Kraton Diff problems

[Hatchetman37]

Hey guys trying to figure out why my rear diff is lacking power if that makes sense I just changed the center diff fluid to 200k and I have 60k in the rear and front it doesn't sound or act stripped just doesn't have the turning power at the front does I don't get it

Hey guys trying to figure out why my rear diff is lacking power if that makes sense I just changed the center diff fluid to 200k and I have 60k in the rear and front it doesn't sound or act stripped just doesn't have the turning power at the front does I don't get it

I did upgrade the front and rear diffs to metal but recently broke the Sun Gear in the rear so I put my stock differential back in put the 60k fluid in it and now it's acting weird like this maybe I need to shim it?

 

[parcou]

Hey guys trying to figure out why my rear diff is lacking power if that makes sense I just changed the center diff fluid to 200k and I have 60k in the rear and front it doesn't sound or act stripped just doesn't have the turning power at the front does I don't get it

I did upgrade the front and rear diffs to metal but recently broke the Sun Gear in the rear so I put my stock differential back in put the 60k fluid in it and now it's acting weird like this maybe I need to shim it?

Hi

Sorry about your issue. Do you have a Kraton 6S? They have all metal gears asking it's posted in the 6S thread. Or is it a Kraton 4S?

You mentioned center diff, so it has to be a 6S. Why would it not already have metal gears...or are you referring to all metal diff housing over the plastic diff housing?

A classic 6S setup with open gears is: 50/500/20K if the motor and bearings are good. Also, no binding in the bearings, and the motor bearings are good also....no suspension resistance as well

 

[Hatchetman37]

Hi

Sorry about your issue. Do you have a Kraton 6S? They have all metal gears asking it's posted in the 6S thread. Or is it a Kraton 4S?

You mentioned center diff, so it has to be a 6S. Why would it not already have metal gears...or are you referring to all metal diff housing over the plastic diff housing?

A classic 6S setup with open gears is: 50/500/20K if the motor and bearings are good. Also, no binding in the bearings, and the motor bearings are good also....no suspension resistance as well

Hey man thanks for the advice. Yes it's the 6s and I was referring to the aluminum diff housings . I ordered a pair of front and rear. Honestly once I changed the center to 500k with 60/60 the problems arose.

Hey man thanks for the advice. Yes it's the 6s and I was referring to the aluminum diff housings . I ordered a pair of front and rear. Honestly once I changed the center to 500k with 60/60 the problems arose.

So I put the 200k back in the center. And changed back to the stock rear diff. .i had it shimmed when I took it out but didn't reshim it when I just put it back in. If I lift yp the front end and go in reverse the front wheels spin fine like the should.the rear is engaged feeling the wheels just don't spin. But it drives ok now under light load. If I really goose it it doesn't get up and wheelie like we both know they should!!

 

[Moirae]

Hey man thanks for the advice. Yes it's the 6s and I was referring to the aluminum diff housings . I ordered a pair of front and rear. Honestly once I changed the center to 500k with 60/60 the problems arose.

So I put the 200k back in the center. And changed back to the stock rear diff. .i had it shimmed when I took it out but didn't reshim it when I just put it back in. If I lift yp the front end and go in reverse the front wheels spin fine like the should.the rear is engaged feeling the wheels just don't spin. But it drives ok now under light load. If I really goose it it doesn't get up and wheelie like we both know they should!!

I think you should look at the center diff. Maybe you snapped a pin?

 

[Hatchetman37]

I think you should look at the center diff. Maybe you snapped a pin?

I'll check that out aswell

 

[parcou]

Hey man thanks for the advice. Yes it's the 6s and I was referring to the aluminum diff housings . I ordered a pair of front and rear. Honestly once I changed the center to 500k with 60/60 the problems arose.

So I put the 200k back in the center. And changed back to the stock rear diff. .i had it shimmed when I took it out but didn't reshim it when I just put it back in. If I lift yp the front end and go in reverse the front wheels spin fine like the should.the rear is engaged feeling the wheels just don't spin. But it drives ok now under light load. If I really goose it it doesn't get up and wheelie like we both know they should!!

Good call on that above post. Recheck the center diff. It is responsible for how the power bleeds. I like it to bleed off more, and not wheelie do 200k center is excellent for me. 500k is more what you want to not bleed power to the front and keep more at the rear.

You like to keep the diffs even for the front/rear.

 

[hobo]

rear diff oil seems a bit thick try 20k in the rear should drive better

 

[KnowAir]

Is the center rear shaft turning while holding the front off the ground and applying throttle? I've had the grub screw that locks the input cup to pinion shaft come loose more than once..
You could lift the rear of the truck and try forcing both rear wheels to turn by hand in the same direction. Either the front wheels or spur gear should turn while doing this. You could wedge a piece of cardboard between the pinion/spur to prevent the motor from spinning.. the rear wheels should be locked if the fronts are firmly planted.

 

[Hatchetman37]

Is the center rear shaft turning while holding the front off the ground and applying throttle? I've had the grub screw that locks the input cup to pinion shaft come loose more than once..
You could lift the rear of the truck and try forcing both rear wheels to turn by hand in the same direction. Either the front wheels or spur gear should turn while doing this. You could wedge a piece of cardboard between the pinion/spur to prevent the motor from spinning.. the rear wheels should be locked if the fronts are firmly planted.

Honestly I can't figure it out. I've been thru every diff multiple times. Nothing is broke or stripped . But it makes a sound when under load like the pinion is stripping. But that all checks out as well! I'm beating my head against a wall here!

