Marz Fork oil change & setting AIR GAP!

[Guest ratchethack]

Changing fork oil is not at all difficult, but it seems to be just tedious enough to stop lots of riders from doing it altogether, and expensive enough to often put professional service on "perpetual hold". After the first change at 1K miles, the Guzzi Service Manual calls for a change every 12K miles or at least every year. The consequences of all-too-common neglect here ain't pretty - or thrifty. Even if you rely on professional service, IMHO, unless you're tight with the service provider and have confidence in the shop's knowledge, experience, and/or integrity, the risk that they'll get it WRONG can be considerable - and that ain't pretty, either...

 

Any discussion of service on the Marz 040 (40 mm) USD fork would be incomplete without mention of it's ridiculously UNDERSPRUNG condition as shipped from Mandello (at least as shipped to the USA)! By the GuzziTech spring rate calculator, they're .64 kg/mm. This is perfect.....if you happen to weigh 125 - 150 lbs.!!! IMHO, this has given rise to the entirely unsubstantiated and undeserved RUMOR that there's something inherently WRONG with the Marz USD fork! NOTE: ANY fork with improperly matched spring rates will perform poorly!

 

In case you haven't already done this, as long as you're changing fork oil, it's a splendid time to properly match the spring rates to your riding weight, and set the fork preload with correct length spacers! This is counter-intuitive for many, but the notoriously WEAK stock springs provide a notoriously HARSH ride and less-than-predictable, unbalanced handling far below the capabilitites of both the fork and the chassis for riders of average weight. Unless you're a real lightweight, you're riding on the air spring, Binky - an exponentially-rising rate at probably less than an inch of available travel near the limit of fork travel in the compression direction!! For heavier riders, this undersprung condition with stock springs is nothing short of extreme!!

 

Lengthening preload spacers to correctly set laden sag WILL NOT make up for an inadequate spring rate! To achieve the inherent excellent ride and road handling that the Guzzi is capable of with this fork, it's imperative to set BOTH the laden AND unladen sag settings in your target range. This is impossible without a match of spring rate to load (see many posts on suspension set-up elsewhere). With up-rated springs and properly set preload, you'll raise up the front end substantially. Now that you'll actually be riding around with CORRECT chassis geometry (at least at the front end!), you can more'n likely drop the triple clamps on the stanchions by as much as 5-10 mm to fine-tune the front end just the way you like it for optimum feel & performance.....It's a brand-new world of handling and riding comfort with a properly sprung & preloaded fork....

 

Springs and spacers are very easily changed at any time without removing the fork stanchions. A fork oil change is more involved, but very straightforward. Best have a Service Manual on hand, but for most marginally savvy wrenches , the following should suffice. I haven't written this entirely in sequence, so be sure to read it all before you start!!

 

You don't need any "special" tools. Standard size sockets, open-end or combination wrenches, and allen keys are all that's needed. Lots of old towels or shop rags. A vise to clamp the fork stanchions in while working on 'em is helpful, but not mandatory. For complete fork dismantling and replacing seals, I made up a fork cradle that protects the finish and clamps the stanchions side-by-side for use in my large bench vise. It works like a Champ - but this is entirely in the "nice to have" category. If you're just changing oil, you can hang 'em up to drain, or lean 'em in a corner sitting in a pan.

 

May I recommend synthetic CARTRIDGE FORK FLUID such as 125/150 (my preference) in place of the conventional (dino grade) products known and sold as FORK OIL, that were/are specified for traditional damper-rod forks, rated by oil wt., such as 5wt., 7.5 wt., 10wt., etc. The Guzzi manual calls for 10 wt. FORK OIL - but it's the 21st Century now, (whether Guzzi knows it or not) and these are cartridge forks.... CARTRIDGE FORK FLUID, since it's synthetic, is a higher grade product and may be expected to provide superior service life.

 

The manual calls for backing off both compression and rebound adjusters fully counter-clockwise before taking the fork caps off.

