Kraton EXB rear diff clicking

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IwatchTV

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Arrma RC's
  1. Granite
Hi all

My kraton exb has developed a clicking rear diff. It only seems to happen when the brakes go on. Forward and reverse seem fine.

I've stripped the diff down and everything seems fine, no chewed cogs, diff oil good.

Before i put it all back together, could I be missing something? Or is it likely someth5just became misaligned and putting all together again should do the job?
 
Hi all

My kraton exb has developed a clicking rear diff. It only seems to happen when the brakes go on. Forward and reverse seem fine.

I've stripped the diff down and everything seems fine, no chewed cogs, diff oil good.

Before i put it all back together, could I be missing something? Or is it likely someth5just became misaligned and putting all together again should do the job?
Only way disassembly and reassembly could fix an issue is if the screws were loose allowing the pinion to slip on the ring gear. But you’d expect it to slip under all power, not just stopping. Usually clicking under braking is the front diff, as it takes the brunt of that load. That’s where I would be looking.
 
I've taken front diff apart and no visible damage there either 🤔.

Have to take the center apart later on as work is calling 😔

EDIT: spotted the smallest of chips on the front input gear. Ah well, Modelsport here we come.
 
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I've taken front diff apart and no visible damage there either 🤔.

Have to take the center apart later on as work is calling 😔

EDIT: spotted the smallest of chips on the front input gear. Ah well, Modelsport here we come.
Same happend to me. One of my sun gears was chipped and the chips were causing the clicking. I have new gears now but rebuilt it with the chipped one. I'm waiting for an Arrma 29mm aluminum diff case to come in and will have to rebuild it anyways so I figured why not finish off the chipped gears first. 😏
 
Ok I'm lost now. I've replaced spur gear (at last). All other gears, after careful examination, look fine in all 3 diffs. Have checked diff housings and shimed up the gears tight. Cleaned everything up, and put back together.

Taken car out tonight, and still the noise is there. Though not as bad (more like a slight creaking noise than loud cracking), but still there.

Thinking that should upgrade to aluminum diff housings, do they really make that big of a diffrence? And would they likely help this?

Very expensive upgrade though 😔
 
@IwatchTV , Sorry but that clicking is always poor shimming of the main/input gears. 99% of the time. Sometimes from a Non-Concentric main gear as well. Or a badly molded plastic diff cup. This assuming the BB's are all in perfect condition. Especially the 2 input gear BB's. Often never considered and over looked. Most of the time the clicking is only observed under load when running/braking hard. Rarely observed on the bench. Unless it is really bad.
Been there numerous times. Even with fresh new builds.
The main/input gears may appear fine, just not shimmed well enough. Sometimes it feels like you are chasing a ghost. I know.
:cool:
 
Thanks.

I've got 2 shims on each gear and they seem really tight.

I'll open them up again tomorrow and see if I can slip another 1 on each of them.
 
^^^Easy there. You need a tick of some play.:LOL:
 
^^^Easy there. You need a tick of some play.:LOL:
What?
A video of what I'm experiencing-


I've literally had everything apart. All gears appear to be in really tight. There doesn't appear to be any damage to and cogs in any of the diffs and of course I've replaced the damage input gear that I originally said about.

My hearing isn't the best but the noise seems to be coming from the rear.

I've had both gearboxes off to check for damage and can't see anything.

Any help at all appreciated. I'm really scratching my head at this.

Will probably turn out to be something really stupid that I've missed 😄
 
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The video appears to show nothing wrong IMHO.
I always feel, it is very hard to get all diffs assembled to sound and perform exactly the same.
And all 3 diffs wear at different rates. F and R rarely sound the same.
You rebuilt and shimmed them as best you can. And seem to understand them well enough.

>>>To isolate better where you think there is a problem, I would disconnect the front and rear center driveshafts (by lifting out the center diff) and spin up F and R diffs by hand or even with a drill attached to the hex axels. Spool up the axles to listen for gear chatter. There will usually be differing sounds from the F and R. And will also sound different going forward as opposed to reverse. The F and R axels should spin freely as it spools down. Not bind to a stop when spun by hand. If it does, the shimming is too tight.
Also, run the motor while it is disconnected. To see if it's a motor issue. A motor alone without the spur connected should be very quiet and fairly silent when it spins. All you should hear is a quiet hum or whine. If it is noisy you may have motor BB issues.
Occasionally, the noise comes from the BB's at the axels. if you got a few bad ones on their way out. I don't think that is the real problem. But check.
But your rig sounds fine to me. No better or worse than several of my 6s rigs after diff rebuilds.
 
Thanks for the advice again.

Unfortunately looks like its an issue with the motor.
Piu it to go while away from the car and it whirrs away nicely. However, when I hit the brake, a slight crack can be heard.

Ah well, gives me an excuse to upgrade to a Max6 combo I suppose
 
Hi again.

Sorry to drag up an old thread.

Had my Kraton out over the weekend and diffs started clicking. (And its definitely diffs this time.)

It's hard to tell which one it is. So have had all diffs apart, cleaned them all up, shimmed(along with input gears) and put them all back in. Them all seem nice and tight, with zero noticeable play.

However the clicking is still there, infact I'd say its worse.

Can diff oil affect clicking? I'm running 60k-200-30k.

When it comes to shimming I found my rear with a hot racing housing needed 1 shim behind ring rear and 1 behind input. My front with stock housing took 1 behind input but 3 behind ring. Center didn't seem to need any.

Is there anywhere I'm missing?

Again sorry for noobish questions, I'm still learning, but to be honest getting more than a tad frustrated with this car now.
 
I'll try and post one tomorrow.

Only does it when running can get it to do it when on bench, so don't know how we'll I'll pick up the noise
 
Sorry for lack of video.

I've managed to fix the problem. Ive made the rear diff an 'open' diff and added a shim under each spider gear. Seems to have done the trick, so far.
 
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