Grinding it out on the track is a great way to spend an afternoon on your dirt bike or ATV unless of course grinding it out refers to the sound coming from your transmission.
If you've been riding long enough, then you probably already know the signs of a transmission gone bad. Grinding gears is an obvious one, failure to go into gear is another as well as straight-out noisy. The most common is when the gears slip which actually feels more like your chain skipping teeth. In fact, many suspect their drive chain first as the problem before a failing transmission.
Preventing and even addressing these problems is sometimes as simple as changing the transmission fluid. In fact, checking the fluid should be a part of regular maintenance, but we'll get into that later. Otherwise, shelling out some dollars to rebuild the transmission is probably in your future.
All moving parts have a limited lifespan. Eventually, the transmission on your dirt bike or ATV needs rebuilding but there are ways to prolong the inevitable and keep you riding for years to come. A well-maintained transmission can last years and outlive most of the more complex parts on your machine, including the engine.
The majority of dirt bikes and ATVs have a manual transmission. Utility ATVs or UTVs typically have an automatic transmission. A manual transmission uses a clutch to change gears. Both transmission types are relatively simple to maintain and any significant issues should be seen promptly by a professional mechanic.
The transmission's job whether in a dirt bike, ATV or even a car, is to reduce stress on the engine. An engine doesn't operate very long at high rpms. The transmission reduces that load to bring the rpms down to a more reasonable level.
A transmission is made up of tiny moving parts including shift forks, "teeth" and other components working in unison along with the clutch (manual transmission) that stops all the moving parts in order to change gears. Without proper lubrication these parts eventually disintegrate. In fact, overtime tiny pieces of clutch debris (this is normal as clutch and transmission share the same oil) and transmission debris end up in the transmission fluid and the last thing you want is the transmission on your dirt bike or ATV using old fluid with tiny built up shards of metal washing over all the vital parts.
Check Transmission Fluid
The transmission fluid is the first thing to check if you're experiencing any transmission problems on your dirt bike or quad. Generally, it looks like engine oil since some dirt bike and ATV models use the same oil in the transmission. It should be clear and look fresh.
If the transmission oil is cloudy, black or a dark brown, it's long overdue to replace the old and pour in some new. To prevent this from ever happening follow the manufacturer's recommendations on replacing the transmission fluids. Just like engine oil needs regular replacing so does transmission fluid. Keep up on this part of maintenance and you'll go a long way towards keeping the integrity of the transmission.
Check Transmission Fluid Level
This is easy and should be done prior to ride day. Check the engine oil level and then check the transmission fluid level. Every time. Running your dirt bike or ATV with low transmission fluid is just like running the engine with low oil. The delicate parts inside shifting you from gear to gear need lubrication which also prevents over-heating. In fact, smelling burnt transmission oil/fluid could mean it's low since that causes more wear on the gears and clutch.
If you're leaking transmission fluid which is evident with the pool of fluid on the garage floor or the outside of the transmission box looks drippy and constantly attracts dirt and other debris, then a gasket or seal replacement is required. There are three seals that can leak as well as two or three gaskets. Usually, transmission leaks occur in a seal near the shifter or at the front sprocket. Fixing this as soon as possible is crucial to the life of the transmission.
As vital as transmission oil is to the life of your machine the maintenance is fairly straight-forward and simple. Always refer to the owner's manual of your dirt bike or ATV to know when to change the fluid and with what type of oil. You might get away with using the same oil you pour into the crankcase which is the case for most 4-stroke models except for Hondas. In fact, for these models changing the oil equals changing the transmission oil/fluid. Others, like all 2-strokes, require specific gear oil like 80w/90 for the transmission. Also, keep an eye on riding hours. Make it easy on yourself and use a meter. Once you've hit that hour mark it's time to change the transmission fluid.
If it's time to rebuild, have no fear. It's a job, for sure, but grab a bearing kit and replace all the worn parts.
Written By: AndrewT