Diff cracking noise

[C J H0W4RTH]

Hi all,

first post on the forum and glad to be part of the Arrma group.

I have recently just changed all the diffs on my Kraton 6s for the alloy Arrma diff case, 300k fluid centre and 60k front and rear. Having big trouble with it and can’t seem to find an answer.

if I hold the rear wheels the front spin fine, if I hold the front wheels the rear wheels spin fine. Driving around slowly all is well, however under hard throttle there seems to be a nasty ‘cracking/clicking’ noise from what must be the centre diff. I have just fitted new gears with 3 shims behind each sun gear.

any help would be appreciated!

 

[jsantoli]

I just went through this with Arrma and my 6s notorious. Email then and let them know. They sent me spiral diffs for the front and rear and it’s perfect now

 

[SrC]

Sounds like front or rear ring and input gears are not shimmed correctly. The clicking is usually those 2 gears skipping from too much backlash under load. Does it happen from a fast speed when hard breaking? Could be the front diff. Hold the rig with the front wheels on the floor firm and pull the throttle. Do the same for the rear wheels. It will help to determine whether it is front ore rear. you want to listen for the clicking sound. Find the problem. don't continue to bash. You will brick those input and ring gears. You need shims on hand

 

[jsantoli]

I tried the Mugen shims in the diff case itself, behind the planetary gear, and in the spiders gears. Also I shimmed the bearing outside of the diff case. Then shimmed the input gear. It still clicked. Arrma knows about the problem because without hesitation they sent me two full diff sets that cost $50 each retail

 

[Simon]

Sounds like front or rear ring and input gears are not shimmed correctly. The clicking is usually those 2 gears skipping from too much backlash under load. Does it happen from a fast speed when hard breaking? Could be the front diff. Hold the rig with the front wheels on the floor firm and pull the throttle. Do the same for the rear wheels. It will help to determine whether it is front ore rear. you want to listen for the clicking sound. Find the problem. don't continue to bash. You will brick those input and ring gears. You need shims on hand

What he said ?
Also, thoroughly clean the rear and input gear and look for wear.

I have found if you stripped one of two teeth off the ring gear, its not always immediately visible if they are not clean.

 

[SrC]

I tried the Mugen shims in the diff case itself, behind the planetary gear, and in the spiders gears. Also I shimmed the bearing outside of the diff case. Then shimmed the input gear. It still clicked. Arrma knows about the problem because without hesitation they sent me two full diff sets that cost $50 each retail

Sometimes its the diff cup or even the bulkhead that have bad production runs. Diff cups can even loosen up and create more slop. ( the 4 diff screws) Sometimes you have to really squeeze in the left side bearing shims to get all the backlash out. The best way to find out how much input gear/ring gear slop there is is to have the whole bulkhead out, so you can visibly see the gears and how well they mesh. Looking thru the bottom of the bulkhead. Off of the chassis. With bulkhead assembled/closed up. The best way.

 

[jsantoli]

I did that. And everything else Arrma suggested and nothing worked until they sent me the exb diff set ups