What's the cheapest way of making my standard Marzo forks harder?
 

It seems my forks are giving me a hard time (can't brake as hard as I would like to before the whole bike starts vibrating, even if I'm using only 1 brake disc...).

Is there a cheap way to improve them for the use I make of them (hanging around Cadwell Park at desesperatly slow speeds...)? Even better if I can do it myself, I'm always happy to learn. Thicker oil? Washers to compress the springs?

You could add a small amount of oil to each leg (equal amounts) until you're happier.

or, add a shim/washer like you say.

I think both these ways will have different effects, although technically doing the same thing.

I think ;)

interesting answer my friend :)
But I could do with a bit more information (what kind of shim/washer, what oil thickness, etc)...

Otherwise I could just ride the bloody thing, but eventually I've got enough handicap with myself no to have a proper handling bike :D

thicker oil slows the compression damping down so it takes longer to get to bottom out but it still will bottom if the bump force is big/fast enough. a combination of thicker and more volume might help but it all depends how far out the springs are or whether its actually to much rebound packing the fork down ( the fork can't recover from one bump before it hits another so eventually it runs out of travel)

Preloading a spring with more washers won't make it harder, it'll increase the ride height but thats all. a spring moves a set amount for a set load, so its rated as say 10kg/mm it'll take 10kg to move it 1 mm and no matter how much you push it it down it'll always take the same 10kg to move that 1mm until the coils on the spring bind together. if you start with a higher ride height there is less chance you'll bottom it as the fork needs to move further. try and set sag up correctly and if possible swap the spring to a one which is correct.

you can put oil in them Tonio, what are you running now?

find out, then go for a thicker oil.

If you had std oil such as 7.5, then you could put 10 weight oil in.

otherwise, just put an extra 5cc's (centiletres) per leg to start with & see how they are. If necessary add another 5cc's per leg.

Giz, Tonio cant swap the springs on his marzocs, at least i dont think he can...

waiting for correction now:)

As alan says tonio.
Are they the early forks or the later ones ??

So if the bike vibrates when you brake are you sure the forks need to be stiffer? Could it be a warped disc? Or not enough rebound damping?

I'm running 9kg linear rate springs in mine with standard weight oil and standard oil amount, the difference was amazing for the price of a pair of springs.

call solent uk ltd and ask for dan, they are now the uk importer of Marzocchi, They are still learning and it takes ages for the springs to arrive but they can supply the later fork springs.
glyn

Fitted Ohlins springs meant for a Honda Firestorm (41mm dia. fork leg) in my early SS forks circa 1996.
When I first put up pics of my bike with the 916 fairing in my DD diary, questions were asked about the fairing hitting the mudgaurd.
With the single rate Ohlins springs it NEVER did

You can swap the springs Alan, although springs aren't listed for it. I have a set of Ohlins monorate .85kg springs in front of me now to suit Marzochis, correct diameter etc, just a little shorter than the standard spring so the spacer tube needs increasing in length to compensate. If you think you can use them Tonio then let me know, I won't be using them now and they'll be going cheap! I boughtthem for Dessie but never fitted them.

Is that a DD rule AK?? going down the more oil/thicker route don't always work, it affects the rebound and on long bumpy sections you might start to get packing down because it takes the oil too long to flow back. I noticed both your bikes were running with about 25 -30 mm unused travel on the fork at Oulton, I didn't get any hard braking photos at the end of the straight to check to see how other bikes were set-up and didn't know whether the fork would actually go to the bottom , it may be the 25mm mark was actually full travel.

My 750SSie has a lot of fork judder (vibration) all the time under braking and changing down gears unless I set the tickover to 1800rpm or above, then its no longer a problem.

Tonio - are you 100% sure that you headbearings are tight, that the disc is true and the front spindle is straight?
I've used std Marzos and Showas and the only braking judder was when the headbearings were loose......
Also at Donny I raced with one of the forks bent by 1/4 inch...I only noticed back home when I noticed the front wheel was turning left when the yokes were straight....
How much fork travel are you using (cable tie around the slider) and have you measured your sag and preload front and rear before you start messing with the spring rates?
HTH, Paul

too late already answered, doh, must type faster :D

no not a dd rule Giz, but as scooter says its if they are the older ones you cant get the springs.

