Sachs Clutch Lock

Let me preface this: there is not another thread on this subject already. I don’t wanna hear it.

I have a Sachs Westlake with a 504 engine. The crankshaft used to lock up on it and after many clutch rebuilds, I never did figure out why. Chalked it up to bad bearings.

So I rebuilt it with a 505 D shaft and a Derbi Motplat flywheel. Set the timing and bam fires right up, sounds great.

Only sometimes when pedal staring the bike, the pedals lock up. When you go to turn the flywheel, it moves, but comes to a dead stop in either direction after 90 ish degrees either way. Felt like a busted or stuck ring so i took the head off - everything looked great. Reduced the problem to the clutch.

Does anyone know what can make a Sachs clutch lock up? It’s assembled perfectly according to the manual. It has probably less than 0.5mm of play. The clutch hub (gear that all clutch components slide onto) looks a little worn, like it’s had a tough life. I can try to take a photo. I’m wondering if maybe the rotation is causing the metal clutch plates to bind up on the hub and restrict them from sliding in and out like they’re supposed to. What do you guys think? Is there a way to modify athe parts to reduce the chances of binding? Thank you.

AlSO: sometimes upon rebuilding the clutch, the bike starts but revs and the clutch does not engage the back wheel at all, further suggesting that the plates are bound up on the hub. Maybe I just need to buy a full clutch assembly. Does anyone have a decent one for sale?

Re: Sachs Clutch Lock

are the slots in your clutch bell all notchy? they can get grooves in them from the little tabs on the clutch plates and cause the plates to hang up.

if you could pop the clutch off and get pictures of everything, it would help a bunch

Re: Sachs Clutch Lock

Sean Colvin /


That’s exactly the kind of info I’m looking for! Never heard that before. Will take a look!

Re: Sachs Clutch Lock

Where on the stroke is it binding? Is it the same spot every time? With the additional 2mm of stroke the piston goes up and down an extra mm so cutting down the piston skirt or using a thicker base gasket could be needed to not make contact. The only time I’ve had a Sachs clutch not engage is when either the nut backs off, or the pads glaze over.

Re: Sachs Clutch Lock

Sean Colvin /

The nut is backing off, even using red loctite!! Which is crazy! Torque monster. I’ll have to double nut it, though I figure I’ll have to modify the nuts to have a lower profile so they can both fit behind the little bell thingy that engages the clutches to start the bike. Hasn’t locked up on me in a couple days. Seems like it’s definitely that center hub, which has some small ridges that have formed in it. I flipped it 180 and I think that has done the trick for now, until the other side begins to wear the same. No bike has ever been such a challenge to sort out! Updates when I get the double nutz on.

Re: Sachs Clutch Lock

Dan the mope Conway /

Hmm... I had the similar problem and it had to do with shimming of the pads... The starter bell center lug shaft had broken off when I had gotten my Sachs suburban and I found that the clutch hub gear had teeth SLIGHTLY chewed up and imperfect, ordered a new starter bell and gear and immediately it ran as it should.

Very stupid clutch design, but miraculously works great.

Re: Sachs Clutch Lock

♣Slew Foot♣ /

Saks are odd somewhere slap together one way summer slap together another I have found in the factory diagrams that a washer goes before the clutch Bell that's only on some older models and if you put one on a newer model it freaking locks on there and it messes everything up other times it's required it's like a crapshoot so you try it without first and then after exhausting all your shipping and everything it's still don't work then you put that washer there and it works some of the clutches had pins in the donuts others had to gang some had three gang clutches there was even a 1-gang clutch with a special weighted donut and it will get you to 45 but it was a Spanish model when they assembled them in New Jersey they basically just had Big mix parts boxes and just put one part on to another willy-nilly if it fit it went out the door

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