Fork Special tools

[Guest Barnapkin]

I'm a newbe at changing my fork oil. Can anyone let me know what I must have in order to do the job properly? I realize that you can give me a list of specal tools that cost hundreds of dollars each, but that's not what I need. What are the basics must have tools? Such as, what size wrench is needed for loosening the cap, etc ... Any additional tips/tricks would be appreciated.

 

Thanks!

[Guest ratchethack]

Barnapkin, it's always a joy to find a fellow do-it-yerselfer! I commend you for doing this. Not because it's such a daunting challenge (it's not!), but because changing fork oil seems to be just tedious enough to stop so many riders from doing it altogether. The consequences of all-too-common neglect here ain't pretty , and IMHO, unless y'er tight with y'er dealer and have confidence in their shop's knowledge, experience, and/or integrity, the risk that they'll get it WRONG can be considerable - and that ain't pretty either... BAA, TJM, & YMMV....

 

Coupla things.

 

You don't need any "special" tools. Standard size sockets, open-end 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 very helpful, but probably not mandatory. 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. Alternatively, you can hang 'em up over a pan to drain.

 

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 not needed if you do a thorough job of pumping the forks out, and take the time to let 'em drain with uppers and lowers still assembled. I've done it both ways several times -- but then, I know what's in there too (and what isn't), having had it fully disassembled the first time for a thorough inspection and faithfully keeping up the maintenance intervals. I also did it once to replace a blown fork seal.

 

It's not absolutely CRITICAL to get out every drop of old oil. Conceivably, there could be a thimbleful or so (or more) trapped inside that won't be much of a problem. What y'er trying to do is get most of the broken-down old oil out along with most of the accumulated sludge, swarf, and dreck at the bottom of the fork lowers. In the case of double, triple, or longer intervals past the last recommended change , a complete disassembly is probably called for, 'cause (assuming you don't have to rebuild the forks at this point) at minimum, that semi-malignant 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 fork leg per the shop manual for the Marz 40 mm fork is 400 ml. May I STRONGLY recommend that you DO NOT use volume measurement for fork oil replacement. Instead, use the AIR GAP measurement method. This prevents over-filling and an unbalanced 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 could allow damaging contact at full bump. You can live with a small volume of old oil mixed with new, but you don't want uneven/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. You'll want to be sure to pump out all the air bubbles as you're doing this by fully extending and compressing the forks many times. It's easier if you re-fill the forks before re-installing 'em on the bike, but if you re-fill 'em on the bike, do it before installing the wheel and brakes. With the forks on the bike, you can remove any excess oil with a turkey baster.

 

May I also recommend CARTRIDGE FORK FLUID such as 125/150 in lieu of the conventional grade of products known as FORK OIL, that were/are specified for damper-rod forks, rated by oil wt., such as 5wt., 7.5 wt., 10wt., etc.

 

While y'er at it, in case you haven't already done this, it's a splendid time to properly match the springs to y'er weight, and set the fork preload with correct length spacers. With up-rated springs and properly set preload, now that you've raised up the front end so substantially with higher-rate springs (getting the sag settings in your target range), and you'll actually be riding around with correct front-end geometry, 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.....

 

Hope this helps, my friend. Have fun!

[jrt]

Ratchet- this topic comes up regularly enough, and you've given a nice complete answer every time. Would you consider writing this up and submitting it as a FAQ?

[sctt2525]

Ratchet- this topic comes up regularly enough, and you've given a nice complete answer every time.  Would you consider writing this up and submitting it as a FAQ?

88630[/snapback]

 

 

Yep, I'll second that! and beg you to put in some pics too please!

 

Scott

[Guest ratchethack]

Ratchet- this topic comes up regularly enough, and you've given a nice complete answer every time.  Would you consider writing this up and submitting it as a FAQ?

Yep, I'll second that! and beg you to put in some pics too please!

Be happy to Gents, and thanks for the interest. But as far as pics - I'm not due for the next fork oil change until some time next summer.

 

I've got a heads-off valve guide inspection/top end refurb in front of this, and I'll more'n likely get a "round tuit" this summer. I'll be sure to take photos and do a write-up on this.

[sctt2525]

Be happy to Gents, and thanks for the interest. But as far as pics - I'm not due for the next fork oil change until some time next summer.

 

 

You're in luck on that...You're invited to do the forks on mine now!!!

[Guest Barnapkin]

Hey sloooowwwww down!

If anyone is getting help, then it's the guy who started the tread.

[Guest Barnapkin]

Ratchet - Here are a few questions:

 

A. Per the dealer comment, I trust my local dealer. Between track days, and real world costs, I need to make up the difference some where. I figured that oil changes eng/fork, should be an owner-level task. I'm not a tool-putz, so I'm confident that I can do the job. There just isn't much accurate info available/comprehensive as to how to/what's needed. I've gotten the "It's easy. All you need to do is ... 2 min off-the-cuff rundown." I just want to do the job correctly (read: no hacks).

B: The pubs that I have all list volumes, so is there a resource that lists the top of tube (while compressed) measurements? Looking at doing all of my bikes, not just the V11. I figured that posting the question here would result in a reasonable answer because Guzzi folks are typically self-maintaining types. I feel funny asking a dealer for the correct info, because why would they want to knowingly give away info that would deprive them of business. (The $$ is in the parts and service, not the sale.)

