Robitronics Mantis diff issues
 

So I had some issues with my stock rear diffs... I was running 3k in them, but the bevels let loose on me... so I changed them up with Savage bevels.

The Savage bevel were a bit more cones shaped, but fit nicely. I gave it a good weekend and they stayed in tact. 2 weekends ago I think they let loose again... I opened them up and all looked good, so I checked the center diff to make sure... nothing. Well the truck just isn't running right again. Seems like it is FWD only. I will be opening it up tomorrow to find out more though...

Is anyone having the same issues?

Is anyone using anything different in their diffs?

RE: Robitronics Mantis diff issues
 

You bought a mantis now? What happened to the hyper ST?

Are the ring and pinion gears the same tooth count between the savage and mantis?

What actually went bad with the mantis setup, the ring and pinion or the bevel gears inside the diff cup?

RE: Robitronics Mantis diff issues
 

Hey Bud... sorry I missed you this year back home, but the NH trip got cut short. We are planning a trip back same time next year. We know what to expect now, so we will definitely hook up for sure... I sent you an e-mail while I was in NH, but never got any reply...

Anyway... I still have the Hyper and man I love that thing. I traded my Savage for the Mantis looking for a backup trugg. If I didn't do something with it would have ended up sitting on my shelves all sad an what not. Kinda like you said it would LMAO!!!

The Savage bevels were a perfect match just a little more coned than the Mantis stockers. I still have to open up the diff case again to see if there is any damage. I am using 3K in the rear. When I pick up the front I can feel it pushing, not hard or anything, but when I try to run it feels like FWD only... 2 weekends in a row now.

When I did open it up last week... nothing was wrong. No excessive where or anything that looked like the diff's were smoked. Maybe there is an issue with the cone length. I'll know more when I open it up this week.

RE: Robitronics Mantis diff issues
 

Diff fluid weight has a big impact on how its going to handle, what weight do you have up front? Is it really only working FWD or can you see the rears pushing also? If its pushing (front wheels sliding opposite the way you are turning) it means either you need to lighten up the front diff oil, or go thicker in the center. What weights are you running all throughout the truck?


I got the email man, you know me though, a lazy *******. I'll definitely catch up with you soon though.

RE: Robitronics Mantis diff issues
 

Hey bcane, you know everytime I see something about a mantis i'm always intregued because my friend bought one. It's amazing that almost everyone has the steering servo issue where the servo saver is too tight and ruins servo's. And now, the rear diff. I just replaced the rear gears with savage gears and has been working well for him. I'm wondering if robitronics has word of these common problems. I heard that HPI has there hands in robitronics. Sort of subsidiary of HPI if you will. Anyway, just thought i'd let you know you're not the only one out there. :)

RE: Robitronics Mantis diff issues
 

claudacio...
Well... the guy I got it from put 7k/10k/3k in it, but I can't say for sure. I checked the rear/center and they were filled with something (not sure though). I did however put 3K in the rear when I rebuilt it last weekend. I need to refill the center diff though... I am running 7k/10k/7k in my Hyper... the rear was a mistake, but for the (BYB) track we are running it works out pretty good. It pushes a little in the corner, but that's probably cause I put the 7k in the rear. The next rebuild I will probably drop it down to 5k...

As for the feeling... It felt like it was running only FWD at the end of our day. It was making that sound like a thrashing diff... but I have not opened it up yet. It's getting late now, so I guess opening it up will pushed off until tomorrow. The front wheels were turning no problems...

GNX5T...
I know Axial has something to do with Robitronics... not sure about the HPI thing though, but it seems HPI is trying to put their hands in everyone cookie jar. Not that I am upset or anything as I am fan of HPI products:D

I haven't had any issues with the steering as I replaced my servo with a Hitec 5645MG... I will have to check servo saver though to see how tight it really is.

RE: Robitronics Mantis diff issues
 

My Robitronics is the same way. I just replaced all of the gears in the front with new Robitronics ones and put 7000 1000 1000 to try and calm the front down a little. It didn't work. The truggy seems like it's FWD as well.

Axial is pretty much an HPI engine, by the way.. ;)
This truck is pretty much a HellFire in my opinion. Nice as a second truck for bashing and whatnot.

RE: Robitronics Mantis diff issues
 

Try going up in weight in the center and rear diffs, also you may want to drop down to 5k in the front also. Thats a kind of funky setup where all the power is mostly getting pushed through the front wheels, and with the 7k in the front its going to push when you try to turn on power. The 7k may be fine in the front but running 1k in the center is more than likely whats causing it to handle like that.

Try 5 or 7/10/3 (F/C/R) or 5/7/3 if you want it to be easier to drive with less power going to the rear wheels.