Serpent S811 "Cobra" 1/8 Scale Competition Buggy Kit w/V2 Radio Tray

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NOTE: Our Serpent S811 kits now include the updated V2 radio tray! The V2 radio tray package includes all the necessary parts and hardware for the conversion, as well as an updated instruction sheet.

This is the Serpent S811 Cobra 1/8 Scale Competition Buggy Kit. This chassis has been designed by Billy Easton to take the 1/8 scale buggy class to the next level by outperforming everything else on the track and providing the racer with the ultimate package. The Serpent S811 Cobra has been designed to provide optimum balance, the lightest possible weight, and effortless maintenance in order to provide the consumer with a product that has the tools out of the box to outperform all the previous buggies they had ever used, whether Pro or Privateer. Serpent’s goal was not just to release another car. The main goal was to produce the best performing car in the market place with a level of quality that is second to none. When you see the parts quality and overall finish of the car you will wonder how Serpent could produce such a high quality car for the price. Then you will wonder why all manufacturers’ cars are not of the same caliber.


  • Geometry: With over 15 different manufacturers tested and countless hours of driving, the geometry is well proven. So many different concepts and suspension styles have been taken into account; any driver will be more than pleased with the S811 Cobra package. The geometry is set up for maximum performance with the most efficient cornering in mind. Utilizing proven roll centers, shock progression and camber links.
  • Weight Balance: The front to back and left to right balance have been greatly enhanced over even some of the most recent buggies. You will definitely not find one side of this vehicle dragging the ground over another. The balance is perfect and it is barely if at all affected by the different types of batteries available.
  • Gear Ratio: The S811 Cobra’s 4.3:1 gear ratio has been proven to give you the most possible acceleration and also allow you to use a much larger variety of clutch bells. This gives the racer the option to gear his car down on a short track if needed. Attention to small details such as this can be the difference between winning and losing.
  • Suspension/Shocks: The suspension is comprised of suspension arms that are almost identical in length, to allow you to maintain corner speed, as well as aid in rough track handling by using proven design concepts and updating them for modern day competition. The 16mm Big Bore shocks will allow you to soak up even the harshest landings on any track world wide as well as help to prevent thermal break down of the shock oil during long mains.
  • Engine Placement: The engine location is a forward placement design and has been maximized to allow for forward placement. But an ideal placement has been found to allow for aggressive handling without compromising the cars overall balance.
  • 4 Shoe Clutch: After countless hours of testing different types of clutches it was determined that a 4 shoe clutch was the best overall choice. Allowing the racer the ability to balance the clutch for carbon and aluminum shoes, as well as utilizing the simplest building concept, the S811 Cobra clutch allows the user to mix and match clutch shoes to perfectly tune the clutch to the specific track conditions. The S811 clutch system will also allow the user to build multiple units that can be changed out quickly.
  • Steering System: The S811 Cobra steering system is the most advanced system ever devised. The bell crank system is angled to better match the caster angle, with an optimized turnbuckle length to eliminate bump steer. The brilliant ackerman design allows changes to be made without the need for link adjustments. Simply change the ackerman plate, reset the radio endpoints and hit the track.
  • Body & Rear Wing: The S811 Cobra body is extremely low profile and fits the chassis like a glove in all the right places with equal proportion cab and sides. The rear of the body is scooped to provide additional down force, which helps guide air to the rear wing. The wing has a combination of different air foils with 2 fins inside of the side damns to aid in keeping the rear of the car planted while providing great side grip and excellent control while flying through the air.
  • Anti-Roll Bars: The kit anti-roll bars are a conventional type, produced with bent piano wire with laser engraved identification marking. But the S811 Cobra Roll Bars are supported by ball bearings to insure they never get sloppy and provide consistent control. An additional anti roll bar kit will be available as an option that is very advanced and even easier for the racer to adjust the wire sizes on the fly.
  • Ball Bearings: The differentials, drive shafts, and all other ball raced components are supported by high quality rubber sealed bearings and are as good or better than the bearings included in any kit.
  • Fuel Tank: The fuel tank utilizes a floating clunk design so the engine wont starve if the car spends too much time on its lid, while the tank top has an overflow to help guide any unwanted fuel out the bottom of the chassis. The tank lid has been designed to minimize splashing during pit stops, as well as prevent fuel contamination to the critical parts inside the vehicle.
  • Transmission: The transmission drive shafts are all captured, so never again will you worry about losing a pin in long main or at local events. It has been designed so that no matter what, your drive train will stay assembled so you will finish any event without troubles regardless of the race length. The drive shafts are produced using tool grade spring-steel and coated with the unique Serpent factory brown finish. They are also laser etched for easy identification. You will not be disappointed in the quality and strength here.
  • Brake System: The brake system has been simplified to help you set your brake system the same every time, no matter how many cars you build. The parts have also been lowered to help keep the CG as low as possible. It uses a piston system and provides superior braking like you have never felt before. Several optional brake upgrades will be available to fine tune the braking system in a way that has never been seen before.
  • Servo Linkage & Camber Links: The servo linkage and camber links have been captured to eliminate the worry of losing a ball cup when you are on a TQ run. This car was developed with one thing in mind, to finish first, you must first finish.
  • Electronics Installation: The electronics installation may be a little tricky the first time, with a couple new steps you have never had to do before. So for some it will be a bit foreign, however after you do it a time or two you will appreciate the packaged unit you get when finished. The assembly is very clean, tidy and simple to remove from the car with no parts that look like they are just barely hanging on and out of place.
  • Chassis, Chassis Stiffeners & Flex Control: After lots of testing the plastic stiffeners that are provided in the kit control the flex in all the right places to help you make it through the roughest terrain. The car is not too rigid, but also is not too flexible.

