Mojave Center Diff disintegrate

[Marski69]

Got 2 Mojave's 1 for my daughter 1 for me
What i've bought/got/done already:
- 2 x 3S Bashing Lipo for 6S total.
- 1 x 4S HV Lipo for use single
- 1 x Rocket-Rc 25Mm for Esc
- 1 x Rocket-Rc 30Mm for motor
- 1 x Metal Servo Arm
- 1 x 25Kg metal servo (first day driving mine broke with no real crash)
- 1 x Dustcover (U need one driving in grass and sea sand and it works)
- 1 x 4 proline dumont paddletires (i like them

Whats on its way:
- Metal steering rack with servo saver (so i can by a better servo without reggrets)
- Metal Servo bracket
- Metal steering hubs back and front
- New center diff because it disintegrated
- Front and back metal diff cases
- Bearing set

Things thats still cross my mind:
- Reinforced centre Drive Shaft
- Hard Steel Differential Outdrive cups
- Front and rear chassis brace

The center diff disintegrate today at driving on the beach.
With 4S HV it worked fine en the car is handeling al that power very good.
With 5 minutes on 6S on the beach with paddletires the centre diff just exploded.
This was no surprise I already thought this would happen
I also knew immediately what was going on.

All in all, I think I have already driven quite a bit broken on 6S, which my daughter with 4S HV does not have.
The car can run on 6S, but actually the drivetrain and other important drive parts such as bearings
are not suitable for so much power "on the longer term" and it is a postponement of execution.
4S HV against that is very suitable for the car, I have noticed.
Would you by a new car, i would first advise 4S HV out-of-the-box and first perform some upgrades to switch to 6S.
If you drive quietly on 6S, it will not matter much, but if you really want to keep the gas on,
you have a short driving time with 6S. Even though it is said that the Mojave is a tank.
It's a great car but on 6S you will soon run into limitations that need to be upgraded.

I will place a Pic of 1 of the Mojaves for the Fan config:

My intention was to use 2 fans with not too much Amp en feed them from the ESC without the need of a external battery.
Very cheap fans from aliexpress and some fan covers from https://shop.alza-racing.com/en/ is the result.
I sawed the filter on the ESC from a metal fan grill from a PC.
I can drive this without any problem in grass, sand, and other loose soil that would normally fill your entire Mojave and cause the fan to jam...
The extra fan cover on the motor is there because I was afraid my dust cover wouldn't prevent my fan from getting fresh air.
That also works

 

[Moirae]

Very awesome your daughter and you both got a mojave! must be a lot of fun. Interesting take on the drivetrain though, I even run 8s sometimes in my mojave with zero problems and have never had a problem with any of the diffs. It has the exb diffs and I did put 500k in the center so maybe that helps?

Welcome to the forums!

 

[hobo]

Got 2 Mojave's 1 for my daughter 1 for me
What i've bought/got/done already:
- 2 x 3S Bashing Lipo for 6S total.
- 1 x 4S HV Lipo for use single
- 1 x Rocket-Rc 25Mm for Esc
- 1 x Rocket-Rc 30Mm for motor
- 1 x Metal Servo Arm
- 1 x 25Kg metal servo (first day driving mine broke with no real crash)
- 1 x Dustcover (U need one driving in grass and sea sand and it works)
- 1 x 4 proline dumont paddletires (i like them

Whats on its way:
- Metal steering rack with servo saver (so i can by a better servo without reggrets)
- Metal Servo bracket
- Metal steering hubs back and front
- New center diff because it disintegrated
- Front and back metal diff cases
- Bearing set

Things thats still cross my mind:
- Reinforced centre Drive Shaft
- Hard Steel Differential Outdrive cups
- Front and rear chassis brace

The center diff disintegrate today at driving on the beach.
With 4S HV it worked fine en the car is handeling al that power very good.
With 5 minutes on 6S on the beach with paddletires the centre diff just exploded.
This was no surprise I already thought this would happen
I also knew immediately what was going on.

All in all, I think I have already driven quite a bit broken on 6S, which my daughter with 4S HV does not have.
The car can run on 6S, but actually the drivetrain and other important drive parts such as bearings
are not suitable for so much power "on the longer term" and it is a postponement of execution.
4S HV against that is very suitable for the car, I have noticed.
Would you by a new car, i would first advise 4S HV out-of-the-box and first perform some upgrades to switch to 6S.
If you drive quietly on 6S, it will not matter much, but if you really want to keep the gas on,
you have a short driving time with 6S. Even though it is said that the Mojave is a tank.
It's a great car but on 6S you will soon run into limitations that need to be upgraded.

I will place a Pic of 1 of the Mojaves for the Fan config:

View attachment 307645

My intention was to use 2 fans with not too much Amp en feed them from the ESC without the need of a external battery.
Very cheap fans from aliexpress and some fan covers from https://shop.alza-racing.com/en/ is the result.
I sawed the filter on the ESC from a metal fan grill from a PC.
I can drive this without any problem in grass, sand, and other loose soil that would normally fill your entire Mojave and cause the fan to jam...
The extra fan cover on the motor is there because I was afraid my dust cover wouldn't prevent my fan from getting fresh air.
That also works

6s is a lot of power if your full throttle all the time nothing will last long I only really use full throttle when taking of from a jump

 

[Camaroboy383]

I'm sure the center melted, definitely no surprise if you ran paddles on the factory fluid.. (or lack there of).. rear traction transferred all that power to the front.. definitely up your center diff fluid to 500k or higher...

