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Nov 19, 2017, 05:12 AM
Car Bashing
Jym73's Avatar
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Mini-Review

VRX - BF-4 - 1/10 4WD Monster truck - Review


VRX - BF-4 - 1/10 4WD Monster truck


I received this VRX BF-4 from banggood to do a review.

VRX (River hobby) website : VRX

This is the RH1046 version. There is a RH1046C which is a crawler version, i guess it has the locked diff. and maybe a slipper.

This chassis is also sold under the brand FTX with the name Mighty Thunder.



Photos :

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Unboxing :

• VRX - BF-4 - 1/10 Monster Truck - Unboxing • (15 min 44 sec)




Specifications :

Quote:
Scale : 1/10
Lenght : 510mm
Width : 335mm
Wheelbase : 340mm
Wheels : Width : 75mm Diameter : 135mm
Gear ratio : 18.1:1
Motor : 550 19T brushed
ESC : 50A/350A brushed
Servo : 9Kg
Battery : 7.4v 3300mah 25c Lipo.
Transmitter : FlysKy GT2, 2.4Ghz, 2 channels, use 8 AA batteries, not included.

Size comparison :

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- From left to right : VRX BF-4, VRX Octane XL.



Parts inspection :

Hardware :

It use allen screws.


Transmission :

Center gearbox :

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- Spur gear is protected by a cover who look like cover which protect a slipper.

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- But there isn't slipper.

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Description:
- The spur gear is held by a 2mm pin and an E-clip.
- 30T brass motor pinion.
- Adjustable motor position, but it use the biggest motor pinion we can put.

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- 60T plastic spur gear.

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- Steel attack and idle gears on bearings.


Center differential :

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Description:
- Plastic center differential with metal gears (more details in the unboxing video).
- The o-rings are outside the differentiel instead of inside like most of the differential.
- It doesn't have gasket, so it seems it can leak if we put oil inside, excepted if it is very thick oil.


Center drive shaft :

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Description:
- Plastic.
- Same design as the VRX Octane XL but shorter.
- Held by a grub screw.
- There is an extension which held the differential o-ring.

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- Big hole in the differential axle for the shaft grub screw.


Crawler conversion :

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Description:
- There are parts available to lock the 3 differential, as an option.


Suspension :

Shock absorber :

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Description:
- Plastic body.
- Aluminum caps and spring preload ring.
- Filled with oil.
- There are 5 hole positions on top of the shock absorber.
- We can eventually put the shock on the a-arm, this will give really higher ground clearance.


Solid axles :

Front :

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- It use the same solid axle than the VRX Octane XL, excepted that the front on the BF-4 has knuckles.
- The steering bars are big and made with flexible plastic which will prevent from breakage.

Rear :

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Description:
- Same as the VRX Octane XL.


Chassis :

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- Side plates have a decent thickness.
- Made with flexible plastic.

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- Center gearbox plate made with stiff plastic and held by 4 screws.

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- Underneath view without the center gearbox.


Battery tray :

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- 139x49mm.


ESC :

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Description:
- 50A/350A brushed.
- Receiver protected in a box.


Body shell :

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Description:
- I repaired it as i can with tape.
- There are many cracked areas.



First thoughts :

- Big size for an 1/10.
- I like the rims design. The rims are enough inside the tires to avoid them to be too much scratched.
- The tires are big, but the pattern design is thin and surely won't have lot of grip.
- For the size of the chassis, it isn't heavy.
- The overall chassis design seems not bad.
- I like the steel attack and idle gear.
- I was suprised to see a center differential.
- It use the same front and rear differentials we can find in the VRX Octane XL, Vandal/Vantage buggy, FTX Cranage...
- It has bearings verywhere, good thing.
- With the 18.1:1 gear ratio, which is high, and the 19T brushed motor, i guess it won't be very fast.
- It is nice to see a manual for the car, the transmitter and the esc.
- On the manual esc there are three models. One of them can use 3s battery, but we don't know which one is on the car.
- Really disappointed to discover a broken in two parts body shell when opening the box.
- I didn't find the screw for the roll bar.



Videos :

Speed test + Off-road :

• VRX - BF-4 - 1/10 4WD Monster Truck - Speed test • (21 min 24 sec)

- It isn't fast but with a brushed 19T motor and a 18.1:1 gear ratio it is a normal speed.
- At this speed it is stable and the chassis will be durable.
- It has the speed of a crawler but with the soft differentials and almost slick tires it doesn't have good crawling capability, even for a monster truck the tires are too slick.
- The front battery position help to prevent the car to rollover while climbing steep slope.
- The chassis isn't heavy for its size and the shock absorbers spring are a little bit too stiff.
- The transmitter has a good range.

In comparison with the SST 1928 V2, which has almost the same speed and almost the same price range (but price can change also), i prefer the BF-4. The BF-4 has more torque and a longer play time, it is more fun to use out of the box.

I will put heavy weight oil to slower the differential, i think it will have better climbing capability and a better steering angle but it will maybe rollover more easily.


