CHEVY K10 - 1/6th - EMO XX Chassis mods!!

[WRXronald]

Got the MT Baja Pro X's in 2.9 (Prolines) on G8 compound -- thinking this will be the setup. Just not that into the scale looking Tusks.

So the 2.9 Pro X's on the Chevy K10. And then gonna do the 40 series Pro X's on the Unimog ----- almost done setting that rig up --- silver cab, flatbed, and completely waterproofed out the gates, gears, electronics, everything torn down and dealt with in advance. Just have the Rx left to install and waterproof.

I'd say grippiness/stickiness of each tire felt similar new -- maybe the X2S3 RC4WD was a little softer overall but the G8's were surprisingly sticky even compared to the JConcept GREEN Tusks to the hand, ya don't notice a big difference and even after cutting the JConcepts foam down, the Proline 2.9 foam is MUCH SOFTER and I didn't cut a V Pattern into it all I did was cut 16 "slits" and leave 100% of the foam in tact. Way softer.

The RC4WD's are super puffy and wide looking which I think looks great on the Unimog -- that's a heavily inflated inner tube tire plus 1/4 thick RC4WD foam on either side of the inner tube taking up space and keeping the sidewall when the inner tube is aired-down.

I should have done some pics of each tire side-by-side --- they are essentially identical in diameter but the 40 series is about 1/8inch or so wider overall at the widest point.

A few pics of each rig now...

Also - when I tore open the portals - I notice the small portal gear also uses a 2mm drive pin

So its been pretty pointless to go machinging out the transmission 2mm drive pin up to 2.5mm when there are still four other 2mm pins remaining. (UGH!!! What is wrong with CrossRC --- I have 1/18 scale rigs using 2mm dowel pins that weigh less than 2lbs all up!???)

Anyways -- going to try out 52100 Bearing steel hardened dowel pins --- in 2mm --- and see if they hold up better than whatever CrossRC uses stock. I got a full set so will do the portal pins in both rigs and also do the transmission pin in the new silver Unimog and then hit 'em hard and see if they hold up.

Hopeful!! But also buying more 2.5mm End Mill bits so I can do all the machining on the lathe if need be after all. That's 10 gears to machine in total on both trucks so assume quite a few end mill failures. If I blew thru 1 end mill per 2 gears that would still cost me over $70 in wasted end mills just to get the job done. fug.

 

[Gula]

Why end mills? Drill bits bro! Roll pins, I've noticed seem to be some of the strongest shit I've ever had as a crosspin....

 

[WRXronald]

I feel like maybe we touched on this before --- is a good idea -- but at 2mm, there's not much "rolling" going on unless your material is pretty thin, thus maybe weak?

Also -- I don't think roll pins come down in the 2.5 and 2mm range --- do you know of a source?

iirc back when you first mentioned the possibility I did a bit of searching - mcmaster carr, etc --- just didn't have anything roll pin down in that range. They had dowel pins of course.

As for the drill bit --- its not a hole thru the gear, just a slot. So the drill is a good potential to just snap right in half the minute you hit the slot to open it up. I mean its a maybe. But technically, it's a job for an end mill -- pretty much the perfect tool ---- keep in mind i'm going from 2mm to 2.5mm so a 1/4mm on either side left/right of the slot to make it wider ---- that's 10 thous. Precisioning that with a drill bit is out of my league. Maybe a tiny file but there's not even any room to move the file up/down in/out.

I did briefly stare at the gear and wonder if I could just punch a 2.5mm drill hole thru it and use a full pin --- but again, same issue - the drill bit flute comes into contact with MOD1 hardened steel gear teeth, not a flat surface --- feels like at least a decent chance I snapping a drill bit, even potentially mid-way thru the drilling -- leaving a hot mess possibly even a piece of drill lodged --- that would kill the gear altogether. So the risk didn't make sense when I had a 2mm end mill, a mini lathe, and a milling attachment for the lathe all set and ready for these kind of things?!

