"Cheap" Micro Fun - WLtoys K989 1/28

SantaClaw

Well-Known Member
Messages
143
Location
North of Norway
So, I was playing around with my tiny k989 the other day.... Ran it for a while.. then made the faithful decision to run it without a body... yay...

Broke the right rear suspension.. And, when I started taking it appart, the front right suspension too, the top ball on the trailing arm was broken on both... Plastic parts...





I presume WLtoys are at the bottom end of RC-Gear, but it's a heck of alot of fun in a small package...


I went somewhat nuts on ebay buying parts for well over 150$ lol

So, I have ordered the following:

A full aluminum suspension kit, it includes, a arms, hubs, front cv shafts, strut towers, shocks (they are just springs, no oil or anything), trailing arms, metal balls etc.

A new engine mount plate in Aluminum, to provide more secure engine and better cooling.

A replacement, more powerful motor, not sure if it really is, but seller calls it an upgrade.

A 5g servo, with metal gears, the stock one is all plastic, not sure if this new one is physically stronger.

A carbon fiber frame, Supposedly a lot lighter than the original, but then again, all the other metal parts makes up for it, I'm sure... lol

A new set of drive gears,.

A pair of aluminum diffs, the front stock diff was actually turning with some resistance, so I suspect it was failing on the inside...

A complete new set bearings for the new hubs, diffs, and center shaft.

A set of Slick tires, with a new set of rims, I have 3 sets, I'm hoping for more grip with these.

And last, but not cheapest, two new aluminum differential housings.





What is clear to me, considering the physical size of these parts.. You are not paying for the Materials... lol


Yeah, It's a beast :D Lots of fun, Hoping for more traction with those new slicks and the added weight.. :D
 
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Goose1072

Active Member
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70
Location
NYC
Wow, wish you had video of before and after would of been awesome!
What motor you planning on installing?
 

SantaClaw

Well-Known Member
Messages
143
Location
North of Norway
Wow, wish you had video of before and after would of been awesome!
What motor you planning on installing?
Yeah, unfortunately it broke, and I already completely dismantled it...

Well, not sure if it's any better than stock, might actually be a miss labled stock motor, I do find it plenty quick as is, but considering the extra weight, I suspect I may have to add a bigger one.

Seller says it's an upgrade... but I suspect it's just a stock one..

Motor

Either way, I wanted to get a new one, as the old has seen alot of action, and has a heatsink glued to the side that I can't get off..

I think my next weakest parts, will be the plastic gears for the center shaft, and the motor, I haven't been able to source metal replacements.

As a proper motor replacement, I think perhaps Surpass Rocket v2 is a decent alternative?

I guess I'd need a new receiver too.

Maybe I can combine that Surpass Rocket V2 with this controller/receiver kit ?

Flysky FS kit

Would that work ? Hm... Wonder if I would be able to squeeze both in there...
 
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SantaClaw

Well-Known Member
Messages
143
Location
North of Norway
Just found this motor combo : Speed CTR Motor
I suspect the motor/esc in that link is too large..

I think the motor you linked to is for 1/18 scale cars.. maybe 5 times the weight of this thing :p

After reading some reviews, I ordered that Flysky remote controller kit + a couple of the controllers for it.. I plan on changing the receiver in my Savage xs for one of those too.. :D
 

SantaClaw

Well-Known Member
Messages
143
Location
North of Norway
Well, I guess we'll find out if it will work..

I ordered that rocket v2 with 3500kv with esc :D I also got a programming card for the ESC.

Rocket 2 3500KV

So with the flysky remote + receiver, it should work...

 

SantaClaw

Well-Known Member
Messages
143
Location
North of Norway
I've had a few Flysky radios before, they are good and especially the GT3B.


A pic I found, if you look at the connector on the cable that goes into the receiver, you get a sense of the size we're talking :D

I don't really know too much about electric motors, I figured I'd give the 3500kw a go, if it is to weak, I'll just buy a bigger model, they go all the way up to 9500 kv in the same size, all are rated at 60 000 rpm... Either way, I suspect it's much faster than the original brushed motor.

Well, I hope the receiver is good, I've read a lot of good things about it.
 

Goose1072

Active Member
Messages
70
Location
NYC


A pic I found, if you look at the connector on the cable that goes into the receiver, you get a sense of the size we're talking :D

I don't really know too much about electric motors, I figured I'd give the 3500kw a go, if it is to weak, I'll just buy a bigger model, they go all the way up to 9500 kv in the same size, all are rated at 60 000 rpm... Either way, I suspect it's much faster than the original brushed motor.

Well, I hope the receiver is good, I've read a lot of good things about it.
wow that combo looks really good, post some video after.
 

SantaClaw

Well-Known Member
Messages
143
Location
North of Norway
Not sure it will fit though... lol

Phew, stock motor, is 2.5 cm long, aka 25mm... The new one is 25mm long...

I was a bit worried when the description for the stock motor was 90 mm



It's a tight squeeze as it is :D

I think the screw holes should be the right distance as well, the diameter of the new motor is also smaller than the stock one...

I guess the gearing is the next thing... The stock motor has a 17T gear, I suspect that's way to big for the brushless one... So I found a 16T brass gear, with similar thickness and roughly the same diameter.

Buuuuut. I plan to gamble on spur gears for the Kyosho Mini-Z

Kyosho metal gear kit

They run a 2mm shaft diameter, and one of those is hopefully a good match..
 
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SantaClaw

Well-Known Member
Messages
143
Location
North of Norway
Well, so far, I only got the set of drift tires, the new wheel bearings, and a new heatsink for the first motor.

