Kraton Loud chatter noise in reverse.

[MattyIce 79]

Hey fam,

yesterday afternoon I started noticing a loud grinding/chatter noise when I hit reverse and every once in a while on braking. Reverse still works fine, I have no problem with that it’s just that the noise seems normal. What could this possibly be? And how to fix it. Thanks a bunch guys !!!!

 

[pa_fullsend]

Only in reverse? A loud chattering, clicking noise usually means shredded diff gears but maybe it’s a motor bearing?

 

[MattyIce 79]

[QUOTE="

Thx for the info, gonna see what do to remedy this ASAP

 

[pa_fullsend]

[QUOTE="

Thx for the info, gonna see what do to remedy this ASAP

No problem. Hope it’s something easy, diffs can be annoying to get into but they’re easy to fix. I’d check them first, then you can clean and refill them anyway since you’re there. And upgrade to fast eddy rubber sealed bearings while you’ve got it apart. If you haven’t already

 

[MattyIce 79]

No problem. Hope it’s something easy, diffs can be annoying to get into but they’re easy to fix. I’d check them first, then you can clean and refill them anyway since you’re there. And upgrade to fast eddy rubber sealed bearings while you’ve got it apart. If you haven’t already

It definitely sounds like it’s coming from the front diff. Like I said, still reverses fine with normal speed (maybe a little less tourque tho). Going forward is completely normal. If it is stripped, is there a upgraded gear that is tougher than stock and take more abuse and maybe last longer? And I will grab Fast eddies too.

PS : I’m still a rook bro. Only been in the hobby for about 2 months. I’m learning how to fix this stuff myself. My hobby store is $45.00 just for them to look at it. (F-that). I’m not gonna have time to tear it down until Tuesday afternoon. Anyway, let me know if you have any info on this, thx a ton brother

 

[Notorious J]

Hey fam,

yesterday afternoon I started noticing a loud grinding/chatter noise when I hit reverse and every once in a while on braking. Reverse still works fine, I have no problem with that it’s just that the noise seems normal. What could this possibly be? And how to fix it. Thanks a bunch guys !!!!

Pop out both dif cups and check the large gear of each (spur, main gear or whatever you call it). Look for chipped teeth. While out, also check the two pinions inside the gear box. Also, check to make sure the the outdrive attached to the pinions hasn't come loose and slid away from the gear box. If all of the above check out, make sure your motor is still snug on the mount and that the mount is still tight to the chassis. Make sure the motor pinion hasn't moved either. If all of these easy visuals check out, then I would open the cups and check the dif internals.

 

[jondilly1974]

It definitely sounds like it’s coming from the front diff. Like I said, still reverses fine with normal speed (maybe a little less tourque tho). Going forward is completely normal. If it is stripped, is there a upgraded gear that is tougher than stock and take more abuse and maybe last longer? And I will grab Fast eddies too.

PS : I’m still a rook bro. Only been in the hobby for about 2 months. I’m learning how to fix this stuff myself. My hobby store is $45.00 just for them to look at it. (F-that). I’m not gonna have time to tear it down until Tuesday afternoon. Anyway, let me know if you have any info on this, thx a ton brother

The only real upgrades right now are metal diff cups. You will need to just tear that front diff down and look for something broken or out of place. You can always buy a built diff from JRC and compare the two.

 

[MattyIce 79]

Thx for info fellas

 

[Camaroboy383]

Most likely a failing pinion bearing, as they get loose they will yeild when power is applied and under braking.... causing the teeth to jump on the ring gear....its imperative to keep an eye on those bearings to reduce the rate of failure...

There Is nothing wrong with the factory ring and pinion strength.. properly shimmed diffs., and maintained bearings are key...

 

[Notorious J]

Most likely a failing pinion bearing, as they get loose they will yeild when power is applied and under braking.... causing the teeth to jump on the ring gear....its imperative to keep an eye on those bearings to reduce the rate of failure...

There Is nothing wrong with the factory ring and pinion strength.. properly shimmed diffs., and maintained bearings are key...

