What size shim do i put behind the input gear on my kraton diffs?

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Have you checked the lash when the whole bulkhead and diff housing is fastened and closed up? You may be seeing too much lash because it is not closed and tight. When closed up you will gain as much as 1mm of less lash. Have you opened the diff cup and checked the sat gears and fluid?
From some hands on experience.
Just some ideas.
 
I have shimmed the pinion/input gear on only one of my diffs so far. That diff is in the rear of my Typhon and isn't getting the abuse either of my Kratons receive, so I would consider this mostly untested. I plan on buying/building a Talion soon and I will do this to the entire truck.

I have broken a pinion and crown gear in both of my Kratons, both were throttle on landings. Looking over both the pinion and crown, it was just broken tips on the outer portion of the crown gear. To me this looked like the pinion was too shallow and didn't have a proper engagement (could have just been an outlier on manufacturing tolerances of the case).

These are the shims I used. They were the cheapest I could find when I ordered a bunch of diff shims last time. They are sized that they will only contact the inner race of the bearing and the pinion/input. I didn't want an obnoxiously huge outer diameter to touch the case or outer bearing race.
43160

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I ended up using shims both behind the pinion and to move the crown gear (don't remember how many or what size in each position). I brushed on a light layer of white lithium grease to read the gear patterns after everything was fully tightened. I think I disassembled, cleaned, changed shims, then reassembled everything 3 or 4 times.

It was really time consuming doing it this way, but I hope it lives a nice long life. Since rebuilding all of the diffs in all of my 6s stuff, none of them have had any issues.
 
I have shimmed the pinion/input gear on only one of my diffs so far. That diff is in the rear of my Typhon and isn't getting the abuse either of my Kratons receive, so I would consider this mostly untested. I plan on buying/building a Talion soon and I will do this to the entire truck.

I have broken a pinion and crown gear in both of my Kratons, both were throttle on landings. Looking over both the pinion and crown, it was just broken tips on the outer portion of the crown gear. To me this looked like the pinion was too shallow and didn't have a proper engagement (could have just been an outlier on manufacturing tolerances of the case).

These are the shims I used. They were the cheapest I could find when I ordered a bunch of diff shims last time. They are sized that they will only contact the inner race of the bearing and the pinion/input. I didn't want an obnoxiously huge outer diameter to touch the case or outer bearing race.
View attachment 43160
View attachment 43161

I ended up using shims both behind the pinion and to move the crown gear (don't remember how many or what size in each position). I brushed on a light layer of white lithium grease to read the gear patterns after everything was fully tightened. I think I disassembled, cleaned, changed shims, then reassembled everything 3 or 4 times.

It was really time consuming doing it this way, but I hope it lives a nice long life. Since rebuilding all of the diffs in all of my 6s stuff, none of them have had any issues.
Nice job.
Machinists Bluing die can be used to determine the actual position and runout of your gears and determine where slop can be minimized with shimming if at all due to wear. 1:1 scale vehicles are also time consuming when shimming a diff housing. And is an art or special skill. Done right, the results are worth it. In 1:1 scale vehicles, done wrong will cost you hundreds if not thousands in $$.
 
These are the shims I used.
Thank you! I just serviced my cars and noticed my Talion rear input gear is too far from the diff gear, the lower 1mm of the tooth don’t reach the diff gear at all, there too much gear lash that I couldn’t minimize even after trying 5 shims on the dogbone cup.
 
Are you following the recommended maintenance intervals? What did the dealer tell you when you drove her in? I would ask for the manager if you can't get any assistance. Maybe the Manufacturer needs to step in. Sometimes the dealer is not sure how to proceed. I am sure a resolution can be had.
20190703_162655.jpg

Take out the input gear. Inspect it. Check the teeth on the ring and the input. Examine the bearings. You should toss all the bearings if they are old. Every bearing. Bearings can wear to the point of excessive lash. You stated both gears are new? If I am correct.
Are you using GPM gears?
 
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If you are referring to the pinions on the front or rear diff, I have never seen the need to shim it. They have allways been deep enough. I think someone on here posted that they shimmed theirs the other day and it ate it in one pack.
Same thing happend to me when i tried to shim the sun gear
 
In my typhon GT8LE build I used KYO96773 on the input pinion on front and rear diffs. This is the first time I have shimmed this location.
 
In my typhon GT8LE build I used KYO96773 on the input pinion on front and rear diffs. This is the first time I have shimmed this location.
Theses shims are ment for the outer bearing between the diff case and bearing. The one i want goes behind the input gear for the crown & pinion
 
Theses shims are ment for the outer bearing between the diff case and bearing. The one i want goes behind the input gear for the crown & pinion
Hmmm, this is the location you are describing I used these shims at ?
 
Is that for the kraton v4 6s??
No as the V4 has extra shims in it already. Take note of the sizes however as they will be the size you want but you might only want to shim under the large sun gears, at least the one on the bottom of the cup just to protect the cup from the little pin that pins on the o-ring
 
Hmmm, this is the location you are describing I used these shims at ?

Like me you are using the HR diff housing which I’m sure had oversized bearing to the stock ones so maybe that’s reason for the variation?!
 
If you are referring to the pinions on the front or rear diff, I have never seen the need to shim it. They have allways been deep enough. I think someone on here posted that they shimmed theirs the other day and it ate it in one pack.
Wish I had seen this before I tried it out and did the same thing today . Only made it half way though a small basher pack. Also I wasn't running hard.

Live an learn. call it idiot tax. seamed like a good idea, I only tried it because I striped the Ring in two packs. And, it didn't look like t was deep enough. I have to admit it felt a little tight. I'll try two shims in the side next. Otherwise, I don't know what to do. Barrings are new, clean, grassed and visually looks like a good fit.

Maybe an aluminum bulk head would help. It's expensive, not to mention a pain in the rear. to fix every couple of runs, Third gear set since Christmas.
 
Wish I had seen this before I tried it out and did the same thing today . Only made it half way though a small basher pack. Also I wasn't running hard.

Live an learn. call it idiot tax. seamed like a good idea, I only tried it because I striped the Ring in two packs. And, it didn't look like t was deep enough. I have to admit it felt a little tight. I'll try two shims in the side next. Otherwise, I don't know what to do. Barrings are new, clean, grassed and visually looks like a good fit.

Maybe an aluminum bulk head would help. It's expensive, not to mention a pain in the rear. to fix every couple of runs, Third gear set since Christmas.
We all pay that "Hobby Tax".:LOL:
 
Perhaps most people don't shim at all. At least initially. But those that do, like myself, just don't shim this particular input gear/ring gear setup at the "input gear". You should shim the ring gear towards the right to the input gear to correct lash.
Sounds like you have a group of worn parts to evaluate
3+ or more MM of shimming and you will risk moving the whole diff too far to the right and the left output cup will lose the left dogbone at extreme articulation. You end up moving the diff. too far off center. Trial and error dictates how much shimming you can get away with. But at some point there are many worn parts to consider replacing.

I put shims on almost all my RTR out of the box. Always on the diff. crown gear side. Never had issues of dog bones which go out of the drive cup, the amount of shims isn't enough to arrive at this result.
 
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