How To is what we do. Our Adventure Maintenance course is built around making a bush mechanic out of you. Instead of boring you to death with theory and whiteboards, we get down and dirty. Changing tyres, fix a clutch, repair engine cases, rescue a drowned bike and learning how to diagnose electrical problems are just some of the skills you’ll come away with. It’s the ultimate course to get you hands on with your own machine and get you out of trouble in the real world.
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Imagine the situation. You’re in the middle of the forest, miles from anywhere. What ever the reason, your clutch in on a downward spiral. It’s starting to slip, forward drive is disappearing and you’re sweating on it. That right there, is not a good situation. Once a clutch starts slipping, the path off the cliff edge is short and steep.
But fear not. All is not lost. We can solve this. You CAN fix a clutch.
A slipping clutch is a very simple problem to understand. A standard wet clutch is made of two baskets and two sets of plates. The inner basket is connected to the conrod and piston piston and so is moving when the engine is running. The outer is connected via some gears to the drivetrain (gearbox and rear wheel). The two sets of plates consist of metal (Aluminium or Steel) and fibre (also called friction). The metal plates connect to the inner basket and the fibre plates to the outer. These plates are squeezed together or pulled apart using a sprung outer plate. When they are squeezed together you have drive. As you pull the clutch lever in, the pressure is relieved and drive is removed.
So a clutch slips when the Fibre plates have worn to the point that they can no longer grip the steel plates. It’s really that simple.
There are several reasons a clutch ends up in this state.
- The clutch is simply old. It’s been used for a long time without replacement.
- The cable (if you have a cable clutch) has had no free play at the lever. It has been slipping the clutch slightly for an extended period and worn the plates out.
- The rider has slipped the clutch continuously with the engine under load. Think driving constantly with the clutch half in. Common causes for this are lack of experience and difficult riding such as bad mud or sand.
Understanding the mechanics allows us to tackle the problem easily. Ideal scenario one is that we have a full pack or a few spare fibre plates. Fibre plates are figuratively cheaper than a pack of instant ramen so carry some. They can be as cheap as £15 ($20). If that is the case, jump for joy. You’ll have a new clutch inside an hour.
If you don’t then it sucks to be you. All however, is not lost. The situation is salvageable. You can try roughing the fibres up a little or you can go old school and make the bike fixed drive. That is achieved by breaking a fibre plate in two and stacking the halves. This makes the fibre plate effectively too thick, but it’ll provide plenty of grip on those metal plates. Riding without a clutch is hard but it really is possible. We’ll have a guide in the coming months on doing this and at that point, we’ll update the article.
Changing your clutch is medium difficulty job. If you’ve used a few tools here and there, possess some patience and aren’t prone to snapping every bolt you go near you should be okay. It’s a job where patience is your biggest friend. We’re going to start the process by laying the bike on it’s side, with the clutch cover facing up. By doing this, oil loss will close to zero and access to the clutch is very easy. It’s worth noting that the clutch cover is on different sides on different bikes.
Once it’s over, you need to move any parts obstructing the removal of the cover. For example, the left hand side cover on the F 800 GS we’re working on, is obstructed by the footpeg assembly and gear lever. That means all of the above have to be removed. We released the clutch cable from the arm to make life easier. The oil filler cap also needs to be removed as well. On the F 800 GS it’s a full depth dipstick and might catch on removal of the cover.
Next up, remove all the bolts from the cover. Clutch covers are often held on with a plethora of bolts. Ideally it’s nice to keep them in order but when you’re out in the wilds, the lack of space to contain them is a limitation. For this reason, keep them somewhere clean instead. We’ll show you how to figure out what bolts go where later.
With the cover off and in hand, be aware that there are often little washers and loose bits that can get dropped. Remember they exist and that they have to go back where you found them. With the cover off, it’s time to remove the pressure plate (That’s the plate with all the bolts on it). These bolts have springs under them. They won’t be tight but they will have long threads and be under sprung tension. Generally it’s good practice to work with grouped bolts like this by undoing or doing up in a star pattern.
Bolts undone? Time to lift that plate off. Be extra careful here. There is often another washer and occasionally a tiny ball bearing that can be lost into the ether. Keep your eyes peeled.
The final step is to check the clutch plates and diagnose the problem. Before you remove any plates, pay careful attention to the order. All clutch packs are assembled differently. On the F 800 GS you can see the top plate is staggered from the plates below. If you’re aware your clutch has been slipping heavily you need to do something about it, as we mentioned earlier. When you remove the plates, note what plate sits in the bottom too. This can sometimes be a completely different size or shape plate than the rest of the clutch pack. You can just see in the images that the metal plates are rounded slightly on one side. Make sure they go back in the same way as you pull them out.
The last point of re-installing the clutch plates, is that fibres need oil to prevent premature wear. Ideally you’d bathe them for a while, but if you’re on the trail you can get away with smearing some from inside the cases. Reassembly is a matter of working backwards from this point. It’s worth noting that the bolts that hold the pressure plate on should be tightened in a star pattern. Even more important is that they are very easily over tightened. The torque number is generally about 10nm. Ideally you’d check your owners manual but if you don’t have one to hand and google isn’t helping work to that principle, If you don’t know what that feels like, wind each bolt down until they’re seated and then go a touch more. It really is only a small amount of tension, so don’t over do it. Remember to always work in the star pattern as shown in the image below.
After you’ve gone backward through the steps, you should be at a point where it’s time to tighten down the clutch cover. To figure out which bolts go in which holes, lay the cover in place. Now put all the bolts in the holes. You’ll see that most of the bolts sit at the same height, with a few sitting high and few sitting low. What you’re looking for is a situation like the image below, where all the bolts are sitting at the same height. When you’ve got that magical scenario, tighten them down in a similar way to the clutch pressure plate. As with that, the torque won’t be a lot as you’re threading into aluminium, so be gentle.
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