Kraton Just bought a used Kraton. What should I check?

[iep]

I've just bought a used 6S Kraton from another forum. Photos show the truck is in great condition. It was a V3 that has had most V4 updates added to it (aside from motor mount) along with upgraded aluminium braces, steering servo and titanium steering plates.. Apparently only ever run on 4S.

Obviously I doesn't come with a guarantee but the seller seems decent guy so if there was an obviously damaged diff or similar hopefully we'd be able to come to an arrangement to get it fixed. The only issue is, aside from visual inspection of suspension etc, I don't know what sort of things to look for. Are there any checks I can easily do on the drive-train (differentials etc) when it arrives just to check that it is not a lemon?

Lastly, I think there were diff shims added on the V4 model. I don't believe these were added to my V3. Can they/should they be considered?

Any thoughts gratefully received.

Cheers.

 

[Woodentop]

Have u got any Pics for a better understanding?
First thing I would do is strip it and put in a full set of sealed bearings, pull the diffs for new fluids and check for any shimming needed, other than that just run it to see what ya got, defo on the bearings u don't know what terrain it's been run on, age of bearings etc, a bad bearing can cause more expensive problems?

 

[veryconfusing]

As someone who has bought numerous used RC's to have extras in the "fleet" and sometime just because. . .
Here is what I would I would do -

Minimal -

1. Check if the chassis is relatively straight with ruler
2. Remove wheels and body - check that pillow balls are tight, check for excess play at every connected joint. There should be small spacers at the top and bottom to set the camber - are they missing ?
3. Does anything look really worn i.e. is excessively loose or bind ?
4. Blown bearings are usually easy to spot - is there a bunch of play / seals missing ?
5. Does the ESC Fan work ? / Motor fan if equipped ?
6. CV\Dogbones - Are the cups on the diffs or case inputs excessively worn ? Are any of them bent ?
7. If All Looks good - quick check all the screws for tightness / is anything backing out ?
8. Power it up - wheels off - spin everything - recheck moving parts for straightness.
( So this sounds like a lot but it would probably take 15-20 minutes !)

Beyond that - just run it. Listen for weird noises / crunching / howling - You are going to end up tearing it down eventually for an overhaul or repair anyway so don't worry too much about it.


Overkill-ish - ? -

I agree with Woodentop above - If you have the time and patience to spare - tear it down completely and replace all the bearings. Almost every
used RC I buy has been put away "wet" at some point and typically hub bearings and others are trashed or nearly so. One bad bearing on the input to
anything can cause a bunch more tragedy. 4s and 6s arma parts are inexpensive though - especially from eBay.

 

[iep]

Man, I keep saying this but, what great forum. Really useful advice guys, thanks.

Below is a link to the truck I've bought:

https://www.msuk-forum.co.uk/forums/topic/243722-arrma-kraton-6s-with-lots-of-upgrades-and-spares/

Looks, to me, like it's been used but not thrashed given the sheen of dirt over t but lack of major scrapes.

I'll check with the seller about bearings and whether he's ever changed them previously. He appears not to have scrimped on maintenance elsewhere.

So, questions:

1. Where do I get a good set of sealed bearings in the UK?
2. What weight of oil should I be using in my diffs (appreciate there'll be opinions on this but is there a good starter)?
3. Weight of oil in the shocks?
4. How do I check whether a diff needs any shimming? Really noob question but, what is shimming? I guess it's just the addition of washers behind pinion or similar to reduce movement? Is there a decent how to guide?

Cheers.

 

[veryconfusing]

Man - Given how clean and obviously cared for that is - I would just check it and run it.


Our 6s stuff is horribly beat on - when one of them is approaching rebuild time, they look like I put them in the dryer with rocks for an hour or so.
I mean really bad - like "Will it survive another 40+ foot jump" - non-stop - replace 1/3 of it at rebuild bad.
( Thanks to M2C and TBR the chassis and braces have never failed! )

I run 30wt in the shocks with stiffer springs as we can never seem to stop going for big air.

Great post on diff fluids and shimming -
https://www.arrmaforum.com/threads/diff-oil.11465/

I run 60/500/30 or 60/1M/30 - I am in Texas and summer is HOT which seems to loosen things up a bit.
We also all like the ability to endlessly wheelie.

 

[Mr.Vylan]

I just bought some bearings from this company. Fast delivery (US), not sure about the UK.
And, their marketing is interesting as long as it does not offend.
https://www.acerracing.com/

 

[RWE2500]

I've just bought a used 6S Kraton from another forum. Photos show the truck is in great condition. It was a V3 that has had most V4 updates added to it (aside from motor mount) along with upgraded aluminium braces, steering servo and titanium steering plates.. Apparently only ever run on 4S.

Obviously I doesn't come with a guarantee but the seller seems decent guy so if there was an obviously damaged diff or similar hopefully we'd be able to come to an arrangement to get it fixed. The only issue is, aside from visual inspection of suspension etc, I don't know what sort of things to look for. Are there any checks I can easily do on the drive-train (differentials etc) when it arrives just to check that it is not a lemon?

Lastly, I think there were diff shims added on the V4 model. I don't believe these were added to my V3. Can they/should they be considered?

Any thoughts gratefully received.

Cheers.

EVERYTHING! I just did the same thing. Looked great in pics but was rough when I got it. Had seen a lot of water apparently. Even shock mount balls were missing.

