front springs

[Guest ratchethack]

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.

I appreciate your thoughts Mike. Coupla thoughts in reply. Some would no doubt consider some of this "splittin' hairs", but since you mentioned it...

 

WRT "wasted", bound coils on progressive springs acting as "heavy spacers" - consider the number of coils that are bound at laden sag fork extension. Then consider that while underway, the fork extends quite frequently beyond this - a most significant 50% of the time! As soon as the fork extends past laden sag, to varying degrees, depending on the amount of extension, these formerly "wasted", formerly bound coils are no longer bound, and are doing what they were designed to do, offering progressive resistance to load and damping. Spacers can't do this, so in fact, the "coil-bound at laden sag" coils are anything but "wasted".

 

Again WRT "heavy" spacers - consider that progressively wound springs are properly installed with the tight coils at the top, thereby placing the relatively minute ounces of mass when coil-bound on the "sprung" end of the fork, leaving relatively less mass unsprung than equivalent straight-rate springs.

 

Rgds.,

 

RH

[Guest mtiberio]

I appreciate your thoughts Mike.  Coupla thoughts in reply.  Some would no doubt consider some of this "splittin' hairs", but since you mentioned it...

 

WRT "wasted", bound coils on progressive springs acting as "heavy spacers" - consider the number of coils that are bound at laden sag fork extension.  Then consider that while underway, the fork extends quite frequently beyond this - a most significant 50% of the time!  As the fork recovers in compression, to varying degrees, depending on the amount of extension, these formerly "wasted", formerly bound coils are no longer bound, and are doing what they were designed to do, offering progressive resistance to load and compression damping.  Spacers can't do this, so in fact, the "coil-bound at laden sag" coils are anything but "wasted".

 

Again WRT "heavy" spacers - consider that progressively wound springs are properly installed with the tight coils at the top, thereby placing the relatively minute (at least for road use, but also for racing purposes) ounces of mass when coil-bound on the "sprung" end of the fork, leaving relatively less mass unsprung than equivalent straight-rate springs.

 

Rgds.,

 

RH

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1) I didn't specify laden, so coils bound by preload at full top out are still wasted.

2) I didn't specify unsprung weight, so wasted weight is still wasted weight whether unsprung or not.

 

but your right, I don't want to split hairs.

[Guest ratchethack]

1) I didn't specify laden, so coils bound by preload at full top out are still wasted.

2) I didn't specify unsprung weight, so wasted weight is still wasted weight whether unsprung or not.

 

but your right, I don't want to split hairs. 

Ah, but what're Forums for, if not to belabor a point or 2?

 

1) No coils are bound at full top out with either of the sets of progressive springs I'm currently riding on. If they were, this would be a poor match of spring to application.

 

EDIT:

 

FWIW, here's a link to shots of many dual-shock setups with progressive springs. None show any evidence of coil-binding at full extension, as I would expect in any proper setup.

 

http://www.guzzitech.com/WilbersSuspensions.html

 

2) If any spring weight whatsoever were wasted, I would most heartily agree.

[bigbikerrick]

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, the argument 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. 

 

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. src="%7B___base_url___%7D/uploads/emoticons/default_wink.png" alt=";)">  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.

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thank you RH, I will give the gentleman at guzzitech a call, are they the same folks of Guzzitech.com ? ( I got an awesome pair of head protectors from them, but I think the fellows name was ed millich) Rick

[Guest ratchethack]

thank you RH, I will give the gentleman at guzzitech a call, are they the same folks of Guzzitech.com ? ( I got an awesome  pair of head protectors from them, but I think the fellows name was ed millich) Rick

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Rick, GuzziTech (guzzitech.com) is co-run by Ed and Todd. You can email Todd at todd<at>guzzitech.com. See their Wilbers shocks and springs page here:

 

http://www.guzzitech.com/WilbersSuspensions.html

 

If you tell Todd I referred you, maybe he'll find a way to put an outrageous excise tax on y'er springs....just kiddin'. Tell him I said, "HEY!" - he'll do ya right!

[bigbikerrick]

Rick, GuzziTech (guzzitech.com) is co-run by Ed and Todd.  You can email Todd at toddguzzitech.com.  See their Wilbers shocks and springs page here:

 

http://www.guzzitech.com/WilbersSuspensions.html

 

If you tell Todd I referred you, maybe he'll find a way to put an outrageous excise tax on y'er springs....just kiddin'.  Tell him I said, "HEY!" - he'll do ya right!

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Thanks for the link, RH .Wilbers stuff looks to be top quality, my next investment in the Guzzi will be the fork springs,I will tell Todd you referred me. for sure, your name should be good for at least a 20% discount im sure! Gracias!

