Z900 A4 Needle roller swinging arm conversion (advice)

[Gray17]

Morning Guys,
Im currently undergoing a full restoration myself of a Z900 A4, have had all frame/chassis parts powder coated, before having this done i dissasembled the swinging arm by removing the existing spacer and phospher bearings, annoyingly damaging 1 and the spacer in the process oops!
I have read many posts regarding the standard bearings and benefits of the later Z1000 needle bearings and decided to go down the upgrade route. I bought a kit from Zpower which is German made ( so should be good quality) but instructions are in German, i tried Google translate but it didnt help as was very basic, i also emailed Zpower who gave me basic instructions. Which ive followed.
Basically the kit consists of a central machined pivot which the original lock bolt goes into, 2 needle roller bearings either side, 2 outer thrust bearings and 2 spacers (if needed).
Before sending arm for powder coating i sealed up both ends to prevent paint ingress.
I have greased up all bearings then gently tapped the 1st bearing in to just below arm surface then, tapped 2nd one until flush using piece of flat metal bar. In each case the shamfered edge went in 1st. I then repeated for the opp side. Now all 4 are in and flush i greased up the pivot shaft and inserted all the way through, it was tightish but could be pushed with fingers with force. Now its in it seems to not turn smoothly, although it will move if you hold it with grips, question is why?, as i was expecting it to move freely, theres def no side play, which is good.
So my guess is the bearings arn't in perfect allinement, so how are you supposed to get them perfect, as both sets are flush with surface, and does it matter as know when in frame and tightened the pivot will lock up forcing bearings to move.
Any thoughts or suggestions, or anyone done this and experienced similar probs?
Thanks

[sean_rfi]

I purchased exactly the same kit fro Z-Power and the German instruction had me scratching my head for a while.
On my swingarm there was a ridge/burr around the opening to the pivot tube which I carefully filed down. I also used a diamond file the create a flat smooth surface for the end/thrust bearing to mate up to. I pressed in the bearings, one at a time, with a nylon rod using a sash cramp - it took a little more force than I would like but was ok once they were moving. I set the outer bearing slightly under-flush.
When assembled the swingarm bolt rotates very smoothly.

[sean_rfi]

Sorry I had meant to include some photos on my reply...

[Gray17]

Thanks for info and photos, like you i made sure mine was perfectly smooth with no burrs before fitting, Zpower had specifcally told me to tap bearings in which i did, not particularly hard either, they are both flush with surface of arm pivot opening. I could try using a socket and push a mm or 2 further down but not sure that would make a difference unless the ends arnt 100% square and parrallel to opening, maybe I've been unlucky with mine.
Strange thing is new pivot shaft pushes in and out under moderate finger pressure, but is tight to turn, suggesting somethings either bent or slightly off, i did try each bearing on the shaft before fitting and each fitted fine and turned smoothly. If i remove the new pivot shaft i can rotate the rollers with my fingers suggesting the bearings arnt damaged, im thinking either the 4 bearings arnt in correct alinement or the swinging arm opening ive tapped them up to is slightly off, question is how do you rectify it now the bearings are in and it painted???

[sean_rfi]

I'm sure you've checked but I assume the swingarm pivot bolt is straight...

[Gray17]

Well as far as im aware the new one is, as was in sealed pack but ill check with straightedge just in case, if you mean the original pivot lock bolt, that runs inside the new pivot I havnt inserted it as yet.
Clearly somethings not quite right thats for sure.

[gray]

and if it is straight, then are the bearings all exactly in line and central. ( If 1 bearing is is slightly eccentric that could explain it)

[Gray17]

Yes i think thats the issue, question is how do i check if they are perfectly in line now there in place.
As far as im aware the swinging arm is straight, but again ill re check this. The bearings were tapped in one after the other until flat to the edge of the arm, so assuming arm hole sides have been cut squarely, due to size i would have thought bearings can only go in parrallel to tube and both bearings are touching each other with no gap between, all are greased, pivot pushes in ok but hard to turn.
I would have expected if pivot bent it would go in at all but im guessing.
Starting tomorrow going to check for straightness on swinging arm and pivot shaft, will also insert original lack bolt shaft too as if that doesnt go in easily then somethings not straight.
It seems parr for the course at mo, the bikes fighting back and at moment its winning!