 

[Engineer]

I've just bought a used 6S Kraton ... It was a V3 that has had most V4 updates added to it (aside from motor mount) along with ...

... the seller seems decent guy ...

Must be the season for V3 Kratons - I just picked one up on this forum from a pretty decent guy as well.

 

[bicketybam]

Check the diffs. I didn’t when I sold mine and it turns out there were broken pins and a damaged sun gear. The truck ran fine the last time I used it so I assumed the diffs were ok. Another thing to check are the shock shafts. Hard to tell they are bent unless you take them out of the shock body.

 

[Woodentop]

The one on the link looks nice and tidy, mine wasnt, as said above my shock shafts were like bananas, bearings and diffs if it's used , no exceptions, for me anyway, it can look great but you never know with used, bearings, shims if needed, and use it, you'll know more as soon as you do ?

 

[bicketybam]

The other thing to keep in mind is that it's a used truck and when you buy it's typically "as is." You can really expect someone to totally tear down and rebuild a truck before they sell it. At best you hope they check for the obvious.

 

[iep]

I've spoken to the seller who reckons it has had so little use that the diffs and bearings are basically as new.

So, sounds pretty good to me. That said, 'as new' might still want some diff shims as I understand it.

Bit of reading suggests the mugel shims as being a good solution but they don't seem to be available in the UK.

Any UK owners found a decent local source of shims for 6S cars?

Cheers.

 

[Woodentop]

Td 310475 or muge0206
Kyosho 96772 or tkr 1222
I'll check the other ones
I'm also in UK and use rc bearings very reasonable in price only abec 3 but they're fine for bashing imo ?
Did u give him the full ebay asking price for it? I personally would have gotten a new one for that price clean or not, with no TX and rx? Imo the v3 servo saver is better if your steering is a bit "laggy" search the circlip-snap ring mod I've done it on all of mine and they've woken up considerably. ?

 

[iep]

Ta for the part numbers. RC Bearings look good. I'll get a set ordered.

Can't seem to find a UK supplier for either the Td310475 or muge0206 shims though. Guess I might just have to suck it up and pay the US postage. That said, there's enough Arrma owners in the UK that surely there's a local option that I'm missing?

No, not full asking we came to a fair deal.

That said, with a split new battery, pile of useful spares (inc the old V3 servo saver) and a load of useful upgrades (granted some more essential than others) I don't think it would have been too bad even at advertised price. Some of the upgrades are ones I would likely have wanted to do myself so, assuming no drivetrain surprises, it has probably worked out at decent saving overall.

As I understand it, the V4 comes with the dreaded spektrum radio too. So, even new, I'd have slung that and dropped in a BS6 RX for my flysky straight away anyway.

All I need now are the bearings, shims, a selection of diff oils.....

It's quite an expensive hobby this.

 

[Woodentop]

Lol, The start up is, batteries, decent charger, spares etc, obviously once the addiction takes full hold and you have multiple cars and eat, sleep and breathe rc @Notorious J runs a clinic for everyone with the same affliction, entrance fee is coffee and doughnuts ?
Seriously though, the shims will slip through, as the cost is minimal they're not worth charging for in customs and mine come within a week usually, new bearings, strip it and shim it if needed and something like 50k f 200k c and 20 r for fluids is a good starting point ?

 

[iep]

Awesome advice. I'm sure none of it is actually complex but there's a lot of choice....

Apparently my truck is coming with 1M in the centre and 10k front rear. Seems to have been set up exclusively for wheelies I may do something about that.

Ordered a set of shims, o-rings and diff oils. £30 all in so not the end of the world.

Now, batteries.... 2x3S or a big 6S.......

 

[Woodentop]

1m.....geez ?‍
Advantage of 2 3s if 1 goes down u always have another for when u get a granite brick etc ?
Not brick brcc

 

[iep]

I have a soft spot for my very old Ansmann Mad Monkey. It runs great on 3S so, yeah

 

[iep]

If you're curious how this went, the truck turned up yesterday. It looks pretty much as the picture. Dusty but otherwise in good nick.

Front bumper has a few scrapes and the body a few scratches but no splits/cracks.

Chassis is ruler straight and has minimal scratches.

Suspension moves smoothly, no creaks or leaks on the shocks.

Front and rear diffs are silky smooth, centre diff feels just a smidge notchy. Since it is full of 1M oil, I'm planning to strip it down and replace with 300k anyway so I can take a look then. TBH, I've ordered a full shim and bearing kit so am likely to take a look at all thre diffs. I just don't expect any issues on the front/rear based on how they feel.

Bearings all seem smooth with no apparent play anywhere. I'll replace as required when I do the diff service.

As to the upgrades, the servo is awesome, the chassis braces look neat and nicely installed. The steering is smooth but with no play. Battery seems pretty new.

Lastly, the box of spares has a full set of A-arms and various other useful odds and sods.

A very quick test run last night on 4S showed to be a bit of a beast. Quite a step up from 1/10 buggies

Ta, for all the advice.

 

[Sandracer_NL]

IMO this applies with any RC you buy, especially a used one. go to the video and the scroll to 6sec. You’ll find the answer in 6sec-9sec. ?

ALL bearings, diffs (oil!), shocks (oil!), are all shafts, cvd’s straight, no strange noises... I would completely disassemble it.