Kraton V4 Upgrade Fails (due to inexperience)! HELP Request

Wmorgan

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Hoping to get a little direction on some upgrades i recently made that aren't having as much impact as i hoped. In fact, except for the diff fluid, the "upgrades" have made negative or no difference in performance.

1) Rebuilt all diffs with 60k/500k/30k. There is a cracking sound that I thought was a loose P/S mesh so I tightened, but sound continues. Seems to be louder when throttling in reverse. I tried to match P/S mesh with my brand new Notorious for sound and feel and spacing, but the cracking continued. I'll tighten more tonight and run again, but really don't think it's that loose. Is there anything else that may be causing the cracking? It only makes it when hitting the throttle. IF it's not the P/S mesh could it be the motor?

2) Savox (SW-1210SG) servo - doesn't turn PL Thrasher tires anymore than stock did. Ordered stock tires from JRC. Waste of money there it seems.

3) Installed Tactic Tx/Rx and set EPA. Off the ground the wheels turn perfectly, however as mentioned in item (2) on the ground the Savox can't seem to turn the tires. Also, while driving it required a wide turning radius as in the width of the street. The St. D/R knob on is maxed to get full turn. What could be causing such a wide turn radius?

4) Set the punch to 9 and running 5000mah, 50C, 6S batteries. Is not as prone to wheelie as I though it would be so don't see a big difference in the punch setting. Is still very fast just not as punchy as i thought it would be.

Overall:
The Kraton still drives and is very fast top speed, but something just seems off. The new diff fluid works great. At full throttle the Kraton sets up evenly on all 4 tires while flying down the road (50ish mph)...but the cracking is annoying and can't turn as sharply as with stock. Also, not as punchy as I thought it would be on 9.

To restate my plan to try and address these issues is to tighten P/S mesh even more and put stock tires back on since Savox can't get it done. I have no ideas on the turning radius or why it's less punchy.

Thanks for reading and for any advice you can offer.
 

olds97_lss

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Not sure what PL Thrashers are. Got a photo or link?

Does sound like the stock servo saver is eating up the torque of your servo. I have the 1210Sg on my outcast and it turns the proline trencher 3.8's with authority even on 6V. I have the old servo saver though that you can adjust, if you can keep it from walking loose on you, which red locktite seems to have done for me.
 

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The cracking sound, sounds to me like a diff mesh issue, the pinion you're talking about I assume is the motor mesh? Most likely the rear diff, have you added any shims to the main gear side if the gearbox case? You want to push it in towards the center outdrive gear, if you don't you will destroy your ring and pinion. The thicker fluids add stress to the drive line so making sure your mesh is tight is really important, also check for cracks in your gearbox cases, front and rear.

One thing to check is remove the servo horn from your servo and see if you can easily move the steering back and forth. If not there may be something that is binding. Check your pillow ball retainers aren't too tight, this will affect speed, and turning radius, but as others have mentioned the servo saver may be bleeding your torque away. If so you should be able to see it split under load.
 

Wmorgan

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The Savox is much better than stock. Almost guaranteed the issue is the dog crap servo saver.
Yeah, I watched rich duberbash video on dissecting the 2019 and all of the lock tight. Interesting thing is the Notorious turns like a champ with the stock tires and I believe the Kraton did as well on stock. The Thrashers are much wider which means more resistance to turning. So I think you're right about the servo saver...I'll know for sure when I put stock tires back on.
 

Wmorgan

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Not sure what PL Thrashers are. Got a photo or link?

Does sound like the stock servo saver is eating up the torque of your servo. I have the 1210Sg on my outcast and it turns the proline trencher 3.8's with authority even on 6V. I have the old servo saver though that you can adjust, if you can keep it from walking loose on you, which red locktite seems to have done for me.
The cracking sound, sounds to me like a diff mesh issue, the pinion you're talking about I assume is the motor mesh? Most likely the rear diff, have you added any shims to the main gear side if the gearbox case? You want to push it in towards the center outdrive gear, if you don't you will destroy your ring and pinion. The thicker fluids add stress to the drive line so making sure your mesh is tight is really important, also check for cracks in your gearbox cases, front and rear.

