Stock shim stacks for the Marzocchi Shiver 48 on 4Ts

Tuning and maintenance of forks, shocks, etc.

Stock shim stacks for the Marzocchi Shiver 48 on 4Ts

Postby Leon_RR250 » Sun Dec 22, 2013 11:45 pm

Hi!

Recently I changed my RR250 to an RR400 Factory 2012 with the red Marzocchi 48mm fork. I just had a long ride in the woods and the forks were really harsh everywhere, moving fast up and down using much of the travel and then stopping suddenly about 7-9 centimeters from bottoming out. I checked the compression shim stack yesterday and I found the following:

32 - 0.1mm (x10)
20 - 0.1mm (crossover)
32 - 0.15mm
30 - 0.1mm
29 - 0.15mm
28 - 0.15mm
26 - 0.15mm
24 - 0.15mm
21 - 0.15mm
20 - 0.15mm
18 - 0.15mm
16 - 0.15mm
14 - 0.15mm
12 - 0.15mm
11 - 0.2mm

I think for those who have tried even once to revalve their forks it is obvious from the description above which parts of the shim stack cause the harsh behavior (blowing through the stroke until there is lots of damping later from the 2nd stage). Also in the external chamber there were only 270ml of oil and the PFP was stuck full open (10 turns out).

I am going to try the following with 300ml of oil in the outer chamber and 2 turns in for the PFP:

32 - 0.1 (x6)
30 - 0.1
28 - 0.15
26 - 0.15
24 - 0.15
21 - 0.15
18 - 0.1
16 - 0.15
14 - 0.15
11 - 0.2

It would be a bit different and without the thicker 0.15mm shims but currently I do not have enough spare shims.

I would be really thankful if somebody could provide the stock shim stack for the Beta 4Ts.

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

Postby Leon_RR250 » Sat Jan 04, 2014 10:21 am

Hi!

Happy New Year to everybody, first of all.

I progressed a bit with the fork. I did not try the shim stack I wrote about previously but the following one:

32 - 0.1 (8)
30 - 0.1
28 - 0.15
24 - 0.15
20 - 0.15
16 - 0.15
12 - 0.15
11 - 0.2.

For the stuck open PFP I used 2.8 mm shims to adjust the preload similarly to what it would be with PFP screw 2 - 2.5 turns in. 93 kgs fully geared with stock (0.46?) springs. 340ml oil in outer chamber. 5W Motul oil in the inner chamber. Not bad at all now but still experimenting with the clickers to find a good compromise from sand whoops to technical rocky forest. I have ordered 0.1mm shims (28 - 12, decreasing by 2 mm in diameter) to try them later.

I am surprised nobody knows or nobody wants to share the stock shim stack.

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

Postby Arctra » Sun Jan 05, 2014 2:45 am

Thanks for the interesting info mate. I am not surprised that you have not had a lot of response because a lot of people don't even bother changing their fork oil regularly, let alone playing with their valving themselves. Besides, getting it right is a bit of a dark art learned by playing around over time. I am no expert, I have just read up a lot on suspension tuning and so what I post is not to be taken as gospel - it is merely my understanding of how suspension works from my reading and talking to suspension tuners.

What are your fork spring ratings as a matter of interest? As far as I understand this will have an effect on your valving - higher rated springs for heavier riders will need less compression damping as the springs need more energy to compress them, and will require more rebound damping as the energy stored in the springs is unloaded quicker when weight is taken off the forks. So just because the shim stacks you have mentioned might work well for your springs, they probably will not be as effective for a different spring rate.

