Worrying noises.

  • Thread starter Thread starter Legs
  • Start date Start date
Ideas that come to mind:
1. Make up a new guide tube with <1mm wall thickness to go on the outside of the spring.
2. Make up a guide tube to slip down the inside of the spring. Something like 22mm dia? Perhaps a bit of elec conduit?
3. Put cable ties around the spring wire at various locations to act as guide buffers between spring and inside of fork.
4. Put a permanent bend in the springs so they don't flap around inside the fork.
5. Forget the new springs and stay with the old ones.
6. Sell the bike.

I like #3 best. Quick, easy and cheap. What could possibly go wrong?
 
Dellortoman said:
3. Put cable ties around the spring wire at various locations to act as guide buffers between spring and inside of fork.
Click to expand...


I like that too though it also has the potential to turn the rattle into a squeak... :o :o
 
Dellortoman said:
OK, put the spring inside a rubber tube, like a push bike inner tube.
Click to expand...

And when that turns to mush? Actually I thought the cable tie ?guides? was a pretty good one...
 
So fork springs are vibrating when engine is at 3K RPM? Engine vibes are reaching the front end. Your triple has the engine mounted on rubber isolators? I'd start there looking for loose or worn motor mount.  Or try a bit more or less spring preload, maybe add rubber washers between spring and preload spacer. Does the noise go away at higher revs?
 
I wonder if it's possible the different winding pitches have harmonic resonance frequencies which amplify one another and what you have is a 'howl' (closed feedback loop) effect? It's a concept I've heard of but Cam might be better placed to advise on this. I think his idea of putting cable ties around the coils (every 6" or so?) is a good one.. I'd also follow up on checking fork oil levels and setting to ~6" air gap as per some older threads...

http://www.laverdaforum.com/forum/index.php/topic,51093.msg98215.html#msg98215
and
http://www.laverdaforum.com/forum/index.php/topic,91940.msg311825.html#msg311825
 
Legs said:
No, the new springs outer dia is 30mm the tube inner dia is 32mm.
Click to expand...
Terry are they the right springs for Marzocchi's as I just measured a set of progressive and they are 31mm OD.
The linear springs I now use, after reading heaps about the linear vs progressive measure 31.5 OD. Neither sets have ever rattled.

I set the preload at 10mm as recommened by race tech,  if the sag is too much then by adding preload all you are doing is negating the spring.. if you need to preload over this then  simple the spring is too soft.
I would suggest speaking to Ikon about your issues as they sold you the springs they should be able to advise on correct preload and also if the springs are correct. I know of someone here in Sydney who bought a set and then discovered they were not correct. Afterall its your hard earned we are talking about here.

Andy yes air gap is important on forks the French have known this for years, they use air over oil as their suspension medium no mechanical springs.

As for our telescopic forks they all contain an air space and as the fork is compressed this air space gets smaller and as such the pressure increases inside the fork. when more oil is added the air space is reduced, and the compression ratio is increased.
This air spring inside the fork tube works in parallel with the mechanical springs and therefore the fork oil level has a direct relationship on the overall stiffness. esp at the last 1/3 or so of travel important for heavy braking etc...

Therefore a linear spring with the correct air gap will be way better than a progressive wound spring.

Chris Pritt wrote a great article about this some time ago and can be found on Laverdamania which will explain things a lot clearer than I can this evening.

http://www.laverdamania.net/suspensiongb.htm




 
Have you identified the source of the noise as coming from the new springs?
I know this is the only change you made but stranger things have happened.
Did you crack the exhaust when raising the front of the bike to remove the forks (for example).
You could always revert to the original springs to prove or disprove the theory.
 
G'day fellas, thanks for all the info.
Grant, I have done the pepsi taste test between the standard and replacement springs and the noise  is apparent with the new springs fitted, tested four times just to make sure. The springs were provide by a Laverda specialist (no names, no courts martial) here in Aussie. The outside dia is 30 mm, leaving 1 mm clearance between the spring and tube which I thought would be sufficient.
I support the front of the bike with a home-made bracket the fits under the frame rails so no stress is placed on the header pipes, I checked the headers, collector and mufflers just in case.
Brett, I have fitted Schreader valves in the fork caps to replace the very rudimentary valves fitted on an RGS, these let the air out, thus creating a bit of a vacuum in the fork leg, allowing the removal of one of the two seals in each leg, reckon this reduces the main problem with these forks; stiction or as called elsewhere, static friction (bit like the ball in the engine breather pipe to prevent oil leaks by creating a vacuum in the engine). Therefore, the air in the fork leg doesn't act as a spring so the oil level may not be an issue.
Hope that makes sense or maybe I'm over thinking the issue :-[
 
My next mod to my forks, not an exact fit but hopefully with a small mod doable.
https://youtu.be/y4H_kiWl2jM
 
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