front springs

[mdude]

hate to bring this up again, but since I have reached the point where I am unable to fit more technical info into my brain (teacher. may I be excused, my brain is full...) I need some spring data. I know theres several threads discussing this at length, but I need to the point info.

I also know I can tinker around with the fine tuning of this to eternity, but I just need something that will make a basic and obvious improvement.

 

I am going to buy new springs for the Marzocchi. Ohlins is way too expensive at 1200 euros, and so is a cartridge conversion from Maxton ($360 + VAT).

 

I have found several companies in Sweden and Norway who can deliver springs (WP), oil and everything, but they dont know sh.. about their own products or the Guzzi, so I must present a clear spec to them.

 

I am close to 100 kgs (whats that in pounds?) in riding gear, and ride in a controlled/brisk manner on medium to long rides on twisty and sometimes quite bumpy roads (think Wales), but I want to know that the bike can handle more.

 

Can anyone give me a clear recommendation on which springs, spacers and oil to order, with all data, which I can then present to the spring guy? Perhaps a sporty alternative, and a cruiser-alternative?

 

Thanks a lot

[beauchemin]

Have a look at this chart http://www.mad-ducati.com/Technical/racete...pringChart.html

 

Unfortunately, we are off the scale of the Traxxion chart http://www.geocities.com/sl_mille/images/traxxion_rate.gif

 

Given your combined rider/bike weight of approximately 760 lbs (540+220) not including luggage or passenger, then you should be looking at a spring rate around 1.10 Kg/mm. My combined weight is 740 lbs and I use 1.05 Kg/mm springs.

 

EDIT: I have documented my experience here http://www.v11lemans.com/forums/index.php?showtopic=6759&hl=

[Guest ratchethack]

mdude, I'm a HUGE fan of doin' this - particularly at your weight, having been down the learning curve on this and researched it extensively. I agree with Chris (Beauchemin) above and would suggest that the Traxxion Dynamics chart is correct at suggesting ~1.1 - 1.15 kg/mm straight rate springs for your weight.

 

I'd skip the idea of "sporty v. cruiser" suggestions on spring rates, since getting the rate right will be your best choice for both. You can fine-tune rebound and compression damping for different modes of riding. One (of many) popular delusions here is that "sporty" has to be "harsh". NOT TRUE!!! With stock springs and your weight, and therefore extremely limited fork travel regardless of spacer preload, you already know what HARSH is!!! Y'er about to do away with HARSH altogether!!!

 

The key to getting the rate correct will be getting your laden and unladen sags in the range of 30-35% laden, and 15-20% unladen. Assuming a 120 mm fork travel, this translates to ~40 mm laden and ~20 mm unladen sag. Depending on the free length of the springs you wind up with, you'll have to experiment with spacer lengths to get both in the correct range.

 

May I commend you on resisting the popular inclination to "throw the baby out with the bathwater" by trashing a perfectly adequate set of road forks!!!!!

 

I'd recommend 125/150 cartridge fork fluid in place of fork oil and a 100 mm air gap.

 

Good luck, y'er on the right track, and if your experience is anything like mine (and many others!), you can expect a tremendous, transformational change - especially at your weight!

[andy york]

I concur with everything said. for informational purposes...I am 215 -225 on any given day ...I installed the 1.2 springson my 02 LeMans. I also have have H & B hard bags on the bike. It works for me but then I like things on the firm side I also played around with the preload spacer length to get the sag where I wanted it. used 5w fork fluid.

 

andy

[dlaing]

Traxxion Dynamics chart is correct at suggesting ~1.1-1.15 kg/mm straight rate springs for your weight. 

 

I'd skip the idea of "sporty v. cruiser" suggestions on spring rates, since getting the rate right will be your best choice for both.  You can fine-tune rebound and compression damping for different modes of riding.  One (of many) popular delusions here is that "sporty" has to be "harsh".  NOT TRUE!!! <_ with stock springs at your weight you already know what harsh is>

 

82225[/snapback]

I speculate that 1.05 would be better suited for touring, and 1.15 would be better suited for sport.

But it may be splitting hairs, and as Ratchet said, with stock springs, "you already know what HARSH is", and going to just about any stiffer spring from 0.90 to 1.20 will actually make your ride smoother on bumpy roads.

[mdude]

thanks all.

seems like 1.10 - 1.15 kg/mm is a sensible choice. with 125/150 cartridge fluid as Rathet recommends. the length of the spring, anybody who has that tattooed in the back of his neck? I'll find out anyway...

 

I agree with you, Ratchet. actually, the decision to go for springs instead of cartridge conversion is largely because of your recommendations, or rantings is perhaps a better word. hail hail!

 

On this relatively crude bike I find it a bit of a waste to spend that much money on a complete new fork as long as you can improve the old one with small means, its easy to do and another good thing is that the Zocch seems to be easy to maintain.

