Z1A Restoration

[CAT3]

Loverly to see another Z1 returning to life & you don't look to be that far away from me either, (Stockport) !
I could lend you my front sprocket holder, but it locates in holes normally in the sprocket & I see from your photos that your sprocket doesn't appear to have those holes.

Keep the good work up though, looking forward to seeing it finished

[MrDavo]

Loverly to see another Z1 returning to life & you don't look to be that far away from me either, (Stockport) !

I was just leaving the Railway Hotel, Greenfield, yesterday when a green Z900 went past, that wasn't you was it Phil? After hours messing with the front end on my bike, I recognised another Zed instantly when it came round the corner.

Anyhow, I have fitted a BT46 to the new front wheel which had come back from Hagon. The first time I ever used proper tyre lube, boght cheap on eBay, left me wondering why I hadn't discovered it years ago, as the tyre went on so much easier. And yes, Floydsz1, I did check I had the same number of tyre levers after as I did when I started.....



Next was to fit the front discs. I knew I had a problem when I got the disc mounting bolts from Z-Power and noticed the label mentioned a special 1.0mm thread. While my hub in the past has had just a single disc, and so virgin threads on the offside, the threads in the nearside I could see were banjaxed, so at some expense I got Timeserts fitted in all 6 holes. Neither I or the shop that fitted them knew anything about a special thread, I doubt they do Timeserts in non standard threads anyway. Luckily Dave Marsden was a star, a quick exchange of emails and he had 6 suitable replacement bolts in the post to me.

Here we are, tyre on and discs fitted, this was all going too well. I'm not so keen on drilled discs, it all looks a bit cafe racer to me, but for now it is what it is.



Front wheel fitted in to forks, it all looks good but there is a mystery gap between axle spacer and fork. That however is a thread of its own in the 'Help' forum.

[CAT3]

No mate, wasn't me !

Time-Serts will be available in most thread sizes & pitche options.
The thing to remember is if you state to an engineering place you want a M8 Time-Sert fitting, unless you specify the pitch they will most likely just fit the standard 1.25 pitch, not the more unusal pitch options. The same applies to other metric thread sizes.

[Ultim8pc]

Lovely project you have there. Just picked up a z1b yesterday from Manchester way.

[Philippe]

Hi MrDavo
the lenght of the spacer of a Z1/A/B is 30,5 mm, the lenght of a spacer of a Z900A4, Z1000A1,2,3 is 27mm.
It's obviuos you have a spacer of the younger bikes which is about 3,5 mm too short.
GrtZ
Philippe

[MrDavo]

Hi Phillipe, you come to the rescue again, although we are getting the two threads mixed up.

Mine is 27.10mm, so I'm glad I took it out to measure it. Now to find the right part 41069018 according to the parts book. Johnny's in the US has them if I can't find one nearer. Thanks again this board is a mine of information.

hat's another mystery solved, I could have faffed around until Kingdom Come and it wouldn't have been right.

[MrDavo]

@ Phillipe, where did you get the 30.5mm measurement from?

I ordered a complete Z1 spindle spacer and speedo drive set (Z1 & Z1A all the same parts numbers), to my disappointment the spacer is 27mm, and using the parts as a set I have exactly the same problem.

I’ve tried turning the fork tubes in the yokes to see if they’re bent, they’re not, and loosened all the yoke bolts to see if the front end was twisted in the yokes. Nothing has worked.

I was warned before I started that building a bike that you didn’t take apart from boxes was a bit like a jigsaw puzzle where you know you don’t have all the pieces, some pieces from another puzzle, and no picture on the box.

Johnny’s motorcycles in Ohio, who I’ve bought parts from before, sells the Z1 spacer by the part number, I’m going to email him and ask if he’ll measure one for me.

A local engineering firm I know, run by a couple of bikers, would probably make a 30.5mm spacer if I was confident it was right.

