Stock shim stacks for the Marzocchi Shiver 48 on 4Ts

Tuning and maintenance of forks, shocks, etc.

Re: Stock shim stacks for the Marzocchi Shiver 48 on 4Ts

Postby Leon_RR250 » Mon Jan 06, 2014 12:17 pm

The picture is cropped on the right somehow but you can still just see on the very right side the 14mm nut I wrote about...

Leon
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Re: Stock shim stacks for the Marzocchi Shiver 48 on 4Ts

Postby GMP » Mon Jan 06, 2014 9:03 pm

I can't see anything close to the cap and adjuster. Wrap the assembly in a rag to protect it, hold the cap with a KYB cap wrench, rap the top of the adjuster with a plastic hammer and have another go at it. Being its a used fork that's been violated, perhaps some savage tried to take the cap off using the PFP adjuster. He'll, that's nothing, I hear over on GGRC some guy is working on his with plumbing tools! :o

FWIW, I just put new bushings and SKF seals in mine, and it was the easiest install I have ever done. Just a light push on the driver, that's it.
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Re: Stock shim stacks for the Marzocchi Shiver 48 on 4Ts

Postby Leon_RR250 » Mon Jan 06, 2014 11:49 pm

I will take your advice but still first try with a 22mm socket tool to screw clockwise the PFP screws. I tried it sometimes but I was stopping since I was putting already a lot of torque/power (and it felt that it wanted to turn clockwise...). Yes, it is quite obvious the previous owner opened the inner chamber cap using the PFP screws instead of using the KYB tool. Assuming that at min preload there is a lock-ring as there is one at max preload, then the PFP screw is jammed with the lock-ring.

Leon
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Re: Stock shim stacks for the Marzocchi Shiver 48 on 4Ts

Postby GMP » Tue Jan 07, 2014 7:51 am

Leon,

Thats exactly what I'm talking about. I suggested holding and securing the comp assy becuse I was under the impression it was out of the fork based on your pics. In any case a shock with a plastic hammer may help free it whether it is jammed to the stop of its just the threads.

FYI, the stacks from my '13 300RR Race (USA bike)

Comp:
<piston>
28 x .1
12 x .1
32 x .15 (3)
14 x .1
24 x .1
22 x .1
20 x .1
18 x .1
11 x .2 (2)
11 x 2.5 (spacer)
<tap>

Midvalve:
<piston>
12 x .15
20 x .1 (4)
11 x .2 (2)
15 x .15
16 x .15
18 x .15
<spring>

Rebound:
<piston>
12 x .15
20 x .1 (3)
17 x .1
14 x .15
11 x .2 (2)
11 x 2.5 (spacer)
<tap nut>

Lots of bleed, likely a measure to avoid cavitation and still provide plushness in light of the high initial cartridge pressure these forks have compared to a KYB. I scratch my head with this one because its so close, if all I rode was technical and rocks I wouldn't touch it, its very good there. I need a litle more support for HS racing in the bigger stuff as I use all the fork often. I know what works in the GG version, I've done it on two 250Rs with success, but that bike is 25 lbs more with more weight up front, so I held off on a mid seasonn change considering I was doing well on it stock. Its amazing how much stiffer the .42 springs feel in the bike than in the heavy GG. I'm looking at just removing the rebound and mid bleed, and leaving the base for starters, to retain the small hit compliance. On the GG I stiffened and two staged the base, but on the Beta you have to be careful because its light and already has a very light front end. I also measured everything to get a precise preload number. The 0mm (last position) is actually 1mm on my fork. I made custom washers to fit under the spring and around the bottoming cone to get 2-3mm preload total. On the four stroke this should not be a concern though.
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Re: Stock shim stacks for the Marzocchi Shiver 48 on 4Ts

Postby Leon_RR250 » Tue Jan 07, 2014 11:29 am

Glen,

I was really happy for your knowledge over at the GG forum, I am even happier we both moved to Beta..! Thank you for the input.

No other fork in the market would work with so much bleed. Even a crossover after a bleed shim? :lol:

I generally hate crossovers and especially bleed shims (you guess with which fork I learned) but maybe the wheel needs to be reinvented with this Marzocchi! I would guess that cavitation is not really an issue with twin chamber forks but for everything there is something new to learn. Thank you for the stacks and your point about pressure! I will print all this discussion on paper and Thursday evening or Friday I will check all the stacks and consider your input and go from there. Currently I believe that my comp stack without bleed and without crossover is not so bad and I am desperate to see the midvalve setting the pros came up with after creating so stiff comp stack with so many 0.15 shims in the tapper. And tomorrow I am buying the correct Red Line oils.

Thank you again!

