Why Guzzi's have such hard fork springs?

[kfz]

Playing about rebuilding my front forks on the Lemon 10000 and have always been horrified by the pathetic springs Guzzi fit in such a well made (expensively made) fork.  Obviously the springs are the same diameter as the 35mm forks (the machine winds them this size so this size they are?), which makes them look silly in such a big fork.

According to the LeMans manual the 40mm forks have 2 springs with rates of 1.4 kg/mm and 1.6 kg/mm.  While my FZ750 has 0.7 Kg/mm and my FZR1000 has 0.8 -0.9 Kg/mm.

My question is why do Guzzi fit these rock hard springs?  Or am barking up the wrong tree and have my math math wrong?  Any suspension guys out there, really interesting stuff. I cant help thinking that the fork would perform much better if it was set up correctly.


Regards
Kev

[rutgery]

wait, you have a le mans 10 000?

I can't really say anything about the spring rates other than guzziololy saying that they (referring to general guzzi front end springs) often are too weak contradicting your spring rate info.

I am curious about why you find the 40mm front fork to be a well made design? To me the forks (with exeption of the dampers) seem to be rather a cheap design, mostly based on the lack of bronze bushings at the top of the lower leg and bottom of the upper. Also, only later 40mm forks received a bottom bushing to help prevent (or at least soften) bottoming out.

[guzzisteve]

Mostly cause they are ridden by old FAT guys. I never had any complaints about being stiff even when they where new bikes, mainly the dampeners.

[Muzz]

I know the springs on the Breva's rear shocks are way too hard.  With the preload set as soft as it will go it is about right for two-up.

[Guzzistajohn]

Old fat guys would line up for a 10,000 LEMON, I bet that sucker will GET WITH IT! 

[kfz]

Very much tempted to get an old set of FZR1000 springs and cut them to length and try em.  Anyone tried this?

Not convinced that the Wirth Springs, unless someone can recommend this route?

Kev

[bodine99]

Mite want to check with some of the Guzzi Vintage racers and see what they use. Race Tech & Progressive must have something

[blackcat]

 

Mostly cause they are ridden by old FAT guys. I never had any complaints about being stiff even when they where new bikes, mainly the dampeners.

[LowRyter]

Very much tempted to get an old set of FZR1000 springs and cut them to length and try em.  Anyone tried this?

Not convinced that the Wirth Springs, unless someone can recommend this route?

Kev

wouldn't cut down springs make them stiffer?

[Tom]

You'd could try an old fix.  Put some spacers in.  Cut whatever pipe available that fits.  Equal length.  PVC works.  Stuff that in and see if that works.  It would tighten up the springs.  How are your cartridges?

[marcdavo]

"wouldn't cut down springs make them stiffer?"

yes.

[kfz]

You'd could try an old fix.  Put some spacers in.  Cut whatever pipe available that fits.  Equal length.  PVC works.  Stuff that in and see if that works.  It would tighten up the springs.  How are your cartridges?

Yes,  other changes to.  The max deflection is smaller since they will coil bound sooner.

Anyway  I dont want them stiffer.  I want them better.

Also putting spacers in does nothing to effect the spring rate.  just raises the min load before they delfect.

Kev

[kfz]

Mite want to check with some of the Guzzi Vintage racers and see what they use. Race Tech & Progressive must have something

Race tech dont do springs for the 40mm LM1000 forks only the 35 and 38's.  They do have a good rate calculator for the LMIII which is pretty much the same weight as the V.  and they say 0.9 Kg/mm , which is a lot less than the guzzi stock spring (according to the manual).

As far as I know only Wirth make aftermarket springs for the 40's.  Academic really since the 40 springs are the same diameter as the 35's anyway.

Kev

[Tom]

One of things you'll have to accept is that the bike is old.  Moto Guzzi built your bike with the technology available to them at that time.  Fixing that might involve replacing the whole front end from a late model bike.  If modifying the internals of the stock set-up doesn't work for you.

[GeorgiaGuzzi]

Mostly cause they are ridden by old FAT guys. I never had any complaints about being stiff even when they where new bikes, mainly the dampeners.

I’m not old... 🐷

[menzies]

GMD Computrack in Fairmount, GA had some springs fabricated for one of my Guzzis's. They cost about $10 more than Racetech or Progressive Etc. He sells and recommends Racetech and I believe he said the same fabricator made these that also make the Racetech springs. They worked well, the bike was an 06 Breva 1100 or an 10 Stelvio, cannot remember.

[guzzisteve]

My Cal2 front end has 3/4" spacers shaped like the washer the o/p was looking for, made to boost up springs for sidecar use.  Dale's in Rock Island, IL had made a bunch 1/2" and 1/4" also. They worked great till I go the Earls fork.

[kfz]

I’m not old... 🐷

Tom,
Yes I understand the bike is a mass of minor changes (though she looks very stock), I still like to improve.

Kev

[kfz]

For those interested I decided to test the springs I have, to see what rate they are. So with some old forks, tape, a rule and a set of digital scales....




Experment caveats -  ITs a potato finger in the air test, only testing the rate right at the bottom of the stoke (Most springs are progressive and rate changes).  Springs are cold. errors due to poor measurement  (best of 3).

So the conclusion is why do Guzzi Springs say they are so hard but they dont feel it is simple. They arnt!  They might start off really high rate but the narrow diameter, miles and  age sooner wears them down.