Attention Sachse Ignition Users

Rocket

Rocket

Full member
Location
Melbourne
I recently started a 30 year 70,000 km service on my '81 180 SII Jota.  Early on in the process I discovered some issues concerning the Sachse ZDG3 optical trigger unit I had installed over 2 years ago (~10,000km).  As I was going to replace the primary chain I removed the ignition cover and was surprised to find cooked dust inside. After removing the primary cover followed by the Sachse rotor (S/r) from the end of the crank (also called the driver sleeve) I found it had been ground down (~0.2mm) by the spacer that sits between it and the primary cover inner bearing race.  :o See attached. As most of you will know the bearing race, spacer and the rotor should all be locked tightly together so they spin with the crank.  It would appear the S/r did not achieve a sufficient compression to ensure this and therefore allowed the spacer to spin independently of the crank and rotor.  I measured the inner bore depth of the S/r which was about 15.2mm.  The original Bosch rotor has a depth of 16.5mm, some 1.3mm difference. I contacted Volker Sachse and he replied that he was only aware of one other case of this happening and that was on his own RGS sometime last year.  He also said that when he measured the bore depths of other 'drive sleeves' they varied between 16.0mm and 16.5mm. Since then he has increased the nominated bore depth to 17.00mm

So I would suggest that all of you guys and gals out there who have fitted a Sachse ignition to a 180 SII or 120 triple last year or earlier to check under the ignition cover for signs of abnormal heat.  If you find some you will need to remove the driver sleeve and check its bore depth is sufficient to clamp hard against the spacer etc.  Volker did offer to provide another sleeve to me but I had already managed to repair the original and increase its depth to 16.2mm which seems to work OK.
I hope that it is only Volker and I who have been affected!  ::) :)

Rod
 

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Howdy Rocket ,

Gotcha now , amazing how it much clearer it becomes with a couple of nice  photos  ;)
Will check mine before the ride to the creek. Good find  :o

If i discover anything untoward will give you a shout ,

Hooksey

 
Hello Lads,
                The 180 II and 120 motors require a little extra care in regard to the ignition timing mechanicals,  that "spacer" which seals ( completes )  the crank shaft to oil seal in particular.  Dependent on type of impulse cam or timing rotor design implemented,  constant pressure is required to maintain an oil tight installation, on that spacer.  Had a few 120's that leaked oil ( pre IIS installation ) even with new oil seal installed. BTW the IIS magnet rotor has the steps on the outer face to assist correct oil seal installation ie when reversed,  its a mandrel that pushes the oil seal in square and has the correct relief's to clear the crankcase and set the oil seal at proper installation height ( depth ).  Inner depth of the IIS rotor is 17m/m  to ensure correct pressure on the spacer.  Literally spent years on my knees at the ignition timing end of an RGS motor.... oh my back.

  Anyway back to the oil leak originating from the inner diameter of the hardened spacer in question,  clean the surfaces of oil and use a suitable low strength higher temperature adhesive to seal the inner diameter of the spacer from oil leak. Apply adhesive and within 10 minutes, torque to proper working tension the impulse rotor to crank M8 fastener bolt.    This procedure has cured all 120's that i worked on,  re oil leaking issues.

* Being non or early CNC manufactured cranks,  the tolerances can be wide,  even the woodruf keyway is not always in the same spot on the crank for the 120, ( vector in this case ) a small error on the keyway produces a noticeable error on the working diameter of the impulse cam or rotor in use.  No matter whom makes the ignition,  these errors need to be allowed for in the overall design of the parts for the wide range of bikes encountered.  Sometimes the odd cranks are even more out of tolerance,  and so we all learn.

Hope that helps,  John.
 
Volker is a really nice guy and will incorparate the changed specs in the next batch for sure or will send a replacement for anybody with the same problem
 
Another penny has dropped.  Last year I installed one of Reds sump plugs (thanks again Red) with a recessed magnet.  While draining the oil I noticed that the magnet was covered by a paste that was obviously attracted to the magnet.  At first I thought it had something to do with the cam block that had broken, (the embedded nut that takes the cam cover allan bolt had broken out) but now I reckon it was the combined grindings of the spacer, rotor and crank!    :'( :'(

Thanks John for the tip on cementing the spacer to the crank.  I did that but for a different reason.  It was to lock the spacer to the crank as a small amount of play was evident as a result of the spacer being held by the oil seal and spinning on the crank, not with it. No oil leaks have been observed so far.  I will be keeping a close eye on this area for a while to come.
Rod
 

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Hi Rocket

Have you resolve the problem of the broken cam block ?

I've the same problem, and don't find a correct solution ...

Regards

Xavier
 
Yep, Redax Engineering came to the rescue yet again.  :-* A wonderful piece of engineering/art and at a very reasonable price.  Red will only let you have the complete set though (6).  It took a few cycles of head torquing/untorquing before the cam blocks would sit correctly. The cams finally spun freely enough after tightening all 12 head studs from scratch, releasing the inner 6 holding the cam blocks and then retorquing the same 6. Not sure if this did the trick but it seems reasonable as this is the way the camshafts have been removed and replaced over its life cycle.
Rocket

PS I tried to upload a picture of the new cam blocks but something is going wrong?
 
I too am honored by contributions from two of the most prolific enthusiasts on the planet.  Between Piet and Tim more than 6,200 posts have been shared with the world!  :)
Rocket
 
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