 

Before removing the stanchions from the bike, don't forget to break the fork caps loose while you've got the stanchions securely clamped. The caps can be threaded out of the stanchions on or off the bike, but for many, the triple clamps will be the best place to hold 'em while the springs and spacers are removed. With the caps threaded out, block up the fork from below to raise the cartridge and rod assemblies high enough in the stanchions so you can get a wrench on the blue anodized jam nuts, break the fork caps free of the jam nuts, and spin 'em off. Compressing the spring with one hand, take out the spacer retainers, spacers, and springs. Now y'er all set to drain and re-fill.

 

NOTE: Before turning the fork stanchions upside-down to drain the oil, tip the forks on their sides over a pan (oil will begin dumping) and carefully remove the long, small-diameter damping-adjuster rods and set them aside. They'll slide right out of the center of the cartridge/rod assemblies.

 

Though the shop manual calls for complete disassembly, removal of the cartridge and rod assemblies from the fork lowers, and separation of uppers and lowers, IMHO this is wise for at least the first oil change, and best for each oil change, but not always required if you do as thorough a job of pumping the forks out as possible, and take the time to let 'em drain with uppers and lowers still assembled. I've done it both ways several times, having had it fully disassembled the first time for a thorough inspection, and faithfully keeping up the maintenance intervals. I also did it once for a blown fork seal and replaced both.

 

UPDATE: Docc has discovered set screws on the inboard fork lower castings that retain the heads of the socket-head anchor bolts that lock the cartridge rod assemblies down at the foot valve (the extreme bottom of the assemblies, just above the wheel spindle). These 5 mm set screws are properly loosened with a 2.5 mm allen key BEFORE the anchor bolts are removed! When re-assembling a completely dismantled fork, it is EXTREMELY IMPORTANT to make sure the hex-shaped end of the foot valves are rotated into the hex-shaped sockets cast into the bottom of the fork lower castings and fully seated so that the o-rings provide a proper seal, and so the anchor bolts fix them in place.

 

Whether dismantling the forks completely (uppers separated from lowers) or partially (uppers and lowers intact) to drain the oil, it's not absolutely CRITICAL to get out every drop. There will be some amount that gets trapped inside -- especially when not dismantling them completely, even after reversing the forks repeatedly while pumping out. This isn't much of a problem as long as you DON'T add new oil by the Guzzi manual recommended 400 ml volume! (see below) The objective here is to get as much of the old broken-down oil out as possible, along with as much of the accumulated sludge, swarf, and dreck at the bottom of the fork lowers as possible. In the case of double, triple, or longer intervals past the last recommended change , a complete disassembly is probably in order, 'cause (assuming you don't have to rebuild the forks at this point with new bushings, o-rings, etc.) at minimum, that semi-malignant little pile of glop accumulated in there will need to be flushed out with solvent and/or scraped out with a stick...

 

The recommended fork oil replacement volume per the Guzzi Service Manual for the Marz 40 mm fork is 400 ml per fork leg. May I STRONGLY recommend that you DO NOT use volume measurement for fork oil replacement! Instead, use the AIR GAP (oil height) measurement method, see full explanation here:

 

http://www.peterverdonedesigns.com/oilheight.htm

 

This prevents both over-filling and an unbalanced (and potentially fork binding) side-to-side air spring effect as the fork approaches full travel. In addition to this, too small air-gap settings in the event that you didn't get all the old oil out will create a prematurely high air spring rate, causing a sudden, jarring effect as the fork approaches full travel. Just a few mm difference in oil height makes a surprising difference in air spring effect. You can live with a small volume of old oil mixed with new, but you don't want uneven or wrong air gaps!

 

Setting air gaps involves blocking up the re-assembled forks as high as they will go in full compression with springs and spacers out, and filling the stanchions to a recommended 100 mm of the top of the stanchions before installing springs and spacers. 100 mm air gap is a general starting point that will work well for most riders of average weight. Be sure to pump out all the air bubbles as you're doing this by fully extending and compressing the forks many times, until no bubbles appear. I find it easier to re-fill the forks and set the air gap before re-installing 'em on the bike, but if you have no way of conveniently holding them and decide to re-fill 'em on the bike, it's best to do it before installing the fender, wheel, and brake calipers so you can pump out the air bubbles individually. With the forks on the bike, you can draw off any excess oil with a turkey baster.

