My Rock Force Project:Samurai

[killjoyken]

Why the name "Samurai"? When I used to manage a muffler shop, I had one customer bring in his Suzuki Samurai for a custom exhaust. He told me some great stories of how his brothers (who had Jeeps) had a hard time keeping up with him on trails. It was pretty well modified and looked really cool on the lift. Anyway, this rig brought back memories of that little Samurai and hopefully it will someday be able to compete with some Axials and Bergs.

I took the Samurai to Dana Rock park in San Jose for some side by side testing against my GC-1 Axial today with Dewmerz and his SWX. I'll post a full review later tonight. For now, here are some pics:

[HiloDB1]

very nice . So how do you like it so far compaired to the GC1? Damn all you guys that already have yours built . I was hoping the mail man would drop mine off today :-(

[Harley]

What is your track width with those wheels and tires?

[killjoyken]

Track width from outside edge to outside edge is 11". That's one of the current problems...it's too damn wide. Trying to wedge this thing through a crevasse was difficult at best. I couldn't walk the tires on the sides and would have to go in at an angle causing the rig to tip sideways and get bound up. Someone's going to have to make special offset wheels specifically for the RF. I'm going to mill down some Dirty Harry adapters on Monday and see if I can get them to work. Another problem is the huge 6mm wheel nut. A 10mm socket is too big to fit the DHs so I may not have enough room to tighten the nut.

As for the axles, they have good points and bad points. I'll start with the good. The worm gears hold the rig on any angle. The tires would slip before the axles would rotate. Best feature by far. Durable as hell to boot. I got bound up pretty bad more than a few times and took a few nastly tumbles to the bottom of the hill and almost every time it would land back on it's wheels and I'd just drive it back up.

Downsides? There's not enough steering. (the wide track isn't helping) I may be able to gain a little more by trimming the knuckles and c's, but I'm going to end up being limited by the axles. Beefiness comes at a price. The dig will probably be necessary for this to be competitive. My GC-1 will literally drive circles around the RF. On one section, my GC-1 was able to make a 180 around a rock without reversing or dig while the RF took 3 reverses. It needs dig bad!

While you do gain clearance under the pumkin, the axles get cought everywhere else. I think taller tires will help a little, but the axles are going to need to be ground down like TLT axles. The lip that runs the length of the axles is the main problem, but the shock/link mounts are also problems. They hang down to the bottom of the axles and get caught frequently. Yet another part I'll have to make. Kyosho really should have gone with a round pumpkin design like Axial and every 1:1 crawler. The screw heads that hold the axles halfs together also like to snag on everything too, esp the ones near the c's. Not sure what I'm going to do about those yet.

The shocks. Well, I used the brass pistons with 20wt and they're way too slow. The instructions say to cut another edge off the plastic pistons and run 15wt, but I seem to have lost 2 of the plastic ones, so I may try drilling a hole in the brass ones. Most likely I'm going to try losi shocks when I switch to a different chassis. I've got a new chassis in mind that I'll be trying out soon.

Ahhh...the chassis. Brings me back to my TLT days. It's like a cross between the stock TLT chassis and the Junfac chassis. Nevermind that it's too bulky and too wide, the worst part was the edges of the skid getting caught on every crest. If it wasnt the axles stopping the rig, it was the skid. If I kept the center of the skid lined up with the peak of the rock it would slide over smoothly, but an inch to either side and I'd be stuck. It's going to take a little grinding to fix this.

After 2 packs, my motor plate is tweaked. I could already flex it with one finger enough to almost take the pinion out of mesh, so I wasn't expecting it to last anyway. I was running a 10t mod for testing and with the stock gearing on 3s lipo it was barely faster than my GC-1's 35t on 3s. The stock gearing is waaaaaaay too low. Motor was hot, esc was hot, and the battery was really hot. To get the same wheel speed as the GC-1 I really had to spin that 10t. Too much amp draw nearly killed a 2100mah Maxamps pack and puffed an old DN 2150mah 15c 3s. Now I've got to shell out another $60 for high speed gears. Along with another $30 for dig. Wow, add wheels, tires, electronics and a comp legal body and this is one expensive rig!

In stock form, the RF was only able to do one thing my GC-1 couldn't, but I'm chalking it up to tires. It was an uphill diagonal line across a 6" gap to the right. Dewmerz was able to cross it with his SWX on Claws, but the Panthers on my GC-1 kept folding over and I'd tip and roll until my rig rolled down the hill and snapped an axle. The RF was able to follow the same line as the SWX fairly easily. Unfortunately, it struggled in places where the GC-1 flowed. It does well in climbs and sidehills well given it's top heavy chassis, but would freqently get hungup when the course had a lot of holes. Dana Rock Park has a lot of jagged rock that will test a rig's ability to slide over rocks, so it was the perfect place to find the RF's faults.

While it didn't meet all my expectations today, there was one saving grace. I drove it back to my car, while I had to carry my GC-1. If that's not a testament to it's durablity, then nothing is. So far on my GC-1, Dana has claimed 1 Axial CVD, 2 RCP straight axles, 1 rear axle housing, 1 rod end, 1 steering link and it's killing my Panthers! As for the RF, 1 bent steering link (that I easily bent back by hand while still attached) and that will soon be replaced with aluminum rod and moved above the knuckes.

Am I dissapointed? A little. If this was a $250 kit like the Axial, then no, but considering the price I expect a little more. When the Axial came out it also needed some tuning to make it good, but not that much. And for the price you had extra cash for mods. The Kyosho (like most Kyoshos) starts at a higher price point, but delivers possiblly the most durable axles ever put on a crawler. With all the great designers and fabricators here on RCCrawler, it won't be long before we see the RF beating out the Axials and Bergs for 1st place.

