HD clutch for the 100-125 Sachs engine

[john durrill]

Has anyone on in the group ever built or seen a 12 spring clutch for the Sachs engine?
 We have some direction on the how and good reasons for the why from the fellow in Holland that Road races  Sachs 125's ( he is the guy with the straight cuts on the liquid cooled rotary valve 38 HP 125 B engine). He runs some vintage enduro events in europe also.
 before we start on this would like some input from anyone that has some knowledge of one.
John & Peter

 

[Gavin Housh]

John, I've never seen a 12 spring clutch for a Sachs motor but J.P. Morgan in San Francisco has expressed intrest in converting the stocker to an all steel clutch. He says that to ride the 125 the way it should be ridden the stock fiber clutch plates wear so quickly that by the end of a moto the clutch lever pulls all the way to the handle bar before it starts to disengage the clutch. Now I haven't had the same amount of wear that he is talking about, but then I don't slip the clutch as much as he does. J.P. no longer owns a 125 so he hasn't had the opportunity to have to make the modification. However he did say that it wouldn't take much more work than mesuring the thickness of the stock (NEW) fiber plates and then take some old ones and grind off the fiber material. Then you could stack up your modified plates to the same thickness of the stock fiber plates. You would probably have to use a surface grinder to get your modified plates to add up to the right thickness. I know this dosn't answer your question but it does address the need for a clutch that won't wear as quickly as the stock one. Who knows if this modification would work and if the stock spring configuration would have the correct pressure to work with the steel plates. Something to think about anyway. Gavin

 

[john durrill]

Thanks for the input Gavin,
  we have never had any trouble with the stock Sachs clutch. its considered by many as bullet proof. But I think that's for things like the ISDT and enduros. MX would require adjusting how you used the clutch and would be based on what state the of tune the motor is in.
 You can beef up the existing clutch by adding 3 springs indexed at 120 Deg. place them in-between the existing springs.
 retainers have to be added the clutch housing to keep the springs in place. rivets or small screws will work. care needs to be taken to not to weaken the housing.
 The folks that road race this engine in Europe do this and it holds up.
 We want to do this to  our 125 / 175 as a safety measure. The little 175 as a good bit more torque than a stock or even a hot 125 of equal power,
 we were hoping someone in the group had one and we could get some specifics on the materials used.
John & Peter

 

[john durrill]

We did the upgrade last weekend to a 12 spring clutch. it seems to work great but the pull on the lever increased significantly. we guess 10 lbs.
 I had the long Magura power levers off my sons 1975 175 Piner to try and that reduced the pull to stock .
 Gavin , if the fibers are wearing that fast its due to slippage. either buy the rider or due to not enough spring preasure or both. talked to Larry last week ( he MX'ed the 125 a lot ) and he had no clutch problems. I would ask him how he rode the 125 and adapt your style to his.
 If someone wants i can e-mail them how we did the 12 spring conversion or post it here if there is enough interest. you would just need a drill press and the right screws, a tap , very good loc-tite  plus 3 extra springs.
John & Peter

 

[Dennis Jones]

John on a different note on my Wassell trials bike I removed every third spring trying to get better feel. Clutch pull is very light and after a season trials I've had no problems. Just another way to adjust our toys.

Dennis Jones