 

When re-assembling, after setting the air gaps, install the springs, spacers, and spacer retainers, leaving 22 mm of threads showing above the blue jam nuts. Docc points out that 22 mm is the point at which the caps bottom on the cartridge rod assemblies. Don't forget to re-install the long, small-diameter damping-adjuster rods that you set aside previously! Install the fork caps and tighten them against the jam nuts. NOTE: The blue jam nuts are counter-bored on the bottom. They MUST be installed the same way they came off! It takes a little down-force to compress the springs enough to start the caps in their threads in the stanchions, but it's easily enough done. Once the stanchions are re-assembled in the triple clamps, you can snug up the caps and re-set the damping adjusters.

 

NOTE: Correct fork assembly is done in proper sequence. Getting the sequence right prevents setting up unwanted internal stresses in the fork that can cause binding and poor fork performance due to excessive stiction. The correct order for torquing fork pinch-bolts is:

 

Lower triple clamp

Upper triple clamp

Spindle (axle) nut

Spindle (axle) pinch bolts

 

By bouncing the fork just prior to the last step above, the spindle will naturally locate itself correctly in the fork lower casting. The fender, then brake calipers are installed in the final step.

 

Hope this helps, my friend. Have fun!

[Guest Nogbad]

Where the hell does the "glop" come from?

 

Why are Guzzi's techs so obsessive and anal about fluid changes?

[Guest ratchethack]

Where the hell does the "glop" come from?

Hey Nog - didn't we cover this about a year back? Have you still not changed y'er fork oil?! Still sweatin' y'er assets, eh?!

 

I reckon it's the same glop that I first noticed when dismantling a set of '64 Norton roadholder forks four decades ago. I've found it in every fork I've had apart since. No doubt the only difference between that glop and our glop is that our glop is slightly more refined...

 

While I've not done a laboratory spectrum analysis on it, I'd expect it's a combination of metallic swarf from slider bushings, road dirt and pulverized bug exoskeleton that gets past the fork scrapers and seals, and the byproducts of degraded oil from shearing of the long-chain hydrocarbon molecules and heat degradation thereof from metal-to-metal contact at the interface of the sliders and bushings.

Why are Guzzi's techs so obsessive and anal about fluid changes?

I reckon Guzzis have been historically engineered before the advent of synthetic lubricants. AFAIK, they still don't specify synthetics. She's an air-cooled ditch-pump motorcycle. She likes her fluids changed...

[Guest Nogbad]

My forks have now done 11500 miles. I'm prepared to bet that if I change the oil I won't find significant "glop".

 

Ok I found glop in a set of Norton Commando forks, but those had never been looked at in 25 YEARS.

 

Interesting "bug exoskeleton" comment. True, the shattered and impacted remains of our 6 legged friends could conceivably get in there. I noticed after a particularly "swarmy" ride home yesterday that the Buell front fender fully protects the fork sliders from "buggery". Not so the V11.

 

Incidentally my friend with the Norton has made me an attractive offer for the Guzzi, thinking that I would automatically want to part with it after the acquisition of the Buell...... I think not. After all, I need something to ride in the winter and when it's raining.

[svjj]

I just changed my fork oil and seals for the first time this winter after 21,000 miles. The fluid was a little dirty but no glop.

[Guest ratchethack]

Did you happen to take a gander at the bottom of the fork lowers with a light source inside the tubes?

 

Enquiring minds just gotta know....

 

I use a "Kleen-bore" rifling inspection tool.

 

I discovered glop at 12K miles and again at 24K.

 

BAA, TJM, & YMMV

[svjj]

Did you happen to take a gander at the bottom of the fork lowers with a light source inside the tubes? 

 

Enquiring minds just gotta know....

 

I use a "Kleen-bore" rifling inspection tool.

 

I discovered glop at 12K miles and again at 24K.

 

BAA, TJM, & YMMV

89056[/snapback]

 

Yes I did look at the bottom of the forks. I did have a small amount of sediment but no glop or sluge.

 

I will pay more attention next time and will do 12,000 mile intervals like I am suppose to.

 

That was the first time I ever did that job and maybe I missed something at the bottom. But I did inspect and clean very carefully.

 

Thanks for the posting I always appreciate more experienced advice.

