Quick Fix: MR-03 Front Suspension

Early articles this month since it's final exams week and I'm taking a vacation for Christmas.

If you're like me, then you like your racing Mini-Z's to have as low a ride height as possible without scrubbing the track. However, with the introduction of the MR-03 comes a slight problem: you can't lower the car enough without 1) having the knuckles hit the C-clip bumpstops on the kingpins, and/or 2) putting way, way too much preload on the front springs, causing a visible bending of the front suspension arms. Although I don't have any way of addressing issue #1 at the moment, I've gotten around #2, and this week's article will be a quick tutorial for reducing the amount of spring preload in your MR-03W front end. (Yes, unfortunately, this method only works on the wide front end. Narrow-chassis fans will have to figure something else out.)

The first thing to notice is that the spring perches (the black bar between the front body clip and the springs) that Kyosho provides for the MR-03 chassis are pretty beefy. The thickness of that piece is what causes so much preload in a lowered MR-03, hence I went out to find something that could hold the spring just as well, but was much thinner.

Behold, the Atomic MR-02 spring perches.



These are molded from plastic, and turn out to be just the right diameter to fit inside MR-03 front springs. They are, however, a very tight fit, so after pulling them off the tree, use side cutters to cut the perches short (you'll need about 1mm of height on the "chimney" portion). Look at the picture to see what I mean. After you clip them, they'll probably be deformed, so use some toothless pliers to press them back into shape. Then pop the MR-03 springs onto your modified perches, they should be a tight fit but with nothing restricting the springs' compression.

Next, prepare the front body clip.



Grab two 2mm-diameter screws (4mm length is better, 6mm max), put them through the bottom of the front clip and superglue them in. I realize not all of us have the new PN aluminum front body clips, but as long as you don't race with a million different bodies then you can do this to a couple body clips without running out of screws. If you have short dowel pins, those will work just as well.

As soon as the glue sets, go ahead and pop your springs-mounted-on-perches onto the screws, and then install the front clip back on the chassis like normal.



You should notice that there's noticeably less spring preload now, this is all due to the Atomic spring perches having a very thin stack height. This should smooth out the driving behavior of lowered MR-03's, at least it'll be a worthwhile DIY until someone comes out with shortened springs.

Also, if you have washers underneath your body mount, you may want to be cautious of the screws protruding out the bottom.



With the PN aluminum body mount this is a non-issue, but if these screws do protrude lower than the rest of the chassis, consider using a dremel to grind the heads flat. (Or you could use special low-profile-head screws, I know they exist but I've never had any.)

So that's it, a quick and easy way to reduce unwanted spring preload in your MR-03W's front suspension. I've only driven the car a little since I did this mod, but the reduced preload seems to bring with it a lot more steering; I hope you guys and gals will find the same improvement. Enjoy!