Atomic High Precision Ball Differential

[arch2b]

High Precision Ball Differential
DN-005
http://www.rcatomic.com/atomic/components/com_virtuemart/shop_image/product/DN-005_m.jpg

[arch2b]

EGR MART (Atomic RC general online distribution shop [in Asia] for those that don't know) has this listed at $30.30. you can expect that to be slightly more expensive when bought from domestic shops. the shop here does carry atomic rc products as well as another online shop.

[arch2b]

as i reported earlier, this is already available for purchase in Atomic RC's main web distributor EGR Mart (http://www.egrracing.com/shop/high-precision-ball-differential-for-kyosho-dnano-p-3142.html).

if your a continental u.s. owner, you'll be happy to know AtomicMods (http://www.atomicmods.com/Products/Atomic-DN005-Dnano-High-Precision-Ball-Differential__14914.aspx) also has this in stock and ready to ship.

PLEASE note, Atomic RC and AtomicMods are completely different business's. people often refer to these places using abbreviations which others misunderstand.

[MrNanoTrax]

we'll be stocking these too... i personally want 2 give one a try ;)

[-J-]

Well, I was able to pick up on of these at my local Atomic R/C distributor today. I'm in the middle of a move, so I won't be able to run it for a while, but I definitely tell you it's a lot more robust and as a result, a lot heavier than the Kyosho diff.

[arch2b]

i think a little added weight to the dnano might not be a bad thing. i look forward to hearing your experiences with it.

[-J-]

i think a little added weight to the dnano might not be a bad thing. i look forward to hearing your experiences with it.

I agree.

I had to take it out of the package, and in doing so, this diff feels really smooth. I know performance on the track is the ultimate test, but this diff feels just as smooth as the new PN diff for the MR-02. Can't wait to get it on the track.

[fraz]

Haven't run yet but we are running and testing tonight. My 962c is pretty dialed on our track from where I last left the setup so the baseline should be prime for testing.

My first impression out of car is VERY NICE. Usually Kyosho ball diffs I consider to be the gold standard. I love their shim adjuster, etc. but they are simply gritty and spring a bit too tough unless you mess with them a bunch. The Atomic was silky smooth out of the box and the spring is much lighter. To give you an idea of range, you cannot lock down this diff so the spur gear will always turn some. What it looks like is they found a tension range appropriate for the little motors with no torque.

As for weight difference, I didn't bust out my scale but it seems comparable to Kyosho ball diff. The construction appears to be aluminum (pressure plates and adjuster) and titanium (axle and spacers) so it is not as heavy as it looks!!!

One mod I am looking at as I type is Dremeling a small opening in the axle housing to access the adjuster nut. The idea is put a finger on the adjuster nut and turn the wheel to adjust with no tools!!

[fraz]

Ok, I will try and be as succinct as possible without ripping Atomic too hard since they have a history of making great products. Here is all of the testing and investigation I did tonight and ultimately, it was a waste and had to go back to Kyosho ball diff. I really want to use this diff but I need to do some engineering recon still and I will keep y'all posted.

PROBLEMS:
1) No instructions and this is not a plug n' play product.
2) Spur gear is not round!! - no matter how you set mesh, the molding on the spur is not accurate enough to be considered round in this scale.
3) Gear tooth pitch is not right - unless they are providing an Atomic pinion gear set, these never mesh right.
4) WARNING: There are 6 screws. They are of 2 different lengths! The long ones are for using the plastic hubs and the short are for the aluminum.
5) WARNING: Aluminum left hub needs modification! No matter which screws you use, there was a total bind when the screws were tightened even to the lightest amount where they would back off.
6) Shim may be needed. When all is said and done, there is not enough gap between spur and motor mount... it rubs!
7) The tolerance of knurled adjuster is VERY small inside motor mount and the diff backed out and undid itself! Not sure if it was from this, the rubbing spur, or the tight mesh... but the diff was unusable and felt like constant drag brake at best.

