Strange drivetrain issue???? MLST

[sg219]

I usually try to figure stuff out by trial and error, but this issue got me stumped.

My MLST has been chillin' for a month or so now because of a drivetrain issue.

The problem is...

I can hold it in my hand and will run, then when I let go of the throttle, the front will die real quick. As if it was only getting minimal power.

Tonight I broke it down.

I found that the screw that goes thru the MIP diff snapped.

I had a rebuild kit on hand, so I rebuilt it.

I tested it and the same thing still happened. The front died real quick. I can hold it in my hands, and it will run like the wind, but as soon as I put it down, it creeps. No power?

I ripped the front diff apart. No issues there. The rear apart. Nothing there.

I'm lost. It just won't get power on the ground. It seems that its mainly the front.

What am I missing?

Rebuilt center ball diff.
Checked front and rear for any issues, and found none.

Somethings not cathing onto something to produce power.

[betty.k]

maybe the hubs are the problem? does tightening the wheels cause binding?

[payaso]

That's weird dude. Any chance you can get it on vid for us. I'd like to see/hear it.

I'm assuming you've tried different batts and shit. Checked all out drives, and grub screws?

Is the new rebuilt center ball diff too loose?




silla

[crazydave]

I dunno, that is odd, the way you describe it. If it ran off the ground, but creeped when you put it down, I would assume its the electronics. That sounds like what a car does with a dead battery, which would mean it wasn't getting juice for some reason.

...but then you say its mostly the front which makes it confusing because that would mean its mechanical rather than electrical.

Have you checked the front diff? Have you made sure the pinion that spins the front diff isn't spinning on the screw? I've been studying these guys that are stripping their diffs, I have a theory that they may be tweaking their bulkheads in crashes. Since the suspensions arms are attached to the bulkhead, and when you crash most of the energy is more than likely being transfered to the bulkhead. Have you taken any hard knocks to the front end lately? Did you take it apart make sure the diff spins freely in the bulkhead? How's your drive shafts and drive cups holding up? Check out mine after less than 10 runs.


So yeah, I don't know, but hopefully I gave you enough fuel for thought to help out.

[sg219]

Tightening the wheels down, doesn't seem to have an effect.

I checked all 3 of the diffs so many times....

The motor is putting out the power, it just doesn't make it to the wheels.

I thought I had the center diff tight enough, maybe even too tight, but maybe its still not tight enough. I wish I had a locker spool for it.

The electronics work fine, Spektrum RX and a Mamba ESC thats fresh from a factory inspection about a month ago.

I Will have to check to see if the front pinion, might be spinning.


I'll try and get some vid of it acting up, it might be a day or two. (I think I'm getting dragged into going camping for a couple of days. )


Thanks for the ideas.... time for another close inspection......

[crazydave]

I thought I had the center diff tight enough, maybe even too tight, but maybe its still not tight enough. I wish I had a locker spool for it.

Hold the two outdrives between your thumb and index finger. With your other hand try to force the gear to spin. It should only slip a little, and require quite a bit of force. The diff action should be a bit stiff, ball diffs aren't meant to be free spinning, and out of the car the stiffness will seem exagerrated.

The more think about tit, the more I'm sure the ball diff must be the problem, since you did just rebuild it, and you said it was working fine before.

[skylinekid]

I would check the wheel hubs and the small pins that are between the wheel hubs and the go through the axle, if only one of them is missing, thats your problem!!! (happened to me ) I would also check the pin by the spur gear and its axle-type-thing. Good luck finding the problem!!!