Mojave Mojave EXB hard to control on grass under heavy acceleration?

[Mooke]

Hi there!

I've had a Mojave EXB for approx 3 months but I've recently has an issue with it veering off under "heavy" acceleration (most noticeable on grass).

The vehicle is for the most part stock, albeit I've changed the suspension geometry a bit, LSD centre diff to a 46t gear differential (wanted more gearing adjustment without a new mount), 60wt shock oil all around, and a slight preload adjustment. Also installed a RW Centre Diff mount and am running 150k centre diff oil.

Electronics wise I'm using a HW Max6 1650kv system w/ 2x 3s packs and a PowerHD WH-30KG servo (@7.4v) and an Absima CR6P (rebranded flysky gt5). Out the box with this electronics setup it was perfect, but now it's just a handful.

I initially thought the culprit was geometry, I don't have any pictures right now and it looks all good. I really want to get some pics up asap.

Earlier I changed the centre diff to the LSD, touched up the geometry (I messed up by applying positive camber on the rear accidentally, learnt not to use carpet as a test platform ;D) and examined the vehicle for any damage. Unfortunately the issue still persists where it veers off and fishtails hitting angles of approx 20-40 degrees, eventually spinning out if I don't correct the steering manually. All whilst occasionally lifting up onto 2 wheels...

I've not checked the front of rear diffs yet, however they don't scream damaged to me, but I really need to crack em open but ngl I've been putting it off lol. When the vehicle is powered on, I spun it up to 100% and all the wheels stopped at the same time and sound healthy when physically testing them, so idk tbf. Also no sign of damage to the tires, they're still all glued on well after about 10 packs.

In no particular order, my guess is (until I get some pics and vids up) are rear diff, correcting the rear positive camber mistake I made or the shock oil change I did. Or the servo saver... Or front slop... However if there is something I've not mentioned that you think is worth checking, please let me know, it'll be greatly appreciated as I'm still scratching my head over this.

Cheers

p.s if anyone could provide the stock turnbuckle lengths measured with a caliper that'd be awesome and greatly appreciated!

 

[SrC]

Did your driving issue start after or before you made all those changes. Seems like you made so many changes that you are chasing a ghost now, not sure which adjustment is the problem. Check your rear diff. First of all Grass is slippery to begin with. I left my Mojave shocks all stock. I feel it works best. I have never considered touching the stock Mojave suspension. Doesn't need it IMHO. To me it is perfect out the box. Just me. 550CST is the stock shock oil per the manual.
I run a V1 RTR Mojo. (Same dimensions).
The rig is top heavy also, FWIW (heavy Body).

My Rear Camber Links measure 35mm at the turnbuckle between the plastic ends.
37mm for the front steering turnbuckle . Measured the same.

I think your problem is the rear diff if it wont run straight under Thr.
You say you have an EXB Mojo, yet you changed the Center diff to LSD???
Stock EXB Mojo already is LSD at the center diff, out the box.
What exactly did you do? Not sure.
I run 60kFR/500kcenter/ 30k Rear. But I run the 3 standard NON LSD diffs. FWIW.
LSD diffs don't need to be much thicker over stock CST. You can adjust the LSD Staging to dial them also.

 

[jondilly1974]

Check all diffs, driveshafts (bent?), and bearings. Also check your from pivot balls and see if there is any binding there or anywhere else in the steering.

My guess is an empty/open diff in the rear.

 

[Megafandrew]

Check the bearings I had two sieze on the left hub and the truck was working against the friction. Ended up ruining the hub from one run on 6S like that

 

[Lynny]

Check the bearings I had two sieze on the left hub and the truck was working against the friction. Ended up ruining the hub from one run on 6S like

Hi there!

I've had a Mojave EXB for approx 3 months but I've recently has an issue with it veering off under "heavy" acceleration (most noticeable on grass).

The vehicle is for the most part stock, albeit I've changed the suspension geometry a bit, LSD centre diff to a 46t gear differential (wanted more gearing adjustment without a new mount), 60wt shock oil all around, and a slight preload adjustment. Also installed a RW Centre Diff mount and am running 150k centre diff oil.

Electronics wise I'm using a HW Max6 1650kv system w/ 2x 3s packs and a PowerHD WH-30KG servo (@7.4v) and an Absima CR6P (rebranded flysky gt5). Out the box with this electronics setup it was perfect, but now it's just a handful.

I initially thought the culprit was geometry, I don't have any pictures right now and it looks all good. I really want to get some pics up asap.

Earlier I changed the centre diff to the LSD, touched up the geometry (I messed up by applying positive camber on the rear accidentally, learnt not to use carpet as a test platform ;D) and examined the vehicle for any damage. Unfortunately the issue still persists where it veers off and fishtails hitting angles of approx 20-40 degrees, eventually spinning out if I don't correct the steering manually. All whilst occasionally lifting up onto 2 wheels...

I've not checked the front of rear diffs yet, however they don't scream damaged to me, but I really need to crack em open but ngl I've been putting it off lol. When the vehicle is powered on, I spun it up to 100% and all the wheels stopped at the same time and sound healthy when physically testing them, so idk tbf. Also no sign of damage to the tires, they're still all glued on well after about 10 packs.

In no particular order, my guess is (until I get some pics and vids up) are rear diff, correcting the rear positive camber mistake I made or the shock oil change I did. Or the servo saver... Or front slop... However if there is something I've not mentioned that you think is worth checking, please let me know, it'll be greatly appreciated as I'm still scratching my head over this.