This product was added to our catalog on June 4, 2010.

Orhan Isvan
Thursday, Jun 3 2010 (about 5 years ago)
Serpent S811 "Cobra" 1/8 Scale Competition Buggy Kit w/V2 Radio Tray
I was on the track today. This car carries unreal speed to the corners. Then, it remains planted in the corner. Then, it exits without breaking its composure. All of a sudden, I became a better driver. I was not aware that I could control an off-road buggy so precisely and so easily at such cornering speeds. This feels like cheating. This car is all about stability and cornering speed. Tip: Despite the fact that I had measured all the tie rods, camber links, steering links, shock lengths, etc., meticulously with a digital caliper during assembly for sticking to the figures given in the manual, my setup system revealed that the resulting camber and toe angles have nothing to do with the ones on the stock setup sheet that was included in the kit. I strongly recommend using a setup system for matching these values with the ones that are suggested on the stock setup sheet. You will not regret! -//- I took the risk of buying a kit from the first batch of production, even before it reaches the shelves of mega stores like A Main Hobbies. Therefore, I will not complain from minor mishaps to be corrected in time. Many bags contained fewer M3 locknuts than the manual shows and there were no concave washers at all. I had a surplus of them in hand so I kept assembling the kit but since I don’t have a surplus of 8x14x4 flanged bearings, I am now waiting for the missing two (out of ten) to arrive. Serpent must correct these at once. Missing parts are not welcome, no matter how insignificant they are. On the other hand, the more I went through the assembly, the more I respected its designers Billy Easton and his team. From major innovative designs like the location of the center diff and consequently of the throttle/brake servo, to minor ones like ball bearing supported anti-roll bars; many details were awesome. More often than not, I said to myself “another detail that I will not have to modify” like the twin setscrew stoppers or “wow, another stone that hits two birds” like the bottom mounted brake discs that not only lower the CG but also enable the user to remove the center diff without touching the brake linkage. There is a 50/50 brake bias spacer, an optional spacer that favors rear bias and additional shims for fine tuning, in addition to the adjustable length of the brake rod. One can adjust brake bias with minute precision and this adjustment will stay put. The drive train is very light and smooth like butter (if not olive oil) due to very precise tolerances. All drive shaft pins are captured. The 10T outer diff crown gears are part of the center drive shafts, XRAY style, so no bulk there. The A arms are beefy. The rears are supported beneath the uprights; the fronts are supported just next to the uprights. Bump steer is minimal, if not non-existent. The steering posts are not perpendicular to the chassis but angled rearwards. Steering is as smooth and play-free as it can be, thanks to the supports between the upper bearings and the carbon fiber steering plate. Very few screws go into plastic. Most screw into captured locknuts (if you can find the locknuts!). The innovative radio tray is secured with 4 M4 screws. Shock absorbers are 19mm bore with 16mm diameter pistons. Pistons with 1.1, 1.2, 1.3 and 1.4mm holes are provided, in addition to a set with drill marks for the user to drill. O rings are beefy and soft. Silk would envy how the operation of the shocks feels like. I will write another review on how the car handles once I receive my Rx battery and regulator together with the missing bearings. I can not give 5 stars to a kit with missing nuts and concave washers and 2 bearings but the design, the parts quality, the finish and the obvious CG deserve much more than that.
Sunday, Sep 26 2010 (about 5 years ago)
Serpent S811 "Cobra" 1/8 Scale Competition Buggy Kit w/V2 Radio Tray
