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RJ Speed Spec Mod

Posted by River Rat RC on August 27, 2015 at 2:05 PM

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Assembly of the Spec Modified was very straight forward. Each step has an matching labeled photograph which I found helpful. Step 1 had a very important hint. An integral part of the construction of the car is the use of plastic chassis spacers. The hint in Step 1 suggests using a 4-40 tap to thread the spacers before trying to screw in the 5-40 x 3/8″ hex screws. I did not do that and wish I had. The assembly process would have been a lot easier. If you have a tap, USE IT! If you don’t have one, get one. If you can’t then you can use my little trick. I was able to get the screws started into the spacers but was not able to get a good enough grip on them with my hand to fully tighten them. To get around the problem, I got them threaded enough to loosely assemble the car. Then, with a second hex wrench, I turned the screws in opposite directions until they were tight.

 

I ran into one issue on Step 13.rjspeed ball stud This step is where you thread two ball studs into the holes in the rear body mount plate. The red arrow in the photo to the left shows the finished dampeners that attach to the ball studs. The first ball stud went in tightly but threaded in without a problem. However, the second one snapped off in the hole. At first, I assumed I had not been paying attention and had over torqued the ball stud. However, after looking closely, the ball stud was not near bottomed out in the hole. A quick email to RJ Speed, explaining the issue, had a new body mount and pair of ball studs arriving a few days later. In an effort not to run into the same problem again, I opened up the holes, ever so slightly, with a thin X-Acto knife. This time, the ball studs threaded into the body mount without issues.

 

Once the basic chassis is assembled, it is time to install the king pins and steering blocks. Here are a few tips for Steps 17 and 18. In step 17 you mount the king pins to the front suspension arms. However, before you do that, the instructions suggest you hold the king pin by the threads, in a hand drill and use some very find sandpaper, and then some metal polish to make the surface of the king pins smooth. This is a very important step in order to make sure the steering block move smoothly up and down on the king pings, as well as, turn easily.

 

Step 18 covers assembly of the steering block. After pressing the stub axle into the steering block, the instructions suggest you run a 1/8 ” drill bit through the hole before you put the steering block into the king pin. This is very important. The hole in one of the steering blocks was very tight and required multiple passes of the drill bit through the hole. I also had to use a thin X-Acto blade to clean up the edges of the holes. Another hint is to use some light grease or silicone lube on the king pins to insure smooth operation. My silicone lube of choice is Bud’s Racing Products #7640 Silicone Lube. It works great on king pins, as well as, ball differentials. Once the king pins are lubed, slide the steering blocks on to them, followed by a spring, a washer and e-clip.

 

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The underside of the car shows the split rear pod setup. The Legend car had a completely solid chassis.

The next few steps cover the assembly of the ball diff, installing the Oilite bushings and adapters, hubs and axle into the rear pod. When you put the diff balls into the 48 pitch spur gear, make sure you use some silicone lube. I’m going to reveal a secret that racing legend Bud Bartos showed me years ago. Well, at least I think he did. Basically squirt some of Bud’s Silicone Lube into an old pill vial (after removing the old pills!) and then put the diff balls in the vial. Shake them vigorously until the balls are coated evenly with the lube. Then pluck them out and put them evenly around the spur gear in the outermost holes. In addition to lube on the balls, I put a thin coating on the diff rings as well. I usually keep a large quantity of diff balls in the vial and use them as needed. Whenever I rebuild a ball diff, I use new balls.

 

Getting the axle to spin smoothly in the Oilite bushings can be tricky. Fear not, however, as the folks at RJ Speed are quick with the hints. Make sure you lube the bushings with a little oil and then slide the axle through the bushings. Attach a drill to the non-diff side of the axle and slowly rotate the axle with the drill. This will serve to break in the surface of the bushings. Make sure you keep the bushings oiled and slide the axle from side to side. This trick really worked well!

 

Rear end of the Spec Modified.

Rear end of the Spec Modified. The DuraTrax motor is installed. The rear dampeners control how much traction goes to the rear tires.

