Kraton Diff problems

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SrC said:
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.
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I am running in a realitivly small area. Loose dirt. . I had it backward in my head I was thinking thicker oil for the rear and lighter up front. Makes sence why my steering was crap lol. Thanks for the info!
 
Hatchetman37 said:
I am running in a realitivly small area. Loose dirt. . I had it backward in my head I was thinking thicker oil for the rear and lighter up front. Makes sence why my steering was crap lol. Thanks for the info!
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I like 60\500\30, f/r/c, but like @SrC said it comes down to what works well for you. But I like the overall balance with that setup and it might be a good starting place for you.
 
I run a track mostly, small, high grip most of the time. I also run 4s alot, just don't have the room to really stretch the legs of 6s. 10-15k F, 50-100k C, 5-7k R.. like I said, loose..not a typical basher.
Trial and error..find what ya like, not what everyone else does. It may or may not be for you.
 
The Rear diff is generally 1/2 of the Oil's CST rating at the front diff. This is for "Open" diffs. (y) Whatever oils you do choose. Best place to start.
 
KnowAir said:
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.
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KnowAir said:
I'd say that's what he meant. Stiff, but if you're stunting, should be good.
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Idk what to do at this point! I just spent all afternoon replacing the input gear and rebuilding the front diff. I literally don't see any problem with the gears they all look good . Its definitely in the front . The rear is fine so is the center diff! I'm trying to post a video i took so everyone can see what's happening. But I can't figure out how to do that on this site lol
 
Hatchetman37 said:
I'm trying to post a video i took so everyone can see what's happening. But I can't figure out how to do that on this site lol
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upload to YT then post link here..
 
Hatchetman37 said:
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!!
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Update to this post ..the rear is fine. It's the front giving me a fit .it acts like the front pinion is stripped even tho I just put a new one on.
KnowAir said:
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.
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Everything checks out man it acts like the front pinion is stripped. Wven tho
SrC said:
Just Link that here....
Videos help us to help you better.
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I'm trying man lol
SrC said:
Just Link that here....
Videos help us to help you better.
Click to expand...
I'm trying man lol
Hatchetman37 said:
Click to expand...
SrC said:
Just Link that here....
Videos help us to help you better.
Click to expand...
Finally figured it out lol.
 
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Main and Input gears together should be replaced as sets. Shimming is important.
Are you sure the center diff is ok as well? Seems you are getting gear slippage for sure. Make sure the 2 Input gear's BB's are in good condition also. Worn out BB's will also allow the Input gear to slip on the Main gear. Also Make sure the Bulkhead is in good condition and not cracked anywhere.
It best at this point to remove the whole bulkhead and build it up like that. Off the chassis. Its the only way to observe too much backlash if that is the issue. If so and both gears are in good condition, then better shimming is needed there at the front. 2 or even maybe 3 shims may be needed on the Main gear side BB. Some ideas.
What was the issue as it turned out?
 
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SrC said:
Main and Input gears together should be replaced as sets. Shimming is important.
Are you sure the center diff is ok as well? Seems you are getting gear slippage for sure. Make sure the 2 Input gear's BB's are in good condition also. Worn out BB's will also allow the Input gear to slip on the Main gear. Also Make sure the Bulkhead is in good condition and not cracked anywhere.
It best at this point to remove the whole bulkhead and build it up like that. Off the chassis. Its the only way to observe too much backlash if that is the issue. If so and both gears are in good condition, then better shimming is needed there at the front. 2 or even maybe 3 shims may be needed on the Main gear side BB. Some ideas.
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Well the truck is only about 3 or 4 months old. The center is brand new exb diff. The front n rear are seemingly fine also. I think I need to shim the input gear it only grinds under power.
Hatchetman37 said:
Well the truck is only about 3 or 4 months old. The center is brand new exb diff. The front n rear are seemingly fine also. I think I need to shim the input gear it only grinds under power.
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Might be worth mentioning the front bulkhead cover does seem to not tighten very well. Like the screw holes are stripped out . Ya know
 
I find that most will shim the Main gear first. But if you still have issues , yeah shimming the Input gear is the next step. I Never had to do that. But have tried installing a shim at the input. Never worked out or needed it in the end. But it's better to always have the gears on the tighter side IMHO. As they bed in, they get looser. Especially if bashing hard. Use a synthetic automotive grease on these gears. Handles friction and heat better. They break in much better IMHO.
All must be very clean before reassembly. Did you top off the diff with Silicone oil or check it???
 
If it's not slipping at the coupler, it's definitely slipping somewhere.. process of elimination. No side to side play of the front diff when seated in the case? Some float at the pinion for and aft is ok I think. Theres gotta be something missing..shim wise, have another look at the Arrma diff parts assembly. Make sure all spacers and shims are there. That's just the starting point. Should be close enough to prevent slipping teeth anyway.
 
SrC said:
Main and Input gears together should be replaced as sets. Shimming is important.
Are you sure the center diff is ok as well? Seems you are getting gear slippage for sure. Make sure the 2 Input gear's BB's are in good condition also. Worn out BB's will also allow the Input gear to slip on the Main gear. Also Make sure the Bulkhead is in good condition and not cracked anywhere.
It best at this point to remove the whole bulkhead and build it up like that. Off the chassis. Its the only way to observe too much backlash if that is the issue. If so and both gears are in good condition, then better shimming is needed there at the front. 2 or even maybe 3 shims may be needed on the Main gear side BB. Some ideas.
What was the issue as it turned out?
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I really appreciate all the help tour trying to give! I guess I'm gonna year it all back down today and just go thru everything again. I have to had missed something somewhere! The front diff turns freely until I put it back in the truck then it acts like something is too tight. Idk I'm not an expert but I'm not a noob either I've never had these issues before. This is my first rc with this many diffs lol. Always been 10th scale before now
KnowAir said:
If it's not slipping at the coupler, it's definitely slipping somewhere.. process of elimination. No side to side play of the front diff when seated in the case? Some float at the pinion for and aft is ok I think. Theres gotta be something missing..shim wise, have another look at the Arrma diff parts assembly. Make sure all spacers and shims are there. That's just the starting point. Should be close enough to prevent slipping teeth anyway.
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I don't believe it is no! But I swear it sounds and acts like the teeth are just gone on the input
 
Yeah you have RC experience for sure. 1/8 scale Diff'ed rigs however can require a learning curve no doubt. And Arrma diffs are notorious for always needing much attention. They are far from the best out there ...unlike like Mugen, AE Losi, Kyosho or Tekno diffs. I noticed this once I got all into The 6s Arrma rigs. I always feel like a slave to these Arrma diffs. Is what it is.
I only use MugenSeiki shim kits out the box with all my Arrma "Open" diffs for starters. And I stay away from the EXB LSD diffs as well.
Running 60k/500k/30k in most of my rigs. FWIW. I have it where I am comfortable with their durability now. I can easily get 20+ and way more runs on my diffs now without failure. I will rebuild them before they fail. I get more life out of them this way.
Like I said earlier, Best to replace Main and Input gears together as a set. No not cheap I know, but just replacing one and not the other will ruin both again sooner than later. That's a personal call there.

How you drive can also brick the diffs. Landing/crashing hard "On Throttle" under load ruins these diffs easily.
 
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You talking about these damn star like rings in the diff. So I can eliminate those? I don't want them in there anyway
Hatchetman37 said:
You talking about these damn star like rings in the diff. So I can eliminate those? I don't want them in there anyway
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Under the sun gear I mean
 
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