Honda-SOHC
SOHC.co.uk Forums => Other Bikes => Topic started by: MrDavo on March 08, 2021, 02:49:41 PM
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I assembled the transmission side of my 1974 Z1A project, only to find a gearshift that was refusing to centre and staying at whichever angle you put it.
Clearly something is wrong, and it needs fixing.
The clutch was adjusted and frees off perfectly, and without the transmission cover fitted the gearchange return works absolutely fine. If I just loosen the four cover bolts the gearchange shaft frees up, but that's with the the bolts so loose you couldn't run it like that.
My suspicion was a bent gearchange rod, when I got the bike (in bits) the cover wasn't fitted, and the shaft could have been bent in storage if all the engines weight had ever been put on it. Suspiciously about the only spare part the bike came with was another gear change shaft, so I decided to change it anyway as the splines for the lever were in better condition. Here it is fitted, and all working perfectly. The return spring is the correct 3 turn early one. It is the shorter modified type, so there is no issue with the spring fouling the boss with the dowel. I presume I've got the arms into drum selector right, unless you can see different.
(https://i.postimg.cc/rpt9KfdM/IMG-5187.jpg)
Happy with my work, I put the covers and sprocket etc back on, I checked all was working well before I tightened the cover up, all was fine.
Then I tightened the cover up - and its binding again, no attempt by the lever to return to centre if you push it up or down. Bugger!
The bosses on the inside of the mission cover are pefect, so its not going crooked when tightening up. I have backed off the clutch adjuster, so the cover isn't being tightened against the clutch pushrod. There's not that many things it could now possibly be. I'm wondering whether to replace the three oil seals the gearchange shaft goes through in case they have turned to stone over time and are causing the drag, but I'm not hopeful - they would drag just as much before the cover is tightened. Also, it can't be a sideways endfloat issue causing binding, as the shaft is free to slide as far as it wants in and out of the cover inside those oil seals.
I'm assuming the parts in my bike aren't that unique, so someone is hopefully reading this thinking 'been there, done that!' I hope so, it has me stumped at the moment.
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No knowledge in this project area Dave but logically if you have changed the shaft, its either the replacement shaft is also bent or the cover is out - does not seem probable but there's only 2 reference points. Have you checked the run out of the removed shaft? This is once again unlikely but you say the spring was modded - could there be a slightly changed casing thats slightly different. Probably (like you) grasping at straws but worth throwing in the hat.
What does the Z1 owners forum have to say?
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Throwing out straws but the weld on the shaft looks new and big, you could check the boss inside the cover to see if its binding on the weld
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Thanks for the replies. The weld on the shaft is stock - here's one for sale, just the same as is my other shaft.
(https://www.picclickimg.com/d/l400/pict/293861833406_/Kawasaki-Genuine-Used-Gear-Change-Shaft-Z1.jpg)
There is no weld at the back of the quadrant to shaft join and that's the moving part up against the boss on the casting. There is no pinching when I put the inner cover on, only the mission cover makes it stiff, and the shaft is quite at liberty to slide sideways in the cover. I agree with Phil it has to be the shaft or the cover, there are no other options. The modified spring was a change by the factory, I have the later, shorter type which doesn't foul the boss on the casting.
I carefully checked to see if there were spacers or washers I was missing but no joy in the parts book. I think the oil seals are clutching at straws myself but I may give them a try. I don't see what could possibly be out of line with the cover, there's no damage or missing bits, but something's not right. Could those oil seals be on the p*ss?
What does the Z1 owners forum have to say?
Crickets so far.
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That's a bit of a conundrum to say the least, is there any way you can check that the lever end is 90 deg to the shaft ?
On such a long shaft that might become an issue?
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Silly question, are the gaskets too thin? I know Honda calculated the gasket thickness into any clearance
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Possible to make a crude-ish set of V blocks in wood to suspend the gearshaft in, then you can rotate it to check alignment more easily?
Just a couple of V in plywood fixed at each end of a 4x2 to allow you to rotate and observe condition.
