EXB Center diff doesn’t spin in diff mount

[PeighDay]

I was replacing the diff fluid today on my Talion and had a spare diff with spur gear that I wasn’t using. Got it all back together and dropped it into the Talion without the dog bones attached and it would not spin freely in the center diff mount. I put back in the old one and noticed that I could spin the center diff a lot easier.

I figured it was bad bearings so I took it all apart and replaced the bearings and the fluid again and put it back together. Same thing happened. Any ideas on what could be causing this? Diff cup is warped?

 

[SrC]

Hmm. Could be the diff cup?? Are both diffs identical in appearance? Assembled correctly?

 

[PeighDay]

Hmm. Could be the diff cup?? Are both diffs identical in appearance? Assembled correctly?

Yes they are. I had them side by side trying to see if there was any difference but I don’t see any. Double checked all the part #s as well.

 

[Robbbbbb66]

Yes they are. I had them side by side trying to see if there was any difference but I don’t see any. Double checked all the part #s as well.

Did you install the diff correctly in the mount?

 

[GraniteFox]

Normally not the diff cup. Possibly some binding in the diff somewhere. Sometimes if the sun gear is not meshed correctly it can bind when you put the top back on. For this reason I line up the pin with the sun gear added on the top. Also if you added extra shims it could bind. I would pull the diff and rebuild from scratch. Slight possibility of warped cup or overfilled diff. No easy answer for this one IMO.

 

[SrC]

^^^ +1
Just rebuild it from scratch, again. Best approach at this point. What I would do.

 

[PeighDay]

Thanks for the suggestions all. I will rebuild it again to see if I can narrow it down.

Did you install the diff correctly in the mount?

Yeah that was one of the things I thought about. Made sure I was a not complete idiot and lined it up with the pinion.

 

[dk3000]

I've had that happen and just taking the screws out and resetting it helped. Just a bit o binding maybe

 

[PeighDay]

I've had that happen and just taking the screws out and resetting it helped. Just a bit o binding maybe

Just for clarification are you referring to the 4 screws into the spur gear or the cover for the diff? I did not install the diff cover and it still didn’t spin freely

Just a little update. Grabbed another diff cup and rebuilt the diff dry with the same gears, bearings, etc and it spins nice in the diff now. Only thing I changed was the diff cup. Time to fill her up and test it out.

Update 2: spins freely until it’s all the way pushed down in the diff mount . The other center diff fits fine though. Might be time for one of these

 

[PeighDay]

I ended up purchasing some exb 29mm alumminum diff cups and the HR Center diff mount to see if could rectify the situation. I am uploading a video to show what I am talking about.

Arrma Talion Center Diff

The HR mounts definitely doesn't allow for the center diff to spin as freely as the plastic OEM part. I tired the exb diff that I just built and it wouldn't even sit all the way down in the HR mount. Could it be that the bearings are to thick? I measured them with my caliper and matched them to the size that arrma recommends.

 

[dk3000]

I ended up purchasing some exb 29mm alumminum diff cups and the HR Center diff mount to see if could rectify the situation. I am uploading a video to show what I am talking about.

Arrma Talion Center Diff

The HR mounts definitely doesn't allow for the center diff to spin as freely as the plastic OEM part. I tired the exb diff that I just built and it wouldn't even sit all the way down in the HR mount. Could it be that the bearings are to thick? I measured them with my caliper and matched them to the size that arrma recommends.

I dealt with those issue and have your solution. Leave everything slightly loose so it has play then tighten top down. I had this issue when I went to install a PPS mount. And from my understanding the exb center differential is 1mm longer than the standard kraton center diff.

 

[PeighDay]

I dealt with those issue and have your solution. Leave everything slightly loose so it has play then tighten top down. I had this issue when I went to install a PPS mount. And from my understanding the exb center differential is 1mm longer than the standard kraton center diff.

Sorry for my lack of understanding. Are you saying to loosen the center diff mount that I just put in from the underside then drop the center diff in and then tighten up the mount.

 

[dk3000]

Sorry for my lack of understanding. Are you saying to loosen the center diff mount that I just put in from the underside then drop the center diff in and then tighten up the mount.

Exactly yes.
Doesn't have to be loose by much but I loosened all 4 from the bottom. Dropped in the diff. I even got my top diff cover on snug then finished with the bottom 4 last. Once done my center differential spun freely

 

[PeighDay]

Exactly yes.
Doesn't have to be loose by much but I loosened all 4 from the bottom. Dropped in the diff. I even got my top diff cover on snug then finished with the bottom 4 last. Once done my center differential spun freely

Perfect. I will give this a try. Thank you for the advice.