The Dennis Kirk Blog
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Your clutch. You often don’t have to think about what’s going on down there. Simply pull the lever, shift gears, and you’re on your merry way. But when the clutch plates start to wear out, you will begin to take notice and wonder what really is happening under the clutch cover.
Fortunately, fixing a wet clutch, found on many motorcycles and dirt bikes, is not too difficult of a task to complete on your own. With the use of some common hand tools and a small part of an afternoon, you can have your clutch pack swapped out with a new one. No need to have your bike sit in a shop and accrue those high rates that can eat into your gas money and riding time.
So how do you know when it’s time to replace your clutch plates? Without visually inspecting them, you will know something is awry if you notice gear slippage. When this starts to happen, it’s time to take a closer look.
The first and most obvious problem that you may notice is if the plates have been burned. You can usually smell the difference, but you can also see the burning or bluing as well. Next obvious would be if any of the plates are warped. You can set them on a flat surface and check for rocking. You can also use a flat Feeler gauge to check for warping. With the plate flat, run the Feeler gauge underneath and check for any gaps between the plate and the flat surface. Also, visually inspect the friction plates for any broken fibers.
If none of those issues are present, there is still one more thing that you should check. Use a micrometer to check the thickness of all the plates. Your manual will provide you with the minimum thickness required for the plates to still be usable. If they are at or under the minimum thickness, it’s time for new plates.
Now that you know what to look for, it’s time to learn how to get to the plates.
First, you will need to assemble the tools and parts that needed to complete the job. The first thing that you should have is a shop manual for your specific bike. In it, you will find a list all the tools that you will need. If you don’t have a manual and need to get the job done, you can figure it out on the fly. The tools will vary per bike, but prepare with a socket set, an extension, an Allen set, a torque wrench, wrench, a flathead screwdriver, gasket sealer and shop rags.
As for parts, you will need a new clutch plate kit, with clutch cover gasket/o-ring, springs, new oil and a new oil filter.
If you know that you will be replacing the plates, soak your new ones in engine oil before you begin. The friction plates, in particular, should be well soaked in oil before installation.
The first step in accessing the clutch plates is to drain the oil. In some cases, it is possible to change the plates without totally draining the oil by leaning the bike over far enough so that the oil does not spill out. But, it is strongly recommended that you do change the oil, especially if there are loose fibers or if the plates are burned.
With the oil drained, you will then need to remove the clutch cover. On some bikes, there may be some other pieces in the way like the radiator hose, brake pedal or a peg mount. Remove these if they are present. Have some shop rags handy before you crack the cover off. There may be some residual oil leftover that could spill out on your shop floor. When loosening the clutch cover bolts, do so in a criss-cross pattern to loosen evenly. The clutch cover bolts on a lot of bikes are often of different lengths as well. To make your life easier while putting it back together, it helps to lay the bolts out in the order that you remove them and to remember where you started. If the clutch cable attaches to the cover, you will need to remove that as well.
Now that the cover has been removed, you will need to remove the pressure plate. Again, use a criss-cross pattern while loosening the pressure plate bolts. Use caution when removing these bolts, as they are spring-loaded. If there are alignment marks on the pressure plate and clutch basket, take note of them. This will help you re-align them later on. Remove all the bolts, springs and the pressure plate and set them aside.
You should now have access to the stack of clutch plates. It’s best if you can remove the whole stack in one piece. If you cannot grab the whole stack, remove them one-by-one, but be careful to put them back together in the order that you took them out. Set the stack aside in that order for now.
With the plates removed, you can now take the time to inspect the clutch basket. Look for any damage or wear to the inner and outer hubs of the basket. If you do have any noticeable grooves or nicks, you will need to replace the basket as well. You can also now check out the pressure plate springs. Many clutch plate kits come with new springs and it is wise to replace them at this time as well.
If everything checks out, you can now begin the reassembly process. Use the old plate stack as a reference for the new plates. Be sure to arrange the new, oil soaked plates in the same order as the old ones and then slip the new plates into the basket.
Next, reinstall the pressure plate, the springs and the bolts, taking note of any alignment marks that may be present. When tightening the bolts, use the criss-cross pattern again to assure that they are being tightened evenly. Use a torque wrench to give the final snug to ensure that they are all even. Your shop manual will have the specified amount of torque needed.
Before you reinstall the clutch cover, you will need to clean off the mating surface. Make sure there are no pieces of the old gasket left on the surface. If there is, use a gasket scraper to scrape off the surface. Use a contact cleaner to remove any debris and residue. Use the gasket sealer to keep the gasket in place before you mount the cover back on.
When reinstalling the clutch cover, reinstall the bolts in the order that you have them laid out in. Finger tighten to start and then torque them to spec according to your manual. Then, reinstall all remaining parts, if there are any that you had to remove to access the clutch cover.
Allow the gasket sealer to set up for the recommended time on the product label before filling the bike with oil. Once it is setup, you can fill it back up and then start the engine.
You will most likely need to adjust the clutch cable because of the new plates. Do this before you go for a ride.
And when you do go for a ride, you should notice that the clutch engages much more solidly and the slippage should be gone.