Honestly I can't figure it out. I've been thru every diff multiple times. Nothing is broke or stripped . But it makes a sound when under load like the pinion is stripping. But that all checks out as well! I'm beating my head against a wall here!

Sounds like something is grinding pretty badly. But it rolls freely with no noise. Even with the wheels off the ground it works good until I punch it then the nasty noise comes back. I feel like I've narrowed it down to the back side of the front diff. Under all the steering and chassis brace.

 

[djrahbee]

Honestly I can't figure it out. I've been thru every diff multiple times. Nothing is broke or stripped . But it makes a sound when under load like the pinion is stripping. But that all checks out as well! I'm beating my head against a wall here!

Sounds like something is grinding pretty badly. But it rolls freely with no noise. Even with the wheels off the ground it works good until I punch it then the nasty noise comes back. I feel like I've narrowed it down to the back side of the front diff. Under all the steering and chassis brace.

I personally would get another diff from jrc or ebay, open it up, compare with the one giving you trouble. Go from there. Keep the old one for rebuild parts. I've done this when I was having trouble with diffs.

 

[KnowAir]

Any evidence on the ring or pinion of it jumping teeth? Rounded edges? How about a cracked diff case or cover? Sounds like something is moving when torque is applied. Inspect the housing and covers really good, are they clean enough to see a hairline crack? Bearings are tight and smooth? If it's a shimming issue, there should be some evidence of the ring and pinion jumping teeth..

 

[Hatchetman37]

Any evidence on the ring or pinion of it jumping teeth? Rounded edges? How about a cracked diff case or cover? Sounds like something is moving when torque is applied. Inspect the housing and covers really good, are they clean enough to see a hairline crack? Bearings are tight and smooth? If it's a shimming issue, there should be some evidence of the ring and pinion jumping teeth..

I would think so but no I just put brand new diff all the way around. Rcawd aluminum ones. And a new center diff.

 

[KnowAir]

Okay, so we're convinced it's not in the diffs. The grub screws for the driveshaft/pinion gears are secure? What kind of shape are the pinion and spur in? Pinion is secure to motor shaft? Just going through what I can think of.. once upon a time, I had a similar problem with my MT4G3, turned out to be a loose grub at the rear pinion input cup..but I couldn't tighten it any more until I removed the cup and chased the threads..rust, mud or threadlocker had gummed things up..
To add.. when that happened, it would only slip on hard acceleration with high traction..not all the time.
And, it did make a clicking type sound..

 

[Hatchetman37]

Okay, so we're convinced it's not in the diffs. The grub screws for the driveshaft/pinion gears are secure? What kind of shape are the pinion and spur in? Pinion is secure to motor shaft? Just going through what I can think of.. once upon a time, I had a similar problem with my MT4G3, turned out to be a loose grub at the rear pinion input cup..but I couldn't tighten it any more until I removed the cup and chased the threads..rust, mud or threadlocker had gummed things up..
To add.. when that happened, it would only slip on hard acceleration with high traction..not all the time.
And, it did make a clicking type sound..

Yes !! I think that's it it's the only thing I haven't checked or replaced. It does exactly what you just said. Only om hard acceleration with good traction! Mine has got to be the front tho. I've done the whole lifting the wheels off the ground routine. And I hear it up front when I aggressively turn the front tires . If I do it slowly you don't really hear anything.

 

[SrC]

Hey guys trying to figure out why my rear diff is lacking power if that makes sense I just changed the center diff fluid to 200k and I have 60k in the rear and front it doesn't sound or act stripped just doesn't have the turning power at the front does I don't get it

I did upgrade the front and rear diffs to metal but recently broke the Sun Gear in the rear so I put my stock differential back in put the 60k fluid in it and now it's acting weird like this maybe I need to shim it?

late reply... but you are better off with 20k or 30k at most in the rear diff. Then you get better steering. 300-500k is usually better at the center for hard bashing. You will get less diff bleed.

 

[Hatchetman37]

late reply... but you are better off with 20k or 30k at most in the rear diff. Then you get better steering. 300-500k is usually better at the center for hard bashing. You will get less diff bleed.

I do have some 30k I'll try that. I have 200 in the center now what about the front? Any suggestions

 

[KnowAir]

late reply... but you are better off with 20k or 30k at most in the rear diff. Then you get better steering. 300-500k is usually better at the center for hard bashing. You will get less diff bleed.

I like my diffs on the free side too, but, that's just me. I didn't think it would cause these issues though.

 

[Hatchetman37]

[ISPOI[/ISPOILER]

I do have some 30k I'll try that. I have 200 in the center now what about the front? Any suggestions

Think I'll put 500k back in the center. As well

 

[KnowAir]

I'd like to believe the slipping or skipping could be reproduced by firmly holding the rig down so as not to allow the wheels to slip, then turn the spur by hand.. but, these 6s motors have more torque than we can prduce with our fingers I suspect..

 

[SrC]

Too free and the diffs will bleed when you traction roll during hard chassis rotation. Makes it kind of hard to drive. Looser diffs/thinner oil works best on low traction and smaller confined areas. How the track guys do it. They are not running super thick oils in their diffs. Wide open bashing is a differnt animal. Hence thicker oil. But the rear should always have aprox 1/2 the CST of the front. For best steering. Some track guys will match the front and center diff oils. But in the end its about your driving style and skill that works for you.