FIXES:
2&3) I have a brand new Kyosho ball diff I am going to take apart to see if ID is the same and if the balls fit. If so, this should solve majority of the problems.
5) The problem was the aluminum Kyosho hub was too long on inner step and diff may have been designed to only work with plastic hubs. There was tons of material on left hub so I got some 600 grit sandpaper on the granite countertop and took some material off the hub where it meets the axle/e-clip/bearing. Once I did this the short screws torqued up nicely and no more binding.
7) I may end up with a round roll of emory cloth to take some material out of the motor mount where the diff slides through. As it stands there is like 0.1mm of space and that equates to 0.05mm per side of the knurled adjuster. If you know about plastic molding... no way this can be perfect in these tolerances. This will be the last thing I mess with though.


NOTE: it would be one thing if I was a rookie writing this up, but anybody who knows me in the Mini-Z community (or r/c community in general) knows I am fast and have a good mechanical clue :) This product needs to get a rev2 before re-releasing and I kind of expect Atomic to make good on the product without sticking me for more money.

[arch2b]

wow, thanks for the insight and review. for the less mechanically challenged folks, this will save them time and money to wait for v2. atomic, like pn has a good record for revisions. i'm sure once they get enough feedback they will do some rework.

does thier website still have a forum? if so i would highly suggest copying your review and posting it there as this is a very new product and obviously very flawed.

[fraz]

atomic, like pn has a good record for revisions. i'm sure once they get enough feedback they will do some rework.

Yeah but I think both of them suck for gouging early adopter customers to pay hard earned $$ to pay for their mistakes. If there is a performance improvement, sure I will be happy to pay. But when there are clear mistakes, they should provide the "fix" parts to customers on a case by case recall basis. Example: PN 94mm LCG motor mount. The part is awesome but hold down screw set up for the upright is a joke and well documented. They fixed it in next rev and expect everybody to pay another $40!!

does thier website still have a forum? if so i would highly suggest copying your review and posting it there as this is a very new product and obviously very flawed.

Neither Atomic nor EGR have forums unfortunately:(


So I tried the Kyosho spur gear swap last night.

~~The good news is the Kyosho spur gear ID fits on the Atomic ball diff.
~~The bad news is the Atomic spur has bigger balls and holes.
~~Once everything is bolted up in the Atomic diff, there is too much of a gap to make up so the diff rings will meet the tiny diff balls used by Kyosho. My next solution that will likely work fine is to make a spacer to take up the difference. I am thinking of taking one of the Kyosho diff rings and gluing it to the back side of the Atomic diff ring to get the tolerance back "in the zone". I will report back on this as I test or if I resort to some other shimming technique.

I think the unfortunate part and the reason that the Atomic diff is so smooth is because of the bigger balls. Though the diff rings are better chromed material so there may be some adopted benefit. However the lighter spring tension range and adjustabillity may make this project worth it.

[arch2b]

i agree it sucks to have to pay for an updated/fixed part but in 10 years mini-z's have been around and parts made, this is the way it's been. to expect anything else is unrealistic. the ONLY time i've hard parts replaced were due to manufacture defects such as screw taps are missing and or at odd angles, etc.

the risk you assume in being an early adopter of anything is that you are the ginuea pig. what would be nice is if they would offer spare parts for order. PN is doing this for many of their latest stuff. Atomic usually sells spur gears seperately as well. this would at least make getting revised parts cheaper than buying the entire ball diff.

3racing has a forum and i'm sure it's only a matter of time before they get into the game. maybe even gpm but i have not heard anything positive from them in a long time. i've had good experiences with 3racing forum responses.

[fraz]

i agree it sucks to have to pay for an updated/fixed part but in 10 years mini-z's have been around and parts made, this is the way it's been. to expect anything else is unrealistic. the ONLY time i've hard parts replaced were due to manufacture defects such as screw taps are missing and or at odd angles, etc.

This is a defect, and a lot of them at that. Not only have I been around Mini-Z from the start, I have been in the r/c game since the late 70's. I can't see this any other way than sensible customer service responsibility is to make good on what was promised. I will not accept excuses even though I am an engineer and can come up with workarounds as good, or better than the next guy. I am not sponsored by any of these folks, nor do I care to be so when I pay out of my own pocket... I get to speak freely :) If my company tried to get away with that, we'd be out of business in a heartbeat. Come to think of it, we have shipped some very buggy releases in the past and boy did we have to spend a lot of time and money to scramble and make it right :)

3racing has a forum and i'm sure it's only a matter of time before they get into the game. maybe even gpm but i have not heard anything positive from them in a long time. i've had good experiences with 3racing forum responses.

