Outcast Input gear/diff noise??

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beefy nugz

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Arrma RC's
Just replaced front diff case and ended up doing a bearing job and checked all diffs. All back together but I can’t figure out what this rough clicking noise is. When you free roll the vehicle you it’ll go from smooth to rough in the same spot of the rotation. I’ve narrowed it down to the rear diff. All gears in diff including including input gear all look perfect inside the rear diff.
Basically when rear diff cover is off I can spin the input drive gear all the way around and its very smooth as it turns the dig bones. As soon as I tighten down the lid to the rear diff the roughness comes back. Pull the lid off and its smooth again!!! It’s almost like putting pressure on the bearings attached to the rear diff causes rough noisy gears.

anybody have any advise?

been working on this for a few days now and it’s getting quit frustrating.
Thanks!!!!
 
If you have the stock plastic diff housing then it might be warping when you tighten down the cover. Try snugging everything down and if it makes the noise just crack the screws loose. Not enough to have the cover be loose but just not as tight as they were when the noise was there. Also if you have shimmed everything try taking out one of the shims to see if that helps. Good luck.
 
I did just add shims to the rear for the first time. I shimmed the center diff only a long time ago. I’ll play with the shims.

Thanks for the idea!
 
Well I just took the 4 shims out and problem is the same. Something must be warped! I tried two different diff case lids and both causing the same thing. I’m running the factory diffs so maybe it’s warped and time to buy a whole new diff. or do you think I can get away with just a new diff case and reusing my gears?

edit: so I didn’t replace the diff case I believe, twas the diff housing
 
When you had everything apart did you remove the pinion? if so make sure its seated properly. Did you clean the ring and pinion before you put it back together, because something might have gotten into one of the teeth. The precision of the gears isnt as great as 1:1 gears so some of them are slightly out of round and they always have that tight spot so you could decide to run with it and replace it when needed or spend money now to resolve the issue. You could also check if the ring gear is not flat against the diff carrier causing it to wobble.

edit: check the screws to make sure they're the same length, if not you might have mixed them up.
 
I been there. This does happen. Sometimes changing out the whole bulkhead will remedy the issue. BUT.....

Take the cover off and rotate the diff with you fingers pressing the 2 diff bearings against/into the bulkhead observe for lateral runout of the diffs ring gear. Sometimes the ring gear is not concentric with the diff case. Re-examine your 4 diff case screws. Use a Caliper to verify that the ring gear is perfectly seated at the 4 screw locations. Sometimes a new diff case will remedy that if the case is warped.
Try that first.

Also as stated above make sure all is very clean at the 2 bearing seats of the bulkhead. PERFECTLY clean. Use a blade and solvent to make absolutely sure the bearings are seated with no fine debris causing them not to seat when the cover is placed back on and tightened. (even the finest sand/debris can cause binding)
BTW needing 4 shims on the rig gear side ball bearings is excessive. I've used 3 at the most before I need to replace the bulkhead A sign of a worn out Bulkhead. They are cheap. Just a lot of time removing all. If you do replace the bulkhead, it is best to assemble it off the chassis and install it as an assembly. This allows you to also see the input gear/ ring gear mesh properly shimmed. Best to shim all dry without lube first. When you have it correct, then lube it.
Just some tips.

Good luck :cool:
 
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About those 4 shims, there’s 1 behind each of the gears.

So I had the wife pick up a new diff case for 7.99 at the lhs :) gotta love her!

so now with everything bolted back up except the motor/pinion it spins magnificently!!!!

And go figure...
I bolt the motor and pinion back up and it didn’t want to turn again. Accept now it’s a little worse!
 
>Are input gear bearings in good condition?
>Check pinion/spur mesh.
>Make sure the motor is spins freely while the pinion is clear of the spur.
>Don't rule out the front diff as a possible issue?
 
Motor and pinion mesh are perfect. Starting to think I need a new motor as this one has doesn’t spin as easily as other blx motors and has made a terrible noise when on the throttle for a cpl years now. I never swapped it out bc it still plants the power and can do standing backflips all day.

As of now all diffs and axels are spinning freely with all new bearings and a new diff case.
Think I might just throw the newer esc and motor from my infraction in the outcast. Then go with a tp/HW combo for the infraction
 
Unless you can find a really good deal on a new motor you might look into getting new bearings for your existing motor. Just make sure you get motor bearings because they are rated for higher rpm's.
 
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