Right side brake rotor protection

When you compete in cross-country races, you know that having skid plates are very important on most courses. There are some that you could get away with not running one, and some that you could just maybe get lucky and not take out your sprocket if you absolutely couldn’t use one. But if you are a successful cross-country racer you can’t take the chance of hitting something and bending your brake disc or sprocket. If you damage your sprocket, you’re likely to throw your chain. If the brake rotor is bent your brake pads won’t get contact in places and in others it will bind every rotation of the axle.
One of the major issues when running a skid plate is ground clearance. The sprocket and rotor are already the lowest point on your ATV.  A skid plate could take as much as 2 more inches of that clearance away. When you get into a rutted course you need all the ground clearance you can get to keep from getting stuck. You just hope that the person in front of you has a lower hanging skid plate and plows it out for you.

GT Thunder Dual Sprocket Guard

If those problems aren’t enough, you then have to replace the part, and they are never cheap. For a long time, most skid plates have been very similar in design. Yeah, some people have tried out some new materials, but for the most part they have been the same. Here at ORC we have a pile of bent and broken skid plates. A major problem that we have with normal skid plates is with them coming loose. Those little 10 mm bolts that are supposed to hold on the protection from rocks gets ripped off by those same rocks.  We started drilling out and tapping the swing arm to hold bigger bolts, but that’s a lot of work, and it only delays this problem.

A Solution

Finally, GT Thunder has come up with a new solution to these problems. They have created a set of round plates that bolt on each side of the sprocket. The plates are just slightly larger in diameter than the sprocket and chain, effectively guarding them both from debris laying in your way on course. Not only does this guard your sprocket, but it also gives you more clearance. And more clearance means fewer rocks or other things of that matter to worry about. I’m not saying to put this on and go run over the biggest rock that you can find though. Although, that might be similar to what Bill Balance might have done when he was testing this product out. Bill ran these guards in the 2006 GNCC series, and once again he won another championship.

Axle moved slightly in order to install inner plate

You can guarantee that Bill wouldn’t run the guards if he thought there was even a chance they would ever fail him.
 Don’t get me wrong though, these sprocket guards will bend and when you hit them hard enough and enough times, mushroom out in the area of impact. When that happens, it’s time to replace them, but after a long period of testing 3 times a weekend at the WORCS races, we’ve yet to need to do this. The first time we used the product, we did have a problem with them. On a wet sandy track we got into the berm and the two plates packed with sand and small sticks. It packed up so tight, that the axle wouldn’t even turn. We called up GT Thunder after this problem, and they had never heard of anything like this happening before. Bill and other top GNCC riders have been testing this for GT Thunder for a while now and have never had any sticks or anything else for that matter get wedged in. Since then, we haven’t had any problems with it at all.
You could also install a regular skid plate on top of these for extra protection, but, that gets rid of your newly gained clearance. And without it, your brake isn’t protected. So, for the brake side GT Thunder created a skid plate that covers only the brake rotor. It is made from a sort of plastic material similar to what a cutting board might be made from. This has held up better to a beating than any other metal skid plate we have used in the past.

Installation

Inner Plate and sprocket in place

Installation of these plates is fairly simple, but does take a little time. The sprocket is held on with 4 allen head bolts that have to be removed in order for new longer bolts that are supplied from GT Thunder. For technical reasons, you might only install the outer plate. If that is the case, all you have to do is remove the old bolts, slide on the new plate, and bolt it on with the new bolts. But if you are installing both plates, it takes a little more time.
For the inner plate to fit over the sprocket hub, it has to go at an angle, and for that to work, the axle has to be slid slightly to the left. Since you won’t be removing the axle all the way from the swing arm, it’s not necessary to remove the right hub. First, loosen the two small set screws in the axle nut, if you forget about these it will make it a lot harder to loosen the axle nut, and if you are able to loosen it, the threads will be screwed up on your axle. Once the nut is loose, then you can take the rear caliper off. It’s ok to remove the caliper before the nut, but sometimes you will need the rear brakes to help stop the rear axle from turning when you are loosening the nut. When those two things are done you can slide the axle to the left, but there is no need to go more than a couple inches.

Dual Sprocket Guard installed

The plate that goes farthest inside (against the swing arm) is the one that is slightly recessed and is made so that the allen heads fit flat against the plate and don’t stick out. Next is the sprocket, then the sprocket hub, and finally the last plate goes to the farthest outside. Bolt these parts on with the supplied allen head bolts and lock nuts being careful not to strip the allen heads. Then it is just a matter of putting the axle back in. Work backwards from how you took it out.

Summary

Currently, both plates can only be used around the sprocket if you have a 06 or later YFZ450. If you have a 04/05 YFZ  you can only use the outer plate. GT thunder also has a kit for the TRX450R and may have others by the time you read this. Both plates are going to cost about $125, and $175 with the brake protector included.

GT Thunder
6748 TR 630
Millersburg, OH 44654
330-674-7122

http://www.gtthunder.com/