 

I discovered when I bought the bike that harsh is not sporty: all the settings was turned way up, the bike was rock hard and skitted along the road like a horny squirrel. frankly dangerous, a coin in the road threw it a meter off the line in turns.

 

so forks first, then rear shock. I'm not sure what to do back there yet. but as long as it works I'll just try to give it the right settings. I am also going to lower the fork in the clamps about 5-8 mm (cause with my gorilla arms I get too much weight on the rear tyre), and change to a 160 width rear tyre. that should do it.

 

then I'll just ride......

[Guest ratchethack]

the length of the spring, anybody who has that tattooed in the back of his neck?

Well, I don't have it tattooed anywhere, but the old stockers happen to be around the corner from my office...They're 29.3 cm.

 

I wouldn't be too concerned if the free length of the replacement springs aren't within several cm of the same length. This isn't important. Installing the new springs, I'd start with the stock 110 mm spacers, check initial sags, and size the spacers accordingly. You'll find that there's no direct "match-up" between sag mm and spacer mm - you have to "extrapolate" and experiment a bit...

 

Fun stuff, gettin' 'er dialied in!

 

EDIT:

On this relatively crude bike I find it a bit of a waste to spend that much money on a complete new fork as long as you can improve the old one with small means, its easy to do and another good thing is that the Zocch seems to be easy to maintain.

mdude, I b'lieve you've grasped the essence of the thing! By modern sport-bike standards, IMHO, should you replace the Marz with the latest and greatest high-zoot fork, you've still got a relatively heavy, mediocre chassis behind it with limitations that could hardly allow the most capable fork to demonstrate what it's capable of...'specially for road use...

 

BAA, TJM, & YMMV

[Guest mtiberio]

you need to know the rate of your current spring. If you don't know the rating on the spring, you can use the following formula. Oh, and by the way, there is no such thing as a progressive spring. They way they achieve this effect is to pack some of the coils closer together, so they coil bind early, leaving the remaining coils to offer the higher rate.

 

 

((diameter of the wire)**4) * 1470000

-------------------------------------------------------------------- = spring rate

((diameter of the spring)**3) * (number of coils)

 

**4 means to the 4th power

**3 means to the 3rd power

diameter of the spring or coil is measured center to center of the wire, measure the OD of the coil and subtract the

wire diameter.

all dimensions in inches return rate in pounds per inch

 

this formula works because all of the various spring steels used in suspension springs have the same bulk modulus. This will not work for hi-tech titanium springs. you'll notice that with the number of coils in the denomenator, this implies that two springs identical except for number of coils, the one with the most coils is softer!

[Guest WildJackal]

I am also looking for fork springs. Unfortunately I ordered the incorrect Yamaha FZ1 springs before the Guzzi Tech post was corrected.

 

I have contacted Customer Service at Race Tech. I gave them the S353410 part number for 1.0Kg springs (from Guzzi Tech) and asked if they have a part number for 1.1 Kg springs. I want to exchange the worthless FZ1 springs I ordered from them for something that will work.

[Guest ratchethack]

WJ, I don't know if you already know this, or if you've seen the previous posts and link:

 

http://www.guzzitech.com/V11S-Jackal-Todd_E.html

 

Todd Eagan at GuzziTech has your same bike (heavily modified per above), and has a great depth of experience with the Marz fork on this bike (as well as on many others). You might consider getting his read. His suggestion on Wilbers fork springs (after I had already done a lot of my own homework on it) came out just about dead-nuts perfect for my weight & reqmt's WRT sag settings.

 

BTW - you can get Wilbers springs directly from Todd. He's the West Coast (or Western States, or some such) Rep.

[bigbikerrick]

Well, I don't have it tattooed anywhere, but the old stockers happen to be around the corner from my office...They're 29.3 cm.

 

I wouldn't be too concerned if the free length of the replacement springs aren't within several cm of the same length.  This isn't important.  Installing the new springs, I'd start with the stock 110 mm spacers, check initial sags, and size the spacers accordingly.  You'll find that there's no direct "match-up" between sag mm and spacer mm - you have to "extrapolate" and experiment a bit...

 

Fun stuff, gettin' 'er dialied in!

 

EDIT:

 

mdude, I b'lieve you've grasped the essence of the thing!  By modern sport-bike standards, IMHO, should you replace the Marz with the latest and greatest high-zoot fork, you've still got a relatively heavy, mediocre chassis behind it with limitations that could hardly allow the most capable fork to demonstrate what it's capable of...'specially for road use...

 

BAA, TJM, & YMMV

82236[/snapback]

Hello Ratchethack, I also weigh as much, or maybe a little more than M dude, where can I get the heavier springs for my marzocchi forks? Does progressive make any springs that will work on our bikes? Thanks.

[Guest ratchethack]

Hello Ratchethack, I also weigh as much, or maybe a little more than M dude, where can I get the heavier springs for my marzocchi forks? Does progressive make any springs that will work on our bikes? Thanks.

