XB Differential Rebuild

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2simplistic

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I went to disassemble my front and rear diff to clean and re-oil for the first time. After dis-assembly, I put it together exactly as it came apart but now the diff is locked up and will not turn. The only way it would turn is if I significantly loosened the 4 screws (50084 on the Diff Gear Assembly diagram) that clamp the differential together. Then oil spills out. So I took it back apart and noticed that the parts in the diagram do not match the parts that came out of the differential. On the "Diff Box Exploded View", I am missing both washers (50057), but have extra parts as well. On the "Diff Gear Assembly" diagram, I have an extra washer and o-ring on the back side of both of the small side differential gears that are not listed on the diagram. These washers do not fit in the place of the washers I am missing. Anyone else run into this?
 
I'm not sure about your extra parts etc but I had a similar problem when I rebuilt my diffs

I thought I put everything back correctly but I didn't have the pin seated correctly in the slot in the diff case. This caused the diff to lock up when I tightened the 4 screws.

I'd double check that you have the pins in the groove/slot before messing with shims etc
 
I'm assuming the o-ring and that extra washer on the spider gears are locking the diff up. There should only be two o-rings in the diff assembly. One behind each gear that rides on the diff cup shaft. And those o-rings should be covered by a shim. Also, there should only be one very thin shim behind each spider gear.

If you could take a pic of the assembly, that would help us help you.
 
50067 is compatible with the X series. I assume you just use what you need. And from the manual, it looks like you just need the shims behind the gears that ride on the diff cup shaft. Also, the manual doesn't show the shims behind the spider gears, so maybe they don't use them.
 
I had the same problem with my TT. Both larger shims were never installed in the diffs. After a couple phone calls to Redcat and then filling out a warranty claim they sent the shims to me. I wasn't spending $40 for 4 shims. Those shims are shown in the manual so they should be there and Redcat should send them to you.
 
Yea, I tried lookin everywhere, but couldn't find any with the right ID and OD. Wasn't sure on the thickness tho. Big shims with little holes seem hard to find, but I'm sure something close would be ok. Not as much selection of shim types in metric.

You need the ID to be 6mm so it holds the O-ring down in the cup and prevents leaks.
 
Just curious, did any of you have dif issues since parts are missing? Just wondering. Unless I have to, i don't plan to tear into mine until the 7075 cases are out.
 
So I too filled out the warranty claim and this was the response I received:

"The factory tests each differential once they are built. If the differentials are too loose, they will add the shims. If they have the proper gear mesh internally, then they do not add them. You should be good to go.

Since we do not sell the shims separately and you feel that you need them, you could visit your local hobby shop to see if they have something that will work."

Is anyone else running without shims behind the gears that ride on the diff cup shaft? Seems like the seal would get tore up.
 
They don't test crap. All 4 screws on one of my diffs were loose. 2 weren't even seated all the way. The shim helps that o-ring to stay seated in the groove.
 
BTW if the diff does feel too tight the shim behind the spider gear should be removed instead (the little shim). One of mine did feel a little tighter than the other, but I left it as is, it'll wear in.
 
I'm kinda wondering if he/they are thinking of ring and pinion mesh. Did you guys explain they are shims that are shown in the assembly manual?

When I called the 2nd time I talked to Derek. When he saw what I was talking about he said no problem, but I still needed to fill out the warranty claim. I did that and put his name on it.
 
So I talked with Billy and told him what Derek had said to Bill_G. I guess the parts diagram is wrong? This is his reply:

"I understand what you are talking about - the shims between the pin and the o-ring inside the differential. These shims are NOT necessary. Although the o-ring looks like it is not being supported properly, once the gear is installed over the pin everything is held in place as it should be and the seal is completed.

I spoke with Derek about this and he understands as well.

Thanks,

Billy"
 
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