OzVMX Forum
Clubroom => Tech Talk => Topic started by: bigk on March 20, 2016, 12:20:24 pm
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I have adjusted the suspension travel in a set of '77 Marzocchi 38mm forks to comply with Australian pre'78 rules (go figure that) by modifying damping rod & reducing chrome tube by 20mm. I have also fitted emulators, correct spring rate & preload, 20wt oil & 130mm air space (all Racetech specs). The forks feel quite stiff in a static test (in the bike), my question is given that some of the main components have been shortened, does the 130mm air space need to be re-calculated? Thanks in advance.
K
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The answer is yes, but most riders wouldn't feel the difference between 130mm and whatever the ideal setting is (assuming 130mm was the ideal air gap in unmodified forks).
I can't see why you'd shorten the chrome tube. A simple spacer on top of the top-out spring seems like a much better way to achieve the same goal...
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And allows it to be returned to stock.
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Suggesting 20W oil should ring a few bells . But then the again , The rice tackers are the gurus . Interesting .
whats a "rice tacker" ? haven't heard that one before, please educate me
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yeah - 20W a bit heavy!!!
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I normally run ATF in my forks. Also go for none or very slight preload with 4.7 springs. For me this gives a good connection with the front and plush first part of travel. If you feel it sits a little low in the corners set up like this then move the damping holes a little higher. Try lower oil/bigger air gap as well. I like around 140/150 air gap.
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Suggesting 20W oil should ring a few bells . But then the again , The rice tackers are the gurus . Interesting .
whats a "rice tacker" ? haven't heard that one before, please educate me
Sounds like a Walterism.
That said, 20W with emulators is a bit whacky.
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I could have done it with a spacer but went the other way as the overall length of the forks was too long for what I want. Don't want a tall bike, so shortened the chrome tubes. 20wt is not unheard of with old forks but since speaking with Racetech have gone for 15wt. They also advised the air space did not need to be re-calculated.
I have pretty much set them up as Slakewell's post for the first test ride & they feel better already in a static test.
Walter is referring to Racetech with his term "Rice Tracker". No help whatsoever in that post but hey let's not miss an opportunity to have a shot at the opposition. Thanks for everyone's thoughts, I'll have it sorted real soon.
K