 

[Jon NC RC]

Good choice for a rig..... EXCELLENT to have the young one involved!!

I had taken my Senton and Mojave to St Augustine for a romp on the sand...... I decided against it personally due to the additional cleanup and the deterioration that sand/salt water introduces. Paddles would put extra stress on the drivetrain/diffs. don't get me wrong....I am NOT bashing you for doing such....it was fun while it lasted. I did run one of my cheap China made rigs.... the salt and sand was NOT kind to it....

If you had already serviced the diffs (opened, cleaned, filled with better wt fluids), then that eliminates the potential that you got a rig that had too little diff fluid to begin with from factory. I was surprised how little mine had when I opened it.... glad I didn't wait any longer to service mine soon after I got it...

I have only ran 6S, it handles it quite well. I never tried 8S like @Moirae.... I have not been kind to it... the drivetrain has not been a problem...I HAVE shredded factory tires....otherwise the thing has taken a really good beating and hasn't let me down.

I went with the Scorched fenders for me to reduce debris buildup....they work.... the dust cover would work well for the sand, but you are wise to do the fans for the heat....a few guys have added some holes in the body to get a little extra air flow (a few small holes can help )

Its obvious you enjoy this hobby, I appreciate you haven't fallen in the trap of buying the most expensive bling available..... While this isn't a 'cheap' hobby, some of the cost can be controlled and still have fun.

When I changed the diff weights (yeah, I have 500k center) ... it really helped overall....

 

[Marski69]

thanks for the diff fluid advice!
Default is 10/100/10.
What I read on the forum I now prefer 60/500/30
But 500 in the center diff also means that it will be hotter which I understand.
So even hotter than the standard 10/100/100 that already exploded
Anyway, the aluminum diff cases can also handle the heat better I think.

 

[SirCrashALot]

Welcome.
Your story sounds like mine.
My oldest daughter loves driving these cars with me. I had one Mojave for about a year and decided to build a second one. You are right. 6S is too much. After a year and a half, i have shredded multiple front diffs. The screws come undone and the diff spur rips the pinion. Also all input and output cups and all driveshafts need replacement. Cups and pins completely worn.
4S is plenty in rough terrain and already borderline uncontrollable. I run bigger motors because of overheating the stock ones. The 4985 HW motors are plenty powerful on 4S. I Have no heat issues and can run them pack after pack. Speed is about 65 kmh. I'm planning to stick to big 4S packs. I am now removing all plastic drive train parts and replacing them with aluminium, as far as i haven't sofar. Meaning all diff cups, front and rear diff housings and center diff supports and top braces

 

[Marski69]

Today ready for the beach with:
2 Mojaves with paddle tires

First time drive with:
- Metal steering rack with servo saver (I like this upgrade steering is much more accurate)
- Metal Servo bracket
- Metal steering hubs back and front (actually should have done this right when i got the cars, i got them from aliexpress and they work great)
- New center diff because it disintegrated (There was 300K standard in the new Diff and I had bought 500K to do this in the center diff, but I decided to leave the 300K for the test and it drives really well with 300K)
- Front and back metal diff cases (Because only the cups are not expensive on AliExpress, but also done right before things exploded again due to a crack in the plastic diff cup / heat)
- Bearing set (wherever I happen to come across bearings during assembly, I replace them)
- All shock absorbers replace the oil with 700k (you wouldn't say it, but this does make a difference)

Experience today:

Great driving with 4S HV 17.4V Graphene lipo.
The entire battery of 9000Mah ran empty with I think 45/60 minutes of driving time.
In short, fun to drive and the car can handle that very well.
When I started driving the 6S when it was empty, it was over after 5 minutes and the rear main Input Gear 10T Spiral gave up.
Although quite on the gas in beach sand with paddle tires.
Wheelies on the beach hahaha I didn't see that coming.
Again, 5 minutes of fun with 6S.
I think at the beach I need to go down a notch with my pinion Gear to go home with empty batteries.
It is a pity that 5S is not an option because (my experience) I think the limit is what the car can handle
If you do not want to repair more than drive, of course.

I think I should also replace the rear and front Chassis Brace with aluminum ones because the plastic
versions provide flex during a roll that the drive train doesn't want I think.
And as soon as I've done that I break something else which is the weakest link...


Update:

I'm just a stupid fck and forgot to secure the screws with loctite.
All 4 screws were loose...
All gears seem to be ok.
So far the car is holding up well after all the upgrades and good advice from the forum.
Thank you very much for that!
Notting broken, tomorrow back to the beach.

 

[SirCrashALot]

I completely missed your remark about the center diff heating up with thicker fluid.
I don't know where you get that from, but it's a misconception.
The heat comes from ' diffing out', meaning: when during acceleration the rear wheels can't handle more power, the center diff bleeds the extra power to the front wheels and they will spin much faster than the rears.
Thicker fluids result in a stiffer diff, so the bleeding of power to the front (rpm difference between front and rear) will be less or almost gone. Meaning: no high rpm's in the center diff's internals, less heat, no more melting diffs.