Great buggy, however, I have had trouble with the flanged bearings used for the rear diff (the ones used for the Differential Outdrive Cups) blowing out. Not sure if the bearings are crap, or there is too much side to side movement with the diff inside the diff housing. I have adjusted the shimming and I see if I will have the same issue when I run the buggy next. However, I am not the only one that has had this trouble, as the owner of my local hobby shop in Japan has had the same problem. Please let me know if anyone else has had the same issue. Other than that issue the buggy is excellent to drive.
Den Lee
Verified Owner
Wednesday, Aug 4 2010 (about 5 years ago)
Serpent S811 "Cobra" 1/8 Scale Competition Buggy Kit w/V2 Radio Tray
Parts quality is top notch, minus a few items. Haven't driven mine yet, but here's some things I've seen during the build... 1. several screws were cheap metal. stripped easily. some were bad choice of screw-head style for their location. 2. brake lever system and radio tray did not fit property. had to remove quite a bit of carbon from the tray so brakes would close without binding. 3. b/c of reversed carb positioning and tight interior space, reaching main needle is rather difficult with my engine (though adjustable, range of function is limited). 4. have heard of throttle servo failure. some say it's due to heat and/or vibration. i'd also consider the possiblity of improper travel adjustment. b/c of the brake style, throttle endpoints must be precise or else you'll burn up a servo quickly... 5. manual is a bit questionable in some places. experience is key, as others have pointed out. will review further after first drive impressions. i will say that the setups are not "typical" for a buggy w/ regard to diff and shock oils (balance front to rear). we'll see...
Saturday, Jun 19 2010 (about 5 years ago)
Serpent S811 "Cobra" 1/8 Scale Competition Buggy Kit w/V2 Radio Tray
This is a good car with tons of potential. The only problem with it is the build. The Manual is not that good and there is no good setups for the car "yet" so if you are new to the hobby this might not be your car, but if you are good with setup, this is the car! I am lucky and have alot of people that I race with who helped get the car dialed and I am faster with this car than I was with my MBX-6 and my Losi. It turns so good and jumps great and so far it is strong. I know it looks like some parts are expensive but most of the parts that wear are the same. You don't need the $55 aluminum clutch because the $19 carbon clutch works great, it is a losi style clutch and the car is light and accelerates great. The car could also use some stiffer shock springs. Give the car a try you won't be sorry, after you go through the pain in the A$$ build you will love the car. Don't let people tell you the build was as easy as other cars, I have built 10 in the last 5 years and we had over 60 years of RC experience building my car and at times we were like WHAT but we did get it togeather and it is nice. Some small things you need to know if you tighten the the sway bars that go into the arms they will bind so you need to put some shims between the arm and the screw that holds the ball ends into the arms so you can tighten them down, and I would pre tap some stuff because the plastic it tough. Good luck
Jack Miller
Tuesday, Jun 8 2010 (about 5 years ago)
Serpent S811 "Cobra" 1/8 Scale Competition Buggy Kit w/V2 Radio Tray
Wow.. parts quality is top notch. Everything goes together perfectly. All parts are nicely trimmed and the manual ( all glossy ) is first rate. Glad I bought it! Drives awesome too like the others have said. P.S look at eb*y for parts.. way cheaper ;)
Daniel Toro
Monday, Jun 7 2010 (about 5 years ago)
Serpent S811 "Cobra" 1/8 Scale Competition Buggy Kit w/V2 Radio Tray
It's Amazing!!!! Point and shoot!!!! The car handles everything well, ruts, groove, bumpy, and has the most corner speed of any buggy I've ever driven....
Adrian Araneta
Wednesday, Jun 9 2010 (about 5 years ago)
Serpent S811 "Cobra" 1/8 Scale Competition Buggy Kit w/V2 Radio Tray
Our track is unforgiving, I mean a lots of bumps, ruts and some placed with plain cement. I would like to hear any honest review about the durability of this buggy. So far nice to hear the handling is a 2 thumbs up!
Monday, Feb 28 2011 (about 4 years ago)
Serpent S811 "Cobra" 1/8 Scale Competition Buggy Kit w/V2 Radio Tray
Yep had the same problem, only on one side. I agree it's a great car for thier first release into 1/8 off road.
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