Kraton 6S issue.

[tshimp]

My Kraton 6S has always jumped well. Off my ramp I can typically get a nice back flip, and a double if things go right. The other day, I was landing some good back flips with ease as is typical with this car but toward the end of my outing, I couldn’t seem to do more than 1/2 rotation and would plant face down. I figured maybe my batteries were weak, so packed up and went home. Today, I got my car out with fresh batteries, and still can only get about 1/2 rotation off the same ramp. I upped the punch from 4 to 9, but same result. The strange thing is on the ground it seems to be just as responsive as ever. It makes no sense that it behaves fine on the ground but when jumping the car will not respond as it usually does. Any ideas?

 

[tntpoof]

Id still think batteries are old not the same punch as new check ir on batts

 

[Greywolf74]

I would check and make sure the front and rear diffs are fully engaging. If one of them is slipping or blown out then the car might seem fine on the ground because its getting power from two wheels but with out all 4 wheels spinning in the air it wont get the same rotation.

 

[WickedFog]

Check the fluid in your center diff.

 

[tshimp]

I would check and make sure the front and rear diffs are fully engaging. If one of them is slipping or blown out then the car might seem fine on the ground because its getting power from two wheels but with out all 4 wheels spinning in the air it wont get the same rotation.

Is there an easy way to do this? I can see all 4 wheels spinning, but not sure how to tell if the front or rear diff are slipping.

Check the fluid in your center diff.

I’ll give that a go. Thanks.

Edit: I pulled the center diff, and opened it up. I don’t see anything that looked like it had leaked around it, but below is a picture. I am new to this hobby, but would have thought there would be more fluid. However, it did seem to be coating and moving through the gears very well. One thing I noticed when doing this is the pinion wasn’t very tight, and seemed to have a little play in it. I tightened that up. Could that also cause something like this?

 

[Greywolf74]

Is there an easy way to do this? I can see all 4 wheels spinning, but not sure how to tell if the front or rear diff are slipping.

You should be able to just put the kit on concrete, or whatever grippy surface, and take turns holding the back end off the ground while giving it gas and see if the tires spin or if they slip. Then hold up the front end while running the kit in reverse. Alternately you could just pull the front and rear diffs and inspect them. I would think that the problem has to be in the driveline somewhere

One thing I noticed when doing this is the pinion wasn’t very tight, and seemed to have a little play in it. I tightened that up. Could that also cause something like this?

Its possible I suppose but if the pinion was slipping then I would think that would affect regular driving as well as flips.

 

[RustyUs]

I sure would like to think issue is diff related, but if you find nothing out of the ordinary with your diffs, then I 'd start a full on maintenance tear down... checking all the bearings (including the motor).

 

[tshimp]

You should be able to just put the kit on concrete, or whatever grippy surface, and take turns holding the back end off the ground while giving it gas and see if the tires spin or if they slip. Then hold up the front end while running the kit in reverse. Alternately you could just pull the front and rear diffs and inspect them. I would think that the problem has to be in the driveline somewhere


Its possible I suppose but if the pinion was slipping then I would think that would affect regular driving as well as flips.

I did this. I lifted my back end and pulled the trigger, and the front wheels that were on the ground spun (along with the rears that were up in the air). However, when reducing throttle and putting a little more weight on the front end (by lifting up more on the backend) the tires would stop spinning with no rotation from the center diff on the front end side only (rear continued to spin). I then lifted the front, and with heavy throttle the rear wheels would spin. Slowing down a bit the back tires would stop spinning with no rotation at the center diff on rear side only. Is this expected behavior?

 

[Hammer Down]

It sounds like the center diff fluid could be a bit heavier weight.. maybe up it to 200k from the stock 100k and see how you like that. ‍
The heavier the fluid in the center diff, the more it will evenly distribute the power F/R.
Choosing the correct weight is a balance between handling and putting the power down where you want it..

 

[nino]

Sounds like everything's fine with the diffs. Weird. So it happened between sessions or was it gradual?

 

[tshimp]

Sounds like everything's fine with the diffs. Weird. So it happened between sessions or was it gradual?

It was during a session. I flipped fine about 4 times one day (had worked fine before that and first ~4 jumps this day), and on the fifth jump it didn't seem to rotate as fast, and I didn't make the back flip that is typically easy. I tried it again, and it failed again. I noticed one of my 3 cell batteries wasn't plugged in all the way (run 2 3S batteries) and so assumed that might be causing an issue, but I just packed up and went home. Then next outing same thing happening. I then decided to increase my punch from 4-9 and still having the issue. When pulling the center diff, I noticed the pinion wasn't as tight as it should be and had a little play, but didn't seem like enough to be causing this. I did tighten it, but not sure it will make a difference.

 

[Greywolf74]

Yeah expected behavior and I'm out of ideas on what it could be. Id suggest Rusty's paln of a full tear down inspecting everything including the bearings replacing anything broken or off along the way.