Articles

CRC Short Course Conversion

Posted:  Wednesday, February 16, 2011
Written By:  Gary Katzer
Copyright:© 2011 Horizon Hobby, Inc.

Unless you’ve been living in a cave, you’ve surely seen the recent trend in 1/10-scale off-road racing where short course trucks (SCTs) are concerned. The problem is that the SCT class has really eaten into the turnout for the stadium truck class as many people have shelved them in favor of the exploding short course class. Many have felt frustrated that their once top-tier truck is now collecting dust even though most S CTs are variants of stadium trucks. CRC, long known for their exploits building some of the best on-road and oval pan cars out there, has turned their expertise to the short course arena with a rather ingenious conversion kit for owners of XXX-T based vehicles. Combining the Desert Truck’s bumpers with some gorgeous carbon fiber, new axles and some other odds and ends, CRC makes it possible to breathe new life into your old XXX-T.


Speed Specs
CRC Short Course Conversion for XXX-T

Part Number(s): CLN7700 (w/Bumpers); CLN7701 (w/o Bumpers)
Vehicle Class/Type: Short Course Conversion
Target Audience: Owners of XXX-T Based Stadium Trucks Who Want An Awesome SCT
Completion Level: Kit

Notes:
Before you make the dive and put one of these conversions together, you need to get your hands on the right one. CRC offers two kits, one without bumpers and one with. The difference is that the CLN7701 omits bumpers and is designed for folks converting a Losi Desert Truck. The CLN7700 conversion kit includes parts for those with every other XXX-T platform truck out there. If you have an original XXX-T, XXX-T Matt Francis or Matt Francis 2, Speed-T, XXX-T Brushless RTR and more, you’ll want the CLN7700 kit. The difference in price is about $15 so, even if you have a Desert Truck you may want to spend the extra money for the full kit so you’ll have a spare set of bumpers.

If you’ve never seen or built a CRC pan car before then you’re in for a treat when you get the carbon fiber components from the conversion in your hands. They’re gorgeous! There are a couple pieces that make up the rear chassis extension along with another piece that becomes the front body mount. Frank and the guys at CRC did a great job turning out quality pieces here. Overall the conversion kit has minimal pieces and goes together easily. I was a bit bummed to see Phillips head screws included for parts of the assembly and would have preferred Allen heads, but that could just be me. If you’d like to see the build, you can check it out on our Ustream Page at http://www.ustream.tv/recorded/8986572.

To complete the build I needed several items. First was a body and, per CRC’s recommendation, I used one designed for the HPI Blitz. I was in a crunch for time so I decided to use one of the Upgrade R/C wraps. Specifically I chose the H&H Rockstar MX wrap for this body. In-all it I spent about 20-minutes on actual painting (one color, black) and about 2-hours applying the wrap. You may wonder how that was a time saver but trust me, it was.

Next I needed to add wheels and tires. The folks at Trackside had told me that the J-Concepts Bar Code tires worked well so I picked up a set. For wheels I stuck with J-Concepts and glued the Bar Codes up to a set of their Rulux wheels in white. Now the wheels I used were designed for the SC10 but, with the new axles that the conversion kit includes, they fit the bill perfectly. Wrapping everything up was my electronics package which, by-and-large, were already in the truck. That meant an Xcelorin 17.5 sensored brushless motor mated to an Xcelorin ESC. With everything locked and loaded I was ready to hit the track.

Top Speed/Acceleration:
One of the great things about this conversion is that it simply builds on what is already an awesome platform. Besides the front axles, bumpers, body mounts and chassis extension this IS my XXX-T CR. That means all the same features and benefits that I’ve come to enjoy are still here. The XXX-T CR’s drivetrain is smooth and efficient as always; however, I have found that the larger tires found on the SCTs tend to shorten the time between diff rebuilds. The XXX-T CR’s transmission is well suited for this application and worked quite well.

With the narrower wheels used on an SCT versus a traditional stadium truck you have less contact area to propel the truck forward. It didn’t matter as I was able to stand on the throttle over-and-over and the truck just scooted right along. With a wider body it did have a little more aero-drag on the straights when compared to stadium trucks but the difference was minimal.

Handling
This is where the rubber meets the road, literally and figuratively. Does this conversion handle like it should? Is it similar or better to other purpose-built SCTs on the market? I’ll tell you that the conversion is very good; again a lot of credit goes towards the base platform here. I will say this is absolutely a competitive platform in short course form. There is one handling quirk to it, and I believe it is due in large part to how the extra length of the chassis was added.

CRC used carbon fiber graphite plates to lengthen the chassis. They’re very strong but they’re also very flex-resistant. The trend in recent years has been to make the chassis more compliant and add flex to them, adding overall grip. The rear of this conversion is pretty rigid and doesn’t have much flex to it which causes the rear end of the truck to not be as planted in some situations. The truck rotates with this configuration on it more than as a stock stadium truck. That may suit some drivers, others it may not.

Jumping
I always loved the way my XXX-T CR jumped; level, flat and easy. The extra length of the chassis moved the transmission, motor, rear shock tower and shocks more rearward, changing the truck’s center of gravity. This changed how the truck jumped quite dramatically and I’ll admit I wasn’t totally expecting it. The conversion jumps with a much more nose-up attitude in stock configuration and can catch you off guard. Now there are a few things you can do to help this. One is to move the battery closer to the front of the chassis, which will make things better. Another is to add some lead in strategic places such as under the bellcranks, on top of the front bulkhead or in the front of the battery tunnel. I found lead very useful and eventually got the balance pretty close by the end of the day.

Off-Power
Whether it was the chassis setup, the J-Concepts tires or what, my truck felt planted when I needed to get on the binders. There were a few times when I got on the brakes a bit too hard and the rear end got a bit light, but never anything that was too outside the norm. The truck transferred its weight to the nose very well and allowed the front end to point the truck in the proper direction on a very consistent basis.

On-Power
This was one of those areas where the lack of flex in the graphite chassis extensions was evident. If I stayed in the groove the rear end followed the front rather obediently, however ,if I pushed the truck too hard or got out in the marbles, I would find the rear of the truck exiting the corner before the front. Going to a softer rear spring or shock oil would make this better. Another option would be to use a softer rear insert in the tires too. It wasn’t something that was horrible, but it was something noticeable.

Out-Of-The-Box Setup
Since this is a conversion of an existing platform there really wasn’t a box-stock setup to reference. Instead I’m going to compare how my truck handled as an SCT versus how the handling was as a stadium truck. They are different animals, even with the shared platform and ancestry.

Everything that I loved about my XXX-T CR was here in this conversion. It turned well, it was stable, it jumped well and it was very durable. It was a bit different in that the truck rotated more in this configuration, especially mid-corner-out and, until I added some lead, it would jump with a nose-up attitude. I played around with different springs and shock positions but I just kept coming back to my setup that I had on the truck to begin with. I guess that setup really was quite good after all.

At the end of the day, is the CRC Conversion worth the time and money? If you are looking to get some more life out of your old truck then yes, it is. It works well, it’s complete and it’s easy to install. You can also use off-the-shelf wheels designed for the SC10, which is nice. This conversion allows you to get more mileage out of your existing truck for a minimal cost.

The CRC Short Course Conversion is a very thorough and complete kit that just about anyone should be able to install in very little time. With the right tires and body you can certainly be competitive with this truck at just about any track. It is a different beast that has its own characteristics and personality; however, it does retain enough of the lineage of the base platform to have that familiarity you’re looking for. Thanks to CRC for making it easy to breathe new life into your old truck and make it new all over again.


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