Upgrade : brushless combo :

• VRX - BF-4 - 1/10 4WD Monster Truck - Upgrade : Brushless combo • (9 min 49 sec)

I bought the Brushless combo here : https://fr.aliexpress.com/item/GoolR...782710970.html
0.6M 26T motor pinion : https://hobbyking.com/en_us/hobbykin...asc=2278281076

Because of the plastic CVD, plastic center gears and without slipper clutch, I'm not sure the drive train will support a brushless motor during a long time, will see...


2s brushless speed test :

• VRX - BF-4 - 1/10 4WD Monster Truck - 2S brushless Speed test • (2 min 28 sec)

- It is geared like a crawler, so with a high gear ratio, which make it not fast.
- I don't think this truck is made to be fast, high gravity center make it roll over easily.
- With the stock motor pinion, 30T, it won't be really faster, something like 40km/h i guess.
- So, it is geared as a crawler, fast as a crawler but with not locked diff, and almost flat tires pattern these don't make it a crawler.

At 139$ this is a strange truck, not very beautiful also. Good for very young child (because it is slow) who want something big. With stock setting it will be durable imo, excepted the body shell which is brittle. Don't expect to make this truck something fabulous. If you want a crawler you will need to lock the diff. and change the wheels, which are big for 1/10 scale, not so easy to find this size. Imo it can be a good crawler, it is really big for 1/10. So, finally, if you want a crawler, buy a truck which is sell as crawler, if you wan't a monster truck, i won't advise to buy this one. It remains something cheap though.



Feel free to ask any questions

More to come , stay tuned
Last edited by Jym73; Aug 10, 2018 at 06:56 AM.
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Nov 19, 2017, 06:53 PM
They sell it as the FTX Mighty Thunder in the UK. Looks like a pretty interesting truck.
Nov 19, 2017, 07:41 PM
Registered User
Chassis looks good
Nov 19, 2017, 11:02 PM
Car Bashing
Jym73's Avatar
Thread OP
Quote:
They sell it as the FTX Mighty Thunder
That's what i say at the beginning of my post

Quote:
Chassis looks good
Yes, that's what i think also.
Nov 20, 2017, 11:00 AM
Registered User
I'd like to see a crawler/scaler based on this vehicle. As a monster truck this thing looks pretty sad, but with a more crawler-based 4 link front suspension and more appropriate tires, it could be a nice budget crawler. Even as is, it seems like it could be a good option. Any RTR usually needs better wheels/tires anyway, and front links would be cheap & easy to deal with.
Nov 24, 2017, 06:35 PM
Registered User
Can u make it quick with a brushless do u think.also there's hop ups already on vrx Web site
Last edited by yamar6; Nov 24, 2017 at 08:41 PM.
Nov 26, 2017, 02:49 AM
Car Bashing
Jym73's Avatar
Thread OP

Speed test + off-road


• VRX - BF-4 - 1/10 4WD Monster Truck - Speed test • (21 min 24 sec)

More info in first post.

Quote:
but with a more crawler-based 4 link front suspension and more appropriate tires, it could be a nice budget crawler.
I agree.


Quote:
Can u make it quick with a brushless do u think.also there's hop ups already on vrx Web site
Quicker with a brushless motor, sure, but surely not as quick as other cars, because of the high gear ratio. It already use the biggest motor pinion we can put. But we can maybe found a smaller spur gear, stock is 60T 0.6M. But with its high gravity center it will be less stable if it goes too fast.

About the hop ups, it share the same solid axle than the Octane XL, same a-arms length, same tie-rods, so some aluminum upgrade are already available for this car. I don't doubt that VRX will provide more aluminum upgrade for this car.
Jan 07, 2018, 07:30 PM
Registered User
Anyone else get this truck it's this or the axial monster truck...Is it worth the money
Last edited by yamar6; Jan 07, 2018 at 07:40 PM.
Jan 08, 2018, 02:01 AM
kiwi power!
jameschen072's Avatar
I actually had a very early prototype of this truck which I‘ve turned into a crawler of sorts... using diff locks and another VRX body shell. Was fun, should get it fixed and running again! It’s actually pretty capable, but would be even better with an Octane-body as that would prevent the problem of the tires rubbing against the wheel arches
Last edited by jameschen072; Jan 08, 2018 at 04:12 AM.
Jan 08, 2018, 07:16 AM
Registered User
Looks good but is it strong enough as a monster truck.would like to put some bigger and wider tires also put a brushless in it
Jan 08, 2018, 09:09 AM
Car Bashing
Jym73's Avatar
Thread OP
Quote:
Looks good but is it strong enough as a monster truck.would like to put some bigger and wider tires also put a brushless in it
There isn't slipper clutch and the center differential is plastic. As a crawler it can be good, as a MT for bashing it won't be as good.

We can surely put a brushless motor, like a 3000kv but with bigger wheels with more traction i'm not sure the drive train will be strong enough for bashing.

Imo an Axial can be better, but not the same price also.
Jan 08, 2018, 11:48 AM
Registered User
Thanks for the info
Jan 10, 2018, 01:35 PM
Registered User
139.00 on banggood looks tempting
Jan 10, 2018, 02:42 PM
Car Bashing
Jym73's Avatar
Thread OP
What do you plan to do with this truck?
Jan 10, 2018, 02:47 PM
Registered User
Make a race monster truck I like that it has a middle diff.but I'm worried that it's not built strong enough for bigger monster tires


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