Senton Senton Mega 4x4 : Melted Slipper Nut !

[Curvin]

Hey All,

I did post this on my build adventure thread , but thought I'd post this up seperately.

I have recently replaced a Spur Gear and I used the new spare nut supplied with the truck on the rebuild. This is what has eventuated after less than a battery pack over 2 runs ( both times truck broke , first time axle after 5 minutes, 2nd run chewed another servo. I have obviously screwed the reassembly somewhere, but I am at a loss at what point or what could possibly cause the spring to get that heated ?

Any and all ideas and suggestions will be appreciated.

 

[Curvin]

Heres the snaps of the slipper assembly in the stages of disassembly.

Apart from the obvious wear on the slipper pad/plate , is there anything that jumps out that I have done wrong in the assembly ?

The Slipper nut was tightened all the way and backed off 1/2 turn of the wheel, which I believed was the consensus So it surprises me it was slipping that much indicated by the damage to pad/plate.

Would that cause the level of heat into the spring to melt the nut and loosen it even more ?

Either way, a plastic nut on a slipper clutch adjustment was always going to be 1/2 arsed.

Any tips, advise, ideas on what has caused it, and/or if I have screwed up the actually order of the assembled parts , that contributed to the carnage ?

 

[Jerry-rigged]

Nothing jumps out at me. Seems odd to me too. Seems like the heat path is slipper pad --> yoke --> Shaft --> spring, but in that case, seems like the shaft would melt the threads off the nut before the spring could get hot enough to do damage? IDK,...

 

[Cheapbastard]

Thanks for all the plastic in the drive train even on a slipper nut Arrma

But seriously for one I might think about changing the bearing on the shaft (could be a problem friction?) and maybe fancy up a washer that might fit between the plastic nut and slipper spring if anything to spread the load on the plastic nut for better contact to compress the spring. Plastic compressing metal good idea right (not)

IDK maybe heat like using aluminum parts finds the next weakest part and takes the impact (in this case heat). As far as how the heat is being generated to melt the nut IDK.

 

[bicketybam]

I really don't think you need a metal nut. I've been able to crank down the plastic one so tightly that it busted the slipper hub.

I've never seen a melted nut but by the looks of the pad and the hub, at some point it was slipping badly. I admit I tighten mine very tight but I am not running the stock spur or differentials. But even on the stock spur, if it slipped upon acceleration I would tighten it. I only wanted it to slip if I landed a bad jump.

 

[TooTall]

What motor are you running? What batt? It looks like an orange colored can with a heatsink and/or fan on it as well.

Could you be running too much power and slipping the slipper a lot, thus building heat down the shaft?

 

[Curvin]

Thanks all,

Yeh I am scratching my head how I generated that much heat , the slipper does look likes it been slipping at some point, but how it heated the spring is the question. I was thinking maybe the nut is screwed on back to front as it does have different surfaces, but I really can't see that being the problem to generate heat ?

I'll swap the bearings as suggested, flip the pad over and do my best dressing the hub plate surface, flip nut ( or use the original which is a little chewed but at least not melted ), and pay more attention to the actual tightness of the slipper.

BTW - The supplied schematic from ARRMA for the parts/assembly is useless , check it out, there is no indication of the actual order and I am pretty sure the internal bushing of the Spur gear is pictured backwards.

I was thinking of placing a washer/shim between the spring/plastic.

I'll have a play and see how I go.

@TooTall ,

GoolRC 3900KV Combo on 2S , should be well within range of the components ( apart from the spur as we all know ).

P.S - ARRMA Parts ETA in Australia has now been amended to December 17th , I kid you not, I doubt we will see any pre 2019!

I Digress

 

[bicketybam]

FWIW, I never set the slipper as per the Arrma video. I remove the assembly and tighten it. I tried their way and I didn’t care for it at all.

 

[Curvin]

Well the ARRMA video doesn't really tell you anything past how to tighten/ loosen. There is no reference how much you should tighten or loosen the slipper, i.e, video is useless, LOL.

There is another video I have watched about correctly setting the slipper clutch, generic but was more detailed.

I'll see if I can find it and pop it up.

 

[Curvin]

Here we go.

 

[bicketybam]

Well the ARRMA video doesn't really tell you anything past how to tighten/ loosen. There is no reference how much you should tighten or loosen the slipper, i.e, video is useless, LOL.

There is another video I have watched about correctly setting the slipper clutch, generic but was more detailed.

I'll see if I can find it and pop it up.

AFAIAK there is no "right way" to set up a slipper clutch. It depends on gearing and power. Arrma gives a general guideline but the rest is up to you. You are running an aftermarket ESC and motor. That alone throws any sort of stock setting out the window. To me a slipper clutch is like a servo saver. How much performance do you want to give up for safety? I have all upgraded driveline parts. I don't want the slipper slipping unless I really botch something up. When I hard throttle I want a wheelie and not a slipping clutch. You are in a precarious situation. You've upgraded the power of the truck and not upgraded any of the driveline. You really can't run it as tight as I do without big risk to your spur or diffs. These trucks were designed to run on a brushed motor.

 

[Curvin]

Well the last video does a reasonable job of explaining or at least giving a better guideline.

There is no ARRMA guideline even for stock, that was my point.

You are right that these trucks are designed to run on a brushed motor, barely , so we are simply polishing a turd using stock parts

 

[bicketybam]

Well the last video does a reasonable job of explaining or at least giving a better guideline.

There is no ARRMA guideline even for stock, that was my point.

You are right that these trucks are designed to run on a brushed motor, barely , so we are simply polishing a turd using stock parts

Speak for yourself! Lol. While the Senton might not be my favorite truck, it certainly isn't a turd. Have you seen it backflip off a jump a d wheelie??

 

[Curvin]

Ha, of course I am speaking for myself, we will need to agree to disagree

If I could find the time energy and lack of apathy to wrangle that Dual slipper you hacked into the truck and could actually get some BLX parts, it could polish up O.K, but as it stands, I am polishing a turd

Yes a wheelstanding Senton is impressive, I'd settle for something that lasts a battery pack at this point.

 

[mitch31875]

Hi all, First post, greetings from Finland The slipper nut on my son´s Granite looked exactly the same. In our case there was a stone stuck between the motor and the nut, and my assumption was that the stone had both loosened and teared up the nut.

 

[bicketybam]

Hi all, First post, greetings from Finland The slipper nut on my son´s Granite looked exactly the same. In our case there was a stone stuck between the motor and the nut, and my assumption was that the stone had both loosened and teared up the nut.

Welcome to the forum and thanks for that input ? I never considered that as a possible cause!

 

[Curvin]

@mitch31875,

Thanks for the heads up, I think you may have hit the nail, there was a stone in the vicinity that dropped out after I disassembled, so most likely the exact same cause.

The whole design layout is so vulnerable to stones/debris jamming moving parts , need to try some ideas to minimize it.

I have already slotted the chassis under the spur.

 

[mitch31875]

Agreed. We also have the Senton and it seems to pick up everything. I got the Dusty Motors shroud cover for it and there hasn´t been a problem with dirt after that. I guess I need to order a cover also for the Granite..

 

[ptr1ck]

If you're really cheap, you can use women's knee high hosiery with the toe cut out to cover the chassis. Have to take the front wheels off to get it to go over though. I did that at the beach. It helped a lot.

 

[Curvin]

Thanks all, I will be playing with a few ideas and I'll post up anything of value.