Trail Slayer Build

[SpareParts]

Hello all,


I have always loved these and other RC forums but I habe always been more of a lurker. In an effort to contribute I finally took some pictures of one of my more interesting trucks and I'll try to detail the specifics that I remember.


I am not really sure what started me down the path of converting a nitro Slayer 4x4 into a trail truck; I think I just love watching the Revo suspension work. I had a bin of parts from when I restored an ebay Revo 3.3 including chassis, a transmission, all the plastics, and other odds and ends. It haunted me because I was always just a few parts away from building another revo for no reason. Well the parts bin finally won when I saw someone selling a roller of the original Slayer 4x4 with an old Tekno brushless conversion kit included.


For a totally unnecessary history lesson, Traxxas originally launched the slayer 4x4 as essentially a Revo 2.5 (short wheelbase, pre-3.3) with no reverse and short A-arms to give it nearly 1/10 short course truck dimensions. They didn't sell it very long and soon updated it to the Slayer Pro 4x4 with the 3.3 engine, longer wheelbase, and slightly wider (but still much more narrow than revo) A-arms. For trail and crawling purposes, short wheelbase and narrowest possible a-arms was ideal! Plus the Tekno electric conversion kit was sweet. It was definitely one of the best conversion kits for the revo, but once the erevo came out there was no need to convert nitros so the various conversion kits disappeared from the market. In summary, I was over the moon to find the Tekno conversion and an original Slayer 4x4. It was obviously a sign that I needed to build a Trail Slayer. (slayer, Trail Edition?)


I love to tinker and I love to clean beat up trucks, so it was a shame that the Slayer I got was already is good condition. Nevertheless there was still plenty to do to adapt it to the trail. I tore it all down to replace worn bearings and rusty hardware, then I swapped the springs to softer ones and lighter shock oil. I wanted to use a HW Axe 550 that I had laying around, and I wanted to keep the mechanical disc brake to use as a drag brake. I partially locked the diffs with earplugs then gave it a test drive with some tires from the Associated Nomad. Safe to say it was way too fast for a crawler! It was very fun to drive as a basher; even with the narrow width it still handled great. But that isn't what I wanted! So my next goal was to gear it down as much as possible.


Step 1 was the diffs. The nitro revos/slayers and v1 of the erevo all use basically the same diff as the slash 4x4/stampede 4x4. The ring and pinion gears are 37T/13T. Interestingly, the Stampede 4x4 brushed version comes with a different set of ring and pinion gears with 47T/12T giving noticeably more gear reduction. I figured I should be able to swap them in pretty easily.....and of course they mounted to the diff just fine but I did have to grind at the diff housing quite a bit to make room. I am hoping they still hold up despite all the material I removed and so far they have been ok.


Step 2 was the transmission. The slayer transmission has less gear reduction than the revo to account for the smaller tires. So I swapped the primary gear for the revo version to get even just a little more reduction. Everything else was going to have to come from the pinion and spur. I was able to fit a 54t 32p spur meant for slash/stampede platform, and you could probably go a little bigger if you did some grinding on the chassis or lifted the transmission with spacers. A (probably not) interesting note is that typically to convert these nitro transmissions to electric, you lock them in 2nd gear. If you don't then you can't use motor braking or reverse because the transmission has one-way bearings and will just freewheel. So if I could use the transmission as intended then I could use 1st gear and get even more reduction.



At this point I also decided that the Axe system was too fast and I couldn't fully turn off the braking/drag brake. I wanted to exclusively use the mechanical brake because I thought it was neat. So I swapped in a HW 1080 with a Holmes Trailsport 550 21t. On the 1080 I could fully turn off the brake and reverse, which meant I could use the 2 speed transmission to gain the lower 1st gear! It also meant I needed to use a shifting servo to get into reverse....but that's pretty neat too, right? I have plenty of other, normal trucks; this one can be weird.


So that is how it currently sits and I enjoy driving it in the backyard. On 3s the trailsport 21t gets enough rpm to shift into 2nd which is always joyous. It is not hard to keep it in 1st gear though for crawling/trailing. The mechanical brake is fun to use and has a nice feel to it. Using it as a drag brake can be a little tricky because it isn't instant. Shifting into reverse is a bit of a gamble and when it works it rolls a few inches before the dogs engage. Just some fun quirks!


The main issue is trying to find appropriate wheels/tires. You really need sct style 2.2/3.0 wheels to fit over the large knuckles and that limits my tire options. I would love to make it look a little more scale and less like a monster truck. I also need to fully lock the rear diff and I am pondering how to add rear steer.

[SpareParts]

Trying posting from tapatalk for better pics. Here are some pics of it in version 1 with the Tekno conversion and the HW Axe:





It was so much fun driving fast with the brushless system that I ended up building another electric converted revo. Now I have a motley collection of a Revo 3.3, Brushless conversion Revo 2.5, and the Trail Slayer.

[SpareParts]

It's hard to find bodies meant for the Revo 2.5 wheelbase. I got both of these off eBay new unpainted. An old proline crowd pleaser and a BRP Stinger. The BRP Stinger packaging didn't even have a website listed and I can't find any info on them.

[meatmonkey]

Seems like a decent mutt of a truck.

Nice to see something different.

[OSRC]

Very cool, nice idea on the diffs to get the gearing down.

As far as wheels, I've picked up some ARRMA SC wheels for my C-Maxx which are 14mm hex, and PL U4 tires. Closest thing to a crawler tire that fit over the big knuckle without a ton of offset.

[350TacoZilla]

I always say how much I love builds like this! I get a kick out of the lego nature that traxxas seems to have always had.

My last project one I started with a summit and made it into something that looked like a slayer pro but had the locking diffs, 2spd, electric obviously.

[OSRC]

Originally Posted by 350TacoZilla

I get a kick out of the lego nature that traxxas seems to have always had.

Traxxas and Tamiya both, I love how much they share parts across models and can be mixed and matched. Makes for some fun builds!

[SpareParts]

Thanks everyone! Yes it's neat how modular Traxxas stuff can be. You can build almost anything you want and their parts support is excellent.

I was considering swapping in the summit locking diffs but I think the driveshaft on the passenger side would end up at a pretty steep angle since the summit diffs are wider. Might still be something I try just for fun.

Rear steer doesn't seem to be an option unless I start cutting up the rear arms or knuckles. At full droop the toe link/steering link contacts the lower a arm so I would have no rear steer when either side is extended. In crawling that would be most of the time. I could try a bit of overdrive to the front by putting the original diff gears in up there, but it might be pretty extreme overdrive.


Some pics of a few different tire options I have laying around. I think the white wheels look pretty good with the body! The larger 2 options will certainly rub the body unless I space them out quite a bit.

Also opened up the wheel wells a bit so the body looks like less of a slab. The proportions are still a little wonky to me but maybe some stickers will help.