Hello y'erself, Rick - Y'er an uncommonly brave man, my friend. I commend you on your ability to unashamedly counter popular consensus and think for y'erself! I reckon you understand full well that you'll more'n likely be bringing down the wrath of Hades' Harpies upon y'erself here with an inquiry on progressive springs!

 

There seem to be some incredibly sharp beaks among those who consider them the Devil's spawn. Me, I've used 'em as replacements in 3 bikes including my present two - including the Guzzi - with outstanding results, IMHO - in full accordance with the "philosophical" intent and successful "fit" of the concept to my needs... I've heard many arguments against 'em, but've yet to hear a single credible one that stands up to the research and hard facts as I see 'em - But o' course, I'm an openly self-confessed and entirely unrepentant Road Geez, too....

 

I had looked into Progressive (the company) springs and ran into a dead-end for an application for the 40 mm Marz USD. Todd Eagan, per post above, may be an ideal source for you, though at 220 lb with gear, you won't be selecting the Wilbers progressives he recommended for me at 180 lb. with fully armored Vanson leathers. Just for refercence, the .7 - 1.0 kg/mm Wilbers that suit me to a "T" are Bestellnr..600-062-01. Y'er likely after ~.9 - 1.2 kg/mm or thereabouts, assuming they offer such an animal...

 

IMHO, making the choice between mildly progressive Wilbers progressives vs. straight-rate springs isn't NEARLY as significant as is getting the rate in the right range. Either one properly matched is going to be a HUGE improvement over stock, properly set-up. Just my opinion here o' course, but I wouldn't let anybody tell you that either choice is "wrong"!!

 

Now I don't want to start another "my racing experience trumps your Road Geez experience" belly-bucking contest here, but with all due respect to Mike's comments above, IMHO, the idea of an intentionally-designed coil-binding spring (as all progressive springs are), is NOT the mechanical equivalent of a virus, or some kind of engineering leprosy, as many seem to believe. NOTE: when straight-rate springs coil-bind, they're not designed to take it, and it means they're extremely over-loaded - this is NOT GOOD! The progressive spring design is simply another valid solution to an engineering problem. If ya don't call 'em progressive springs (because somebody says there's no such thing ), you can call 'em "variable rate" - or you can call 'em pomegranates, for that matter - and I reckon they'll work every bit as well...

 

Don't let the Phililstines distract you, my man! Give Todd a shout over at GuzziTech and ask his opinion. He's an uncommonly knowledgeable and helpful kind-of-a-guy.

[docc]

Can anyone confirm the spring rate of the stock Marz spring?

 

How about a chart showing dressed-out rider weight to spring rate?

[Guest ratchethack]

Can anyone confirm the spring rate of the stock Marz spring?

82344[/snapback]

Docc, FWIW, I was bound and determined at one point to find a local suspension shop that could accurately rate my stock springs. The woods 'r full of 'em around here, but not a one of 'em could do it. So I tried to measure 'em myself on my workshop bench with a bathroom scale, a calculator, and a Rube Goldberg pile of weights, clamps, metric rulers, beams and blocks. Sounds easy enough, dunnit? But no good. The main problem was that my scale didn't go high enough, and by "splitting the load" with beams, I couldn't get accurate, repeatable reads beyond the first few cm of travel - the results I got weren't anywhere near ideal, but somewhat helpful. I gave 'em a partially educated "guesstimate" of .6 kg/mm.

How about a chart showing dressed-out rider weight to spring rate?

See Chris (Beauchemin)'s first link in post #2 above. It's combined vehicle and rider weight, assuming 50/50 fore/aft distribution, which we ain't quite got with our Guzzi's, but helpful nonetheless...

[Guest mtiberio]

Now I don't want to start another "my racing experience trumps your Road Geez experience" belly-bucking contest here, but with all due respect to Mike's comments above, IMHO, the idea of an intentionally-designed coil-binding spring (as all progressives springs are), is NOT the mechanical equivalent of a virus, or some kind of engineering leprosy.  NOTE: when straight-rate springs coil-bind, they're not designed to take it, and it means they're extremely over-loaded - this is NOT GOOD!   The progressive spring design is simply another valid approach to an engineering solution.   If ya don't call 'em progressive springs (because somebody says there's no such thing), you can call 'em "variable rate" - or you can call 'em pomegranates, for that matter - and I reckon they'll work every bit as well...

 

 

wasn't meant as a slam on the technology, hell my konis have "progressive" springs out back, and I never had forks good enough to care about up front, so any experience road or track could trump mine on this . it was just a comment to state that there is nothing magic about progressing springs other than being easier to match to a bike (less iterations) and slightly heavier than the correct linear spring (wasted bound coils make a heavy "preload" spacer). If you want to use my formula to compute the various rates of a progressive spring you can by computing the free length rate, the rate after the close section of coils "bind" , etc. Its tougher on springs that have a continuously variable inter-coil spacing, as they bind one coil at a time rather than one section of coils at a time. And you are very correct, this type of bind I describe is nothing like the destructive bind a linear spring could (but never should) experience.