One thing to check is remove the servo horn from your servo and see if you can easily move the steering back and forth. If not there may be something that is binding. Check your pillow ball retainers aren't too tight, this will affect speed, and turning radius, but as others have mentioned the servo saver may be bleeding your torque away. If so you should be able to see it split under load.
Yes, the pinion mesh is the motor mesh as in the pinion and spur gear on center diff. Wrong terminology on my part? I have not added any shims on any of the diffs as there seemed to be plenty from stock.
The pillow balls are HR and I tightened just before "locking" the balls...is that too tight!! Must be...is there a better gauge to know how much to tighten? I bet that's it! Thanks dude on that issue!!
Now if I can figure out the stupid cracking! I hope it's something simple bc I'm a lazy SOB.
 

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Servo was not a wasted upgrade, trust me. It's leaps and bounds better in quality alone and will last way longer than the stock which most likely would have crapped out on you within a few months time as most rtr servos do. It's more a preventative upgrade than anything and if there's nothing wrong with it, its doing its job. ;)
 

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I have stock tires on mine but that Savox will push the wheels on carpet at a stand still, so unless you got a bad one, it's not the servo.
 

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Yes, the pinion mesh is the motor mesh as in the pinion and spur gear on center diff. Wrong terminology on my part? I have not added any shims on any of the diffs as there seemed to be plenty from stock.
The pillow balls are HR and I tightened just before "locking" the balls...is that too tight!! Must be...is there a better gauge to know how much to tighten? I bet that's it! Thanks dude on that issue!!
Now if I can figure out the stupid cracking! I hope it's something simple bc I'm a lazy SOB.
A painful way to set your pillow balls up is to remove them from the a-arms and tighten them down just so the pillow balls stay put if you raise them up, then slowly loosen them off till they fall down by themselves. I like them to be slightly loose as they tend to tighten when dirt gets in, you should be able to move the knuckle around and the threads fall down no matter which way you hold the knuckles. The other way to do it without removing them is to loosen them just enough that you can feel the slightest wiggle at the knuckle where the pillow ball is seated.

You didn't use the wrong terminology, it is just not likely the place you're issue is coming from. If you haven't shimmed the gearbox where the outdrives come out, you are very likely to strip your gearbox ring and pinion. I know it's a pain, but it's better to check it before you end up with a stripped gear set and an undrivable car.
 

Wmorgan

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A painful way to set your pillow balls up is to remove them from the a-arms and tighten them down just so the pillow balls stay put if you raise them up, then slowly loosen them off till they fall down by themselves. I like them to be slightly loose as they tend to tighten when dirt gets in, you should be able to move the knuckle around and the threads fall down no matter which way you hold the knuckles. The other way to do it without removing them is to loosen them just enough that you can feel the slightest wiggle at the knuckle where the pillow ball is seated.

You didn't use the wrong terminology, it is just not likely the place you're issue is coming from. If you haven't shimmed the gearbox where the outdrives come out, you are very likely to strip your gearbox ring and pinion. I know it's a pain, but it's better to check it before you end up with a stripped gear set and an undrivable car.
For the pillow balls that sounds like what I did. I initially just tightened and wondered why they didn't move and then realized you don't have to crank everything down tight. So I loosened until they moved freely. I think I'll still check that, but also wonder if the ultra wide Thrashers might have impacted the turning radius as well?
Now, for the "gearbox where the outdrives come out", is that also the center diff. With 500k do I need to shim at the bearing where the shaft enters?
Are you sure your steering endpoint adjustment is not whack? Maybe check that again manual page 24.
I checked that again and extended and shortened the range with same result. I then compared how it turned to the stock Notorious and those tires moved fully on the same surface. I'm really thinking it's the damn tire width.
Not sure what PL Thrashers are. Got a photo or link?

Does sound like the stock servo saver is eating up the torque of your servo. I have the 1210Sg on my outcast and it turns the proline trencher 3.8's with authority even on 6V. I have the old servo saver though that you can adjust, if you can keep it from walking loose on you, which red locktite seems to have done for me.
Here's a pic of stock on top of the PL TRENCHERS...my bad.
15580592663372390034684744955348.jpg
 
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Wmorgan

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You running the servo at 6v or 7.4v? Might need to toss a BEC in there and use the high volt setting for those.
So I can change the servo voltage? Also, how do I change the servo voltage? And one more, why do I want to toss a BEC?...sounds kinky.
 