Leon
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Re: Stock shim stacks for the Marzocchi Shiver 48 on 4Ts

Postby GMP » Tue Jan 07, 2014 1:08 pm

Leon,

The 4stroke is a different animal, more weight and compression braking on top of that. Usually you find stiffer single stage stacks. The stock midvalve I listed is pretty tame, float is .75mm. The fork is awesome on everything but big whoops and landings. NO deflection, just a firm controlled ride. So the trick is getting a little more support out of it without screwing up the good manners. FWIW, on my GG I had the same float, no bleed, but two 20 x .15 face shims so that is like six 20 x .1s compared to the four on the Beta and it was still very good in the rocks.

You can get a CC fork to cavitate if the mid/base balance is off, that is the mid is stiff and base light. Oil being displaced by the damper rod flows through the base, remainder through the mid. If the mid can't handle it, extra gets pushed through the base and there is a cavitation on the rebound side of the piston if the pressure is low enough. The fork then feels like crap. You have to address both. This is not a problem on this fork, I think one reason why all the bleed, and the SKF seals, is to get a compliant ride on the trail trash from a CC fork, and getting the front end to bite.

If you have no luck getting stock specs, you could look to a well tuned KYB SSS used on say a WR450 as a place to start, as the forks share the same cartridge and rod dimmensions. I'm sure the pistons are different but probably not that different, and the pressure is lower. May be better than a wild guess.
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Re: Stock shim stacks for the Marzocchi Shiver 48 on 4Ts

Postby Leon_RR250 » Fri Jan 10, 2014 9:58 am

I have not received the shims yet so hopefully I can do something from Monday and test it soon.

Leon
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Re: Stock shim stacks for the Marzocchi Shiver 48 on 4Ts

Postby GMP » Fri Jan 10, 2014 10:53 am

I put my upper/lowers together and immediately noticed a difference in feel moving the bad one past the worn section of anodizing. Not going to work very well or long like this so apart they come again. The other fork has some wear starting as well. Going to give re-coating a shot with a PTFE impregnated T3 anodizing. Currently selecting a shop to do it. What is there from the Zoke factory IS NOT T3, just the red T2 with a PTFE coating, slick yes but hard no. A true T3 hardcoat is black/grey, black/brown, or a dark green, not pretty red. The Kashima process the Japaneese use impregnates moly disulfide as part of the process and is a dark gold color. I'm polishing out a score mark that runs about 6 in. or 150mm long. I also found the bushing on the bad fork to have a "twist" in it when removed and in a relaxed state. Cause or effect? All wear is in the rear of the tubes and is well beyond the lower clamp area. Also not confined to a circular area but pronounced streaking or scoring. Funny how this showed up all of a sudden, last oil change was fine. Since that change I did a day of MX track time, long ride with lots of whoops, plus a HS race that used a track, so a lot of big loads, landings, flex?, that the fork does not usually see. I'd really like to know exactly why. I'll be happy to get a decent season out of them while I devise a replacement plan and procure the hardware.
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Re: Stock shim stacks for the Marzocchi Shiver 48 on 4Ts

Postby Leon_RR250 » Mon Jan 13, 2014 12:25 pm

The plastic hammer worked..! 4 powerful hits on each cap were enough to be able to screw it clockwise... Thank you for the tip! The PFP adjustment works again (and I think the 2,8mm washer I used was more than the 2 turns in for the PFP... I will remove it of course)! I got the shims but I have to continue tomorrow with the actual valving...

Leon
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Re: Stock shim stacks for the Marzocchi Shiver 48 on 4Ts

Postby GMP » Mon Jan 13, 2014 1:55 pm

Leon,

PFP is a little over 1mm preload per turn if I remember correctly. I'll check again being my assy is apart. It might pay to disassemble your compression assys completely and carefully, inspect and clean/grease everything considering its obvious abuse in the past. Pay particular attention to the circlips and groove in the PFP adjuster as the upper one was likely stressed. Watch out for the detent spring and ball, its held by the circlip as well. Work with your hands and parts inside a plastic bag.

My uppers go out to RaceTech in CA tomorrow for a T3 re-coat and hone. Over the last week or so I talked to more anodize shops and learned more than you can imagine. Bottom line is you need a special fixture with an internal cathode and acid bath pump to assure correct and even deposition on the ID of a fork tube. Most shops can do this, but you pay for the setup so the price is too high. The large high volume suspension guys who do this a lot have their anodizer do this so the cost is distributed and not too bad. I buffed the score marks from the ID of the tube with some aluminum polish on a paint roller mounted to a long rod and chucked in my drill! Worked perfect! Hopefully dimmensions are OK and I get two very military looking fork uppers back in a few weeks, I'll keep you posted.
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