3Racing is "ok" but their quality has never been top shelf. That said, I have run a few limited 3Racing parts. I would rather use a stock Kyosho part or a Frankensteined Atomic part as first choice :)

The last I heard of GPM, they were disolving or at least getting out of the r/c biz.


Oh and one other thing... my fastest and best functioning dNano... uses stock gear diff. HAHAHAHA!!

[arch2b]

i agree with you again, but it's been this way for 10 years. it's not something new nor is it likely to change. i've been around since the begining of z's too and never been sponsored, nor car to be as well. every couple years you run into this same argument and you will again in. yes, it sucks.

3racing at least listens to feedback and provides a means to do so. i agree i would rather buy other stuff before theirs but they listen and there is some value to that.

many make the same argument for the mini-z as well :0 another debate that will last as long as they are available.

thanks again for sharing your experience here. it's nice to get seasoned rc vets :)

[fraz]

So the diff rings are d-rings which is good but the shoulder is not deep enough to center an additional ring. The only solution I can see right now is to glue a Kyosho diff ring on top of one of the Atomic ones. That _should_ work ok. I will try that next.

[patrick38]

hi there

wich one off ball diferential do you people like the most ??
kyosho ore the atomic one ?
hope too hear from you
newbie waiting for his dnano

[Marcro]

I'm glad I read this before splurging. I was going to pick this up along with their disc damper set. Thank you for this review and I hope a V2 comes out soon.

[MrNanoTrax]

kyosho's ball diff is fine... only thing i'd recommend is replacing the stock spacers with thinner washers to allow for more adjustment since the "1" plate setting is worthless

[Jellis]

I thought it was kind of a toss up between the 2 diffs mening they both had there own set of proplems. I'm a machinist by trade so I didn't have any proplem fixing either diff.

The kyosho diff was easy to fix I fully compressed the spring 40 or 50 times to take some of the tension out. Then I found that armature spacers from a slot car motor are an exact replacement for the thick plastic stock shims and they come in various thicknesses .020",.010", .007", .005" for and almost infinate adjustment. If you have a local slot car track (good luck) they should have them in stock.

The Atomic diff had many more problems 1. Adjuster nut and spring hit axel housing, 2. LR drive hub hit axel in center of hub, 3. Gear very loose on hub ( I havn't fixed this yet), 4. Gear seems to be a different pitch than pinion.

1. I fixed the axel housing by reaming it larger I think a drill bit might crack the housing. Also be carefull to make is just smaller than the bearing diameter so the bearing has a lip to set against. I also changed the aluminum nut to a nylon lock nut that I machined round, Drilled a hole in the side of it and made a slot in the axel housing to adjust it without removing the axel.

2. I machined the LR hub back there was alot of material and this didn't hurt anything

3. I havn't fixed the gear on the hub yet

4. I have been running the gear with the stock pinion and other than a little bit of noise I havn't had any problems but may seem a little bound up even with a good gear lash

I did a back to back test of both diffs last weekend 100 laps each taking out the worst 15 laps for my crappy driving.

The atomic diff was first with an average lap time of 4.79 and a fast lap of 4.41

The kyosho diff was a little faster with an average lap time of 4.61 and a fast lap of 4.23

I know some of this was covered in other posts but you know the saying everyone has an opinion and something something .........

[arch2b]

could you share pictures of your modified atomic diff?

[Jellis]

Arch it dosn't look any different than the stock diff

[arch2b]

i'd like to see the milled changes made :)

[MrNanoTrax]

i'd like to see the milled changes made :)

co-signed... pls post pics!

[Jellis]

Sorry guys I've removed all my atomic diff's and replaced with Kyosho. My 962 had an atomic diff in it and it always seemed like a dog I changed the motor thinking that was it and it only got a little better. I finally broke down and put a kyosho diff in it and its a rocket ship now so no more atomic ball diff's for me unless they fix all the problems.