[callison]

I neglected the WP's on my 97 Sport 1100i for 58,000 mlles. The rebuild charge was a tad over $500. I was lucky I didn't have to have the fork tubes re-chromed as they weren't so bad that they couldn't be turned down in a lathe. Now... is there anybody that thinks it isn't necessary to take care of fork oil on the regularly scheduled interval?

[dlaing]

I neglected the WP's on my 97 Sport 1100i for 58,000 mlles. The rebuild charge was a tad over $500. I was lucky I didn't have to have the fork tubes re-chromed as they weren't so bad that they couldn't be turned down in a lathe. Now... is there anybody that thinks it isn't necessary to take care of fork oil on the regularly scheduled interval?

89241[/snapback]

Yah the labor charge for the four or five services would have been about twice the rebuild charge, so congrats on the cheapness

But then again, you probably did enough damage that you will need new tubes and a new rebuild after your next four 12K services, so you will pay then anyway ....or just splurge and get the year 2010 model Ohlins Super R&T for only $10,000 ($3000 2006 US dollars)

Or just get a second hand 97 Sporti forks with low miles, for under $1000.

If you order now, I'll sell you my Marzocchinis for $500 as cheap insurance against rebuild and re-chrome.

They were serviced at 11.5K and pulled at 26.9K...so I guess I was a little negligent, especially for not doing it annually.

[mike wilson]

IWhile I've not done a laboratory spectrum analysis on it, I'd expect it's a combination of metallic swarf from slider bushings, road dirt and pulverized bug exoskeleton that gets past the fork scrapers and seals, and the byproducts of degraded oil from shearing of the long-chain hydrocarbon molecules and heat degradation thereof from metal-to-metal contact at the interface of the sliders and bushings.

89040[/snapback]

 

Plus quite lot of condensation from moist air drawn in as the fork extends. Sucked in on a warm day, it will condense that night and settle to the bottom of the pile. Then get mixed up the next day as a fresh charge is drawn in.

 

I know they are supposed to be airtight but, in an absolute sense (ahem), they are not.

 

m

[mike wilson]

Interesting "bug exoskeleton" comment. True, the shattered and impacted remains of our 6 legged friends could conceivably get in there. I noticed after a particularly "swarmy" ride home yesterday that the Buell front fender fully protects the fork sliders from "buggery". Not so the V11.

89042[/snapback]

 

It's good to know that American designers place a high priority on buggery and protection therefrom. I am as suprised at that as I am at the lack of thought or protection on Italian machines.

 

mike

who has been protected from buggery for about 200,000miles.

[Guest Nogbad]

I neglected the WP's on my 97 Sport 1100i for 58,000 mlles. The rebuild charge was a tad over $500. I was lucky I didn't have to have the fork tubes re-chromed as they weren't so bad that they couldn't be turned down in a lathe. Now... is there anybody that thinks it isn't necessary to take care of fork oil on the regularly scheduled interval?

89241[/snapback]

 

Yes. Me. You can't attribute 100% of the wear to not changing the fork oil. 58000 miles is a lot, and even with fork oil changes they may have worn out anyway. The difference is probably less than 10,000 miles extra life if you had changed the fork oil, so you actually made the right decision to leave it in there from an economics perspective.

 

I am going to service my Marz forks at 12000 miles, i.e. in the next month. If I find that the oil is reasonably clean, and that there isn't a whole load of "glop" in there then the forks will go back together with some best quality synthetic fork fluid and they then won't get touched again unless I have to change a seal. I suspect the most economical way with forks is to service them only when a repair is needed.

 

Guzzi are anal about fluids.

[Guest Nogbad]

It's good to know that American designers place a high priority on buggery and protection therefrom.  I am as suprised at that as I am at the lack of thought or protection on Italian machines.

 

mike

who has been protected from buggery for about 200,000miles.

89898[/snapback]

 

I was pleasantly surprised. I rode briskly across Salisbury Plain early in the morning and the bug splat was so bad I had to stop halfway to clean my visor. The 'Bolt's fairing was a mess, but not a bug on the fork sliders to be seen.

[Guest ratchethack]

Yes. Me. You can't attribute 100% of the wear to not changing the fork oil. 58000 miles is a lot, and even with fork oil changes they may have worn out anyway. The difference is probably less than 10,000 miles extra life if you had changed the fork oil, so you actually made the right decision to leave it in there from an economics perspective.

