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 Post subject: Marzocchi 35 magnesium
PostPosted: Sun Sep 14, 2014 3:10 pm 
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Joined: Wed Nov 03, 2010 3:19 pm
Posts: 192
Location: Auvergne, France
Does somebody have drawings, technical informations about the 35mm marzocchi racing magnesium fork?


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 Post subject: Re: Marzocchi 35 magnesium
PostPosted: Mon Sep 15, 2014 5:56 am 
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Joined: Tue Nov 09, 2010 9:14 pm
Posts: 85
Images: 19
Location: Brisbane
la tige wrote:
Does somebody have drawings, technical informations about the 35mm marzocchi racing magnesium fork?


no but I have 2 sets that need to be restored and rebuilt so I am very keen to see it as well


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 Post subject: Re: Marzocchi 35 magnesium
PostPosted: Mon Sep 15, 2014 8:25 am 
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Joined: Wed Mar 21, 2012 9:56 am
Posts: 112
What do you need to know ? I re-manufacture these from scratch so have some idea of what is required to make them work.


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 Post subject: Re: Marzocchi 35 magnesium
PostPosted: Mon Sep 15, 2014 12:27 pm 
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Joined: Wed Nov 03, 2010 3:19 pm
Posts: 192
Location: Auvergne, France
It's for a friend of mine, president of Ducati Club of france, who needs to know how it works and how it can be settled.

another friend has ordered a pair from you for his tt2, seems to be very happy, nice work ;)


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 Post subject: Re: Marzocchi 35 magnesium
PostPosted: Tue Sep 16, 2014 8:22 am 
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Joined: Wed Mar 21, 2012 9:56 am
Posts: 112
We all seemed to cope well enough in the good old days. Then someone had the great idea to put small knobs on suspension. Now we are all looking for that eternally elusive perfect set up. The following is only my view regarding the 35mm gp forks.
Feel welcome to read it, digest it, even use it, or simply dis-regard it.

The dampers are by no means a modern cartridge system but perform quite well if set up and in good condition. Clearly all valves, seals and seats need to be checked and in good order before commencing any settings. In my view, the design is let down by not having ptfe bushes fitted. This results in 'sticktion' under braking as both the tube and leg deflect slightly.
The forks I manufacture are much the same as the originals, but are machined to have the bushes fitted giving a much smoother action.

Firstly, the basics are always determined by bike and rider weight.
Amongst other factors to consider are un-sprung weight of the front wheel/disc setup. (A heavier wheel/tyre discs etc will transmit more force from the track/road to the suspension.)
With no rider on board, I look for 15-20mm of static sag on the travel. This should increase to 25-30mm with the rider. this can be achieved by fitting a spacer above the spring of different length.
Spring rate is a matter of fitting a tell tale O ring or tie wrap around the slider. Take the top nut off and fully compress the fork leg. Take a measurement of where the O ring is sat. Now the good bit. -- Get out on the track, go really really fast, and some seriously heavy braking. These forks have a traditional Marzocchi tapered cone on the damper so slow the movement down in their final few millimetres of travel so the result of the heaviest braking should still leave at least a couple of millimetres of travel remaining. If they are bottoming out, a stiffer spring is probably in order. Upping the pre-load is simply not the answer to this.
It may be possible to shorten the same spring and use a longer pre-load spacer to compensate. This effectively creates a stiffer spring. Remember to check there is enough gap left between the remaining coils to allow for the fitted pre-load and total movement. (plus 25% for the spring to 'breathe')

The knobs on the legs adjust only the rebound damping. Compression damping can be slightly altered by using a thicker oil. but no miracles are possible here. Note, -- A thicker oil will have the effect of increasing the damping on the same rebound setting.

For a TT2 in race trim (lightweight) I start with 260mils of 15w synthetic fork oil in each leg.
As for springs, 27.5 outside diameter, 4.25mm wire dia, 48 coils. Rate conversion being 30.6 lb/ins or 0.546kg/mm.


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 Post subject: Re: Marzocchi 35 magnesium
PostPosted: Tue Sep 16, 2014 4:11 pm 
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Joined: Wed Nov 03, 2010 3:19 pm
Posts: 192
Location: Auvergne, France
Many thanks ;)


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