Rotating clocks.

[nice2day]

Just curious to know if other ETZ have found their Tacho and Speedo are very loose in the rubber housings?. .. My ones can be turned very easily and I am certain they will rotate during a ride. I suppose some owners just glue the rubbers to the circular holding frame? Maybe my ones have dried out?


Les

[Kruh]

Yes, my tacho was loose, althought the whole rubber housing was rotating. After a ride the tach would rotate a few degrees.
The rubber housings are the original ones (40 years old). Which means they got hard.

I don't like the idea of using glue.
The simplest way to fix that I've found is to just stick a bit of tape on the aluminium mount.
In particular, I used a piece of double sided tape (the softer, thicker kind), its around 1mm thick. Doesn't stick much to the rubber and can be removed easily without residue. The main point is to just add material to make it all thighter.

[DAVID THOMPSON]

a little piece of the thick rubber tape between ring and clock may help
at a location that it does not show like the rear bottom area

[nice2day]

Many thanks for your replies Kruh and David. Its always a pleasant feeling when you find that the problem you have is shared by others on their machines.
Kruh points out that it is the rubber cup assemblies that turn in the mounting and yes, that is the same with my ones and it is not the clocks turning inside the cups as I seemed to imply in my question.
So it is just a matter of using some rubber or tape in a convenient position to fix the problem and that is simple enough. I guess the original design could have been improved if there was a small cut-out or notch in the aluminium mounting frame holes and the rubber cups were moulded with a corresponding bulge to anchor them and stop the rotation. That is very unlike MZ to have missed a simple trick like that......Thanks again

PS:
I suppose if a small hole was drilled somewhere near the back of the fame holder, a self tapping screw of selected length could be screwed in to hold the rubber cup. Just one on each clock would be enough. If the hole was small and the screw actually made its thread in the aluminium rather than the rubber, the screw point just needs to protrude only about 2mm to stop the cups rotating. The screw could then be fully tightened down flush (maybe a "countersunk" screw could be used?) and painted black. This is just an idea but I don't think I have the heart to drill my mounting frame even though the mod would not be that noticeable.

[Puffs]

Following a biased and flawed moderator choice (someone posting aggressive personal attacks is rewarded, while my technical posts are removed - behind my back & without any justification!), I have withdrawn from this forum.

[nice2day]

Maybe the 251 does have a different alu holder ring then? The part number would reveal.

BY the way and I could make this another thread but I have searched many times but have never came across a Parts Book for the ETZ 250 as a complete download. I do have the 251 version and others. However many MZ parts sellers show the full listing of the ETZ 250.

Les

[Kruh]

Many thanks for your replies Kruh and David. Its always a pleasant feeling when you find that the problem you have is shared by others on their machines.
Kruh points out that it is the rubber cup assemblies that turn in the mounting and yes, that is the same with my ones and it is not the clocks turning inside the cups as I seemed to imply in my question.
So it is just a matter of using some rubber or tape in a convenient position to fix the problem and that is simple enough. I guess the original design could have been improved if there was a small cut-out or notch in the aluminium mounting frame holes and the rubber cups were moulded with a corresponding bulge to anchor them and stop the rotation. That is very unlike MZ to have missed a simple trick like that......Thanks again

PS:
I suppose if a small hole was drilled somewhere near the back of the fame holder, a self tapping screw of selected length could be screwed in to hold the rubber cup. Just one on each clock would be enough. If the hole was small and the screw actually made its thread in the aluminium rather than the rubber, the screw point just needs to protrude only about 2mm to stop the cups rotating. The screw could then be fully tightened down flush (maybe a "countersunk" screw could be used?) and painted black. This is just an idea but I don't think I have the heart to drill my mounting frame even though the mod would not be that noticeable.

To be fair to MZ, I don't think they had in mind that the housings would rotate after a few decades.
This wouldn' be an issue with new ones, them being softer and thicker (not squished like old ones), therefore more friction and less play between parts.


That screw idea is one way to fix it, but unnessecarily complicated. When the issue can be fixed by just sticking aomething between the housing and mount. And it would be a shame to do such modifications to the frame.

[Puffs]

Following a biased and flawed moderator choice (someone posting aggressive personal attacks is rewarded, while my technical posts are removed - behind my back & without any justification!), I have withdrawn from this forum.

[Blurredman]

You know, I presume you're all mainly talking about the later type of rubber holders, which typically have vertical lines above the aluminium loop.. These are softer, and have the ability to be manipulated better.

One of my bikes I have the earlier type rubber (does not have any vertical mould imprints above the aluminum loop), these are quite the opposit of what everyone is talking of here, because no matter how much I lubricate the metal to rubber surface before install, it is one of the biggest pains to get the clocks out of these rubber cups. The later type not a problem.

The earlier types can be found on mainly the lower capacity TS bikes and I think the first iteration of the TS250. The later ts250 seem to have a revised moulding, maybe MZ knew that they were so difficult to get the clocks out that they made this change. Of course, as Kruh says.. decades later they are now too loose. This is my theory.

I think the rubber stuff that MZ have used has held up extremely well. Rubber clock mounts, the foot rests and gear change rubber and of course the front gaters that still don't have any cracks!

[Kruh]

Absolutely, the rubber parts stood the test of time.
I too have the original front gaters on mine (1980), they are in great condition. Although, just as the rubber cups the gaters have gotten stiffer. Still even the cups aren't to bad.
On other old bikes they tend to get rock hard.
Only rubber pieces that didn't held up so well are the cylinder fin dampers. But I was able tu revitalize them.
Sadly, the new stuff is very poor quality. I recently installed a new rubber kickstarter stop. Now, after a few months its just as cracked as the 40 year old original one was.

[dave47]

MZ didnt miss a trick; they just stopped using it. I can't remember what MZ this came from.

[nice2day]

Great replies Thanks...

Les

[Kruh]

MZ didnt miss a trick; they just stopped using it. I can't remember what MZ this came from.

DSC_0105.JPG

Very interesting. I noticed on my TS250/1 there are notches in the aluminium, but never gave it much thought. Interestingly, despite the notches, the original rubber housings don't have that protrusion. Maybe the later years they stopped...
So I assume they used that type of rubber housing, atleast, on the earlier TS/0 models.

Edit: Just looked upa some photos, TS125/150 models had that type of housing.

[dave47]

It could have come from a ts125.
My late Supa5, 1980, didn't have those slots

[AlanJ]

Hi Guys,
Just thought I would stick me 5 penneth in. My 4 wheel chariot is a Ford Focus CC which is a steel roof convertible, and as such has rubber seals to keep the water out (very important) They are susceptible to hardening so, three times a year I spray these seals with Wurth Gummi Flege rubber care and I must tell you it works a treat, no leaks. Now, I also use it on my bike's rubber parts with good results.
Have a good one Alan.