[gray]

if there was some foreign material in the recess where the bearings go then that would make 1 or more bearing off centre.
A patch of rust, some powdercoating that has got by the plug you put in before sending off for the powdercoating or an imperfection in the steel of the bearing recess like a seam in the pipe or a burr from previous owner's butchery.
try putting the swingarm pivot bolt in from 1 side and tap it through till its just at the point of touching the bearing on the other side. Look in with a torch and see how central it looks from that side. then take it out and slide it in from the other side and look in and see how central it looks from the other side. If 1 side seems more off centre then that at least tells you which side is worst, so you only have to remove 1 side and see if there's an issue to se seen.
Theoretically its possible you might have deformed a bearing putting it in. As a rule of thumb bearings and seals should be fitted so the bearing or seal number is to the outside ( that way you know what to reorder before you strip a bearing out)

[Gray17]

Thank you for the information.
First i inserted the original solid, central lock bolt, which was a very tight fit, but went all the way through the new pivot without issue, but i did clean it up on the buffer wheel 1st. I looked at the angle which looked pretty central.
I then removed the new cenral pivot and pretty much did as you’ve suggested, it would appear that indeed 1 side was causing the issue.
, rather then both.
I gently tapped that side out and examined the 2 bearings, both rotated smoothly around the shaft with no sticking and all 4 were inserted writing out before the next. Next i used a very fine file and gently filed the internal surface of the swing arm, there was no evidence of paint, but a bit of corrosion, next I re greased the 1st bearing and pressed it back in, then reinserted the new pivot, it rotated fine, so at this point i had 2 bearings at 1side and the 1st one at the other (total 3) and all was ok.
Next i reinserted the central solid lock bolt again, yes still all ok smooth rotation (great now were getting somewhere) I removed both pivots and pushed in 4th bearing after re greasing. Until flush with edge, then tapped it about a mm or so further using a suitable socket.
Reinserted the new pivot, greasing it 1st, it was a tight fit but went through ok. Now it will turn 360 deg smoothly but you have to use a pair of grips to do it, it wont rotate in your fingers, not sure of thats correct but the swing arm doesnt whizz up and down just pivots smoothly so seems ok? Finally greased main lock bolt, with this in place you can rotate the pivot with a socket on the large nut and the new pivot rotates with no notchiness and zero side to side movement, which i believe is correct.
My best guess slight corrosion was enough to shrink the roller bearing pinching the pivot or the bearings when inserted the 1st time were not in perfectly line, either way seems ok now so happy.
One thing i did notice in Seans 4th photo was it looks like his swinging arm has a shoulder, mine def doesnt which would guarantee the bearings inline if you tap them up to it, whereas mine are in free air.
Couple of things spring to mind on the kit.
1st the instructions are very poor, even zpower do not know for sure, so this could be improved, 2ndly what stops the bearings from moving further inwards in use? As theres no shoulder. In the old arangement you had the step on the phospher bearing, up to the swing arm external end, alao they were line bored for perfect alinement, the new bearings cant be line bored, just tapped or pressed into place which can result in being off very minutely but enough to cause un smooth rotation.
Finally it shows how close the tollerances are are if a bit of corrosion (and i do mean a bit) can cause rotational issues.
My thanks to all for the comments and help.
Hopefully rhis will give years of service as did the original, was i right to go down the upgrade route??? And yes i did read the pros and cons before purchase so only time will tell.

[Ultim8pc]

I've tried that kit from Z-Power and gave up fitting it as it just didn't seem to fit properly and came with no instructions. A mate of mine who restores bikes come over for a look at them and he agreed that they didn't fit properly. So I went back to bushes. I did explain the issues I had to Z-Power and they didn't really have much to say. I do love Phil and the gang at Z-Power but when I still see them selling items which are poor quality or fail to fit properly, it does annoy me.

[Gray17]

Agreed, they arn't very well instructed and as you say Zpower know very little about them.The service is excellent though.
Yes i had issues fitting in what should have been straightforward however hopefully now fitted correctly they will give years of trouble free service, Zpower arn't the only people who sell this kit its also sold on ebay in various countries so hoping the install will be successful as very few reports of failure on the web. In fact very little write ups at all.

[gray]

now its done I'm sure it'll be great. If there isn't a grease nipple fitted to the swingarm already , you could fit one while the swingarm is off for future ease of maintenance . they're not dear.

[Gray17]

Yes its got a grease nipple, removed it when i had grit blast and powder coating done, it will be reinstated before fitment to frame.
As you say handy for furure maintenance.

[Ultim8pc]

Agreed, they arn't very well instructed and as you say Zpower know very little about them. Yes i had issues fitting in what should be straightforward however hopefully now fitted correctly they will give years of trouble free service, Zpower arn't the only people who sell this kit its also sold on ebay in various countries so hoping the install will be successful as very few reports of failure on the web. In fact very little write ups at all.

Glad you got it sorted. Maybe you could do a write up?