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For the pillow balls that sounds like what I did. I initially just tightened and wondered why they didn't move and then realized you don't have to crank everything down tight. So I loosened until they moved freely. I think I'll still check that, but also wonder if the ultra wide Thrashers might have impacted the turning radius as well?
Now, for the "gearbox where the outdrives come out", is that also the center diff. With 500k do I need to shim at the bearing where the shaft enters?

I checked that again and extended and shortened the range with same result. I then compared how it turned to the stock Notorious and those tires moved fully on the same surface. I'm really thinking it's the damn tire width.


Here's a pic of stock on top of the PL TRENCHERS...my bad.
View attachment 38433
I never know what to call things, but the big silver gear in the main gearbox case, not the cup needs to be snug against the little input drive gear that comes from the center diff, this is at the front and rear. Usually the rear is where the load goes so it's more likely to be the issue. https://www.arrma-rc.com/tv/channel/tutorials/jylZ01QB4w8 please watch this, the bit you're interested in is where the gearbox is assembled and Thomas shows the shim on the outside of the main diff gear 8:15 . There are other tutorials about this to, but the main thing is that you have some pressure inwards towards the smaller input drive gear, and thus tightening the mesh.


This is what a slipping diff sounds like, it will eventually fail altogether and you'll need a new main diff gear and input drive gear if it sounds like this.
 

Wmorgan

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I never know what to call things, but the big silver gear in the main gearbox case, not the cup needs to be snug against the little input drive gear that comes from the center diff, this is at the front and rear. Usually the rear is where the load goes so it's more likely to be the issue. https://www.arrma-rc.com/tv/channel/tutorials/jylZ01QB4w8 please watch this, the bit you're interested in is where the gearbox is assembled and Thomas shows the shim on the outside of the main diff gear 8:15 . There are other tutorials about this to, but the main thing is that you have some pressure inwards towards the smaller input drive gear, and thus tightening the mesh.


This is what a slipping diff sounds like, it will eventually fail altogether and you'll need a new main diff gear and input drive gear if it sounds like this.
Seriously, thank you for your help! I don't know what to call things either I just piece together what I hear folks call it on here. I'll tighten the mesh and share a video if it still makes the same noise. I checked diffs and no cracks. Mine cracks on throttle while that video seems to crack on breaking.

I'll share if I actually figure something out.
 

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Seriously, thank you for your help! I don't know what to call things either I just piece together what I hear folks call it on here. I'll tighten the mesh and share a video if it still makes the same noise. I checked diffs and no cracks. Mine cracks on throttle while that video seems to crack on breaking.

I'll share if I actually figure something out.
If it is a similar sound it doesn't matter, they will eventually slip on both breaking and accelerating. There is a way to test it, you can hold two wheels on the ground(front pair or rear pair) *be careful* and give the car a fair bit of throttle, if it makes the noise one way and not the other it is generally the wheels that are on the ground that the diff is playing up.
 

Wmorgan

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If it is a similar sound it doesn't matter, they will eventually slip on both breaking and accelerating. There is a way to test it, you can hold two wheels on the ground(front pair or rear pair) *be careful* and give the car a fair bit of throttle, if it makes the noise one way and not the other it is generally the wheels that are on the ground that the diff is playing up.
A question I have is if it's necessary to fill diffs fully when rebuilding. All the factory filled diffs I've seen have been half full. Maybe it's a mistake to completely fill diffs?
 

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For the pillow balls that sounds like what I did. I initially just tightened and wondered why they didn't move and then realized you don't have to crank everything down tight. So I loosened until they moved freely. I think I'll still check that, but also wonder if the ultra wide Thrashers might have impacted the turning radius as well?
Now, for the "gearbox where the outdrives come out", is that also the center diff. With 500k do I need to shim at the bearing where the shaft enters?

I checked that again and extended and shortened the range with same result. I then compared how it turned to the stock Notorious and those tires moved fully on the same surface. I'm really thinking it's the damn tire width.


Here's a pic of stock on top of the PL TRENCHERS...my bad.
View attachment 38433
Ah, the trencher X 3.8's. I have the standard 3.8 trenchers. They are taller with more sidewall and more narrow.
 

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So I can change the servo voltage? Also, how do I change the servo voltage? And one more, why do I want to toss a BEC?...sounds kinky.
Your ESC has to support the 7.4v for the servo. If you're on the stock blx ESC it only has a 6v built-in BEC. You would have to get an external BEC that supports higher voltages. I think they run bout $20 for a decent one.
 
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