Sachs 505 Clutch Issues

Haden Asay /
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Hello everyone,

My 1980 Sachs Suburban with a 505 1/d, unfortunately, still hasn't seen much riding. I have now had the clutch apart at least a dozen times with varying results. The bike is completely stock and it great condition with around 800 miles on it. Here is everything that I was able to find out:

With the stock 1.2mm shim in, there is no axial play and the clutch is always fully engaged. With this, I was easily able to get the bike up to just under 30mph, but of course, it would die at stops.

With three 0.2mm shims in, there is optimal axial play (between 0.4mm and 0.6mm) and I can get the bike to idle at stops, but it seems as though the clutch never fully engages because, at full throttle, the bike only gets up to around 15mph. When the bike is idling on the stand, the rear wheel is always spinning, I can stop it with the brake and the bike will still idle, but when I let off the brake, the rear wheel starts spinning again.

I then decided to try and see if I could get the bike to idle on the stand without the rear wheel spinning so I took out all of the shims and ran it like that, but this had the same results. The rear wheel would continue to spin when I let off the brake. The bike's idle sounds fine so I don't think that it's just idling too high and I can't get the idle any lower without it dying.

I also tried out running four and five 0.2mm shims and had the same results as three, except the bike was harder to pedal with the engine disengaged, as expected. I would have also expected to be able to go faster than 15mph with more shims, but no dice there somehow.

I was having issues with the center gear hub and the plates hanging up on certain spots of it, but I was able to remedy that by sanding those spots down. All plates move freely along the gear. The two fiber plates appear to be in great condition, one is 3.5mm thick and the other is 3.4mm. I've scuffed them up with 200 grit sandpaper multiple times. I am completely clueless as to what might be causing my issues. I am considering buying 0.1mm shims and/or the aftermarket clutch plates sold by lucky2 strokes and playing around with those, but it is entirely possible that my problem is somewhere else and I would just be wasting money.

Any suggestions would be greatly appreciated. Hopefully, with some help here, I can finally this thing out on the road as the clutch is the only thing holding me back. Thank you.


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