Tonio, I know I did ask you about the discs on Monday, please do get them double checked mate, as that is what would concern me 1st also check headstock too

Whilst not perfect I Ran hagon Progressive springs in my 583 some slate them but they worked well and were good enough for the fastest lap at caddy, Cost about £30 and are listed on hagons site for the early ss marzocchi forks.
glyn

Setting the sag right is definitely the first thing, start with 20-25 mm. Then knowing how much travel you actually use is critical. It may be that you have too much oil in them and the last bit of travel is "hyraulicking", i.e. the air gap is all used up too soon.

Tonio, good advice from Scooter:)

I only use factory forks in my bike.

:D

which factory ones?;)

:p :lol:

Charlie and his chocolate ones

You two are so nasty to me :sniff:

























:lol: :lol: :lol: :lol:

Thanks for all the answers guys... I'm 99% sure the disc is fine. I haven't crashed yet so I can't see any reason why it would get warped... I had warped discs last year and the feeling was totally different...

I think my problems started when I did the 2 changes below (unfortunately I did both in the same time and so don't know which one could be the cause of my problem):
- fitted a 6.5kg spring to my Ohlins rear shock (instead of a 7.5) following the advice of a mate.
- fitted a pair of jacks (built by Rich @ Louigi Moto) to raise the rear of the bike.

Anyway I'm not tired, so I'm now off to the shed taking the forks apart, I need to see what's inside :D (I've even been suggested that they could be empty of oil in regard as how they behaved in static... ).

6.5kg sounds a bit on the light side for the rear spring Tonio, I'd have said 8kg would be about ideal. could you try putting the original spring back on and see if that improves it? I would have said raising the rear ride height shouldn't cause problems under braking particularly, of course I may be wrong though!

Whilst you have the forks apart, measure the springs - outside and inside diameters, free length, and also the length of the spacer tube. The springs I have may well fit.

Right, a few things which may speak to you more than to me.
First, the lenght of the forks I was using at Cadwell, I have absolutely no idea of if it was "bottoming" or not...

The leaking left leg...

And finally, even if Dr AK is always saying "read your tyre you numpty" I never think about doing it. So I just had a look at the front tyre and I must reckon I've never seen it being so worn in the middle and with so many wrinkles...

And

Which still makes me think I've got a suspension problem rather than a brake problem. Off to the shed again, now I'm starting the surgery bit :lol:

Tonio are your forks always that mucky? only I'm thinking leaking fork seals?

Yes Jon, the left leg is always leaking :)

And finally what I found in the left leg:


Zimbo, dimensions of the left leg spring are 280 x 35 x 25mm.

That's it for tonight, after all Cadwell is in about 6 weeks :)

Heh, I bet that was fun round all but two corners of Donny then!

Good job you have some replacements lined up, and that they have decent springs fitted already ;)

Fortunately I'm off to Rockingham on Monday for a bit of testing....:lol:

Isn't that cheating? :lol:

back to the thread :D
Zimbo, what dimensions are your springs? I've put mine somewhere in that thread...

the ones you got me didnt fit!!!!so i'm not sure its worth calling them!!

Your Joking
How bad is that, they are the Uk importer for Marzocchi too, HMMM not very good that, sorry mate
Glyn

thats ok mate...it wasnt your fault!!! JUST couldnt be bother to go with them again...have had some work done on them last week..so will see on friday at caddy what they are like!"!!

U there this friday??
May see if i can get out of the shop for an hour or so.
Glyn

yep, i'm there on friday...going to have a run out in the fast group,not so sure that is a good idea, seeing they are racing there this weekend..lol I will be there all the weekend,my mates are doing the derby round,so will be helping them out!!

going to test the new clutch thats has just been fitted..hopefully i might be able to rev it past 6k this time!!!lol