quick question on forks

M

Mingh

Hero member
My marzo 38's are shot. play on bushings and hi speed comp gone.
found a complete set of ceriani 38mm for 550? off an SF (SF2 i think). are they comparable in any way? same lenght, springs, stiffness, offset, travel and suspension behaviour? Or do you guys reckon i'll be off cheaper and better with replacing bushings, progressive springs and a cartridge emulator? Or should i not mess with it and send them over to maxton or similar folks? for the record: Koni's in the rear
 
For less than that Maxton will make your forks better than new.
SF forks are too short for a triple but you could always buy longer stanchions from Wolfgang if you decided on that route.
I guess springs and spacer arrangement would be transferrable from your Marzos.
 
Cartridges and emulators won't conceal slop between slider and stanchion, though.  No bushes to replace, either.  

Don't think it's finacially viable to heve the sliders bored and the stanchions chromed/ground to fit.  NOS Marzo sliders could well be avaialable here and there, perhaps OCT or Wolfgang.  Slap in a pair of new stanchions and THEN send the stuff to Keith or Maxton to get the internals sorted!  That will make the forks better than new.

piet
 
I see where you're going Piet and you're probably right. But just for my understanding/analysis:
-Stanchion wear: not measured, and not as bad (yet) that you can just wobble the stanchions in the sliders by hand, but when walking the bike with engine of, there are some audible clicks when rolling over a bump that i can't assign to something else.
-As to the compression damping: at low to moderate riding speeds it does things mostly as said on the tin. Not bad for its age at least. But when riding 120kmh or more, the forks overshoots on every slightest ripple in the road surface. It dances like a japanese richter scale while the road is smooth and the rear wheel tracks it with much more zen. However the bike still holds a line in a sweeping 100k/h (or faster) turn, where i expect it to bounce away from the apex.
 
It sounds more like stiction than damping.
Remember too that often front end problems originate from the back as the forces pivot through the bike. How good are your rear units?
Do you have properly matched tyre sizes? Is your fork oil the correct weight and at the correct level?
To check the forks you need to get the springs out and check the forks through their travel both assembled with the wheel, guard and everything, and individually. A good time to feel the damping each leg over the full travel with new oil. Freeplay slider to leg is unlikely to be heard as a click when assembled with oil.
 
Mingh,

The stanchions only wear at a patch fore and aft, close to the lower end.  This takes the brunt of braking forces and heavy suspension deflection.  Unfortunately, the sliders will also have corresponding wear patches.  The resulting clearance is what allows the sliders to wobble back and forth under braking.  Turning the stanchions through 90? helps to take up some of the slop by letting the slider work on an unworn portion of the stanchion, gets you through a few more years.

Springs are often quite audible in the Marzocchi forks.  They are fitted with a shroud tube to prevent them bending out under compression and clonking/rubbing against the inside of the stanchion.  Once the shrouds are omitted, things start getting loud.

If you're satisfied with the rebound damping with the oil you're using, fill up a bit more to increase compression damping by reducing the air cushion.  This actually works like a very progressive spring, getting firmer the further the forks are compressed.

Wish my forks were sensible to the slightest ripple.... :D

piet
 
'Sensible to the slightest ripple' isn't always a good thing. Think sensible in a way of a Spanish lesbian with PMS, La tourette and a butcher's knife. That's how mine do above 120 km/h. You'd think twice before you upset it.

Being a) a lazy arse b) short on time and c) mechanically challenged, i'll go for the easiest option and start by adding some oil as you mentioned.  The clicking doesn't sound like the sleeve over the spring is missing. I've had that on other forks.

The stiction path sounds interesting as well. The forks are particularly slow moving when you try to compress them with bodyweight. Rears are NOS Koni's with adjustable rebound. They're fine, Filter small buzz and big bumps,respond faster, and track well in the bends. Will take them off to check for wear on the swingarm bushes.
 
Mingh don t know where you are or bike some RGS Marzs  forks from Alan Bell on Ebay at present.JAT

Lemon
 
Mingh,

I had a very similar problem at the front end - even with emulators above 120 Kph.
The solution for this one was easy - I got the front wheel balanced!!!
Problem solved.
 
SimonR501 said:
Mingh,

I had a very similar problem at the front end - even with emulators above 120 Kph.
The solution for this one was easy - I got the front wheel balanced!!!
Problem solved.
Click to expand...
that sounds VERY logical. I'll get into that one first. No other hypothesis can explain why it's so apparent at higher speeds.
 
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