KTM’s Rubber baby buggy bumpers are only found on the 450SXF and 250/300SX.

Dear MXA,
My friend told me that my KTM have rubber bumpers inside the clutch that have to be replaced when they wear out. I took my clutch apart, but I couldn’t find any rubber bumpers. I feel like an idiot asking this question, but can you tell me where they are and how to tell if they are worn out?

Don’t feel bad. Most KTM owners have trouble finding the rubber dampers the first time they take their clutch apart. KTM has two types of clutches, the 125SX, 150SX, 250SXF and 350SXF do not have rubber bumpers, only the 450SXF and 250/300 two-stroke KTMs have rubber-damped clutches. You don’t need to take the clutch completely apart to test the damper’s condition. You do need to remove the bolt-on pressure plate ring, conical Belleville washer, spacer ring, pressure plate, clutch plates and dowel-like steel drive pins. Once you get to this point, grab the inner hub while holding the inner hub nut and wiggle the inner hub back and forth. Watch where the six posts stick up through the oval slots in the pressure plate and note if the posts are moving inside the ovalized holes. If the rubber dampers are still good, there will be very little movement from the inner hub versus the posts. They can have a little give, but if they are moving more than 1/8th of an inch, you will need to replace the six rubber dampers.

The kidney-shaped rubber bumpers allow the forces exerted by hard acceleration or landing from jumps with the throttle wide open to be absorbed, which is why DDS (Damped Diaphragm System) clutches are only found on the 450SXF and 250SX two-stroke.

To replace the rubber dampers, you need to remove the inner hub nut and lock ring. By this point, you should be able to lift the inner clutch hub plate (the part with the posts sticking through it) out of the inner hub. This will expose the rubber dampers. The rubber dampers are underneath the plate that the six posts stick through. New dampers will run about $25. Put the new dampers in your inner hub (they only fit one way), and put the clutch back together in reverse order.


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