The first seller I ordered the new diffs and bearings for that diff, cancelled the order after 17 days.... saying it's hard to export atm due to corona.

so I ordered new diffs today. The new diffs also come with bearings, so that's a plus. I thought about getting Mini-z diffs and special driveshafts, but that's like 80$... so I'll go with the cheapo balldiffs for now.

Cheapo Balldiffs



I also ordered a tub of shock grease, these are not oil filled shocks, but you can fill them with special grease to get proper dampening...

The only other thing that hasn't been shipped yet, is the new brushless motor ofc... I hope they end up shipping it and not canceling like the other two...
 
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olds97_lss

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HPISF Supporter
Messages
2,599
Location
Dekalb, IL 60115
I've been running my 1/32 losi micro-high roller a lot lately. Fried the 2.4ghz brushed/brushless esc/receiver board though when I was transplanting it into the micro-DT chassis. Really shot myself in the foot there... should have just left it alone. :(

I run a brushed motor in it, the brushless was too low torque on the bottom end and too fast/hard to control once it did get moving. Found a generic 20A brushed esc, but the brakes in it suck, so I have forward/reverse...

Yours looks like it's the size of my micro sct which I think is also 1/28. It's too big/fast for running around my house, so it just sits.
 

SantaClaw

Well-Known Member
Messages
143
Location
North of Norway
This is about the size of an avg smartphone...

I was told these break all the time, though I never had that issue, I've ordered some replacements.


Spurr & Diff gears



In other news, I have been expecting the new chassis for a few days, but it hasn't been delivered like it says it should have been, so not sure what is going on, hopefully I'll get it and a few more parts for this little car on Monday.
 

SantaClaw

Well-Known Member
Messages
143
Location
North of Norway
Well. to summarize what I have got:

Carbon fiber Chassis.
The set of 15 gears mentioned above.
The two new Diffs.
Diff housings.
Tires.
Motor mount.
Motor gear in brass.

Missing the metal suspension parts, rims, the new brush-less motor, though I expect it this week, and the new Radio.

There are some issues with the new Differentials though, they may be made for the Mini-Z, this means they require longer driveshafts, the cups are shorter than stock , though the listing says they are for the K989. Missing too many parts to see for sure if it will be an issue.

They also bind up the center shaft somewhat, so I need to investigate how to fix that.
 

SantaClaw

Well-Known Member
Messages
143
Location
North of Norway
So, after spending an hour or so, sanding down a washer to make 1 shim for one of the new diffs... I seriously hate whomever made these... lol

I first had to drill a 5mm id washer to 6mm, then I had to sand it down, to about 1/3'rd thickness for it to fit 1 of the diffs... Without shims, there is WAY too much slack in the diff gears, to the point where the brand new gears can skip...

I do NOT recommend buying any of the K989 branded ball diffs. Get one for the mini-z and get two long wheelbase cv shafts (10,5mm) for the same car....
 

SantaClaw

Well-Known Member
Messages
143
Location
North of Norway
Righto, still waiting for the suspension parts (includes body mounts), new servo AND the bloody radio.

I did try the new motor out today, I've got it hooked up to a switch under the car, so you don't have to disconnect the battery or remove the body to do so, the ESC is TINY, I connected it to a HPI reciever just to test it out, and the motor/drivetrain works great, the new diffs are in, and they work just fine, I had to modify the holes in the motor mount a tad, but otherwise it fits nicely.

The motor ran sweet, very silent.


IMG_20210323_184724.jpg
 

SantaClaw

Well-Known Member
Messages
143
Location
North of Norway
Ok, I got the rest of the metal parts...and yeah.. they are of extremely low quality. the driveshafts where indeed too short for this car, so I have ordered long ones...

The lower arms, are so tight on the lower diff housings they can't really move.
So I'll have to sand them.

The metal parts kit comes with balls... but get this. The shocks, and other parts do not works with balls... and there are no parts to mitigate this fact... so yay.. I'll probably end up with a mix of plastic and metal parts.

the lower control arms, should have balls in them for the knuckle, there are some very loose fitting bushings in stead, so loose that they allow 0.5-1 mm movement in the bushing... yay! not sure If I'll have to glue them in place or something

The new servo also arrived today despite being sold as a direct replacement metal gear servo, it has a different number of teeth, and ofc the screw it comes with is too short for the stock servo saver.

Of the metal parts that are decent.

The shock towers, and the uhm... Well.. knuckles seems to be decent...

The control arms are wobbly, and too long, needs to be sanded both in length diameter and with for the mounting holes.

The shocks cannot be mounted as it stands. I tried to fit them to the plastic shock towers, but that didn't work either..

The lower A arms are a mess, they have loose bushings that do not work as balls as they should be. they also require sanding to fit the diff casings..

Threads are also cut sloppy on everything, so the screws feel loose. This will require a lot of locktite.

The aluminum engine mount plate comes with three screws, 1 do not fit the part at all.

For some reason this metal part kit comes with two new cv shafts... These are too short for the new diffs, but they would fit fine on a stock car. They do seem inferior to the OEM cv shafts...
 

SantaClaw

Well-Known Member
Messages
143
Location
North of Norway
Right, after some investigation, looks like the shocks will fit, just not the way you'd think... lol you use the balls, but the balls stay on the outside of the shock mount.. lol
 

SantaClaw

Well-Known Member
Messages
143
Location
North of Norway
Never mind, they do not fit... lol

And the upper control arms have bad balls as well, so, so sum up. the metal kit for this car, at least from this ebay store is poop.
 

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