MZ ETZ 250 Clutch outer pressure bearing.

[nice2day]

Sorry. Another bearing question please.
The bearing that fits in the clutch pressure worm mechanism is a 6302 type. Now considering this seems to get quite rusty and gritty (I know it shouldn't) I was thinking maybe fit a double sealed type in here to keep it fresh. It could be a metal or rubber type. The bearing only turns a short while while you decompress the cluch. Any views (Actually I know what's coming ) most will say why bother, use a normal bearing ...but to me I reckon a sealed bearing here is beneficial...
Les

[Guesi]

The bearing is turning always, not a short while.
It is connected to the crankshaft. So it will turn when the crankshaft is turning...
And it is lubricated by the gearbox oil.
If it gets rusty, then there might be water coming into the gearbox.
So you can protect the bearing from water by using a sealed bearijg, but the water will still be in the gearbox.
So try to find the reason why there is water (mostly the rubber cap of the clutch cable or the O-Ring under the rev. counter drive cover....

[Kruh]

The bearing must be an open type. Because the gearbox oil lubricates it, but it also goes thru the bearing to lubricate the rev counter worm gear.
In fact, when I take that rev counter drive cover off my bike, there is always oil that comes out as well.

[nice2day]

Many thanks Guesi and Kruh. I realised this morning I was wrong on how the clutch operates. Yes, the bearing turns with the crankshaft rotation, not just when the clutch operates so I will buy an open type bearing of C3 clearance to match the main bearings. The bike, as far as I know spent most of its life outside, and moisture may have got in, probably from the clutch cable seal or maybe it never had a gearbox oil change? Thanks again for your help chaps..it has avoided me buying the wrong bearing again

Les

[Blurredman]

This is an intesting debate.

I genuinely have forgotten whether I left the sheild/cover in or not. I know I certainly opened it up on the clutch facing side, but I think I left the worm drive side closed. However, that said, I always inspect and re-lubricate the tacho worm with standard grease when I have it apart.. I believe I did this specifically to keep oil from coming out of the engine/moisture from getting in. The grease lubricates the tacho drive so I thought that would suffice there.


You know, I think the MZ engines are quite susceptible to water/moisture ingress. There are many places that traditional oil seals aren't used but could be the weaklink- for example the clutch cable entrance is not the best, I like to put a bit of grease inside the rubber cap. Anyway, with every oil change, on both my MZ's I find it can have traces of moisture. And most people might agree. I have tried my best to keep the engines moisture free, but alas being a gearbox, If moisture does occur, it won't really burn off as it doesn't get hot enough relateively to naturally in a 4t when moisture can occur.

[Puffs]

Yes, when I drove the thing in the rain I also saw water inside, I think it entered through the clutch cable gizmo. Try to seal that off properly. Or only ride in the sunshine...

[jam23a30]

I've been told the large "O" ring under the rev counter drive is the typical culprit for moisture ingress. the suggestion was change it once a year as it flattens due to load from the clutch operating mechanism.

True or not I will be replacing mine as soon as the parts arrive

Andy

[Kruh]

I don't see that big o ring to be such an issue. Especially if its not that flat. I'm still using the original one ona mine - no leaks.
Another potentional leak is the tach drive bushing, it too has a o ring on it, and I've notice them being loose.

The clutch cable seal is an issue. I installed a brand new cable and that rubber cap/seal. But after only a few months, the cable was pretty rusty. Even though, I never ride in the rain.

Also the oil fill cap is also a breather for the gearbox, and it has a pretty large hole which is yet another place for moisture to get in.

[Blurredman]

I agree with Kruh actually- I never get oil drips from the tacho o-ring seal..