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 Post subject: Marzocchi Z5 problems
PostPosted: Wed Jun 05, 2013 11:03 pm 
Dirt Disciple

Joined: Mon Jan 28, 2013 3:28 pm
Posts: 40
I bought a Marzocchi Z5 fork off ebay last week and it arrived today. I believe it's the 99 model (the seller thought it was and it also had no disc brake mounts). I've recently finished building my own bike up and had so many bits left I thought I'd put the old one back together in case someone wants to use it like once a year! So the forks were the one things missing so I tried to find something cheap on ebay, and the z5's fitted the bill.
Had a couple of problems though. I've contacted the seller so I'll just paste my message to him below so you can all see what's up and hopefully help me out;

The first issue came with the actual fitting. My stem would not fit smoothly onto the steerer. It was an extremely tight fit. The only way I could get the stem to fit was to use a mallet to hammer it on. Luckily it didn't damage the stem but by fitting it this way it presented another problem. I was not the able to use the top cap to fine tune the tension in the headset, as the stem had been fitted too tightly. As I had to fit the stem with the mallet there was no way of doing it gently and this essentialy compressed the headset too much, resulting in very stiff steering.
I'm not sure what could have happend to the steerer but it is either enlarged or misshapen. The stem came straight off another fork with a 1 1/8 steerer so I know it is not the stem at fault.
The othe issue I had was, although the steering was not working correctly due to the overtensioned headset, I still wanted to try out the forks and see if they were working well. I refilled them with air as you said. However, they were still compressing easier than I would expect, but the main problem was they were not rebounding. They would almost bottom out and then not come back up again. However much air I put in I had this same problem. I don't suppose you know the exact PSI they should be set to do you? As I am having a problem finding instructions for this particular model and year online as the are so old.

THANKS GUYS!!!


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PostPosted: Thu Jun 06, 2013 6:40 am 
retrobike rider / Gold Trader
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Get a steel ruler (or similar) on the steerer and see if you can spot it being mis-shapen near the top. I've had a few fork steerers that have been badly cut, giving a bit of a lip on the top which makes fitting a stem difficult. Hopefully this is your issue as it is easily resolved by lightly filing the outside edge of the top of the steerer.

You shouldn't need much air in them, pretty sure that they will be low pressure. 30 psi ish?

As for the rebound, might be worth stripping the forks down and doing an oil change. If it's old sludgy oil in them then it won't be doing them any favours. Some 7.5wt oil doesn't cost much from a local motor bike parts shop and servicing the forks is very simple. Happy to post up a 'how to..' guide if you'd like?


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PostPosted: Thu Jun 06, 2013 8:57 am 
Dirt Disciple

Joined: Mon Jan 28, 2013 3:28 pm
Posts: 40
EarlofBarnet wrote:
Get a steel ruler (or similar) on the steerer and see if you can spot it being mis-shapen near the top. I've had a few fork steerers that have been badly cut, giving a bit of a lip on the top which makes fitting a stem difficult. Hopefully this is your issue as it is easily resolved by lightly filing the outside edge of the top of the steerer.

You shouldn't need much air in them, pretty sure that they will be low pressure. 30 psi ish?

As for the rebound, might be worth stripping the forks down and doing an oil change. If it's old sludgy oil in them then it won't be doing them any favours. Some 7.5wt oil doesn't cost much from a local motor bike parts shop and servicing the forks is very simple. Happy to post up a 'how to..' guide if you'd like?

Yes if you could send me a 'how to' guide that would be excellent please! I'm a bit confused as to what is actually in these forks. Obviously there's the air in there but sounds like the air is mixed with oil? Not had much luck finding anything myself online for this exact year/model like I said previously.
Could you just describe with a bit more detail what you suggest I do about working out the problem with the steerer? Are you suggesting I measure the diameter?
Thank you for your help


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PostPosted: Thu Jun 06, 2013 12:51 pm 
retrobike rider / Gold Trader
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No probs, will get some pics later and upload them.

For the steerer I was thinking of using something that is straight (metal ruler), lay the edge against the steerer as see if its is straight. If there's a gap between the ruler an steerer then it's bent. As it was the stem you were having problems getting it on, it may be out at the top. Hopefully it's just the top few mm and you can trim it down.

The internals are really simple. Let air out and remove top cap. There's the oil. Below the oil is the damper. Think the z5's will only have a damper in one leg and the other will be a dummy shaft. The 'How to' will show it better than I can explain.


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PostPosted: Thu Jun 06, 2013 1:12 pm 
Dirt Disciple

Joined: Mon Jan 28, 2013 3:28 pm
Posts: 40
EarlofBarnet wrote:
No probs, will get some pics later and upload them.

For the steerer I was thinking of using something that is straight (metal ruler), lay the edge against the steerer as see if its is straight. If there's a gap between the ruler an steerer then it's bent. As it was the stem you were having problems getting it on, it may be out at the top. Hopefully it's just the top few mm and you can trim it down.

The internals are really simple. Let air out and remove top cap. There's the oil. Below the oil is the damper. Think the z5's will only have a damper in one leg and the other will be a dummy shaft. The 'How to' will show it better than I can explain.

I'm still 100% certain on what you mean regarding the steer, but it's probably just me being dim :D.
To be honest I didn't spend any time really in actually trying to work out what might be wrong with them. Was just trying to get the rest of the bike put together and was planning on sorting the steerer issue at the end. I have had to buy two 10mm spacers though as the steerer was little long. So there may be some room to cut a bit of it off. What do I then do about the star nut that's in there though? Guessing that's going to need to go a little further in before i cut any of the steerer anyway. Hopefully it will be easier to sort than cutting it anyway.


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PostPosted: Thu Jun 06, 2013 3:01 pm 
retrobike rider / Gold Trader
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You can knock the star fangled nut down further, so shouldn't be a problem :)


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