C: I would love nothing more than to upgrade the sprinds and add racetech valves to every bike, but for now stock will have to do.

 

Thanks.

[Guest ratchethack]

Ratchet - Here are a few questions:

 

A.  Per the dealer comment, I trust my local dealer.  Between track days, and real world costs, I need to make up the difference some where.  I figured that oil changes eng/fork, should be an owner-level task. 

I'm right with you here Barnap....but then, in my case, as a dyed-in-the-wool do-it-y'erselfer, I can't think of much that shouldn't be an owner-level task, unless it's stuff like spooning on new tires without leaving a mark on the wheels, re-boring cylinders or re-cutting valve seats...

There just isn't much accurate info available/comprehensive as to how to/what's needed.  I've gotten the "It's easy. All you need to do is ... 2 min off-the-cuff rundown."  I just want to do the job correctly (read: no hacks).   

B: The pubs that I have all list volumes, so is there a resource that lists the top of tube (while compressed) measurements? 

In many circumstances I figure WE'RE the best source of info available!!!

 

The manuals are more'n likely submitted to Tech Pubs by the Engineers who either design, or at least specify the gear. Often, they seem to lack a "maintenance perspective".... IMHO, one example of this is fork oil replacement. Assembling a dry bike on the factory floor, fork oil measurement by volume would seem to be the most expedient when there's no old oil to drain! The fact that in practical application, draining old fork oil's often a hit-or-miss proposition with varying results as far as getting it all out doesn't seem to occur to the Engineers, and I can see how this common circumstance might therefore fail to get into the Service Manual - particularly if you're working for a tiny company like Guzzi, specifying an outside supplier's fork like the Marz, and service is not - nor has it ever been - your business! I've had varying results going with the 400 ml volume measurement myself many times -- it's not haunted (I hope), yet it's surprisingly inconsistent.... This makes getting the all-important AIR GAP correct a real challenge (if not impossible) unless it's measured directly. After draining the forks, it's no more difficult than measuring 400 ml in a graduated cup.

 

I replaced my springs with a Wilbers (German) set that was specified by Wilbers specifically for the Marz 40 mm fork on the Guzzi. They offer different rate springs for different weight riders. Their recommendation was 100 mm air gap. This is a starting point, and you can go up or down slightly from here to suit as needed. To increase the air spring effect, you increase the air gap, & vice-versa. One of the reasons I pay such close attention to this is that just a few mm change in air gap has a large effect on the "air spring" force. I've carefully measured my fork travel with these springs and 100 mm air gap by the ol' zip-tie on the fork tube method with near-stoppie-producing braking and over sharp-edged pot-holes. With a 100 mm air gap, I've yet to bottom-out, but I figure I'm just close enough - I'm getting 110-115 mm travel out of an available 120 mm full travel. I figure 100 mm air gap is spot-on for me, and would likely be a good setting for most riders under most conditions. I also figure that it would be suitable for most riders as a starting point with any kind of spring. Keep in mind that the "air-spring" force rises exponentially with fork travel, and this force is ADDED ON TOP OF the rate of the springs, so you get a rapid "hockey-stick" rise in combined rate approaching the end of fork travel.

I feel funny asking a dealer for the correct info, because why would they want to knowingly give away info that would deprive them of business.  (The $$ is in the parts and service, not the sale.)

This may just be my own perception, Barnap, but I've always found that the VERY BEST dealers and service shops have a philosophy that sets them apart - they figure the more open and helpful they are with info for do-it-yourselfers that others tend to consider "proprietary", the more business it brings them in the long run. I can think of a couple Guzzi dealers/service providers who frequent this Forum who seem to be pretty good examples of this...

 

It sure doesn't hurt to ask (within reason!). Do you consider yourself a "good customer"? You might be "worth it"... I faithfully give lots of aftermarket business to those who've helped me out... A select few actually seem to take notice!

C: I would love nothing more than to upgrade the sprinds and add racetech valves to every bike, but for now stock will have to do.

Gotcha. My accounting/justification scenario goes something like this: I save about $400 every time I do a fork oil change. In the process, I do lots of stuff that no one else is gonna do: The entire front-end gets cleaned and waxed, the brake calipers get scrubbed out and blow-dried, and every fastener in the operation gets cleaned, thread-locked, and properly torqued where appropriate. In the grand scope of things, a new set of springs is a paltry price at $120 USD! As noted lo these many times, IMHO the pitifully weak stock springs are 100% of the "problem" with the otherwise superbly-performing stock Marz forks, and the stock damper valving seems to me to be more'n plenty good enough for Road Geez purposes - at least as long as you don't start messing with it by hacking-in somebody's very expensive idea of "racing fork" valving modifications....

 

BAA, TJM, & YMMV

[Guest ratchethack]

Say Barnap - FYI - if you haven't already tackled this yet, per request, I re-posted this as instructions in the "How To" Forum. I re-worked it a tad and added a few additional NOTES.

 

When you get done (or even in process) - by all means post back. I'm more'n interested in any and all feedback and/or suggestions on improving the "How To"!

[Guest Barnapkin]

I'll give feedback. I't will be a few weeks because I'll be away for two weeks on a business trip. Thanks.