# A Review of mking's Fun-XT Chassis



## TK Solver (Mar 18, 2004)

I really enjoy racing X-Tractions and I've posted comments and results of time trials now and then. I was recently sent a "Fun-XT" by mking and I'm impressed.

The chassis arrived in a dressed up Altoids tin, displaying a detailed illustration of "The AFX Magnatraction Chassis" on the top and a listing of the ingredients on the bottom. Inside was a JL-XT chassis with wide pick-up shoes, matched magnets, and o-ring front tires. The ingredients listing also said that the gear train was buffed with a wire brush to reduce friction and that the box included stock rear tires "treated with Pam for buttery goodness".

Opening the tin, the chassis was tucked in nicely along with two extra sets of rear tires. The tires are on the car appeared to be stock JL rears and low-profile o-rings up front. Just a quick spin of the wheels with my fingers and I could feel that the gear train was smooth. It was time for some testing.

My track is a four-lane Tomy road course on a 12x6 table. Each lane is 82 feet. There are six long straights and seven different curved areas. The fast time is 6.154 seconds for a SG+ F1 car, with typical times for "magnet cars" in the upper 6's and low 7's. 

I group X-Tractions, Magnatractions, and Tyco HP7s together in a variety of "classes" including XT Tuners, XT Muscle, GT Sports Cars, and GTP Race Cars. I try to match the best chassis with the GTP cars and those chassis get low profile silicone tires in the back and front wheels/tires to lower the car. The fast time (was) 8.863 for a Silk Cut Jaguar with the average at 9.110 for the 21 GTP XT's in my collection. The average time for the 30 cars in the GT Sports Car XT group (Vipers, Ferraris, BMWs, etc.) is 9.255. Those cars also get hand picked chassis and silicone tires in the rear. The average time for the 16 XT Tuners is 10.138. They run all stock parts. The average time for the rest of the XT cars is 10.313 and they run mostly stock parts.

I also have 90 JLTO's and the average time for those in 13.375 with the fastest being a Corvette Gran Sport at 12.172 and the slowest at 14.299.

Whenever I get a new XT, I time in the chassis first, without a body. Typically, these times are in the low 9's but I can usually tell if a chassis has potential. I ran about 50 laps with several of my existing cars to get warmed up and then put the mking Fun-XT chassis on the track. It timed in at 8.884 on its 10th lap which was better than average but I was holding back because it jumped the slot a couple times in two different curves on previous laps. It coasted well. It accelerated well out of the turns. It definitely had potential. I just couldn't stay in the throttle as long as I wanted to.

Fast but "jumpy" chassis often handle the curves better with narrow pick-up shoes and this one responded well to the switch. It ran an 8.513. Anything below 8.75 gets my attention as a prospect for use with the GT cars. But I was gaining confidence in this chassis and started trying different rear tires. A gummy Weird Jacks set included in the tin helped some and I got it down to 8.427. A set of Buds silicones got it down to 8.241 and I was licking my chops to try a set of Buds low-profile Tuff-Ones silicones. Anything below 8.25 is a prospect for my GTP cars. I knocked off a couple of laps around 8.1 with very little effort and then focused on a fast lap and ran a 7.795 -- one of the best ever.

I cleaned the tires and put a Silver Toyota GTP body on it and cruised a couple laps in around 9.1 each before putting the hammer down on lap 3. The monitor read 8.736, smashing the old fast time by .127 seconds! Just to make sure I wasn't leaving some speed on the table, I tried swapping the wide pick-ups back on but it got jumpy again. Swapping back, it ran sub 9's over and over. That Toyota has never been happier. There is a slight drag as the car is sitting so low but the speed and handling through the turns easily overcomes it.

There is no doubt that buffing the gears makes a big difference. You can see the difference in the mesh and as I said earlier, the car "felt" smooth just rolling in my fingers. I can't easily test the significance of the matched magnets as I don't know how the magnets in the rest of my cars match up. The o-rings up front lower the car. The chassis responds well to lowering the rear too, and handles the speed well with silicones back there.

I had a blast testing this and wound up with the fastest XT in my collection when it was finished. Yeeha!

- TK Solver


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## Scafremon (Dec 11, 2006)

Very nice write-up! 

What do the narrow pick-up shoes do to improve a fast/jumpy chassis?


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## roadrner (Jul 21, 1999)

Nothing. Check the track connections, guide pins and tire roundness.  rr


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## TK Solver (Mar 18, 2004)

Nothing? You don't think the stepped shoe interacts differently with the track than the flat shoe? I see a difference every time I make a switch. Without exception, the wide, stepped shoes result in quicker acceleration on the straights and less control in the corners. The car becomes more sensitive. Same track, tires and guide pins. A faster chassis does best with the narrow shoes but some of the slower chassis can be perked up a bit by using wide shoes.


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## micyou03 (Apr 8, 2003)

I find the wide shoes to be better all around.


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