OzVMX Forum
Marque Remarks => Yamaha => Topic started by: IT400C on November 19, 2009, 01:43:41 am
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Hi Guys,
Is there anyone in the Brisbane area that rebuilds C model monoshocks? Or for that matter, is it something that I could do? I've checked out the parts diagrams, and apart from the unknown of releasing the Nitrogen (and refilling it afterwards), it doesn't look too technical.
But I don't know if there are any little tricks/pittfalls I should be careful of...
Thanks
Tony
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tony , get rad motorbike shock repairs to do it , should find him in ph book
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A fine hypodermic syringe is the tool for getting the gas back it (obviously with the attachment to connect it to a regulated nitrogen bottle). Alternatively, its fairly easy to buy a high pressure schrader (normal tyre type) valve and modify the shock to accept it.
Same syringe can be used to empty the gas out, or you can simply slowly unscrew the top of the diaphragm cover. Most of the time, there's no gas left in them anyhow.
As the parts book suggests, its all pretty straight foward. They're harder to bleed than most shocks, but a little patience will prevent it being a drama. Also, accept that you'll make a mess when it goes back together.
Three likely pitfalls:
1. Rust on the shaft under the felt top seal.
2. Torn/split gas-oil seperator diaphragm. Have been told that they're very hard to find new.
3. You local bike shop won't be able to put enough pressure into it. The gas pressures were REALLY high in these old shocks, as the gas was intended to provide some of the spring effect. Walter/YSS can supply stiffer springs, allowing you to drop the gas pressure down to modern levels.
I am looking at converting my YZ125X to a modern valve piston, but it looks like being a BIG job.
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2. Torn/split gas-oil seperator diaphragm. Have been told that they're very hard to find new.
I wouldnt be surprised if a bladder from a modern shock could be made to fit as there is certainly lots out there when i was looking for some bladders a while back, but if not then you can just convert it to a floating piston to get you out of trouble.
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Nah, the screw-up with the B & C model monoshocks is that the diaphragm is a big diameter thing - about 110mm, inside a bulbous lump on the end of the shock.
I've recently learned that the early (works) monoshocks were modified Citroen car suspension. I wouldn't bet money on it, but it might be possible that the diaphragm is the same as a Citroen one.
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well that is big hey!
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We fitted a schrader valve to the said bulbous lump on my YZB, whack as much pressure as you want, ;)
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you're right about the pressures - my YZB has 420psi as standard.
cheers
Rossco
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2. Torn/split gas-oil seperator diaphragm. Have been told that they're very hard to find new.
I wouldnt be surprised if a bladder from a modern shock could be made to fit as there is certainly lots out there when i was looking for some bladders a while back, but if not then you can just convert it to a floating piston to get you out of trouble.
Sound slike you are unfamiliar with the first YZ monoshocks there Leith.
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Nah, the screw-up with the B & C model monoshocks is that the diaphragm is a big diameter thing - about 110mm, inside a bulbous lump on the end of the shock.
I've recently learned that the early (works) monoshocks were modified Citroen car suspension. I wouldn't bet money on it, but it might be possible that the diaphragm is the same as a Citroen one.
Yes I heard that too.Thats what Lucien Tilkins used of the first CZ monoshock
http://www.mxworksbike.com/Tilkens_mono.htm