Mojave Mojave Max6 scratchy

[RC-Dude]

Got a Mojave EXB with a Max6 1650kv and Hobbywing ESC. It's really scratchy when going slow. Like nearly impossible to do a slow crawl drive. Checked the whole drive train, opened all diffs. Checked all bearings and bearings on motor. All in good condition. Running a 20T pinion. The other Mojave (not EXB) with the same Motor & ESC does not have that problem.

As soon as I give more throttle it is fine. But it uses more battery than the normal stock Mojave.

Wondering if I could get a change by going to a 18T pinion. On another ESC I would try and change timing but the MAX6 Esc seems to not have that option.

Any ideas?

Before I install a MAX6 Motor for a test from another car. It's like the 4985 MAX6 motor has a bit more resistance than normal. Not sure why.

 

[Senton_Prime]

You check the motor bearing/bearings!?

 

[Jimbobjr]

Perhaps there’s a little more resistance in the exb because of the lsd diffs used in it. Maybe swop out the center diff and see if the problem goes away.
Another thing maybe to check is pull the motor apart and see if it’s pack with dust. Mine get very dirty and had one lock up once.

 

[Hammer Down]

The 4985 1650kv is a bigger motor than stock with larger magnets.. Sounds like what your describing is “cogging”
To achieve a slow crawl without “cogging” you’d need a sensored motor and esc.

 

[Engineer]

ESC settings the same? I suppose the quickest and most definitive test is to swap motors and see if the issues follow the motor.

 

[Jimbobjr]

The 4985 1650kv is a bigger motor than stock with larger magnets.. Sounds like what your describing is “cogging”
To achieve a slow crawl without “cogging” you’d need a sensored motor and esc.

I think he has the hwmaxx6 in both. One has the issue and the other doesn’t. At least that’s how I’m reading it.

 

[Hammer Down]

I think he has the hwmaxx6 in both. One has the issue and the other doesn’t. At least that’s how I’m reading it.

Ah, ok I misread that.

 

[RC-Dude]

Thanks for the feedback.

The diffs are not the problem. When the motor is not connected there is little resistance. Resistance is significantly more when pinion and spur are connected.
Had taken the motor apart to check for dirt. That was no problem as I always seal the open threads. Bearings are fine. There is the possibility that I inserted some plate, bushing in the wrong order. Had asked about this in another tread about the 4985 Hobbywing. Not sure where something might have gone wrong.

Basicially it's heavy cogging. Quite some resistance if I push the Mojave without any lipo connected. Heavy cogging in a motor that seems to be assembled in the right order. Not much to do wrong there. Can't pinpoint it yet...

Guess I need to open the motor again and see what I can find...

Not sure what I am missing. It's simply coggy.

 

[RC-Dude]

Update: I exchanged this 4985 Max6 1650kv motor in the same Mojave EXB rig for another 4985 Max6 1650kv. Same problem. Also very coggy. That rules out that this motor is the problem. Will have to look at ESC, punch and gearing instead.

 

[Cypher]

Update: I exchanged this 4985 Max6 1650kv motor in the same Mojave EXB rig for another 4985 Max6 1650kv. Same problem. Also very coggy. That rules out that this motor is the problem. Will have to look at ESC, punch and gearing instead.

Have you figured this out? I'm kinda nervous about mine now, I'm currently installing the Max6 with HW 4985 motor and 18T pinion in a new Mojave EXB. Hope if i run into the same problems, you already figured this out

 

[RC-Dude]

• Certainly not the motor. Exactly the same cogging with another Max6 4985 1650KV.
• Have to check all the diff and wheel bearings on the Mojave. Actually serviced the whole rig a few weeks back. Opened all diffs, refilled oil, checked bearings etc.
• I the problem is not gone I will change the punch from 5 to 4 on the MAX6. But I don't really expect anything there.
• I still there I will take a MAX6 from another rig and check.
• Then do software update.
• Then cry if nothing works.

Hobbywing Max6 is one of the most reliable setups there is for 6s.

 

[TL01magic]

check rear "dog bone" drive shaft, both ends for binding from wear.

on mine, with worn rear drive shaft cups at rear diff and center diff it can bind up if not it the grooves caused from wear.

it is often low speed wear the shaft can move out from the seated position caused from wear, but at high speed it settles into the right spot.

perhaps that's issue, if not my next would be isolated front end / rear end as being cause (by removing respective drive shaft)

 

[RC-Dude]

check rear "dog bone" drive shaft, both ends for binding from wear.

on mine, with worn rear drive shaft cups at rear diff and center diff it can bind up if not it the grooves caused from wear.

it is often low speed wear the shaft can move out from the seated position caused from wear, but at high speed it settles into the right spot.

perhaps that's issue, if not my next would be isolated front end / rear end as being cause (by removing respective drive shaft)

Thanks for that info! I will have a closer look at the shaft and cup.

 

[RC-Dude]

Checked the rear and front separatly. Both tight when rolling the Mojave. Kind of weird. Bearings are good. Mesh looks Ok - then it looks tight. Set the mesh new and the problem there again. Like I am not able to set the mesh anymore.

Keep setting the mesh wondering what's wrong. I set the mesh and it's OK. Turn the spur half a turn and it's tight again. Get my son to check while I am turning. Using a torch and checking again and again. Sees what I see. Turns out the spur is not centered on the casing. On the right you see there is a bit more distance. Not much but enough to mess with the mesh every half turn.

At least good to know what the problem was. Had already given up on that Hobbywing 4985. Obviously when screwing the spur to the casing that difference is so little that the plastic casing bends a bit. Screws in and all looks fine.

 

[TL01magic]

Good job pinning down the issue.

My spur is same, but difference / offset small enough to spoil meshing.

feel bad for missing that as suggestion lol

 

[RC-Dude]

@TL01magic - your post was actually helpful. Tested the center diff only connected to front then to rear with the same result. Drive cups in center diff started turning even though I have 300k oil in it. That then eliminated the front or rear diff setup as the souce.

The spur in the picture is a lot bigger than the real size. So it looks a bit worse in the picture. Now that I know the problem I can adjust the mesh on the tight side so there is a tiny bit of play. Half a turn further there is pretty much play. Should be fine.

So thanks to everybody!

 

[TL01magic]

Yay!

I've never wore out a mod1 pinion before so not too sure how far they wear before failing.

below is pinion from my mojave, the pinion has prob 30 runs on it.

Am not sure what broke the tooth, but wouldn't be surprised that as the pinion wore down the mesh at the most loose part got even more loose and to the point that the angle of tooth engagement there was cutting into the pinion tooth and eventually broke it off.

Must of happened on last two runs, thought it sounded terrible...but checked nothing was binding and just kept ripping lol....it only sounded bad when going slow...so the temp fix was...to go fast


I guess my point is maybe consider replacing spur with a centered one / it may shorten long term life of pinion from uneven wear / tooth engagement.

That said, for the runs I got out of the pinion that failed, am not going to replace my non-centered spur.

 

[RC-Dude]

Check the spur if it is fine. If it is fine - keep it. It has more than double the number of teeth and therefore more than twice as long a lifespan. One turn of your pinion is less than half a turn of spur.

 

[TL01magic]

Check the spur if it is fine. If it is fine - keep it. It has more than double the number of teeth and therefore more than twice as long a lifespan. One turn of your pinion is less than half a turn of spur.

I did give it a look over, it's less then half as worn as the pinion and no damaged teeth...

but I think is a good idea for me to replace it. It definitely is not "mod1" shaped teeth anymore lol, noticeably sharper...

Maybe it would quickly wear out a new pinion, actually probably would