[Guest ratchethack]

Por nada, mi compadre.

 

BTW, Todd's a man of many hats (and helmets). He's also the Chief Guzzista of the So Cal Moto Guzzi Owners Club. One of my riding buddies had dinner with him on Tuesday in Newport after he got back from Daytona. Unfortunately, Todd wasn't there in time to see the epic wins of Guaro Guareschi on the MGS-01. Todd knows Guareschi personally, and said he would have been very difficult to beat.

[dlaing]

Don't let the Phililstines distract you, my man!

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The idea of all that metal to metal contact of progressive springs kind of worries me.

But I have never heard a study that complained about metal build up in the oil from using progressives, so who knows

Besides, if you blow out your Marzocchis by using progressives and not changing the oil, you can always upgrade to something better.

[bigbikerrick]

Por nada, mi compadre.

 

BTW, Todd's a man of many hats (and helmets).  He's also the Chief Guzzista of the So Cal Moto Guzzi Owners Club.  One of my riding buddies had dinner with him on Tuesday in Newport after he got back from Daytona.  Unfortunately, Todd wasn't there in time to see the epic wins of Guaro Guareschi on the MGS-01.  Todd knows Guareschi personally, and said he would have been very difficult to beat. 

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I would have loved to see Guaro race on the mgs 01 myself. That is one awesome bike!

[mdude]

Ok, guys. Been trying to order fork springs this weekend. That was not a fun thing to do. Even though I had all available data and knew what I was after, both guys I talked to was completely unable to help me: They not know what spring rate means, they never 'eard of Marzocchi, they not habla, they not able to read product lists, they lose interest, they rather sell me new bike instead....

 

In most product lists there is a replacement spring listed, but I understand from you that this spring generally is too soft for a fat geezer like me. Bike and me weighs at least (100kg+240kg) 340 kg, maybe a bit more. Thats 755 lb, if I'm not wrong.

 

What I need is product numbers. So, dear Guzzisti:

 

Q1:

can anyone help me with a product number that enables me to order fork springs for the stock Zocchi fork with:

spring rate of 1,1-1,2 kg/mm

with spacer material

from either:

Ohlins

WP/Proline

Wilbers

 

Q": how do you convert kg/mm to Nm/mm? thats the standard rating in most lists.

 

As far as I can see there isnt many over in the States who're willing to ship internationally, so I would like to order in Europe. But if I can I'll of course order from the US, yesserreee! I'll of course pay shipping fees.

But I still need product numbers.

 

If you think this implies that I am a bit mechanically thick and not able to take care of myself, you're probably right. But Im workin on it.

[Dan M]

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

 

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Ratchet,

 

I'm also in the midst of getting mine dialed in. I'm using Wilbers' progressives from Todd E. I've done quite a bit of searching here before I started in and thanks to you found plenty of good information. I have to go a bit longer on my spacers; I have 26% unladen sag with the stock ones. But here is the rub. In a prior post you say to prop up the fork to fully retracted position when measuring for 100mm air gap. The directions do not illustrate this. The directions are also in German so not much help to me. Anyway I asked Todd and he said to fill & measure with forks fully extended. It makes sense to me to fill with them extended, and that is how I've measured air gaps on other (non cartridge) forks but you've clearly done your homework on the Marz 40. Whadda ya think?

[Guest ratchethack]

Dan, I think either you or Todd must've misunderstood.

 

If you filled the forks to 100 mm air gap with the forks fully extended, I don't know how much fork fluid it'd take, but you might need a couple of liters! Filling by volume (not recommended!), it should be around 400 ml per side.... On top of this, you'd more'n likely hit something dangerously close to full hydraulic lock of the forks as soon as the tire hit the floor, and/or blow-out the fork seals if you tried to ride it that way...

 

One of the things that dawned on me as I researched this stuff (last time around for cartridge forks) is that it's very very easy to make false assumptions that whoever you're communicating with not only understands basic suspension operation, but that they also use the same terms! This is a challenge with written instructions from mfgr's, suppliers, and customers! On top of this, if you thought you understood it frontwards and backwards at one point, and then haven't thought about it again for a long time, it's easy to slip and get things backwards unless and until you give it a good re-think (don't ask me how I know... ).

 

The instructions on the Wilbers I got from Todd indicate "Luftkammer - 100". This means air gap, 100 mm. I remember verifying this with Todd. As I posted previously, I would use the term, "retracted", or "compressed" position (front wheel blocked up with fork as high as it will go - springs & spacers out) for correct fork position when measuring air gap.

