a pro by any means, this is just the method I use.

[bluebill]

great pics and explaining! ive never shimmed a diff, but is that the only place that needs shims? i thought i remember reading there was two places to shim.

[2fast]

I noticed that when I fill my diffs with grease they seem a little tighter. Does anyone else fill theres with grease??

[Revo¹]

You also need to shim the diff side to side, not just pinion depth. Also, you should never shim a dirty diff...always thoroughly wash all grease off before shimming.

Grease (inside the diff cup) will make the diff seem tighter when you spin it by hand, but it is actually less vicious than diff oil, so it will not perform as well as diff oil.

Grease on the ring and pinion is fine, since metal gears need lube, but you only need a little, just enough to coat the gears.

[yzf128r]

Yes you can also shim the output shafts of the diff, but that very rarely needs to be shimmed. The input is usually the part that wears first and starts slipping.

[Revo¹]

The ring is harder than the pinion, and the diff moving side to side is what wears the pinion. Pinion depth should only be shimmed AFTER you have the diff itself shimmed side to side. If you can move the diff side to side without the pinion in, it needs to be shimmed.

[yzf128r]

Hmm. Every time I have had a clicking diff, the process shown above has eliminated the problem. From my experiences the mesh between the ring and pinion loosens up, which is why I shim it. I have never had a problem with the mesh on the internal diff. gears.

[michindi]

This may be a stupid question but why shim?

[2IS]

And where do you get these shims from?

[yzf128r]

This may be a stupid question but why shim?

after a while the gears begin to wear and will start slipping. You can shim them to stop the slipping and get more life out of them.

[yzf128r]

And where do you get these shims from?

I get shims from my lhs. They are just 6mm bearing shims.

[Chachi_RC]

I got the same shims as in the picture from my LHS. 6mm shims.

One thing that I have found with the diffs that makes a big difference is to not tighten the out case to much. It really starts to bind the action quite a bit. There is a fine line between just tight enough and too tight. WIth the outer case, you aren't really needing to keep any liquids in like the inner case. The grease is sticky enough to stay on the ring gear pretty well.

[Revo¹]

I have never had a problem with the mesh on the internal diff. gears.

I am not talking about shimming the internal spider gears, I am talking about shimming the output shafts, to stop the whole diff from moving side to side in the diff case.

[SlotterHouse]

Tagged: Just in case I forget....

[bmxdude]

thanks, great how to!

[Revo¹]

[Here] is the proper way to shim your diffs...

[h8tow8]

When your diff starts clicking what is the best way to find out if it's front or rear diff? Please be as detailed as possible.

[Brewers74]

Hold your truck planted to the ground watch to see if its the rear or front tires that skip a beat

[anr2442]

For me clicking on hard acceleration is rear... And clicking on hard braking is the front.

[h8tow8]

Tks for input guys I'm going to give those recommendations a try and see if I can figure out where mine is coming from.. sounds like it's on the acceleration, will know more tomorrow..

[randy0050]

i'm sure saving this post !!! great stuff guys

[bip]

I have had my E-Revo since 3 April and have had to change out both diffs already. I know most will advise me to adjust the slipper and/or use 4S versus the 6S I currently run. How about this, Traxxas should build an RC that can handle the motor and ESC. I may be fairly new to this hobby but I know a crappy product when I buy one. Chevy doesn't tell my not to stomp the gas on my Vett because it will break stuff. If this were a full sized car, it would have been recalled. The E-Revo needs to be fixed! I can't believe Traxxas is allowing their customers to suffer like this. I am VERY disappointed in them. How is it that LOSI's diff can hold up and Traxxas' cannot? Traxxas reminds me of the Gateway computer company of the late 90s. They were an up and coming company, neck and neck with Dell but lost their loyal customer base due to distribution of inferior products and poor response to customer feedback. Traxxas take note; a bad reputation is hard to recover from. PLEASE FIX THIS PROBLEM ASAP!

[WesleyK]

Very simple, actually.. The losi diff is made for a car that weighs 13 pounds without batteries and gas. The revo weighs in at 9 pounds without batteries and 10.9 with. Thats a huge difference for the diffs to handle.
That and 6S, 6S is just a lot of power, on any RC. If it is not the diffs that break, something else will break.
It's almost impossible for traxxas to get better diffs in the e-revo without redesigning a lot. A possible solution for you might be shimming your diffs, something that is not possible in the factory because it different for every diff, but it will improve durability. Another solution is to get a castle link (which should be in the box...) and adjust your Punch control to 30-40% or so.

But yeah, they could have gone for 1/8 diffs when they designed this car, but i guess the didn't think about that when they made the Revo (not the E-Revo). Almost everything on this car is 1/10, except for the diffs.

[bip]

WesleyK, that's all good info, however the bottom line for me is; The Castle Mamba can handle 6S and if they are going to put that setup in the car, it should be able to handle it's full power. My Rustler's motor can handle a 3S and I run it with a 3S often. The Rustler can handle it. I understand normal wear and tear but the e-revo is a flawed product. For a $1K car it should work much better than it does. I still believe they need to fix the problem. They have my money and I have a flawed truck. If this is common place in this hobby and acceptable, I guess I'll have to find a new hobby. I love the RCs but RTR should be RTR. The Slash is a great truck with a ton of hop ups. They need to fix the E-Revo with hop ups. But I guess I'm the exception. Seems everyone just accepts what they get and are willing to try and fix the problem or use a portion 30-40% of what they paid for. If I were abusing the thing, by towing my kid in his wagon or doing tug of wars, I'd blame noone, but all I do is drive on tracks, track like conditions, parks and dirt. I'd don't think it's fair that in just a month I've had to replace two diffs . I love the truck when it's running, but mostly it seems to sit on my work bench in peices .

[WesleyK]

I have my revo for almost 6 months now, both 4s and 6s runs and i have just rebuild the front diff today. Starts to show some wear but its still fine. Looks like some of us have luck with the diffs and others have not.

I will agree that if a product is ready to run, and comes with 6S lipos and advertising it should be able to handle 6s. The stock revo isnt, you totally right on that. But punch control is a great way to save the diffs, i barely notice the setting but my diffs are still in good shape as i wrote before. It only helps with putting the power down, like a slipper clutch but electronic. You should try it.

[bip]

WesleyK,

I apprciate your advise. In lue of a better alternative (like a Traxxas fix) I will try the punch control option. Thanks for your time and recommendations.