Cheers

p.s if anyone could provide the stock turnbuckle lengths measured with a caliper that'd be awesome and greatly appreciated!

Possibly a broken diff outdrive pin I’ve broke a few in the exb diffs and it would pull to one side or the other the 4985 has a lot of power to wear parts out.

 

[Mooke]

Did your driving issue start after or before you made all those changes. Seems like you made so many changes that you are chasing a ghost now, not sure which adjustment is the problem. Check your rear diff. First of all Grass is slippery to begin with. I left my Mojave shocks all stock. I feel it works best. I have never considered touching the stock Mojave suspension. Doesn't need it IMHO. To me it is perfect out the box. Just me. 550CST is the stock shock oil per the manual.
I run a V1 RTR Mojo. (Same dimensions).
The rig is top heavy also, FWIW (heavy Body).

My Rear Camber Links measure 35mm at the turnbuckle between the plastic ends.
37mm for the front steering turnbuckle . Measured the same.

I think your problem is the rear diff if it wont run straight under Thr.
You say you have an EXB Mojo, yet you changed the Center diff to LSD???
Stock EXB Mojo already is LSD at the center diff, out the box.
What exactly did you do? Not sure.
I run 60kFR/500kcenter/ 30k Rear. But I run the 3 standard NON LSD diffs. FWIW.
LSD diffs don't need to be much thicker over stock CST. You can adjust the LSD Staging to dial them also.

What I meant is I changed the LSD to a gear diff back to the LSD to make sure it wasn't a sloppy diff build causing issues. But after what you said I'm just going to keep it LSD

Thank you ever so much for the link lengths, going to dial it back to factory just to be sure!

To everyone else, will check for the possibly damaged parts mentioned tonight and order some fluids tomorrow and open that rear diff. Rebuild my shocks whilst I'm at it, feel I did a sloppy job anyway (different rebound rates and effort levels put into each shock)

Tyvm will get back soon with how I got on

 

[Mooke]

Haha, this is just my luck at the moment...

Good news, first thing I checked to find damage was the front bearings in general.

I discovered the front left bearing was seized, makes sense as that's the direction the car steers off under heavy acceleration (goes straight when I adjust the trim and go slow), however in the process of taking the 2.5mm grub screw in the hex out, I was dumb and one thing lead to another and I stripped it... Used heat but got hasty and didn't use enough heat, not to mention I used power tools... Star shaped torx bit, vice, hammer and heat gun, anyone? MIP tools are great but they don't solve user error...

That sudden feeling in your gut when you strip a screw, is that something only I get? Guess who played stupid games and won stupid prizes D:

 

[Lynny]

Haha, this is just my luck at the moment...

Good news, first thing I checked to find damage was the front bearings in general.

I discovered the front left bearing was seized, makes sense as that's the direction the car steers off under heavy acceleration (goes straight when I adjust the trim and go slow), however in the process of taking the 2.5mm grub screw in the hex out, I was dumb and one thing lead to another and I stripped it... Used heat but got hasty and didn't use enough heat, not to mention I used power tools... Star shaped torx bit, vice, hammer and heat gun, anyone? MIP tools are great but they don't solve user error...

That sudden feeling in your gut when you strip a screw, is that something only I get? Guess who played stupid games and won stupid prizes D:

Sucks it stripped but at least you’re getting somewhere with the problem having.

 

[Mooke]

£8.99 soldering iron and a 2.5mm MIP ballend won this round.

 

[Mooke]

Continuing on, just wrapped up tonight's wrenching session (it's 4am for me as of writing this, evening work/jobs suck). Noticing wear on the diff outdrives in the rear atleast (didn't check the front), slight indent on them from the dogbone pin, so will order some spares to avoid any future downtime.

The rear diff wasn't dry but needed a top up, only got 15k on hand at the moment so it'll have to do. Thanks to @SrC I got the suspension dialled back to normal geometry wise aswell.

As mentioned the front left was super gritty so I've gone ahead and swapped both the bearings in the left hub as I already had a set on hand, so that's all sorted now.

Can't drive until Saturday at the earliest so may check my shock build prior to then aswell but sort of want to ensure it was the bearing gone bad before making further changes.

Cheers!

 

[SrC]

Seems like you got things sorted out.
Yeah its always good to test one change at a time. Been there. I had made too many major changes to one of my older rigs that sat for years and then I noticed it was all wonky. I was chasing a ghost trying figure it out. Couldn't put my finger on it. One by one I just undid many changes. It was the stiffer springs that was the problem. Not obvious at first. It was an old TC3 carpet car that ran fairly fine as is . Just rebuilt with too many changes. Live and learn.

 

[Mooke]

Hi everyone,

Quick update, just ran a 7100 and 5000 mah battery down to storage voltage over like a 2 hour hike in my area, found an awesome location that if the paths were wider, it would be ideal for the big scale stuff, almost like the dream RC driving road... I didn't take any images but it's a former archeological site with these perfect, crisp, loose, dusty small gravel paths that zig zag down a plains / downs area. I live a 20 minute walk from it and didn't know it existed, must be pretty new.

Knowing it exists, can't wait for the warmer weather a few sets of batteries!

Not forgetting to mention it drives like a dream again, thanks everyone!!