Can a sprag clutch wear out?

[mikeb01]

Originally Posted by ricknaz

This is the answer in most cases. I went through all of this last year. I suspected the torque limiter from the start but I was told by mechanics that it would be the sprag. After spending money on parts and tools I wasn't happy the first time I hit the starter after doing the job only to hear the starter freewheeling again.

There is a simple test to determine whether you have a sprag problem or a torque limiter problem. Remove the torque limiter and draw a line on it like in the photo below. Put it back in and press the starter button until you hear the freewheeling sound. Pull it out and i'll bet the marks don't line up any more.



If you find that you're torque limiter is slipping you can disassemble it and add a washer to increase the pressure on the gears. You can see the washer I added to mine here. It's a bit tricky to line up the 3 large gears when you put it back together. Don't bother trying to line them up when you press them back together. If you put the small gear in a vice you can turn the upper and lower gears individually with a big pair of multi grips until they line up with the centre gear.



I used a bearing puller like this one to do the job.

I had the dreaded slipping happening on the starter clutch / torque limiter on my EC450 2009 model.

I noticed that the front plate of the torque limiter that sits immediately behind the circlip was slightly concave around the circlip/washer, which was reducing the pressure on the friction plates. I removed the circlip and pulled the stack of plates off and noticed the other side was identical - the plate stack is symmetrical, and because the other side sits behind those concave washers it was in perfect condition.

So I reassembled with the plate stack reversed, squashed it together in a vise with a couple bits of wood to protect it so I could fit the circlip, and now my bike starts beautifully. I did not need to shim it at all!

Your post was very helpful in identifying the problem so thanks very much!