WLtoys K929 1/18 4WD desert buggy - RC Groups
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Mar 17, 2016, 09:52 AM
Car Bashing
Jym73's Avatar
Mini-Review

WLtoys K929 1/18 4WD desert buggy


WLtoys K929 1/18 4WD desert buggy

I received a WLtoys K929 1/18 4WD desert buggy from gearbest.. It is at 40$ on EU warehouse and 47$ on US WH for the moment (17 march 2016).

Not a new car at all but i will give my thought and impression.


Shipment packaging :

Well packaged and box reinforced.

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Obviously it come in an other strong box with bubble plastic.

Box :

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Box content :

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- Car.
- Radio.
- 1 7.4V 2s 1100mah battery.
- 1 plastic tamiya wrench.
- Manual.
- Charger.
- Charger adapter.



Car design :

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Wheels seems a little bit small compared to body.

We can slightly change body design :

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Without roof, fake spare wheel and wing. This the configuration i prefer.

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Without roof only.

open the body :

Rear clips access is a little hidden by the fake spare wheel.

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Body move from the rear. There is a fixation on front :

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Roll cage :

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Mounted with screws.



Size comparison :


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From left to right : BZ444 1/10, HuanQi 1/16, WLtoys K929, WLtoys A212 1/24.



Plastic :

- A-arm : quite rigid but have a little bit flexibility.
- Chassis plate : quite rigid but have a little bit flexibility.
- Upper deck : thin and very soft plastic.

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- Linkage : quite soft plastic.

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Prevent from breakage on hub carrier but can do bend dog bone by wheel's axle's cup.

- Knuckle, C-hub, Hub carrier : quite rigid but have a little bit flexibility.

- Roll cage : quite soft plastic :

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Transmission :

- Plastic center drive shaft.
- Plastic diff. out drive.
- Steel dog bone.
- Steel wheels's axles.

Ball bearing :

- 7x11x3 on bevel gear and diff. qty 6.
- 8x12x3.5 on spur gear qty 1.

Bushing :

- 4x8x3 and 8x12x3.5 in hub carrier.

Gear box :

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Diff. :

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4 small planetaries on steel axle.

Motor pinion mesh :

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Imo too tight on spur gear. Not adjustable without do modification.

Motor pinion should be 0.7 mod. Hard to find different tooth number of this module.

Wheels and hex hub :

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SCT design. Without foam.

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7mm.

Shock absorber :

There is a little bit oil inside bt quite empty.

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It seems that they can be filled with oil. 2 small o-ring at the bottom held by a cap clipped.


Electronic :

Servo size :

5 wires, so we must change esc and receiver if we want to only upgrade the servo.

- thickness : 13mm.
- Width : 29mm.
- Height : 29mm.
- Height to fixation : 19mm.

Batterie :

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Top : WLtoys 1/18, Bottom : 18600 7.4V 2S.

Battery size :
- Thickness : 17mm.
- width : 30mm.
- lenght : 52mm.

ESC :

Rx/ESC 2 in 1, waterproofed by a kind of transparent silicon.

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First thought :

- Technical design seems not too bad.
- Don't tight too much screws as they can strip plastic.
- Soft plastic on roll cage will surely well protect the car.
- I will try to fill shock absorber.
- Body's design isn't the most beautiful for this version. Paint job to come ^^.

First test :

I tested the car during 1 minute only. Transmission done a "strange" noise. After opened gear box i discovered that 1 ball bearing on front diff. was missing :

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I didn't read that this can happen often on WLtoys 1/18. 7x11x3 ball bearing is on the way.




Modifications and adding :

Motor protection :

The only thing i done before test it is to add a protection on the motor to avoid the problem i had with the HuanQi 1/16 and a small pebble :

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Synthetic tissu used for filtering.


Motor pinion :

Two things :

1 - motor pinion is too thigh on spur gear. I enlarged the upper screw hole (no need to enlarge it too much) to change motor position :

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Left : before mod. Right : after modifcation.

2 - Motor pignon alignment isn't good with spur gear :

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We can see that there is worn trace on spur gear and motor pinion but not on all the surface of the teeth :

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Trace is black on spur gear and more shiny on motor pinion.

I have done 2 things to straigthen this. Remove the heatsink "glue" who is under motor mount and who doesn't help to have motor support flat on the chassis :

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Imo this heatsink is useless.

