Kraton Question for those who have replaced a diff

[chalmene]

Ok, so I recently managed to break one of the planetary gears in my front differential, split it right in two. I ordered a new diff, and when replacing the input shaft (shaft which connects to the center axle, part # AR310498) I notice there is almost 1/8" of play which can allow one of the bearings to slide partially out of it's seat. It looks like there should be a shim/washer to take up the slack, but no mention of one in the manual. And I don't know if once the diff is installed (haven't built new diff yet, waiting on shims), if the play will disappear. But that will still leave one of the bearings improperly seated... Has anyone else noticed this?

 

[OrangeDRAGON]

The differential itself should push up against the input gear to keep it firmly planted against its inner bearing.

On the opposite side I loosen the grub screw on the driveshaft input cup and finger-tight push it towards the diff and re tighten the grub screw. On mine I have appx 1-2mm gap between backside of input cup and the bearing race and I've never had a problem.

You can grab the input and try sliding it while the diff is installed and really should not have any play, if it does I would add shims to the diff to bring the mesh tighter.

Hope that's helpful!

 

[chalmene]

The differential itself should push up against the input gear to keep it firmly planted against its inner bearing.

On the opposite side I loosen the grub screw on the driveshaft input cup and finger-tight push it towards the diff and re tighten the grub screw. On mine I have appx 1-2mm gap between backside of input cup and the bearing race and I've never had a problem.

You can grab the input and try sliding it while the diff is installed and really should not have any play, if it does I would add shims to the diff to bring the mesh tighter.

Hope that's helpful!

Thank you, yes that sounds about right. I will have about a 2mm gap also. It just seems that this would allow the outer bearing where the gap is to be able to slide partially out of it's seat. Not sure if this would cause an issue, just concerned is all.

Also, there is no gap at all on my rear diff, and I know the two are identical assemblies. So this has me wondering what is up...

 

[Josh nortz]

I just had all 3 out lol. Had a bad rear ring and pinion... mostly opperator error for sure... but i pushed pinion gears in and then set drivecups tight against front and rear to keep things tight... i need a spacers kit to shim the diffs before i do it again... it could be a tad tighter i would say...

 

[chalmene]

I just had all 3 out lol. Had a bad rear ring and pinion... mostly opperator error for sure... but i pushed pinion gears in and then set drivecups tight against front and rear to keep things tight... i need a spacers kit to shim the diffs before i do it again... it could be a tad tighter i would say...

Yea I reinstalled everything, and once your diff is back in it is tight again. Just the design I guess. I went ahead and shimmed out the diff also. Just a heads up if you cannot find those Team Durango planetary gear shims that have been out of stock, these work also: http://www.ebay.com/itm/291288147429?_trksid=p2060353.m2749.l2649&ssPageName=STRK:MEBIDX:IT They are the same, only 2mm larger in diameter but they fit just the same.

 

[Vanning]

I checked my Kraton and the input shaft cups that enter into the front and rear pinion gears have very slight play. They are not pressed 100% into the bearing race. There is about a hair of play. I don't think it matters that much because the pinion is held by the ring on the inside. On the outside...you basically just havt to have the grub screw on the flat and have the cup hold the bearing in it's housing. I would set it a hair off of being tight against It, this way there isn't any side pressure on the pinion bearing.....it just rides free with no side force. Just set the cup against the bearing is how mine feel from the factory.

 

[chalmene]

It's kind of hard to explain, but I'll do my best. When the drive cup is fully installed, and diff is in place, the drive cup does not sit against the outer bearing. There is about 1.5mm gap between the two. It obviously has been riding like this since I've had it, so I'm sure it is fine. It just seems it should be tighter to keep the bearing from sliding laterally. But oddly enough, the rear drive cup sits flush... Maybe next time I have the diff out I'll add a shim or 2. I'm not too worried, just find it odd.

 

[Vanning]

It sounds like something is preventing it from going towards the bearing 1.5mm. 1.5 mm is way too much of a gap. My Kraton was loaded with red lock tite on the drive cup and I had to clean it up. Maybe that is preventing it from sliding back that 1.5mm. But you are saying it sits flush. There is a metal insert inside the bulkheads. The 2 bearings sit in it....maybe yours is worn out or missing ???? It is hard to understand what is wrong with yours but I do know what you are saying. There might be another reason why you blew the diff up in the first place. IDK hope you get it corrected, good luck and keep us posted.

The gears inside a diff are not called planetary gears...they are differential gears maybe even spider gears. Planets are found inside a 3 speed automatic transmission and are use to produce first, second and third gear ratios. Just for the sake of proper lingo to help a brother out even more.

 

[chalmene]

Yes, well they seem to be referred to as planetary gears in the parts listing, so wanted to keep everyone on the same page: www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXEPXY&P=ML . Tje metal insert in my diff is not worn out, and would not retain bearings at all if it was missing. Also, all the old red loctite has been cleaned, and cup is firmly seated on the whole length of the flat spot of the shaft. It can go no further...

It is obvious something is out of tolerance, Im sure its not the diff or pinion, those have been replaced. Only thing left would be the diff case lol, maybe Ill order one and see what I get. Otherwise Ill have to shim the pinion I guess.

 

[Vanning]

Oh ok...that's interesting that they are called planetary in a spider gear diff. It's not even a planetary diff. But that is just trivial to us anyway and more for haha's. Anyway.....I may have discovered the reason why you cracked one of your gears in half on your front diff. I will post it in a new thread.

 

[Raji]

Is there an upgrade for ar310498 ?
I just striped one

 

[nulli]

My input gears have lasted well for over 30 packs (shimmed after about 10). The outermost part of the teeth show some wear but mostly they look pretty decent.

 

[Raji]

My input gears have lasted well for over 30 packs (shimmed after about 10). The outermost part of the teeth show some wear but mostly they look pretty decent.

What is the advantage of shimming the diff?

 

[Rtappy1985]

It helps reduce some of tge slop in your gears there by tightening them up for a better mesh less chance of breaking of teeth