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

[Wmorgan]

Looks like the shim wasn't properly installed before the cover was put on. It shouldn't look like that.

You are correct...It wasn't properly installed. I reshaped and put back in carefully this time. Have some shims coming so hopefully i can get a few runs in while I wait.

 

[Wmorgan]

Where was it sitting? On the outdrive? Are the bearings still alright, check that the shields aren't damaged.

The shaft cups were chewed up on the thinner wall so replaced those. Went ahead and rebuilt diff and nothing else was wrong.

 

[Mbizzle]

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.

I have the same cracking problem!! Rebuilt all diffs and made sure mesh was good several times yet the cracking noise persists when giving it throttle and significant torque. I may be sending this back to Horizon Hobby (Arrma) to troubleshoot because I can't find the culprit and this started a few runs after purchasing brand new.

 

[Wmorgan]

I have the same cracking problem!! Rebuilt all diffs and made sure mesh was good several times yet the cracking noise persists when giving it throttle and significant torque. I may be sending this back to Horizon Hobby (Arrma) to troubleshoot because I can't find the culprit and this started a few runs after purchasing brand new.

You didn't change anything? It started cracking running stock? Are they paying for shipping?

 

[Primarrma]

I have the same cracking problem!! Rebuilt all diffs and made sure mesh was good several times yet the cracking noise persists when giving it throttle and significant torque. I may be sending this back to Horizon Hobby (Arrma) to troubleshoot because I can't find the culprit and this started a few runs after purchasing brand new.

Have you checked the input shaft cup grub screw is tight? If you're 100% confident you have got a good tight mesh on the main diff gear and input gear, then check the front and rear input shaft cups aren't slipping(the bit that the center dogbone slot into).

 

[Wmorgan]

Have you checked the input shaft cup grub screw is tight? If you're 100% confident you have got a good tight mesh on the main diff gear and input gear, then check the front and rear input shaft cups aren't slipping(the bit that the center dogbone slot into).

Does the front portion come off fairly easy and in one piece? Looking at it and I think I've seen the whole front suspension removed from chassis. After fixing the outer shim that was all twisted and rebuilding front diff still getting the cracking sound from front end and it's definitely louder when throttle reverse. I now notice a loss of overall power. It's still fast but it doesn't wheelie as easily as before. Must be something wrong behind the diff at the center driveshaft...the crown gear bearings??
New stock tires are in so I'll swap those out from the Trenchers and see if steering has improved. Will also check the pillows for tightness as well.

 

[Primarrma]

Does the front portion come off fairly easy and in one piece? Looking at it and I think I've seen the whole front suspension removed from chassis. After fixing the outer shim that was all twisted and rebuilding front diff still getting the cracking sound from front end and it's definitely louder when throttle reverse. I now notice a loss of overall power. It's still fast but it doesn't wheelie as easily as before. Must be something wrong behind the diff at the center driveshaft...the crown gear bearings??
New stock tires are in so I'll swap those out from the Trenchers and see if steering has improved. Will also check the pillows for tightness as well.

You can access the grub/set screw without removing anything? It's on the outside of the gearbox case.

 

[Wmorgan]

You can access the grub/set screw without removing anything? It's on the outside of the gearbox case. View attachment 38715

But that's underneath the red Arrma bulk head and bell crank. I'm thinking it's gotta be that bearing. That's my next Target at least.
And to think all of this because I didn't vent my stock tires. Tsk, tsk, tsk

 

[Primarrma]

But that's underneath the red Arrma bulk head and bell crank. I'm thinking it's gotta be that bearing. That's my next Target at least.
And to think all of this because I didn't vent my stock tires. Tsk, tsk, tsk

I'm pretty sure you can get to it from the side, do you have a hex driver with a long shaft?

 

[Wmorgan]

I'm pretty sure you can get to it from the side, do you have a hex driver with a long shaft?

Very long shaft (that's what she said)! ?
But will I be able to get the bearing out and replace it? Plus while I'm in there I was planning on replacing the bearings on the bell crank.

 

[Primarrma]

Very long shaft (that's what she said)! ?
But will I be able to get the bearing out and replace it? Plus while I'm in there I was planning on replacing the bearings on the bell crank.

I thought you said you rebuilt your diffs and replaced the bearings?