[MrDavo]

I may have found the cause of my spindle problem, Someone with a lot of experience suggested the bottom yoke as a likely culprit, and I think he may be right.

Having lined and tightened everything up as best as I could,I took my measuring stick and put it across the forks at the top, so the blades of the vernier just touched the fork tubes just under the yoke.



Then I slid the vernier, without adjusting it, down to just above the oil seal... and there's a gap!



I cant measure it, as the vernier is at the extreme of its travel, but clearly the fork tubes aren't parallel. Obviously by the time you get to the bottom of the fork leg, the gap is much bigger. I have ruled out bent stanchions bu loosening the tubes and turning them, nothing happened. Assuming the top yoke is correct (my only evidence is that it came with the bike, and the clocks fit straight on) the culprit has to be the bottom yoke I think.

[Philippe]

Hi MrDavo
I own you an apologize . I gave you the wrong measurements... I was confused about the parts but I checked them out now.
Change the dimensions I gave you in my previous post!
In order to make it up to you I went on the attic of my workshop, took some spare parts and took pictures.

the parts of the Z1/A/B front spindle

As you can see the collar has one small thicker part

the front fork with the spindle mounted

The parts are mounted but not torcked up

Z1/A/B and Z900A4/Z1000 lower yoke

The lower belongs to a Z1/A/B, the upper is for a Z900A4/Z1000 mind the position where the bolt has to come, the Z1/A/B is more to the rear

Z1/ A/B and Z900A4/Z1000 upper yoke

The red one is for a Z1/A/B, the black one is for a Z900A4/Z1000

the parts of the Z900A4/Z1000 front spindle

These parts make the front spindle of a Z900A4/Z1000.

When putting the front fork in the yoke work carefully.
You have to make sure that only the bolts of the upper yoke are torqued up when putting the front fork in. Put the front wheel in and compress the lower forks until there's no more gap between the collar and the right hand lower fork. Tighten the axle clamps , start with the front and then the rear nut. Make sure you put the axle clamps in the right direction.
When all this is done you can torcque up the bolts of the lower yoke.
It should work out correctly.
Good luck
GrtZ
Philippe

[MrDavo]

Thanks for taking the trouble, Phillipe. Unfortunately having bought another axle and spacer (exactly the same) I now have 3 sets, all Z1. I'll see if I can sell the extras.

The yokes I have are definitely Z1 then, the top has the gauges bolting into the yoke, the cuts for the lower clamps are at an angle.

I had another play with the front end last night, and tried setting it up following your instructions. The results were exactly the same, I have forks too far apart at the bottom for both ends of the axle to be flush with the fork legs. I think the most likely explanation is an accident damaged lower yoke. I'll pull the front end apart again over the weekend. My wife says its like when she is knitting and has to undo it all when she finds a mistake.

I'll see if D&K will take the lower yoke back that I bought from them, at least I've painted it for them and polished the bolts. Unfortunately the two lower yokes they have in stock as for the Z1 are both the later type, with the cuts parallel to the wheel. If anyone has a Z1 lower yoke that know is straight, let me know. That said, I also need to double check the front yoke isn't twisted, by putting it on a perfectly flat surface. I know I should have done this first.

[MrDavo]

I stripped down the front end again, and swapped the yokes for the set that came with the bike. I had to drill out the screw for the steering lock, I'm going to tap it then find a grub screw the next size up. I hadn't wanted to use the original yoke, as the stem has been nicked by an angle grinder while removing the lower bearing. However I reckon if it ever snaps there I've already hit a tree or something equally solid. anyway, mission success, the spindle now fits perfectly, no mystery gap any more.

Putting a straight edge along the bottom of the yoke that came off, the cause of all my problems became obvious, I really should have tried this before I fitted it to the bike.



Front end all put back together I might have a go at building the brake calipers next. I need all the seals and pistons, I've seen full sets advertised on eBay. Brake pads seem hard to find (out of stock at places like Z Power), surprising as they are something that wears out.