Then we will agree to disagree. Yesterday during a bash session at a construction site, my ring gear stripped for about the tenth time from beginning of summer til now. Freshly rebuilt dif, shim under each of the sun gears but only one each on the satellites (one shim on one side of each shaft) and one shim on the outside of the bearing, ring gear side. I do everything I can to make sure I'm not landing on throttle and the jumps weren't that high. That ring gear is the most expensive part of the dif, and replacing them is becoming too much of a regular thing. Also note, this is in an aluminum HR gear box which I thought would help alleviate the issue

 

[MattyIce 79]

Most likely a failing pinion bearing, as they get loose they will yeild when power is applied and under braking.... causing the teeth to jump on the ring gear....its imperative to keep an eye on those bearings to reduce the rate of failure...

There Is nothing wrong with the factory ring and pinion strength.. properly shimmed diffs., and maintained bearings are key...

Thx CB 383, everybody’s been so helpful, just can’t wait till I have time to tear ‘er down. Once I get it apart, I won’t know exactly what I’m looking at but, I’ll figure it out one way or the other. I probably send pics once it’s apart if I can’t get it fixed. Went ahead and bought some replacement parts I’m gonna use during rebuild. Thx again

 

[Camaroboy383]

Then we will agree to disagree. Yesterday during a bash session at a construction site, my ring gear stripped for about the tenth time from beginning of summer til now. Freshly rebuilt dif, shim under each of the sun gears but only one each on the satellites (one shim on one side of each shaft) and one shim on the outside of the bearing, ring gear side. I do everything I can to make sure I'm not landing on throttle and the jumps weren't that high. That ring gear is the most expensive part of the dif, and replacing them is becoming too much of a regular thing. Also note, this is in an aluminum HR gear box which I thought would help alleviate the issue

@notoriousj, I love ya brotha, and i hate to tell you this like it is, but your doing it wrong my friend...

here is why.. all the time you've spent on the inside of the diff with shims on the planetary's, shims on the suns doesn't do any good at saving ring gears.. or pinions...

they are, in themselves two separate systems..

Now you want to cut your ring and pinion gear breakage back or to none at all you need to focus on the outside of the ring gear.. 1 shim is not enough ever.. I've touched a bunch and 1 is never enough..

Put 2 shims of the thickness that's in there now.. (assuming it is the arrma shim) when installing the cup on the pinion be sure the cup is flush with light pressure, (I use my thumb and pointer finger and pinch the cup and pinion).. then tighten your set screw...

I've also had 1 or 2 diffs that were still loose and needed a .1 shim under the pinion to tighten it back up..

I broke diffs daily before shimming.. mainly from standing backflips... since shimming I knock on wood have not smoked one ring or pinion, and there is some serious run time on my outcast...

In my experience, the pinion bearings will begin to start yielding (wobble) around the 12-15 battery cycles, and will continue to yield further as time goes on... hence my routine of a teardown and inspection every 6 cycles or so..

Blah blah blah.. ramble on! ☝ just my experiences grain of salt buddy, grain of salt..

Thx CB 383, everybody’s been so helpful, just can’t wait till I have time to tear ‘er down. Once I get it apart, I won’t know exactly what I’m looking at but, I’ll figure it out one way or the other. I probably send pics once it’s apart if I can’t get it fixed. Went ahead and bought some replacement parts I’m gonna use during rebuild. Thx again

Keep us posted, we will be glad to help

 

[Notorious J]

@notoriousj, I love ya brotha, and i hate to tell you this like it is, but your doing it wrong my friend...

here is why.. all the time you've spent on the inside of the diff with shims on the planetary's, shims on the suns doesn't do any good at saving ring gears.. or pinions...

they are, in themselves two separate systems..

Now you want to cut your ring and pinion gear breakage back or to none at all you need to focus on the outside of the ring gear.. 1 shim is not enough ever.. I've touched a bunch and 1 is never enough..

Put 2 shims of the thickness that's in there now.. (assuming it is the arrma shim) when installing the cup on the pinion be sure the cup is flush with light pressure, (I use my thumb and pointer finger and pinch the cup and pinion).. then tighten your set screw...

