Gearbox Issues

[Agronski]

Look at pages 19 and 70 in the pdf manual - the sliding 1st-and-3rd combined gear on the mainshaft is what you care about. It should move along the mainshaft towards the fixed gear at the splined "main sprocket" end of the clutchshaft (i.e. not the end with the gearshift) . When the gearbox is in 3rd, the gap between the smooth side of the moving gear cluster on the mainshaft, and the fixed gear that meshes with the main sprocket gear on the end of the clutch shaft, should be 13mm.

If that's still confusing, you can double-check by counting gearteeth and comparing the assembled gearbox with figure 38 (page 21).

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[suzukix7]

Many thanks for your reply mate, I'm having a go at it today!!!
When joining the crankcase halves back together, do I have to put the right hand crank bearing on the crankshaft first and drift the casing over the bearing, or put the bearing in the crankcase and drift the whole crankcase over the crankshaft?

Many Thanks

Dave

[Agronski]

Going by the manual, the process is:
1 - heat left crankcase, install bearings
2 - heat case-half with bearings, install crank, shafts, gearbox etc.
3 - heat right-hand case half
4 - while the case is still hot, apply jointing compound and screw case halves together (check alignment on gearshaft 6004 bearing!)
5 - heat right-hand bearing with mandrel, install over righ-hand crank *while right-hand case half is still warm*

If you try and install the bearing first, as you force the case down onto the bearing you will put a differential axial load on the inner and outer races of the crank bearing, which is a Bad Thing. Heat the casehalves in the oven or on a hotplate, and ideally heat only the _inner_ of the bearings by means of a mandel - if you heat the whole bearing, the outer race will be a much tighter fit into the case. What you're aiming for is expansion of the inner to facilitate a smooth fit over the cool crank, and a cool outer to facilitate a smooth fit into the warm crankcase half. If you have a lathe (or a friend with one) you could use one of these: http://www.sweller.co.uk/mz/tools/tls_htmand.html

Let us know how it goes - fortunately my TS doesn't need her main bearings changed, but I'm curious about how easy it might be when she _does_ need 'em...
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[suzukix7]

Thanks for that mate.

I thought I would replace my crank bearings as I was splitting the cases anyway to look at the gearbox.
I've ended up taking all the shafts out today and replaced all the gearbox bearings as a matter of course and I have taken the selector mechanism out too as I'm not convinced it's working properly. There looks to be some wear on the selector quadrant on the first two cut outs but I'm being picky to be honest. I've ordered a new quadrant and spring as the gear change claws don't seem to be far enough over to engage fully on the quadrant. It is difficult to simulate a gear change whilst trying to hold the casing firm, turn the gears and operate the gear change though!!
I will fit the new parts and put the clusters in and put it back together!!! I am tearing my already thinning hair out with this, especially as I've put quite a bit of cash in already.
Do you know any MZ mechanics in the Midlands area, or any other areas for that matter?

Dave

[Agronski]

The TS150 gearbox is a masterpiece of engineering covering up a lack of sophistication and an awful design ethos of 'make it cheap, make it zero-maintenance and make it from aluminium'. They weren't really designed for servicing, from the feel of things - more for bumbling around East German streets at 45kmph year after year with a twice-yearly Autobahn trek to Zchopau and back to clear the pipes and requisition a new spark plug from the factory...

If the windows in the quadrant really are worn out (surprising, but not impossible) that might be the entire problem. More likely is a worn retaining plate, weak return spring, or bent quadrant-piece - see https://www.gabors-mz-laden.de/pic_show ... .002_1.jpg - the manual calls that "elastic", but I think they mean "flexible". See also the note about the MM/3 gearboxes on page 70 of the pdf manual where it explains the adjustment/alignment of the quadrant/dogs.

Stick with it - it's a very simple gearbox, you should be able to get it back to nominal after a bit of trying. As for finding a mechanic - I'd be surprised if you could find one that's even heard of MZ, let alone worked on one - unless they specialise in older bikes. Either way, it won't be cheap. Welcome to the wonderful world of owning a 'Classic' - less of a hobby, more a very expensive form of masochism

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[suzukix7]

Ok, if I had any hair left I would have pulled it out by now!!
Bike is now jumping out of gear in top instead of 3rd!!!!
I have replaced clutch plates, adjusted clutch so that the adjuster screw is just about touching the pushrod, clutch is as near to slipping as I dare.
It engages gears fine but then just jumps out of top gear even after being engaged for a miles or so without warning! chain is adjusted correctly, it's even had a new cush drive! Bike was stripped and gearbox adjusted correctly with no visible worn dogs/pinions. Quadrant was renewed as well as selector fork and spring and ball bearing!!
If I stripped it down again I wouldn't do anything different, also replaced all gbox bearings too!!
Spent far too much money and time on this now, any ideas guys what this could be??

Dave

[MichaelTorre]

Did you ever get to the bottom of this, ?

Regards,
M