CMX S10 Blazer

[ndecisive]

A few months ago I got into RC crawlers, starting with a CMX chassis and a TBG repop of the old BoLink S10 Blazer body. The body fit the 252mm wheelbase pretty well. I do wish I had mounted it differently, the pegs are flimsy and ugly.





Right away I upgraded to bearings instead of the included bushings in the kit, and installed a 90T spur and 17t pinion.

For electrics I used a 27T HPI Saturn motor and SC-15WP ESC. I wish the ESC had fwd/rev mode instead of just fwd/brake/rev.

It is painted like a real S10 Blazer I had many years ago.



The first real excursion I found the stock tires to be adequate, but my old Blazer had wagon wheels and TSL SX tires. I bought some RC4WD wagon wheels and ProLine Swampers. The Swampers were 1.9 so I sliced a pie shape wedge out of them and super glued back together to fit the 1.5 wheels. The bead on the tires was no way going to work with the beadlock rings that came with the wheels so I just super glued the tires to the rim.



New tires = way better traction = twisted up drive shafts



This has been a recurring theme, I don't think it is as much a durability issue with the shafts as it is a lack of slipper clutch. When the tires get wedged into a crevice something has to give, and there is nothing in the drive line engineered to take that so the driveshafts twist. I've now broken two, even tried inserting a screw down the center of the shaft and it still twisted up and broke the yoke off.

 

[ndecisive]

Some more action shots

 

[Zukiiholic]

Looking pretty good.
Are you just replacing the driveshafts with stock ones?
Can you order stock parts for the CMX?

 

[ndecisive]

Yea so far I've ruined two sets of stock CMX parts, and one set of plastic SCX10 shafts that really didn't fit very well so I wasn't surprised they broke. On one set of the stockers I screwed a screw inside hoping it would help, it prolonged the life a little but rather than twisting the shaft the yoke tore off. MST makes a steel driveshaft, but they're $20 each and while that's not outrageous I'm worried it'll just break something else.

 

[ndecisive]

Quick update, pics to follow later this week. With out a doubt the single biggest flaw with the CMX is the lack of a slipper. It's a huge issue, the drive line is very capable but something has to give or something will give. When a tire is wedged between rocks or wrapped up in tall weeds even this 27t motor has enough torque to strip hexes and wind up drive shafts. It really needs a clutch to slip before the breaking point of other components.

I've been working on fitting an Axial slipper clutch on and have about arrived at a functional solution. Also have upgraded driveshafts again to the readily available Axial Wild Boars. Parts availability for the CMX is the #2 fault, necessitating some parts department problem solving.

Stay tuned... Once the reliability problem is addressed I can finally move on to the lights and bumpers and whatnot and start making this more than just a lexan body!

 

[ndecisive]

Screw backed out of the axle pinion... needs Loctite. Duh... And of course it's the front axle with a million parts to disassemble to split the case open.



Here is a preview of the Axial slipper install. The drive pin on the CMX top shaft is larger than the Axial so some modification was necessary. I also am hoping to keep it all contained within the CMX gear cover. The hub was trimmed down to nearly flush and the groove for the pin made larger with a grinder. Because the pin is free floating intended to be held captive by the hub I will be replacing it with a roll pin from the hardware store.



I have not quite figured out the tension spring yet. The CMX uses a 3mm screw to hold everything on the top shaft and there isn't a good way to keep tension on with only a screw.

 

[ndecisive]

Slipper clutch conversion complete!



I used a 3mm threaded rod and lock nut from the Traxxas parts pile and the spring and bushing from an Associated T2 clutch. Works beautifully. Red Loctite on the end of the rod that threads into the top shaft.

And aside from the adjusting nut, the gear cover still fits.

 

[ndecisive]

Slipper success! Wheeled all afternoon Saturday and nary a part was broken. More than one instance of clutch slippage saved the driveline from damage, and never did I feel like the clutch was holding it back from making it over, around, or through.

Now on to the fun stuff, front and rear bumpers, nerf bars, cab visor, lights... and so on!

 

[ndecisive]

The only photo I have of the real thing, this was a day or two before it went to the scrap yard. Too much motor, not enough tire, wrong drive train, and the body was totally shot, there was little/no floor left except for the transmission tunnel and the seat braces.

 

[Zukiiholic]

Nice work on the slipper clutch..
I was just thinking of using the scx10 trans..

 

[spaceman5280]

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The only photo I have of the real thing, this was a day or two before it went to the scrap yard. Too much motor, not enough tire, wrong drive train, and the body was totally shot, there was little/no floor left except for the transmission tunnel and the seat braces.

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