I've also had 1 or 2 diffs that were still loose and needed a .1 shim under the pinion to tighten it back up..

I broke diffs daily before shimming.. mainly from standing backflips... since shimming I knock on wood have not smoked one ring or pinion, and there is some serious run time on my outcast...

In my experience, the pinion bearings will begin to start yielding (wobble) around the 12-15 battery cycles, and will continue to yield further as time goes on... hence my routine of a teardown and inspection every 6 cycles or so..

Blah blah blah.. ramble on! ☝ just my experiences grain of salt buddy, grain of salt..



Keep us posted, we will be glad to help

Ok, I hear you. Where I've been doing it wrong is on the pinion side. In the HR case, there's no way I could get another shim on the outside of the bearing, so that's not gonna happen. About the pinion, I have always seated snug to the gear box and left it like that. Never considered trying to snug it up to the main gear and then tightening it down. Since we're on the subject, what size shim do you use behind that pinion? I'm willing to try anything at this point, as I've recently become accustomed to buying those 43T spiral cut main gears in bulk, and they're not cheap.

 

[Camaroboy383]

Really? Cant get another in there? Even if you start the half way, then tap them in with the handle of a screwdriver? Seems you should be able to fit them, but I've never had the aluminum housing.. I cant see it being a different dimension from the factory case opening...

If you cant get them in the carrier side then go to a .2 pinion shim..

 

[Camaroboy383]

Also to reiterate the pinion and drive cup.. I just want to be sure its clear... carrier out of the case, (ring and diff)...

Install your pinion shim on the pinion shaft, install it into the case, use your thumb on the pinion, and your pointer finger on the drive cup and pinch.. seating the cup against the inner race of the outer bearing.. don't squeeze but light pressure.. then tighten the cup grub...

Wobble the cup.. it should be solid and not move.. if it wobbles and you know the bearings are good loosen the grub and start over with more pressure..

Any movement in the cup equals the same amount of movement on the pinion side.. all bad

 

[Notorious J]

Also to reiterate the pinion and drive cup.. I just want to be sure its clear... carrier out of the case, (ring and diff)...

Install your pinion shim on the pinion shaft, install it into the case, use your thumb on the pinion, and your pointer finger on the drive cup and pinch.. seating the cup against the inner race of the outer bearing.. don't squeeze but light pressure.. then tighten the cup grub...

Wobble the cup.. it should be solid and not move.. if it wobbles and you know the bearings are good loosen the grub and start over with more pressure..

Any movement in the cup equals the same amount of movement on the pinion side.. all bad

I know it was mentioned elsewhere, but what's the size and thickness of the shim you use? As far as the install of the pinion goes, that would be how I normally do it, minus the shim.

 

[Camaroboy383]

Use a .2 thickness... any shim 8mm I.d with an o.d of no larger than 12..
https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.com/ulk/itm/380662572855

These would be ideal as they are 10mm o.d... but from Hong Kong, better if you can get them locally

 

[MattyIce 79]

Hey family, here’s what I got!! I’m not exactly sure what I’m seeing. Doing hear any grinding noise when turning outdrives both ways. How to proceed guys. I’m gonna look at book too. Also I believe the thin brass ring came from left side. He

Thanks

 

[jondilly1974]

Yes the shim should be from the left side.

 

[Camaroboy383]

Ok get in a little deeper.. pull the diff and the ring gear out.. as dilly said, shim came from left side (ring gear side)... once you get the diff and ring removed you can grab the cup and wiggle it up and down..side to side..

does the small pinion gear and cup move around? Does it have any play in and out? Notice any deformed teeth on the ring or pinion gear?

Cup should be seated against the bearing inner race...

Next clean the grease off the ring gear and bearings... grab the outer race of the bearing and wiggle it... (pay attention to the yeild if any from outer to inner race) do they wobble?..

If all of this is tight, it's time to open the diff for an inspection.. but we will cross that bridge when you get there...