GPz11 forks question

[moizeau]

Could someone advise me please. I have stripped the forks and have new forks seals ready but.... is it worth replacing the 2 bushes in each fork before rebuilding them?

The manual just states 'check for wear'. Well there is, but is it excessive?
The reason I ask is that on my first Zeph11 I replaced the fork seals only for them to start leaking again. I changed the bushes and all was good, though I think the Zeph bushes I replaced were at the top next to the fork seal, the GPZ bushes are at the bottom.
https://images.cmsnl.com/img/partslists ... 1_238d.gif
Cheers

[Philippe]

Hi Pete

personally I wouldn't replace them. Just mind that you put the openings of the bushes to the sides when rebuilding the forks and to put the oil seals in AFTER you asembled the forks. If you put the seals in before sliding the tubes with the bushes on them you risk to damage the oil seals.
GrtZ
Philippe

[moizeau]

Thanks Philippe, I was leaning in that direction with the bushes being at the bottom of the leg.
Next question.
2 owners ago one anti dive must have packed in or leaked or something because it was removed and the fork blanked off. Very odd because this would surely cause the forks to react differently to each other.

I have the other in a box.
The fact that these are bit like hen's teeth and if you find one will it work? Alongside the fact that this tech disappeared on later models.
The posts I've read say these are unserviceable? Is this true or is it better to remove the one fitted and revert to standard forks? Or leave it in place but blanked off for an authentic look?
Cheers

[Philippe]

Hi Pete

to my knowledge you can easily blank off the other as wel. I don't think it makes a big difference. I think it was a period habit when a few Japanese constructors wanted to add something "special" to differenciate themselves from others.
A few years later they stopped using the anti-dive because it didn't make much difference.
That's the story I've been reading somewhere, I don't know if it's correct. Perhaps others can tell you more.
GrtZ
Philippe

[johnA]

Hello sir you can get the anti dive rebuild kits off the gpz zone website if you want to keep your bike standard. If you blank them off you need a channel down the blanking plate to let the oil flow between the holes in the forks.

[moizeau]

Thanks John. I'll have a look into that. I haven't taken the existing blanking plate off yet to see if a channel was known about when it was fitted. Thanks again for the info.

[moizeau]

Just had a read through the section explaining the anti dive courtesy of GPZ Zone and John for the heads up. Very interesting. Now I understand a little more and why just blanking them or them not working will blow fork seals.
http://gpzzone.co.uk/technical/antidive.html
Might be of use to someone, like me, that didn't understand the system.
Thanks John.
The GPz1100 isn't mentioned on their site, but I'm hoping the same anti dive system was fitted to all models with it?

[moizeau]

If you blank them off you need a channel down the blanking plate to let the oil flow between the holes in the forks.

That'll be a no then.
So if I did understand the tech correctly, this non channelled blanking plate would leave the fork in maximum anti dive mode, or maybe even stiffer.

[Garry.L]

A repair kit for the Anti-dive is cheap enough (If the same)..

https://gpzzone.com/anti-dive-repair-kit

When I stripped mine on the Turbo I found the plunger (below) was seized on the Brake fluid side so needed a good clean out of crusty brake fluid and soaking in Oil. It's interesting that the Anti-Dive units were universally slagged off and blamed for poor handling & ride yet Kawasaki's own service schedule said these plungers and seals should be replaced every two years.

(not my Pics).....

255347192_1309554992837362_5262035525138509047_n.jpg (203.64 KiB) Viewed 5684 times

255340139_1309555072837354_8920117174330598309_n.jpg (153.46 KiB) Viewed 5684 times

[Garry.L]

A little more...

https://www.youngtimerbikes.de/forum/vi ... gYBI#p6747

[moizeau]

Thanks Garry, the one still fitted is free, the other, in the box, is crusted up. John, thanks for the CNC drawings, very easy to understand, cheers. I'm going to have a go at freeing the dead one up. The rubber boot may be the biggest issue to source, though with further inspection an O ring may suffice.

[DocSteve]

Hi Pete

personally I wouldn't replace them. Just mind that you put the openings of the bushes to the sides when rebuilding the forks and to put the oil seals in AFTER you asembled the forks. If you put the seals in before sliding the tubes with the bushes on them you risk to damage the oil seals.
GrtZ
Philippe

Hi there, I’m sorry I don’t understand. What do you mean - the sides of what go to the sides of what and how can you fit the seals after you have assembled the forks? Sorry for my amateur questions.

[moizeau]

The bushes have a cut down the length of them (see pic 1). Guessing Phillipe means the slot must be placed to the left or right, not fore/aft to minimise wear. The seals being fitted after assembly requires a special tool, a home spun tool (a tube of the correct diameters, I have a tufnul one for my TY) or gently tapping it in working slowly round the seal in 10 minute ish (think of a clock) increments, continue for several rotations until the seal is seated. A tube is better and doesn't risk damage to the seal of forks.

[Simonic]

I used the kit from the GPz zone on my Zx1100A1. I found the kit and instructions to be excellent