The Hyper 9 detailed by its lead designer,
Tim Bump

Introduction  
   
I want to thank HoBao and OFNA for the opportunity to lead the Hyper 9 project. It was a pleasure working with one of the finest engineering teams in the R/C industry, which included the owner of HoBao, Daimler Chu.

The Hyper 9 is a completely new design from the ground up with many new and innovative ideas. Several criteria were set and met in this new design. Weight was number one and always a concern with every part designed for the buggy. Next, in order of importance, was side to side balance, low center of gravity, ground clearance, all on as narrow a chassis as possible. On the performance side, the buggy had to accelerate, corner, jump and land better than any other buggy on the market. In this article I will reveal many of the new and secret design features of the Hyper 9.

  
   

     
   
Note: Some pictures are of the prototype model taken at OFNA's Black Ops Department (If you see any food crumbs on my kitchen counter, don't blame my wife Jenni. I got hungry while snapping these shots). The shape of some parts have changed on the production car, but all the geometry is the same.

  
   

Pictures of Hyper 9 as seen at the RCX Show in Pomona

     

     

       

   
New! Video of Hyper 9 at Revelation Raceway


This was the first run of the preproduction Hyper 9 with Jeremy Kortz driving. The test went very well.
   
Keep it Light  
   
The number one goal in the new design was to keep the Hyper 9 light weight. Reduced weight equals faster acceleration and cornering speed. Smaller 8x14mm bearings have been used throughout the chassis (except for the rear 8x16mm wheel hub bearings). The number of screws was reduced, the plastic was reduced and the amount of aluminum used was reduced.  The part count in total has also been reduced.  
   
Chassis Balance  
   
The engine was moved toward the center by using a 40 tooth spur gear and keeping the 13 tooth clutch bell. In doing this, the center drive line angles are also straighter, reducing scrub on the joint pins.
Moving the engine closer to the center drive line did not allow room for the rear brake on the center outdrive, so the disk was moved to the rear pinion shaft.
The engine was then angled 25 degrees toward the center for four reasons. 1. Allowed clearance between engine mount flange and center drive shaft. 2. Moved weight toward center of chassis. 3. Lowered center of gravity. 4. Pulled pipe toward center of chassis. All this combined with the asymmetric aluminum chassis plate balances the buggy left to right with a half tank of fuel.  
   
Ground Clearance  
   
Ground clearance has been something overlooked for years by most 1/8 scale designs. The chassis has been shortened for clearance front and rear while keeping the same wheel base as the Hyper 8.5. The bend for the 10 degree kick up in the nose has been moved forward as much as possible to increase clearance. The aluminum chassis plate has been reduced in size, cut on all four corners, and the side guards have been angled up for extra clearance. This is especially important when the chassis leans and squats while exiting a corner.
 
   
Gearing  
   
The buggy accelerates and has greater top end speed because of the 11/43 gear combination at the front/rear gear boxes and the 13/40 combination at the center differential. The faster spinning center differential also reduces the torque effect of the engine.  
   
Low Center of Gravity  
   
Here is a list of items on the chassis that has been lowered for a lower center of gravity; steering servo, throttle servo, engine, radio box, center differential, all brake hardware, shock towers, rear wing, air filter and the fuel tank.
   
Better Cornering and Better Jumping  
   
Most of the testing for the new Hyper 9 was setting roll center points front and rear for better balance through the corners and better jumping. The new buggy has better matching roll centers that make the buggy more consistent as the track conditions change. The front roll center was lowered quit a bit while the rear only a little.
The Hyper 9 runs stiffer front springs, and the front end rides higher. This, combined with the reduced weight, allows the buggy to jump farther (chassis does not scrub off speed on face of jump) and recovers from landings faster (chassis does not bottom out as hard).
   
Front C-Hub and Steering Knuckles  
   
The C-hub and steering knuckle has been reduced in size and weight. The kingpin axes are directly in the center of the front tires. This reduces the shock on the steering servo when hitting rocks, holes and pipes. Front bump-steer has been eliminated with longer front tie rods and better alignment.

 
Note: The steering knuckle is deceivingly strong for its size.
Front Kick-Up and Caster  
   
The chassis has a 10 degree kick-up with 20 degrees total caster. The bend in the kick-up has also been moved forward to increase ground clearance aft of bulkhead.
 
   
Adjustable Ackerman  
   
The ackerman is a very important adjustment and sometimes overlooked by most racers. The Hyper 9 has three ackerman positions for steering from mild to wild. The ackerman is adjusted by changing the ackerman wire in the center of the servo saver. While I am on the subject of the ackerman wire, I found aluminum ackerman plates with bushings and screws bend, brake and fall apart. I found that a 2.8mm wire to be much more reliable, tighter and more consistent. I knew people were going to think the wire was cheap, but the performance and reliability proved to be much better. A great example of when simple is better.
   
Throttle/Brake Linkage  
   
The throttle/brake bellcrank is angled 25 degrees inline with the carburetor so no binding occurs. The bellcrank also allows the servo to be laid down and moved forward for better weight distribution. The brake linkage is a very simple wire with a z-bend, not a bunch of little parts held together with bolts and nuts. Brake bias is very easily adjusted with a nylon nut on the threaded rod end. Another example of when simple is better.

   
Low-End Needle Adjustment  
   
The low-end needle is very easy to adjust, and in most cases easier than traditional buggy designs. The body only has to be lifted a few millimeters and the needle can be seen through the side window. You also do not need a long screw driver because the carburetor is closer to the right side of the buggy. Another plus is the idle stop screw is easier to adjust.
   
Rear Wing  
   
The rear wing mount is a small block mounted on the rear shock tower and the formula style wing is held on by four screws. The mounting area on the wing is thick to prevent braking and tearing. This greatly reduces the weight and lowers the CG. A more traditional wing mount will be available as an option part so racers can use different wings.
   
Fuel Tank  
   
The fuel tank is made oversize with a filler insert that screws down inside to allow the tank to be adjusted to maximum capacity. The tank lid is designed to provide a perfect seal every time it is closed even when the tank is hot or cold. This is due to the newly designed spring touching only the middle of the self centering lid with a V-shaped seal.
   
Shocks  
   
Still testing.
   
Sway Bar Mounts  
   
Sway bars are held in place by two set screws angled to allow for different diameter wires.
   
Miscellaneous  
   

Right side guard is tall to protect servos and forms the lower have of the receiver/battery box. The number of screws you have to remove to take out radio is the same as the old buggy because of the one piece design.
   
The suspension arm fingers at the outer ends of the front and rear lower arms are shorter to eliminate flex.
   
The differentials are the same diameter and have the same fluid capacity as the old ones, but are a few millimeters shorter.
   
Rear Toe is adjustable from 2 to 6 degrees total. Rear anti-squat is adjustable from 1,2, and 3 degrees.