Yokomo Super Dog Fighter 870c G Force Competition Cup Indoor Carpet Track Testing

Only about a week to go until the 2024 G Force Competition Cup! 😀(#gfcc).
I'll be entering my 870c into the Vintage Buggy Class. The Super Dog Fighter is a great buggy overall, but its vintage design means it's kinda out of its element on an indoor carpet track. 😅 Some "short comings" of the kit setup include:
lack of suitable tires for the vintage sized wheels
lack of wheels that fit the kit wheel hubs
FRP chassis flex causing the belt to skip
poor L - R weight balance
very short dampers with limited stroke and no optional springs.
Yokomo have recently put out some optional 2.2 inch wheels and carbon pieces to replace the factory FRP ones. But still nothing for the shocks.
I've spent the last six weeks in a cycle of modify, test, modify and test again in an effort to improve on the 870c's performance. This footage was from the final day of testing. I suspect I'll have to make minor adjustments when I run at Tsukuba for the first time.
SPEC LIST:
Carbon Main Chassis
Carbon Upper Deck
Carbon Servo Mount
45g Weight Added to improve balance
Wide Rear tread
JC Racing 2.2 Wheels
VP Racing Hyrbid Evo Front
VP Racing Pyramid Evo Rear
Carbon Shock Towers
Modified Stock Dampers
Kyosho Springs
Shock Oil Front 600
Shock Oil Rear 550
69T Spur
35T ~ 38T Pinion (will decide at the venue)
ELECTRONICS
G Force Neo Fast 21.5T Brushless Motor
Hobbywing Justock ESC
G Force Dyna 3800 Lipo
Futaba Reciever
Savox Servo
Motor Cooling Fan
This final setup is a bit of a compromise between performance, risk and aesthetics. During testing I fitted several different carbon shock stays, but their design made them prone to failure in the event of a collision. The best handling was achieved with the Big Bore Shock Tower set by Unfair RC. This allowed me to "borrow" the dampers from my YZ-4 SF2. And that totally transformed how the buggy jumped. Ultimately I decided against using them for two reasons. First, personal opinion, but they seemed too large for the buggy and looked somewhat out of place. Second, the large number of pre-drilled holes for upper link and shock mounting creates a failure point. That combined with them being REALLY tall made me wary of using them in a race situation. A crash (which can be seen in my previous 870c video) split the carbon shock tower from H2-RD right where several holes had been drilled for the upper links.
So hopefully my 870c will do ok, There are forty participants in the Vintage class, including the Legend Himself, Masami Hirosaka, so I don't think i've got any chance of a podium finish. But it would be nice to come somewhere in the top twenty...😊

[@AddamsPlayground]

I have to say that looks like a perfect day right there! A nice running buggy and a great track all to yourself! Great driving David and thanks for setting up all the camera shots for us to enjoy it too!

[@n22pdf]

Yeah it looks amazing Addam 😊 Pete

[@KaiCityRC]

This was a totally unplanned video! When I got to the track and found I had it all to myself (for the best part of four hours and on a Saturday too!) I couldn't waste the opportunity. 😁 All I had with me was my smartphone. No stand or anything, so most of the time it's propped up against a wall, pillar, barrier etc. A lot of angles ended up being useable due to camera shake, but there was enough footage for this short video.

[@Nlangkirby135]

Thats a massive improvement for your dogfighter buggy.

[@KaiCityRC]

Thanks! I think I lost count of the number of times I changed the shocks, springs, oil, etc in an effort to find the right setup. Learned a lot in the process and had fun. It is still far from ideal, but I can now get around the track reasonably well without keeping the throttle pinned on every jump. 😁

[@lo2713]

Nice, i do miss mine. Hopefully i’ll be able to buy another soon. It was great to drive. But like has been said. Limited options for setting up shocks and mine seemed to be be a touch nose heavy when jumping.

[@KaiCityRC]

Yokomo began releasing some optional parts, though they are mostly carbon versions of the kit FRP pieces. They also have 2.2 inch wheels, but only available in pink. Aside from its tendency to nose dive on jumps, I really like how the 870c drives and its simplistic chassis design is very easy to work on. 👍

[@lo2713]

@@KaiCityRC yeah, i do miss it. Easy to work on aswell

[@Toystheyrenot]

Nice run and the Super Dog Fighter looks dialled in now. All the best at the races! 👍😊

[@KaiCityRC]

Thank you 👍

[@HBTCX]

ノーズダイブが酷くて、マトモに走らない状態からここまで仕上げたのですね。 というか、デイビッドさんGFCCに参加するのか～。 他にも有名KZbinrさんが出場するので、気が向いたら見学に行くかもです😁

[@KaiCityRC]

コメントありがとうございます。まだノーズダイブするのですが、前よりはよく飛べるようになりました。GFCCにも参加予定です。現地でお会いできたら良いですね😊

[@Jaysqualityparts]

People said they used to be fragile does that seam the case on the rere David? Also how is it on the track in general?

[@KaiCityRC]

I've crashed my 870 a lot! 😅 For a small sample, check out my recent "Flight School Fails" video. Some of them have been pretty bad ones too. 😬 The wing gets ripped to shreds in short order. I also broke an aftermarket carbon shock tower. But that's it! At least in my experience, it has been pretty tough and reliable. I dismantled it to check for damage and found none caused by weak parts. Most of the issues revolved around screws working loose, despite the use of thread lock. You definitely need to put quite a bit of blue thread lock on this buggy, much more than you normally would. The grub screws for the hubs in particular work loose all too often. I love the way it sounds on track. Being belt driven and having this refreshingly simple transmission with a minimum number of rotating parts, it sounds eerily quiet and super smooth. My TT-02B and YZ-4 sound agricultural by comparison. 😁 On the flat sections, it's a joy to drive. 👍 Sadly, it all falls apart on the jumps.😞 Built to the manual specifications, it will nose dive heavily, the severity depending on the shape of the ramp. I found it very difficult to keep the nose up, often resorting to keeping the throttle pinned until just before the wheels hit the ground. The issue is the short stock dampers, very little droop, springs not suited to carpet tracks and shocks that are very difficult to built correctly (aeration/emulsion dampers, but without bleed screws). The towers are quite small, so options for mounting longer shocks are limited. With the right suspension setup, the 870c would be very capable. It's also very easy to work on, should anything go wrong. 👍

[@coygtrc]

Runs great. Good luck there 👍

[@KaiCityRC]

Thanks 👍

[@TastierBackInThe80s]

Looks to be slightly nose heavy? Nice music choice. How does it perform opposed to the other modern day Re-re's? Thanks for sharing.

[@KaiCityRC]

Yeah, it still tends to nose dive depending on the shape of the jump. It certainly takes more effort to jump smoothly than some of my other re-re's on the track. The JJ Ultima drives really nice and jumps well too. But despite the awkward landings on the 870c, it still managed to lap Carnosa RC Park about one second faster than the JJ with identical electronics. I'll be taking the JJ to test at Tsukuba the day before the race, so it will be interesting to see if I made the right choice. (it was a toss up between the 870c and the JJ). I've done as much as I can with the stock 870c dampers. It jumped much better when I fitted upgraded "Big Bore" shock towers and borrowed the dampers from my YZ-4 SF2. But for various reasons, I opted not to run them. I'm under no illusions of winning the Vintage Class race (or even coming anywhere in the top 10), but I am determined to compete and finish the races with the least amount of assistance from the track marshals! 😅 If I can get around and keep things right side up, I'll be happy! 👍