 

Another thing I discovered is that while filling the forks, it's best to get both tubes filled to ~300 mm air gap, then extend the fork and compress it at least a dozen times to get all the air out of the cartridges before you do the final fill and measure the air gap.

 

I wouldn't assume you need to go longer on spacers until you get the new springs in and get a read on BOTH sags, laden and unladen. Remember - you need them BOTH in the indicated ideal ranges, 15-20% unladen, and 30-35% laden.

 

Oh yeah - one more thing...Achtung! For optimum Wunderbar operation, tight coils on progressive springs are installed at the top!

 

EDIT: From the moto gear manual archives in my workshop drawer: I'd forgotten I have a page of English translation that came with the German einbau-anleitung. I just found it. All above confirmed.

[Dan M]

Dan, I think either you or Todd must've misunderstood.  

 

If you filled the forks to 100 mm air gap with the forks fully extended, I don't know how much fork fluid it'd take, but you might need a couple of liters!  On top of this, you'd more'n likely hit hydraulic lock of the forks as soon as the tire hit the floor, and/or blown-out fork seals if you tried to ride it... <_>

 

One of the things that dawned on me as I researched this stuff (last time around for cartridge forks) is that it's very very easy to make false assumptions that whoever you're communicating with not only understands basic suspension operation, but that they also use the same terms!   This is a challenge with written instructions from mfgr's, suppliers, and customers!  On top of this, if you haven't thought about stuff you thought you understood frontwards and backwards at one point, and then haven't thought about it for a long time since, it's easy to slip and get stuff backwards until you give it a good re-think (don't ask me how I know... ).

 

The instructions on the Wilbers I got from todd indicate "Luftkammer - 100".  This means air gap, 100 mm.  It doesn't say anything more about air gap, it assumes the measurement is understood.  I would use the term, "retracted" position (front wheel blocked up with fork as high as it will go, springs & spacers out) for correct fork position when measuring air gap.

82923[/snapback]

 

 

Ratch,

 

My question to Todd was: Should the 100mm air gap measurement be taken with the forks fully compressed?

His reply was: No, it should be measured with the forks fully extended.

Hard to misunderstand any of these terms - I think neither Todd or myself would mistake compress for extend or the reverse. Perhaps Todd is thinking of a conventional fork. I don't know.

I guess I'll measure what the gap is now both compressed & extended, measure how much old fluid I extract and decide from there. To further confuse me the illustration in the German instructions show 1) a conventional fork & 2) measurement taken before springs are installed with no illustration of the fork being proped up. :!:

It would make sense that the air gap difference would be approximately the forks travel - 120mm+/- So 100mm compressed would be about 220 extended. Or maybe less of a difference since the piston & valving are taking up a lot of fluid space below. ??? Anyway, your input is much appreciated and I'll let you know further progress.

[Guest ratchethack]

Dan, maybe Todd had sumpin' else on his mind?

 

I have ZERO doubt on this. I'm afraid he was wrong, my friend.

 

I don't blame you for wanting to get this right. You can call y'er trusty local moto-shop for their take, but be sure to say they're cartridge forks.

 

In the absence of a trusty local moto shop , here's some corroboration:

 

EDIT: You may've missed my EDIT above.

 

from the Wilbers USA translation page:

 

"5. NOTE: The fork has to be fully compressed when filling the oil."

 

EDIT #2:

 

From Adventure Rider Forum - Topic, Fork Oil Change

 

http://www.advrider.com/forums/showthread.php?t=73718

 

From post #2 at the above link:

 

"....the oil height (measured with the springs out and forks fully compressed) is absolutely critical to setup. Therefore: NEVER SET FORK OIL HEIGHT BASED ON OIL VOLUME!!! Always measure the air gap- a tiny difference in volume will make a huge difference in height and therefore bottoming resistance."

 

EDIT #3:

 

From Suspension Tuning, by Jacques Strappe (not a bad site, BTW)

 

http://www.strappe.com/suspension.html#level

 

see: Front Suspension, oil level

 

"measure the oil level in each leg with the forks totally compressed."

[Dan M]

Dan, maybe Todd had sumpin' else on his mind?   I have ZERO doubt on this.  I'm afraid he was wrong, my friend.

 

Call y'er local moto-shop for verification, and be sure to say they're cartridge forks.

82932[/snapback]

 

Thanks, I'll take your word for it. I was thinking about this just now on my drive home. I always try to use a common sense approach to these matters (although after more than 25 years in the car business I know that common sense & engineering are not always dovetailed ) I realized that you have to have the fork blocked up to do the spring job anyway so it would follow that you would keep that position for filling and spring installation.

 

Thanks again for the shove