When you attach the left side wheel hub and have it so that the axle spins freely in the rear pod without too much play, tighten the grub screw. It should leave a slight impression in the surface of the axle. If you are worried about it not making enough of a mark, you can apply a marker to the end of the grub screw that touches the axle. When you tighten the screw, it should mark the axle. Remove the axle from the pod and then carefully file or grind a flat spot into the axle surface. This is highly recommended so that the wheel hub will not slip on the axle.

 

The rest of the assembly is pretty straight forward. Just make sure you follow the steps and consult the helpful photographs.

 

Running Gear

The old school Novak 410-HPc ESC sits atop the battery tray (left). The Futaba S132H high speed servo.

The old school Novak 410-HPc ESC sits atop the battery tray (left). The Futaba S132H high speed servo.

Part of what makes the Legends car and the Spec Modified racing so competitive are the rules. Basically, if it does not say something is allowed in the rules, you can’t do it. Here is a link to the Spec Modified rules. A set of the rules are included in the instruction manual for your reference. For running gear, I went with a mix of old school and new. The new school gear was in the form of the motor, battery and radio. I went with the recommended DuraTrax Photon Speed 2 Brushed Motor. This is a stock motor that is used in Legends class racing and will also be used for Spec Modified. I also went purchased a DuraTrax Onyx 2000 Battery. It is a 7.2V, 2000mAh NiMH six cell pack. This is a widely acceptable configuration for Legends and Spec Modified. Check with your local track as to what they are allowing. You may find “Pro” class which will allow 1S LiPo batteries and brushless motors. The final new gear that I purchased was a FlySky GT-3C 2.4GHz Radio Controller and three channel receiver. This radio is very popular with many members of my local RC club, First Coast Bashers of Jacksonville, FL. The radio is very high-tech and is loaded with features, yet it is very reasonably priced. It can control up to 10 different models. You can name each model on the big, bright digital display. The Flysky GT-3C does not use AA batteries. Instead, it comes with a rechargeable LiPo battery pack that you can charge right in the radio by connecting the included USB cord to your computer or a wall adapter. It saves money and weight. Additional receivers can be found online for under $10!

 

The DuraTrax battery is mounted on the bottom of the car to keep the center of gravity as low as possible.

The DuraTrax battery is mounted on the bottom of the car to keep the center of gravity as low as possible.

For old school gear, I went with a vintage Novak 410-HPc electronic speed controller and a Futaba FS-132H high speed steering servo. Both are long discontinued and in fact, had not seen the light of day since 1992. I was extremely happy that they both worked as if they were brand new.

 

I mounted the battery on the left side of the car. This keeps as much weight to the inside of the car to help turn more easily on an oval. I used two old PureTech battery straps to secure the battery in place. The black one goes around the battery from end to end, keeping it from moving back and forth in the car. The smaller, pink one wraps around the battery and the left side of the chassis, stopping it from shifting side to side. The instructions suggest using a strap end to end and use an adhesive Velcro strip between the battery and the battery plate to keep it from moving side to side. Eventually, that’s probably the way I will go. However until I’m positive of where I like the battery, I’ll go with the extra strap.

 

The Body

 

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As you may know from reading previous articles, I had a very long time away from the RC hobby. Over 20 years to be exact. The two vehicles I’ve reviewed so far on this site were both ready-to-run and came with pre-painted bodies. The RJ Speed Spec Modified came with an unpainted body, so I was going to be forced to put my old spray can paint skills to the test. It would be one thing if I was painting it just for myself. However, since I was going to be revealing it here on www.rccentric.com, the pressure was on.

 

rjspeedvertThe body came with a sheet of pre-cut mask for the windows, as well as the “air filter”. They came in very handy and made it easy to block off the windows so they would remain clear after the paint was finished. I purchased some Lexan spray paint from Tamiya, deciding on bright red for the base with blue for the accents. In addition to the provided window masks, I got some Frog Tape from the hardware store. Frog Tape is a multi-surface masking tape normally used for house painting. It is supposed to make clean lines while not leaving any residue when removed. I used it to mask off the sides as well as the hood and the stripe on the roof.

