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For those of you who think you might have a slipping clutch, check this out.
I have an '82 GS1100GK, shaftie of course. It's been a pretty good running bike, strong and always reliable. However, I've noticed that it has this tendency to slip during hard acceleration. Around 5,500-6,000 RPM, the engine will "break away," especially in second or third.
I never complained about it too much - what do I really need to run it that hard for anyway, right?
Anyway, today my father and I were going to do a little run out to Skyline Drive (you Virginia area riders know what I'm talking about). We got to a stop sign, and he asked me if the bike was running okay and all. "Sure, let's do it," I said, and we pulled away. Except this time, instead of the usual smooth acceleration, I got this horrendous grinding noise. The GS putzed through the intersection, and my dad pulled around the bend, not realizing that I wasn't just giving him space, but actually couldn't get going.
I called a buddy and we trailered the bike back to the house. We did some diagnostics on it. You could let the clutch out in any gear, and nothing would happen. No wheel spinning, nada, zip, not even grinding. So I took the clutch cover off, and thinking of all the grinding and the sudden failure, I expected to find a clutch that had literally exploded. But lo and behold, the clutch was in great shape! I miked it, and it was well within spec. There was no way this thing was slipping.
We did some other tests, including backing the boot off of the u-joint, and placing a wrench on one of the bolts to lock the shaft. Then, we tried to turn the rear wheel, and it did, in fact, turn. This meant that the problem had to be rear of where the u-joint bolted up; either the u-joint itself, the splines between the shaft and the rear drive, or the rear drive box, I thought.
Well, we took it all apart. U-joint was fine. Splines were fine. We tried to move the final drive around with the wheel on the ground, locking the input splines with a spare drive shaft. We couldn't get it to turn - which left us pretty confused. It had slipped before, we thought, so why was it now engaged?
In an effort to do some visual examination, we took the final drive unit off. That was when the problem became obvious. There was metal dust all over in there - it looked like a brake drum. The teeth on the Rear Joint Assembly (part no. 14 in the Rear Wheel diagram on BikeBandit) were almost totally worn away, except about a 1/16" of material on the very outside edge, which we presume the teeth on the final drive didn't touch because when the whole wheel assembly was compressed within the bike, the teeth were pushed in past that point. When we'd taken the wheel off, the final drive unit came out a little bit - enough to engage with the 1/16" of normal gear tooth left, which explained why we couldn't turn it on the ground.
Suddenly, the powerband slippage made sense. It wasn't my clutch letting loose - it was the little bit of friction holding that rear wheel joint together giving up, and the final drive teeth spinning loose and progressively shaving down the Rear Joint Assy. teeth, until one day it had just had it.
I know that's a long story, but I thought it would be worth sharing with you all. When the 50,000th GS newbie comes along complaining of mysterious clutch slippage, you might point him/her in this direction. I don't really need any help from the experts here...I pretty much know what to do.
There is one thing, though...Any ideas for alternatives to paying BikeBandit an exorbitant $115 for one of these bits? I feel like paying that much for this chunk, I might as well have an encounter with a bandit. Is remachining a reasonable option? Or does anyone, I dunno, have one laying around they'd like to sell?
Happy riding, gang. I'll be on the road with you again shortly, I hope.
-Dominic
I have an '82 GS1100GK, shaftie of course. It's been a pretty good running bike, strong and always reliable. However, I've noticed that it has this tendency to slip during hard acceleration. Around 5,500-6,000 RPM, the engine will "break away," especially in second or third.
I never complained about it too much - what do I really need to run it that hard for anyway, right?
Anyway, today my father and I were going to do a little run out to Skyline Drive (you Virginia area riders know what I'm talking about). We got to a stop sign, and he asked me if the bike was running okay and all. "Sure, let's do it," I said, and we pulled away. Except this time, instead of the usual smooth acceleration, I got this horrendous grinding noise. The GS putzed through the intersection, and my dad pulled around the bend, not realizing that I wasn't just giving him space, but actually couldn't get going.I called a buddy and we trailered the bike back to the house. We did some diagnostics on it. You could let the clutch out in any gear, and nothing would happen. No wheel spinning, nada, zip, not even grinding. So I took the clutch cover off, and thinking of all the grinding and the sudden failure, I expected to find a clutch that had literally exploded. But lo and behold, the clutch was in great shape! I miked it, and it was well within spec. There was no way this thing was slipping.
We did some other tests, including backing the boot off of the u-joint, and placing a wrench on one of the bolts to lock the shaft. Then, we tried to turn the rear wheel, and it did, in fact, turn. This meant that the problem had to be rear of where the u-joint bolted up; either the u-joint itself, the splines between the shaft and the rear drive, or the rear drive box, I thought.
Well, we took it all apart. U-joint was fine. Splines were fine. We tried to move the final drive around with the wheel on the ground, locking the input splines with a spare drive shaft. We couldn't get it to turn - which left us pretty confused. It had slipped before, we thought, so why was it now engaged?
In an effort to do some visual examination, we took the final drive unit off. That was when the problem became obvious. There was metal dust all over in there - it looked like a brake drum. The teeth on the Rear Joint Assembly (part no. 14 in the Rear Wheel diagram on BikeBandit) were almost totally worn away, except about a 1/16" of material on the very outside edge, which we presume the teeth on the final drive didn't touch because when the whole wheel assembly was compressed within the bike, the teeth were pushed in past that point. When we'd taken the wheel off, the final drive unit came out a little bit - enough to engage with the 1/16" of normal gear tooth left, which explained why we couldn't turn it on the ground.
Suddenly, the powerband slippage made sense. It wasn't my clutch letting loose - it was the little bit of friction holding that rear wheel joint together giving up, and the final drive teeth spinning loose and progressively shaving down the Rear Joint Assy. teeth, until one day it had just had it.
I know that's a long story, but I thought it would be worth sharing with you all. When the 50,000th GS newbie comes along complaining of mysterious clutch slippage, you might point him/her in this direction. I don't really need any help from the experts here...I pretty much know what to do.
There is one thing, though...Any ideas for alternatives to paying BikeBandit an exorbitant $115 for one of these bits? I feel like paying that much for this chunk, I might as well have an encounter with a bandit. Is remachining a reasonable option? Or does anyone, I dunno, have one laying around they'd like to sell?
Happy riding, gang. I'll be on the road with you again shortly, I hope.
-Dominic
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