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I think it’s unlikely that we’ll spot a bent shaft in a photo that you (or I, anyway) can’t see by eye.
I agree that it HAS to be the shaft or the cover, there really are no other candidates. I thought about gasket thickness, and considered a mod to the inner cover from a service bulletin but there is no sign of a problem when the selector is assembled and the inner cover tightened, only when the outer mission cover goes on. If there was a need to rectify a problem the service mod would already have been done in the bike’s previous life.
Bullet bitten, new shaft and selector ordered from Z Power. It’s a PMC replica part still being produced, I suppose as long as riders are beggering up the splines people will need them.
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What makes me think it must be an alignment issue is the fact that everything is 100% perfect until those last few turns on the bolts that secure the transmission outer cover. If the gearchange was fouling inside its cover then it would happen all the time, not just on final tightening of the outer cover.
I think the shaft HAS to be bent or else there is a problem with the cover, but that has been used, and there is no damage or wear. Also the cover locates on a couple of dowels on the crankcase so no misalignment is possible. Ok I'd have 2 bent shafts, but that part is quite vulnerable when the engine is out and the transmission cover is taken off, which it soon is to disconnect the clutch cable. After that point if the engine is moved around like that, a heck of a lot of side load can be put on that shaft without really realising it.
Looking back at my rebuild thread, here is the engine going in, and the shaft is totally unsupported by the transmission cover, as it had been since we brought it home from Essex in a van. The cover was wrapped up and put away to save it from scratches, in the meantime that shaft was always vulnerable to getting bent.
(https://i.postimg.cc/qRs8vFHh/IMG-4647.jpg)
That photo was posted last August, so we've come on a bit since then (!).
My philosophy, wherever possible, is 'do it once and do it properly'. To that end I have bitten the bullet and ordered from Z Power the 3 oil seals and a new gearchange shaft. If it doesn't fix the problem there will be a great wailing and gnashing of teeth, but if you eliminate all the possibilities the solution should be there.
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Right this is driving me bloody nuts. The job is stopped until the issue gets sorted out.
As I see it, the problem can only lie in the gearchange mechanism or the cover, there literally aren't any other parts for it to be.
I have fitted a new gearchange spindle with the selector mechanism, and checked that the fouling as per the two service bulletins isn't the issue. I have the 3 spring coil with the shorter 'legs' that don't foul the centre boss, and until the outer cover is fully tightened, everything is working just fine. The cover looks fine, but is a Z1B one, according to John Brookes' book. If it made a difference I'm certain that someone would have documented it, so I'm assuming all covers (z1 to Z900) are interchangeable, except for chain oiler issues. please tell me if I'm wrong.
The cover has no damage that I can see, and all 4 mounting points still have the original miiled finish, so one isn't shorter. Locating the 4 mounting dowels is a faff, but possible, maybe it should be easier. If the cover (or the posts with the locating holes) was bent at all I shouldn't be able to locate all 4 dowels at all, you'd think. getting the 4 bolts in place and tightened isn't a problem.
However, after I cleaned up the hole with wet and dry, put in new oil seals, greased the shaft, and all was well until I tightened up the rear lower mounting bolt, then the same problem, the gear lever suddenly doesn't want to centre any more. Something is slightly on the p!$$ somewhere, and once the cover is tightened we have binding against the shaft where it passes through the cover. I can't leave the cover less tight, or use spacers / washers to change the alignment as then I would probably have clutch adjustment issues.
The new PMC gear selector rod was anodised black. A carp out of focus photo I know, but, where the gear rod crosses the frame tube, you can see a witness mark which corresponds to the hole thorough the alloy casing. I wondered about just getting this hole drilled oversize, but then you have support issues, and could bend or damage the inadequately supported gearchange when using it.
(https://i.postimg.cc/zB3KT76j/IMG-5204.jpg)
This has to be sorted. Although I can't see what's wrong, I eliminated the shaft by replacing it with a new one, now I need to try another cover.