[jimmock]

Looking and sounding good.

The job on the front hub, was this helecoils ??

Are they 8 x 1.25 or 8 x 1.00 ?

[MrDavo]

Hi Jimmock, they were Timeserts, a cast iron (I think) insert that was screwed into the enlarged hole. They are a lot stronger than helicoils, I was advised to have this done for something so safety critical. They were 8 x 1.25mm thread, however I realised I had a problem when Z-Power sent me 2 sets of disc bolts marked 'special 1.0mm thread'. I used them on the 'virgin' side of the hub where there had never been a disc mounted before, and Z-Power sorted me a set of 6 1.25mm thread bolts for the other side. although not the right thread, as they are screwing into iron inserts rather than alloy, it won't be a problem. Apparently I could have had 1.00mm thread Timeserts fitted, but I didn't know in time that this was a thing.

I have fitted the front brakes, here are the parts ready for building. All parts were new other than the caliper bodies, which had been professionally painted.



A trail build of one of the calipers, with new pads was too tight to fit on the disc on the side for the extra disc. A bit of head scratching made me realise I could get a bit more of a gap if I removed the paint from the mounting face for the inboard pad as the paint was quite thick. I also had to get paint out of the sliding bushes as they were tight. The calipers now fit over the discs, but only just.



Mounted on the bike, the wheel turns but they feel a little draggy. I don't see how I can possibly get more clearance, the pistons are pushed right back and the inner pad mounts now are paint free, I can only hope they will be free once they have worn in a little, but don't turn the discs blue first!



Before I fit the new four way splitter, I had to address the steering lock screw, I had to drill the old one out. here I am cutting a new thread in the hole, furtunately I hadn't used too big a drill. That all worked, I will fit the hoses and try bleeding the brakes once I get a new flexible hose to replace one that came with the bike and had the wrong fitting.



I'm starting at the front and working my way back, next I have to put some oil in the forks and fit the indicators and headlamp, to see what's what, and work out what parts I haven't got yet.

[Andrew_s]

A trail build of one of the calipers, with new pads was too tight to fit on the disc on the side for the extra disc. A bit of head scratching made me realise I could get a bit more of a gap if I removed the paint from the mounting face for the inboard pad as the paint was quite thick. I also had to get paint out of the sliding bushes as they were tight. The calipers now fit over the discs, but only just.

Mounted on the bike, the wheel turns but they feel a little draggy. I don't see how I can possibly get more clearance, the pistons are pushed right back and the inner pad mounts now are paint free, I can only hope they will be free once they have worn in a little, but don't turn the discs blue first!

Hi Dave,
Just a thought, but have you checked the depth of the discs - the twin set-up on the Z900 uses 7mm discs (the single set-up is 5mm), I'm not sure if this is the same for the Z1 (someone advise I'm sure), but it could be the PO bought oversized discs in error when he went for drilled discs?

Cheers, Andrew

[jimmock]

A trail build of one of the calipers, with new pads was too tight to fit on the disc on the side for the extra disc. A bit of head scratching made me realise I could get a bit more of a gap if I removed the paint from the mounting face for the inboard pad as the paint was quite thick. I also had to get paint out of the sliding bushes as they were tight. The calipers now fit over the discs, but only just.

Mounted on the bike, the wheel turns but they feel a little draggy. I don't see how I can possibly get more clearance, the pistons are pushed right back and the inner pad mounts now are paint free, I can only hope they will be free once they have worn in a little, but don't turn the discs blue first!

Hi Dave,
Just a thought, but have you checked the depth of the discs - the twin set-up on the Z900 uses 7mm discs (the single set-up is 5mm), I'm not sure if this is the same for the Z1 (someone advise I'm sure), but it could be the PO bought oversized discs in error when he went for drilled discs?

Cheers, Andrew

Z900 has discs with 4 bolt mounting to hub.