And bend a little bit motor mount to have a better angle. Result :

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I must removed motor heatsink because there is not enough place for it under the motor now. I should glue it back, without glue it won't stay in place.

Drive train :

Only replaced 8x12x3.5 and 4x8x3 bushing by ball bearing.

Spur gear box :

As i do on all my cars to sealed gearbox, i added thick grease on every cover's edge of spur gear cover. Works pretty nice :

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Videos :

Stock speed test :

• WLtoys - K929 - Stock : speed test • (3 min 9 sec)

Not too bad. It seems that the too tight motor pinion on spur gear make a noise that i don't like. I won't wait too much to do a modification.

Modified speed test :

• WLtoys - K929 - Modified : speed test • (2 min 31 sec)


BMX track :

• WLtoys - K929 - BMX Track • (10 min 25 sec)


I didn't opened spur gear cover since my BMX track bashing, here is the result :

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Motor pinion and spur gear stay clean. Thick grease on cover edge works with me.

Parts compatibility :

1/18 vortex is also sold by hobbyking :

Racing buggy : spares .
Short course : spares .


Reviews :

SeByDockY's review


More to come, test video, speed run...
Last edited by Jym73; May 03, 2016 at 01:29 PM.
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Mar 19, 2016, 04:37 PM
Registered User
TechTronic9000's Avatar
How is the turning radius ? Can you take sharp turns with it ?
Mar 19, 2016, 05:15 PM
Car Bashing
Jym73's Avatar
I can't tell exactly as i use it during a short time, i won't say it do sharp turn but it isn't too large, will see in the run test video. I hope receive the ball bearing quickly.
Mar 19, 2016, 05:24 PM
Registered User
TechTronic9000's Avatar
Quote:
Originally Posted by Jym73
I can't tell exactly as i use it during a short time, i won't say it do sharp turn but it isn't too large, will see in the run test video. I hope receive the ball bearing quickly.
OK, looking forward to more tests (after you fix it). By the way any idea how this model stacks against a Subotech ?
Mar 19, 2016, 05:33 PM
Car Bashing
Jym73's Avatar
You talk about Subotch coco? If yes, hard to compare a 1/18 to a 1/24 as 1/18 is bigger.
Mar 19, 2016, 05:44 PM
Registered User
TechTronic9000's Avatar
There is the SUBOTECH BG1506 which is 1:12 (larger), not a buggy but still 4WD.
Mar 19, 2016, 05:48 PM
Car Bashing
Jym73's Avatar
Same, 1/12 is almost the size of 1/10, 1/18, as you can see on the photo in first post is more close to 1/16. The main problem with the Subotech 1/12 is the parts support, hard to find.
Mar 20, 2016, 06:06 AM
Registered User
TechTronic9000's Avatar
OK, now I'm waiting for your ball bearing to arrive.
Mar 20, 2016, 06:22 AM
Car Bashing
Jym73's Avatar
Me too look forward that it arrive.
Mar 20, 2016, 12:02 PM
Registered User
mike_o's Avatar
I don't understand the ball bearing issue; Was it never there? Or did you loose it while driving?

Secondly; The shock: Can they be - and remain - filled with oil or will the leak?
Mar 20, 2016, 12:17 PM
Car Bashing
Jym73's Avatar
I received the car with a missing ball bearing. Mistake of worker at factory.

I think they can be filled with oil. But to see if they leak i should use them on the car.
Mar 21, 2016, 04:51 PM
Car Bashing
Jym73's Avatar
34$ at US-LA WH, at this price it is interesting.
Mar 22, 2016, 05:24 AM
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TechTronic9000's Avatar
Quote:
Originally Posted by Jym73
34$ at US-LA WH, at this price it is interesting.
That's a great price for entering this car related hobby
Mar 22, 2016, 11:09 AM
Car Bashing
Jym73's Avatar
The only thing i done before test it is to add a protection on the motor to avoid the problem i had with the HuanQi 1/16 and a small pebble :

Name: WLtoys K929 motor protection.jpg
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Description:
Synthetic tissu used for filtering.
Mar 24, 2016, 03:59 AM
Registered User
TechTronic9000's Avatar
Where did you get that fine mesh (synthetic tissue) ?


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