Kraton Rebuilt diffs, now I have a bad noise

stianbirkeland

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I have rebuild all the diffs, and now i have a bad noise when I pull the trigger. I have checked all the diffs, and can not see any problems. What shall I do?
 

lonee

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  1. BigRock
sorry, but what exactly means "a bad notice!"?
What happens? Noise, no rotating, lift up like a plane? (just kidding)

First of all, if you turn the main shaft at the spur gear position, did the wheels rotate smooth and in the same direction?
Turn the shaft by hand an disconnected motor.

Did the motor turn without be connected to the spur gear?

Please check these items first..... Then we do the next.
And maybe you can make an better description of you're problem.
 

stianbirkeland

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The noice it makes sounds like one of the gears have failed, but all of them looks good. (I had to replace some of them when i rebuilt the diffs.)
When i disconnected the motor and turned the shaft all wheels turned the same direction. The rear assembly looks fine, but the front assembly feels hard, when i turned one of the wheels the other wheel turned the other side, but not smooth. I think that can be the problem. But when I take out the front diff, it feels good. Do i have to rebuild it again, for the third time?
The motor seems fine.
There is also some play in the diffs, is that normal?
 
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lonee

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  1. BigRock
You will have a little play into the diffs because of the backlash into the gears itself.
Normally the diff have to turn smooth. Maybe you have a small deformation within one gear or shimmed it to much.
I think that you have to open the front diff again to see what happens...
 

stianbirkeland

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I saw a video on youtube, he said that it was better to put two more of the small shims in the diff. I can try to take them out.
 

Qwin

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I saw a video on youtube, he said that it was better to put two more of the small shims in the diff. I can try to take them out.
I am no expert but what I have experienced. Too many shims cause gear to bind if you accelerate suddenly. Is there less noise if you accelerate gradually up to full speed
 

lonee

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  1. BigRock
The most important thing is that the diffs are running smooth when mounted into the diff box.
The shims are for the distance from the big gear to drive shaft gear. That connection had also be smooth.
Sometimes there are small deformations on the small gears into the diff. It it is so, the diff also don't want run smooth.
Work point after point. First check the diff itself (small gears into the diff).
Then put it into the diff box and check the manishaft gear and the bit diff gear.
It´s all clear at that points, all will be OK.
 

Qwin

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I saw a video on youtube, he said that it was better to put two more of the small shims in the diff. I can try to take them out.
Also check if the noise is coming from the main input gear. If there is to much free play between input gear and the main gear when assembling it will be noisey.
 

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lonee

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Theyfore I asked for an disconnected motor.
Next step will be to check that the spur (main) gear is running round and the pinion (input) gear is running round of the spur gear.
Also the recommended play in-between them (thin peace of paper thickness 0,05-0,08mm max 0,1mm)
We will see what the answer after check the diff can tell us
 

stianbirkeland

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I have found the problem. It was the rear(!) input gear that was stripped. That happened to me once before.
I don't have the small shims that sits next to the bearing on the diff, can that be the reason?
Thank you all for the help!
 

lonee

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  1. BigRock
no, sorry I have no part number. I buy mostly several shims in different dimensions at my rc-dealer.
It is like a washer but a lot thinner and different sizes and thickness.
I do shim also other parts on the rc-car. For example the space between the hex-bulk (hex wheel adapter) and the bearing.
And so on. So you need to measure the diameter of the shaft and afterwards buy different shims in several thickness.
0,05, 0,1, 0,15mm if you're dealer have so. Then you can shim you're diff very well, because you have all choices below to 0,05mm.
 

Typhon

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Ive had issues twice with my typhon and being a semi rookie i overlooked something so simple. Once i lost rear power and disassembled my diffs and on another run i lost front power and did the same. I blew a planetary gear in my center diff once so i keep thinking this was the issue. But the simple issue i overlooked was the ball cup for the front and rear driveshafts. The set screw backs out and then it halfass grabs or not at all the input gear making you question why it gets a tad of power? With a long allen driver you can reach both set screws and fix your truck in a minute vs the alternative. After a run or on a new truck i suggest some stronger loctite.
 

Blaz3atrail

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i hope this is my probelm changed out both input gears in diffs and redid center diff it was dry haven't had time to run it but im hopeing ive got it there all shimmed and not too tight fingers crossed
 
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