Anyone want to buy any atomic ball diff's LOL Cheap I have 4 of them

[Jellis]

I also did a post a couple weeks ago about the 2 diff's back to back in my lambo but the improvement wasn't so drastic.

The Kyosho diff with the proper shimming is in my opinion way better than tne atomic I would even say that on the HTUSA track it's worth at least .3 sec. per lap

If anyone needs help finding the slot car motor shims that fit the axel maybe I can help but please check for a local slot car track first

Thanks
Joe

[Jellis]

I meant to add the guy that raced my 962 last week went from running 4th or 5th in our group to not only winning but won by 2 laps the car was fast...... and all we changed was the diff

[nitrojunkie]

I was there and witnessed the whole deal.The difference was night and day.There was not a lot of time spent on the Kyosho diff either 10 mins tops.

[MrNanoTrax]

i've been messing with the atomic diff and discovered if you sand the containing screw to where its smooth, the diff housing problem is eliminated. also, the RIGHT rear alum. hub needs to be attached just off the bearing to prevent it from restricting rotation (perhaps a shim would work but not sure what to use). now it performs just as well as the kyosho... best time on Circuit F1R @ NanoTrax is 6.62 seconds (Porsche 911 GT3, Kyosho Ball Diff) and i tested the Race Spec Gallardo yesterday with the Atomic Ball Diff and clocked a 6.94 seconds.

[Marcro]

I'm confused as to which differential to buy if any at all.
Almost sounds like the stock unit is best?
I'm not a machinist, and I don't like fiddling around with parts trying to make them work. I am a much simpler plug'n'play type of person. What do you recommend for me?

[MrNanoTrax]

stock diff sucks.... get a kyosho joint, add heavy ball diff oil of your choice and keep it movin ;)

[fraz]

also, the RIGHT rear alum. hub needs to be attached just off the bearing to prevent it from restricting rotation (perhaps a shim would work but not sure what to use).

I block sanded the backside of my left aluminum hub with 600 grit. Then had to carefully deburr it and doing so will keep it from bottoming out on the e-clip. The plastic and aluminum hubs are quite different and it appears the Atomic diff was designed around the stock plastic part.

Still would like to know how you got it to work so well. The gear teeth are a different pitch and/or profile from what I have seen.

[LBRC]

After a close look at the Atomic diff I figure that someone along the line screwed up and released it with a bushing width 2mm wide ball bearing instead of the 2.5mm that it needs, a 0.5mm spacer/washer between the 2mm bearing and thrust washer housing would also work. Note that with a new 2.5mm bearing it now matches the Kyosho Ball diff’s spacing exactly.

http://lbspd.com/v-web/gallery/albums/album208/dn_diff_compair_400.jpg

Another problem I had with the Atomic diff is that the adjustment nut tended to loosen up as you drive, but a drop of thread-lock fixed that. I use the non-hardening type and put a small hole in the motor mount so the diff can be adjusted by holding the nut with a push pin or small screwdriver while turning the left wheel.

http://lbspd.com/v-web/gallery/albums/album208/Atomic_Diff_Adjust.jpg

Even after replacing the bearing I can’t say I’m exactly happy with the Atomic diff, the gear pitch seems ok but there is definitely something wrong with to shape of the teeth, too wide, so it needs to be backed off from the pinion more than I like and even then you can hear it so even if it's not affecting performance it's still annoying. However the lap timer doesn’t lie so with the new bearing, lock-tight, and mount access hole I guess I prefer the Atomic over the Kyosho, but only marginally. With work both can be worth while but it took forever fiddling around with spacers and eventually new springs for the Kyosho’s average lap time to actually improve on the stock gear diff, with the right size bearing in the spare parts drawer it only took a few hours to dial in the Atomic. Note, the Kyosho ball diff in the above photo is out of an 80 gram modified Epoch not a 45 gram dNaNo so even though the spring on it is lighter than the stock spring its still heavier than the one I ended up using on the Kyosho ball diff in my 962C Porsche.

[edhchoe]

I started liking my Kyosho ball diff. I have it set at the maximum loose setting without slipping. I had to grind the top and bottom plastic pieces on a sand paper to lessen the spring force. Do you guys let it slip at all?