Then I found the 4 more pins one 2mm in each portal, and well... i do plan to get to them if/when the 2mm bearing steel fails. Already nabbed a few more end mills -- going to start at 2.5mm end mill and try to plunge into the slot directly and finish the job in a single pass (although more likely to snap a bit) I just found cheaper 2.5mm than 2mm and the 2.5mm is a bit stronger of course (irony here, lol a bit of a pun as well I suppose?)

 

[Gula]

When you break the drill bit, mill it out. If you break the end mill, you're done with the part....Use a U.S size that fits a 2.5mm hole. It's a roll pin.....may need some elbow grease/press fit......rc10 roll pins?

 

[WRXronald]

Is a good point, also when I snap a drill bit if there's enough left you can usually just take it back out to sharp near 135 degrees on the bench grinder, if it breaks short i just keep the solid end for a, you guessed it, dowel pin spare.

Thanks for the RC10 reference as well - searched and does look like they have tiny roll pins that could fit.

Guess I'll order up a set and see how they go - can't hurt to try!

I don't mean to be a prick, but still not getting how a hollow roll pin can outperform a solid dowel pin, this is pretty much the answer my physics brain gave me when I thought it thru --- ie I was expecting to see the dowel quite a bit stronger -- Google AI tends to agree.... Is there a basis for how a hollow pin could outperform a solid pin of same size and material? Its almost like comparing same size/material tube to rod --- the rod is quite a bit stronger, usually, no?

A solid dowel pin is significantly stronger than a roll pin (spring pin) of the same material and size, particularly in shear strength and resistance to bending. While roll pins excel at retaining parts and absorbing vibration due to flexibility, hardened dowel pins are superior for high-load applications requiring maximum shear strength and precise positional alignment.
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Key Strength Differences:

• Shear Strength: Solid dowel pins (especially hardened steel) offer superior strength when resisting forces that try to shear or break the pin.
• Axial/Load Bearing: Dowel pins provide maximum resistance to axial loads (push-out/pull-out forces) and maintain precise alignment.
• Flexibility & Fatigue: Roll pins (coiled or slotted) are flexible, making them better for absorbing shock, vibration, and handling dynamic loads without fatiguing the hole, but they are generally lower in sheer strength compared to a solid pin.
• Installation: Dowel pins require precise, reamed holes, whereas roll pins are designed to be compressed, allowing for wider hole tolerances.
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In summary, use a dowel pin for rigidity and shear strength, and a roll pin for assembly flexibility and vibration damping.

So if i'm shearing somewhat decent quality stock CrossRC steel dowel pins (haven't put 1045 hardened or 52100 bearing steel to the test yet), the roll pin doesn't stand a chance, no? Any clue what these roll pins are made of -- must be hardened I guess - kinda look like they are.

 

[Gula]

I think it comes down to the metallurgy, aka roll pin becoming almost like a "shock" in your drive train...... a springy steel would spring back, vs a hardened pin/dowel would shear during a shock load....?

I've installed 1-1.5" diameter roll pins into 6-8" chrome rods in the ends with fittings that are 20' long at a job for an earthquake protection company......not solid rods/pins....?!

Can't hurt to try...

 

[Gula]

Remember "any" play or slop in the drive train is usually what kills it. I've found that I've had to use some Teflon tape around a bearing or shaft to make up the space........super quality bearings too. My h10 optic is sloppy on factory ones....

 

[WRXronald]

That starts to make some sense to me -- could see where "spring" in the pins might absorb short burst shock loads rather than resist them to the point of failure and shear. Def worth a try they seem cheap enough.

I've certainly noticed any play in the dowel pin fitment -- leads to early failures --- its that shock impact being able to load up and then hit the part hard whereas with constant contact the load can't build as much.

 

[Kingduck]

The truck looks amazing. I love the tires

 

[WRXronald]

Thank you Kingduck!! I'm sticking with these for now, def got that gnarly goin' on.

Yet to get them into anything yet but soon very soon!

Tusks prolly going up on the bay unless someone here wants them. Shipping makes things half pointless these days!

 

[WRXronald]

MUD and short Rock Climb - -

STAIR-A-THON -