 

I am going to service my Marz forks at 12000 miles, i.e. in the next month. If I find that the oil is reasonably clean, and that there isn't a whole load of "glop" in there then the forks will go back together with some best quality synthetic fork fluid and they then won't get touched again unless I have to change a seal. I suspect the most economical way with forks is to service them only when a repair is needed.

 

Guzzi are anal about fluids.

Nog, if you're doing your fork service with an "agenda" - that is, to prove something, I have no doubt that you'll find exactly what you're bound and determined to find, regardless of any benefit to the performance of your forks, to your ride, or any peace of mind you may gain from adherence to the recommended OEM service....

 

I seriously doubt if you'll find "a whole load" of anything that doesn't belong in your forks, and I suspect that most of the oil will appear to be relatively clean (by sight). What I found twice was probably no more than a few grams of debris each time, and most of the oil appeared relatively clean (by sight). Again, I didn't have the "glop" analyzed, and I didn't weigh it, but I did look at it very closely, and I'm as positive as I can be that it wasn't doing any good in there. I've been reassured to know as a rider who generally NEVER likes to find himself caught behind the maintenance curve , that it hasn't been allowed to accumulate. I can also be absolutely sure that after getting it out of there while doing the recommended fork oil changes that there is NO CHANCE of anything from within these little accumulated piles of glop plugging up, or prematurely wearing out the damper valving or slider bushings. I'm also confident that, as Mike pointed out, there's no accumulation of water in the oil to oxidize components and dilute the effectiveness of lubrication, and that the operation of the forks isn't further compromised by the undeniable certainty of breaking down of the protective lubricating ability of the fork oil itself over time, as the oil molecules decompose, as is normal and expected. I suspect the latter two items, while not visibly darkening the oil, are the most significant reasons for specifying 12K mi change intervals, and removing the "glop" while ye'r in there is just an added benefit of proper service.

 

It's not at all easy to see anything in the bottom of the fork lowers without a light source that you can actually extend inside the tubes. Again, I used a bore inspection tool designed for inspecting rifle bores. If you don't have one, most dedicated shooters do, and you might be able to borrow one.

 

Look, I know that most riders don't - and many won't ever - do this service, NOR will many have it done for them. Many will consider it easier and "cheaper" to ignore it altogether. I knew a guy who put over 100K miles on his Toyota without ever changing the oil once until he sold it. I have no doubt that he considered this a "cheaper" way to "maintain" his Toyota. I reckon that's human nature, but I don't think it's any too good for any vehicle. But statistically, I suppose that most riders are likely to sell their Guzzi before fork performance starts to head south from neglect of service.....

 

I don't think that Guzzi specifies maintenance intervals that are "too short" or that they're somehow "anal" about fluid replacement. If anything, IMHO they err in the opposite direction! First, Guzzi fails to lube many things altogether, including the rear wheel splines, driveshaft splines, shift lever shaft, shock eyes, and cush drive collar - all of which suffer rapid premature wear from lack of lubrication unless and until properly attended to (as designed). Next, none of these things appear on the service schedule at all, and I consider this a serious omission. Not that consensus will make any difference to anyone, but I've noticed that many longtime Guzzisti whose business it is to service Guzzis seem to agree with me on all of this.

 

Barring a debilitating accident that would prevent me from riding, I plan to be riding my Guzzi until I can no longer enjoy wobbling around mountain roads, so in many cases, my service regimen is more or less more thorough than "by the book". I'm in it for the long haul.

 

The maintenance of your Guzzi is up to you as rider and owner, but generally speaking, I would caution others against the idea that following the OEM service intervals is unimportant and unnecessary.

 

BAA, TJM, & YMMV

[Guest Nogbad]

Nog, if you're doing your fork service with an "agenda" - that is, to prove something, I have no doubt that you'll find exactly what you're bound and determined to find, regardless of any benefit to the performance of your forks, to your ride, or any peace of mind you may gain from adherence to the recommended OEM service....

 

No I won't. My only "agenda" is to determine the most efficacious regime from an engineering and economic standpoint. The condition of the forks is of course an ABSOLUTE matter; the presence or absence of moisture, debris or fluid discolouration, and the condition of the seals and sliding surfaces.