[killjoyken]

Also forgot to add: I had 6oz in the front tires and 3oz in the rear and I think the front could definitely use more weight. On some climbs it would lift the right front wheel, but it wasn't torque twist. It wouldn't rise with throttle, it would just hang there and bumping the throttle wouldn't bring it down. I'm hoping more weight in the wheels and lighter shock fluid will cure this.

[Harley]

Great write up. It is good to hear the pros and cons after some real testing.

Thanks again. I won't have mine until next week and it will go right to 3D modeling....

[stampedeproject]

You might want to look at the Pro-Line Epic rear Beadlocks instead. They will shave 1/4" off the overall width for you.

You are on target with the shock oil, I still need lighter oil and I think I used 30Wt and its SLOW.

Just posted a video of the rig with a Novak 4.5R KV brushless system that I think proves your point, the gear reduction is way way to much.

Looking good man!!

[Dewmerz]

It was fun today watching Ken drive two crawlers switching back and forth between profiles on the DX3R. Several times I thought it would not make it but it did even though it did not look as elegant as the other crawlers we ran today. Dana Rock Park took out my SWX today so half way though the run I had to fall back to my SW3.

I like the axles but the chassis turned me off from looking for a kit. When the axles are available separate I will most likely pick up a set. I'm not a huge fan of the front link setup but it did appear to work.

[killjoyken]

Where's your star, Newbie?

Yeah, running 2 rigs at once is a little frustrating. Run the line, switch profiles, run it again, get mad when RF gets stuck, rinse and repeat. Keeping mental notes of all the needed improvements was wearing me thin....

[Harley]

The side by side drive time was great I am sure. I will do the same thing with my Berg. My hopes are not very high right now......

[killjoyken]

Originally Posted by Harley0706

The side by side drive time was great I am sure. I will do the same thing with my Berg. My hopes are not very high right now......

Stock RF vs a Berg? That should be fun!

On another note, I found a way to fit my DHs. Take the narrowest hub adapter, bolt it to the hub, then bolt the wheel to the adapter! Not exactly quick change, but it works.

Nevermind, track ended up the same at 11" with Panthers. Crap.

Just shot an email to Vanquish about making wheels for the RF. He's local so hopefully we can get something made.

[goobs]

Originally Posted by killjoyken

but I seem to have lost 2 of the plastic ones, so I may try drilling a hole in the brass ones. Most likely I'm going to try losi shocks when I switch to a different chassis. I've got a new chassis in mind that I'll be trying out soon.

nope u didnt lose them cuz mine didnt come with them. i know i searched for 20 min.

i personally would like a new chassis also and a 4-link.

i also agree with ur write up 100%. everything u said i experienced. i was running 5.5" rubicons too!

[JohnRobHolmes]

Wow that is a narrow body!


Interesting issues with the crawler. I was worried about the gear ratio. Does anybody know what the reduction at the axle is? Maybe a motor could be ran to them with no tranny, or a tiny tranny with minimal reduction.

[EeePee]

...

Originally Posted by stevep

The standard axle ratio is 30:1 and the final drive ratio with the included pinion and spur gear is 143.33:1. It's quite a bit higher ratio ("lower" gearing) than most crawlers, which is why it's able to use a more standard motor. The optional "high speed" worm gear set changes the axle ratio to 15:1. The full range of final drive ratios using the optional gears ranges from 46.8:1 up to 161.25:1.

I'd build it with the high speed gears. That should lessen the parking brake effect. Then try the Tekin Push adjustments.

[JohnRobHolmes]

2:1 at the motor would be plenty for most guys then. 143:1 is just rediculous unless you run some crazy fast motor!


Problem would be clearing the driveshaft around the motor without using an idler gear. All kinds of cool things that could be done with these axles though.

[Reflection]

Originally Posted by JohnRobHolmes

Maybe a motor could be ran to them with no tranny.

2 motors,direct drive would definitly be interesting.

What size pinion/spur is in there stock? Once I can get my hands on one of these,I'll be looking for ways to speed it up. Final drive on my current comp rigs is in the 35:1 area. I'll need to get close to that in order to be happy with it.

[killjoyken]

The kit gives you a 18/86 with a 30:1 gear reduction in the axles good for 143:1 total reduction. The High speed gears are 15:1 which would give you a 71:1 reduction with the stock spur and pinion.

The smallest 48p spur I have is a 60 and the biggest pinion I have is a 31 which would give me a 58:1 total reduction. I'm running 47:1 in my GC-1, so it's close. Actually, that would probably put the motor into the driveshaft. Let me rethink this...:?

[JohnRobHolmes]

Mock it up before discounting it. The pinion is large enough that the spur center (output) may clear the motor. A longer output shaft may be needed to put the yokes beyond the motor case.

[killjoyken]

Originally Posted by JohnRobHolmes

Mock it up before discounting it. The pinion is large enough that the spur center (output) may clear the motor. A longer output shaft may be needed to put the yokes beyond the motor case.

I'm pulling the motor right now. I did manage to find a 34t pinion also. I had a question for you John. You list your 35t handwound at 1565kv and the Cobalt 7t at 1834kv. How can the 7t have a lower kv than the 25t?

[JohnRobHolmes]

The 7t is slower because:

It has a larger armature diamter than a 540
It is longer than a 540
The magnets are stronger than a common 540
It has 7 motor slots instead of 3 (the big one)

Were you running your 10t with some advanced timing?