The easiest way to get to the front gearbox case bearing is to remove the four gearbox case chassis screws and the rear hinge pin brace screws(all in the underneath of the chassis) then whole front end lifts off. Just make sure you get the center dog bone in when you put it all together again.

 

[Wmorgan]

I thought you said you rebuilt your diffs and replaced the bearings?

The easiest way to get to the front gearbox case bearing is to remove the four gearbox case chassis screws and the rear hinge pin brace screws(all in the underneath of the chassis) then whole front end lifts off. Just make sure you get the center dog bone in when you put it all together again.

I rebuilt the diffs by taking off the cover plate and the bearings on the side shaft cuffs, but not the bearings at the crown gear.
I see those screws. I'll try that and report back.
I'm going to take a video of it driving with the issues I'm having and hopefully when I get all fixed and share here so other Arrma noobs might benefit from your help as well.

 

[bicketybam]

I take the front end off to replace the gearbox bearings.

 

[Primarrma]

I rebuilt the diffs by taking off the cover plate and the bearings on the side shaft cuffs, but not the bearings at the crown gear.
I see those screws. I'll try that and report back.
I'm going to take a video of it driving with the issues I'm having and hopefully when I get all fixed and share here so other Arrma noobs might benefit from your help as well.

You'll also have to remove the two steering post screws, the chassis support screw and servo link, but it's easy, just get into the habit of removing things and putting them back together, otherwise you'll end up doing it twice.

 

[Wmorgan]

You'll also have to remove the two steering post screws, the chassis support screw and servo link, but it's easy, just get into the habit of removing things and putting them back together, otherwise you'll end up doing it twice.

I know, I've been reluctant/lazy but have found it's not as difficult as I thought once I start...what really bothers me is I think I like wrenching too much, especially when it results in a positive solution. Freud's anal retention theory comes to mind for some erotic reason...??

You'll also have to remove the two steering post screws, the chassis support screw and servo link, but it's easy, just get into the habit of removing things and putting them back together, otherwise you'll end up doing it twice.

So I got it apart and replacing bearings. Still not seeing what may be causing the cracking as nothing seems broken. However I'm curious about the center see pic. It looks like exposed ball bearings. They look fine just curious if they can be replaced??

 

[Wmorgan]

It looks like I have the fast Eddy replacement bearing. Any performance issues with replacing exposed with sealed bearing??

 

[Notorious J]

It looks like I have the fast Eddy replacement bearing. Any performance issues with replacing exposed with sealed bearing??View attachment 38791

Sealed are better all around. Less likely to have dirt trapped inside, which ruins bearings more quickly. I'm positive that once you have replaced all the bearings with the Fast Eddy's, you will feel a noticeable difference.

 

[Primarrma]

I know, I've been reluctant/lazy but have found it's not as difficult as I thought once I start...what really bothers me is I think I like wrenching too much, especially when it results in a positive solution. Freud's anal retention theory comes to mind for some erotic reason...??

So I got it apart and replacing bearings. Still not seeing what may be causing the cracking as nothing seems broken. However I'm curious about the center see pic. It looks like exposed ball bearings. They look fine just curious if they can be replaced??View attachment 38789

I think that's what you found in the diff case, the steel cover of the bearing?

Replace it, reshim the main diff gear to the input drive gear, test.

 

[bicketybam]

I know, I've been reluctant/lazy but have found it's not as difficult as I thought once I start...what really bothers me is I think I like wrenching too much, especially when it results in a positive solution. Freud's anal retention theory comes to mind for some erotic reason...??

So I got it apart and replacing bearings. Still not seeing what may be causing the cracking as nothing seems broken. However I'm curious about the center see pic. It looks like exposed ball bearings. They look fine just curious if they can be replaced??View attachment 38789

There is supposed to be a metal shield on that bearing.

 

[Wmorgan]

Having dismantled the entire front end and rebuilt the front diff twice I'm a little discouraged that I haven't found anything that may be causing the "cracking" sound. I was really hoping that I'd find a blown bearing or something, but so far everything seems fine. I'll finish swapping out the stock bearings with Fast Eddy's and put her back together. I'll do the same for the rear and test. The new stock tires from Jenny's came in so I'll put those on as well.
Best case is the cracking will be gone but I won't be able to point to anything as the culprit. Worst case is the cracking will still be there and I won't have a clue about what to try next.