Z25 lateral movement issue

Mcivor047 · Feb 5, 2017

Hi Fellow Benelliista
Not sure if you can see from these pics but the Z25 gear and shaft have some lateral movement to the point that the gear is rubbing against the crankcase and giving it a slight burr visible in the pic3. the shaft can be pushed in, as in pic4 to show a slight space between the gear and crankcase.
The only thing stopping the Z25 coming out any further seems to be that it is running against the inside of the primary ring gear.
I have since taken the Clutch basket off and taken the gearbox out and removed the Z25 and notice that the bearing holding the Z25 on the alternator side has a circlip to stop it moving out towards the alternator. but the bearing doesn't have a lip behind it to stop it moving to the clutch basket side.
how is the bearing fixed to stop it moving towards the clutch side. Should the bearing be loctited on reassembly and will this be enough to stop this movement?
I have ordered a new Z25 even though I couldn't visible see any damage, but the gear wouldn't slide up and down it past the halfway point.
BTW the original reason I stripped it down is because the starter motor would just spin when I tried to start her, assuming that the sprag starter clutch had died, but on removal it seemed fine and engages in the one direction, only slipping on the very odd occasion when spinning it in both hands.
Any advice would be greatly appreciated with this.
Cheers Mark

Mark T · Feb 16, 2017

Get an Aprilia.:doh:

Redbaron57 · Feb 23, 2017

Mark, I see you had no helpful replies and wonder how you got-on with this problem over these last few weeks. I have not dismantled my Benelli this far but while waiting for new Z25 and coupling parts to come from Maniac Motors I spent some time examining the parts manual and workshop manual to try and fathom your problem. The manuals do not make it obvious but I gather the clutch end of the Z25 shaft is supported by a roller bearing Item 13 on the crankcase drawing attached and it is retained by a little collar, Item 2 on the Satellite Gear & Freewheel drawing attached, held by two screws secured by thread compound. If that is correct the two screws and retainer plate have come adrift on your bike. Is that what you found? Cheers, Rolf

Mcivor047 · Feb 24, 2017

Thanks for your response Rolf, Yes its a curly one, I got my parts from Maniac Motors yesterday. I know the bearing you mention but it is actually a needle roller bearing on the clutch side. so the Z25 is able to move along it no problem. There is a larger roller bearing on the alternator side but this is only held in place by a circlip which stops it moving towards the alternator there isn't a lip behind the bearing to support it and to stop it moving towards the clutch side, i'm assuming that this bearing should be loctited in place which is what I will do when I put it back,together. But its a strange method it seems to me, as the only thing that was stopping it moving any further was the fact that it was running against the clutch bell housing ring gear, and when you take into account that the clutch bell housing has about a 1mm lateral freeplay on it, the Z25 gear did actually rub against the crankcase slightly and has worn a mark on it. it could have been worn further into the crankcase if the ring gear wasn't there to stop it. but hopefully the loctite solution will fix it, as when the nut with the Belville washer holding the alternator drive is tight all the items on the shaft are held in place, so the only fixing point is the roller bearing face to the crankcase with loctite. Hard to believe really. Will keep you up to date as to how it goes together. Cheers Mark

Redbaron57 · Feb 24, 2017

Mark, my bike is 250km away so I can't examine it just now. The service manual seems to be remarkably free of any useful information about the Z25 shaft bearings. If you still have it in bits, could you please post a photo from the clutch side, with Z25 removed, showing that needle bearing? It would be even better if you could get a shot through it to the sprag clutch assembly inside.

Mcivor047 · Apr 17, 2017

Hi Rolf
How did you go with yours, mines back together now and running sweet and starting fine. I only had to replace the outer ring with countersunk holes for the bolts and the actual bearing, apparently the inner part that engages on the Z25 shaft rarely needs changing according to Maniac Motors.
Cheers Mark

Redbaron57 · Apr 17, 2017

Hi Mark, I'm glad you got your bike sorted. At idle my TRE K had sounded like the can of coins the Salvation Army bloke shakes as he walks through the pub. I found the alternator drive was all loose. Only a new female half coupling and new coupling rubbers were required. The splines in that half coupling were badly flogged but the Z25 shaft was not too bad. I did not even remove the clutch cover because the backlash in the Z25 assembly did not seem to be much more than in the new one. I put retaining compound on the splines for the male and female alternator drive half couplings, used a modified Class 10.9 bolt and Manic Motors cone washer for the Z25 shaft and fitted Kawasaki coupling rubbers. That action made the engine a lot quieter and smoother. I have since ridden it a few thousand km with no further trouble. I may never need that new Z25 assembly and male half coupling I bought. A few unrelated gremlins have since revealed themselves but I addressed them and think I now have a reliable bike. It ran 500 km on rural roads over Easter with no problems. Next job is to complete a few remaining actions for the 20,000 km service, including the valve clearances. After that I was intending to have the bike remapped but it is now running so well I am not convinced a remap is necessary. Cheers, Rolf.

Z25 lateral movement issue

Mcivor047

Mark T

Redbaron57

Mcivor047

Redbaron57

Mcivor047

Redbaron57

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