 

I cut and fitted the body to the car while it was still clear, which makes it easier to see where the holes for the body posts should be made, as well as, cutting holes for the the wheel openings, steering linkages and nerf bars. Once cut, I applied the Frog Tape to the outside of the body to prevent over spray. Over spray is what can happen when using spray cans to paint the body. A mist is produce when painting and it can hang in the air and sometimes become deposited on the outside of the body. Wait, you say. Didn’t Wally say in the beginning of the article, that the body came with a protective film on the outside? Yes I did but I forgot that fact when I was preparing the body.

 

I laid down a number of light coats of red, taking care not to put on too much paint during any one coat. If you apply too much paint at one time, it can get very thick and can also create drips. I allowed the body to dry completely between each coat. I used a hair dryer to help speed up the drying process. If you use a hair dryer, please be careful not to get the dryer too close to the paint. It can bubble and do all sorts of other ugly things to the paint.

 

After I was happy with the coverage of the red paint, I removed the tape from the inside of the hood, roof and sides of the car. What I did not notice was the circular piece of pre-cut mask for the “air filter” came off with the tape from the hood. The multiple light coats of blue paint followed. Normally, I would have laid down a coat or two of silver or white to seal off the red paint and prevent any of the blue coming through the red. Remember, when painting Lexan, you lay one coat behind the other. This is reverse of traditional painting where you apply the base and then paint the accent colors over the top of the base. In this case, I didn’t have any white or silver and was too impatient to wait until I could get some. I took extra care to make sure I limited the amount of overlap of the blue over the red so there was no bleeding through.

 

Once all the paint was dry, I removed the masks from the windows and the Frog Tape from the outside of the body. It was then that I realized there was the handy protective film on the body. I also noticed the air filter mask had been replaced by blue paint. In order not to look like a total noob, I took some adhesive backed vinyl diamond plate chrome material and cut it out to cover the air filter. A black Sharpie marker was used to define the edges of the air filter. Thin black automotive pin stripe tape was used to add a finishing touch to the edges of the windows. Finally, I dug deep into my box of vintage decals to complete the body. All told, I was pretty happy with the way it came out. Not bad for a 23 year layoff, eh?

 

Road Test

While I plan to eventually race the RJ Speed Spec Modified car on a regular basis in the northern and central Florida area, I was not able to test it at a track in time for this article. I charged up the DuraTrax battery and headed to a nearby office park on a sunny Saturday afternoon to see how the Spec Modified performed.

 

With the battery connected and body attached, I turned on the FlySky GT-3C transmitter first, then I turned on the car. You never want to turn on the car before the radio. You always run the risk of the car lurching or taking off before you get the radio on. The GT-3C bound to the tiny 3 channel receiver immediately. I tweaked the steering trim just a touch and adjusted the ESC so the power was right where I wanted it.

 

I set up an informal oval to test on, by laying out a couple of baseball hats from the back of my car. I always recommend setting up some sort of objects to drive around so that you are not just driving aimlessly around a big parking lot.

 

The steering and throttle were very responsive and the DuraTrax motor/battery combination provided plenty of power. While the parking lot looked clean, there was a fair amount of grit, which made it difficult to make sharp turns without the car spinning out. I added a small spoiler to the back of the Spec Modified which did help. Adjusting the dampeners on the rear pod helped a bit as well but I think I really needed some tire traction compound to increase the grip on the rear tires. Even without traction compound on an ungroomed parking lot, the car handled well overall.

 

I think that Rick Jordan and RJ Speed has really hit the mark with the Spec Modified. It is a logical next step for those that want to move up from the Legends car. It is also an excellent choice for an experienced racer, like me, who wants to be able to do some car tuning but still race in a limited cost, spec class.

 

Look for a follow up article after I’ve had some time to get this car to the track a few times.

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