DK have an OK one for sale (it will be a challenge to match the professionally polished finish of the existing cover) but off a later bike than mine. Firstly, does that matter? Secondly, before I take the plunge, can anyone loan me a Z1 transmission cover to try first? It can be in any state as long as its all there, and preferably in the Greater Manchester region so I can pop by to pick up and return it, but I'll go farther afield if necessary, or pay any necessary postage.
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The only 2 things that can tighten that, straight, shaft are:-
1 the holes not in line when casing done up
2 the distance between the boss inside cover and boss in crackcase too small.
You could check 1 with a close fitting drill shank or dowel and 2 by trapping a lump of plastecine in there and measuring it
Hope that helps a bit
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Similar to Bryan's checks, could you use graphogen on the shaft where it comes through the cover to see if it improves at all, any significant improvement would confirm alignment pinching.
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Thanks for the feedback, I don’t think (2) is an issue because the gear change is perfect until the outer case is nipped up. I think the fact that the rear lower dowel takes a bit of persuading to line up is a clue.
I did try cleaning up the hole in the cover and using plenty of grease, still binding. I could try a dab of Redline assembly paste, I’ve got no graphogen. I am keen to try another cover, but not if I pay through the nose for one and find no difference, like the shaft.
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Could also try bolting cover up correctly with no shaft, then place the shaft in to the case the wrong way (just until it gets past the lever spline) from the outside just to see if you can "sight" it up as having misalignment in any direction.
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That could be interesting, I’ll give it a shot.
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I decided I had to try another cover, so I put out an appeal on the Z1 owners forum. Within a few hours i was riding to Rochdale to pick one up.
Guess what? If you replace the cover as well as the shaft, it still binds! Impossible but true. At least I didn’t waste another £75 or so to find out. The guy I borrowed the cover from had suggested I try a washer between the cover and crankcase, in the corner that makes it bind when tightened, the lower left. Nothing to lose, I tried it, using a small spring washer over the dowel and it works! I can fully tighten up the cover without binding.
It shouldn’t work, but it does. I can’t work out why, but life’s too short to overly worry about it. Next job is to reassemble with all the parts I left out to get to the bottom of things, and check I still have a free gear change, and clutch action.
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I decided I had to try another cover, so I put out an appeal on the Z1 owners forum. Within a few hours i was riding to Rochdale to pick one up.
Guess what? If you replace the cover as well as the shaft, it still binds! Impossible but true. At least I didn’t waste another £75 or so to find out. The guy I borrowed the cover from had suggested I try a washer between the cover and crankcase, in the corner that makes it bind when tightened, the lower left. Nothing to lose, I tried it, using a small spring washer over the dowel and it works! I can fully tighten up the cover without binding.
It shouldn’t work, but it does. I can’t work out why, but life’s too short to overly worry about it. Next job is to reassemble with all the parts I left out to get to the bottom of things, and check I still have a free gear change, and clutch action.
That's properly mental. Will the gasket seal properly with the washer in place?
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No gasket, the cover is the one that Honda call the ‘mission cover’.
It is supported at each of its 4 corners, with through bolts that screw into the crankcase, and dowels on the case to locate the cover. I wonder if the dowel in the problem corner may be damaged somehow, possibly slightly ovalled, but it’s hard to check as it’s embedded on the crank case and in an awkward place. It’s the sort of thing you should sort out before you put the engine in the frame. :-\
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As you say Dave, may be the dowel - mayby bent to one side (i.e., at an angle?) which is countered by the insertion of the washer changing the cover angle to match the dowel. You could open up the hole in the cover where the dowel enters (although you may not want to 'bastardise' te cover)
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No gasket, the cover is the one that Honda call the ‘mission cover’.
It is supported at each of its 4 corners, with through bolts that screw into the crankcase, and dowels on the case to locate the cover. I wonder if the dowel in the problem corner may be damaged somehow, possibly slightly ovalled, but it’s hard to check as it’s embedded on the crank case and in an awkward place. It’s the sort of thing you should sort out before you put the engine in the frame. :-\
Ah of course. Sounds like you've got a pragmatic and workable solution there Dave. But still bloody annoying...