 

I seriously doubt if you'll find "a whole load" of anything that doesn't belong in your forks.  What I found twice was probably no more than a few grams of debris each time.  Again, I didn't have it analyzed, and I didn't weight it, but I did look at it very closely, and I'm as positive as I can be that it wasn't doing any good in there.  I've been re-assured to know as a rider who NEVER likes to find himself caught behind the maintenance curve , that it hasn't been allowed to accumulate.  I can also be absolutely sure that after getting it out of there while doing the recmmended fork oil changes is that there is NO CHANCE of anything from within these little accumulated piles of glop plugging up, or prematurely wearing out the damper valving or slider bushings.  I'm also confident that, as Mike pointed out, there's no accumulation of water in the oil to oxidize components and dilute the effectiveness of lubrication, and that the operation of the forks isn't further compromised by the undeniable certainty of breaking down of the lubricating ability of the oil itself over time, as the oil molecules break up, as is normal and expected.  I suspect the latter is the most significant reason for specifying 12K mi change intervals, and removing the "glop" while ye'r in there is just an added benefit of proper service.

 

I disagree. The working fluid is not subject to high thermal or shear stresses, and the bearing loadings are light, especially when you compare the conditions inside an engine. Most car engines go for over 12000 miles between changes with synthetic oils. 12000 mile fork oil changes are probably a waste of good oil. Provided the fork design keeps the dirt and moisture out, and allows any wear debris to descend to stagnant areas in the base of the slider oil life should be indefinite from a viscosity stability and corrosion standpoint.

 

It's not at all easy to see anything in the bottom of the fork lowers without a light source that you can actually extend inside the tubes.  Again, I used a bore inspection tool designed for inspecting rifle bores.  If you don't have one, most dedicated shooters do, and you might be able to borrow one.

 

I'll flush it with kerosene and see what I find

 

Look - I know that most riders don't - and many won't ever - do this service, NOR will many have it done for them.  Many will consider it easier and "cheaper" to ignore it altogether.   I knew a guy who put over 100K miles on his Toyota without ever changing the oil once until he sold it.   I have no doubt that this was a "cheaper" way to "maintain" his Toyota.  I reckon that's human nature, but I don't think it's any too good for any vehicle.  But statistically, I suppose that most riders are likely to sell their Guzzi before fork performance starts to head south from neglect of service.....  

 

Maybe.... I personally quite enjoy fettling the bike. You clearly think I am out to encourage a "gas and go" mentality but I'm not. After all, how many times have you experienced a breakdown right after your car of bike was in the shop? There is an argument that if something is working leave it alone, particluarly if you have to disturb a lot of parts, as you do with fork oil.

 

I don't think that Guzzi specifies maintenance intervals that are "too short" or that they're somehow "anal" about fluid replacement.  If anything, IMHO they err in the opposite direction!  First, Guzzi fails to lube many things altogether, including the rear wheel splines, driveshaft splines, shift lever shaft, shock eyes, and cush drive collar - all of which suffer rapid premature wear from lack of lubrication unless and until properly attended to.  Next, none of these things appear on the service schedule at all, and I consider this a serious omission.  Not that consensus will make any difference to anyone, but I've noticed that many longtime Guzzisti whose business it is to service Guzzis seem to agree with me on all of this.

 

Perhaps, perhaps. I think 12000 miles for forks is anal. I think 6000 miles for tranny and bevel box is anal. 6000 miles for engine oil is about right. 24000 miles / 2 years for driveshaft grease is too long given the water spray , high loading and limited movement it is subjected to.

 

Barring a debilitating accident that would prevent me from riding, I plan to be riding my Guzzi until I can no longer enjoy wobbling around mountain roads, so in many cases, my service regimen is more or less more thorough than "by the book".  I'm in it for the long haul.

 

Better make sure "more thorough" doesn't simply mean "more pointless" or "more wasteful"

 

The maintenance of your Guzzi is up to you as rider and owner, but generally speaking, I would caution others against the idea that following the OEM service intervals is unimportant and unnecessary.

BAA, TJM, & YMMV

89918[/snapback]

 

Show me a 10 year old vehicle that has always had ALL the OEM items done every time.