You might want to take a look at this Shim ReStackor application for assistance: http://www.shimrestackor.com/Code/Sampl ... rofile.htm

Also, it is good you mentioned you have used Motul 5W oil as the SAE grade (i.e. 5W) is actually nearly irrelevant for suspension tuning purposes. Instead you should know the viscosity of the fluid at different temperatures - typically measured in centi strokes (cSt). There is a good reference of fork oil viscosities here: http://www.peterverdone.com/wiki/index. ... sion_Fluid

So your Motul 5W fork oil - I presume it is the "Comfort Light 5" rated oil - has a viscosity of 18.2 cSt at 40 degrees celcius, and 4.0 cSt at 100C. Now I believe the "Mazocchi Fork Oil" (which is not given a weight rating) is 26.1cSt@40C and 5.25cSt@100C which as you can see if quite a bit more viscous than the Motul you have used. So the less viscous oil you have used is going to flow through the valving and via the shim stacks easier than the stock Marzocchi oil which may account for your different feeling forks, assuming you are using the same clicker settings. As far as I know the clicker settings simply control the aperture (or size of the hole) that the oil flows through before being pushed past the shim stack. So, assuming you were using a clicker setting of 12 clicks out (anti-clockwise) from fully seated (turned in as far clockwise as you can go) with the stock fork oil, to get the same rate of oil flow with the less viscous Motul 5W oil you might need to have the clicker set to a more restrictive setting like only 8 clicks out from fully seated (when you have turned the clicker all the way clockwise the hole the oil has to flow through is its smallest, and as you wind the clicker out anti-clockwise it opens the hole up more to allow more oil to flow through at a given pressure).

Because your fork oil is hydroscopic it absorbs water over time, so it will get thicker and more syrup-like over time - i.e. more viscous. So that is why it is important to change your fork oil regularly - if I remember correctly the Marzocchi manual recommends every 8 to 16 riding hours which is almost as frequently as every second engine oil change. The harder your forks work, the hotter the oil will get and the more the oil will break down - so the more frequently your fork oil should be changed.

So as you can see, the shim stack on its own is only part of the story. You will need to know what spring rates are in use, the oil being used and how fresh it is, and the terrain and riding style (faster more aggressive riders, or rougher terrain, will require different valving to slower smoother riders).
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Re: Stock shim stacks for the Marzocchi Shiver 48 on 4Ts

Postby GMP » Sun Jan 05, 2014 9:05 am

Likely the reason no one responded is because there are very few 4stroke race models with that fork here. I could give you 300RR Race specs but they would be way too light.

All good info by Arctra. Another thing you should know is the inner and outer oils in this fork mix, like in a Showa. How? I believe when the bottom of the cartridge enters the bottoming cone, pressure on the OUTSIDE of the damper rod seal rise dramaticlly, forcing outer oil past the seal. As the cartridge compresses further, excess inner oil is expelled from the top as the piston inner seal crosses the shaft recess, as in a normal bleed. The more the fork is bottomed or close to bottomed, the more this happens. So keep this in mind when choosing oil, and use the same.

How am I so sure? Unfortunately my right upper tube was trashed and the outer oil extremely fouled with aluminum, worn anodizing, and even shards of aluminum. Some of this fouled oil made its way into the cartridge, it was obvious. As far as the cause of damage I can't prove anything but the larger shards of aluminum could not be traced to any internal part of the fork, except perhaps the inner walls of the upper. I suspect these larger debris were left over from mfg and trapped in the bottoming cone, finally making there way out. Either that or a bushing / land problem that side loaded the slider, but action has always been smooth. So I would suggest a complete disassembly and thorough flush, with mechanical means like a brush, to avoid this possibility.
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Re: Stock shim stacks for the Marzocchi Shiver 48 on 4Ts

Postby Leon_RR250 » Sun Jan 05, 2014 11:24 am

Thank you Arctra, Thank you Glen for your replies..!

Good info all together! Sorry Glen for the damage in the tube. Hopefully it won't be too costly to fix.

From the color of the oil I took out it seemed to me like Motorex 7,5W which I was using in the Marzocchi 45s. It's impossible to find the correct Marzocchi oil here in Finland. Because of the many 0.15 mm shims (one behaving like 3-4 0.1mm shims) that I am still using I decided to go with the Motul 5W since I had it already on the shelf. I will have tomorrow some more testing time in really sloppy and rocky conditions and I will come back with more news. The springs are stock, 0.46s I believe.

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

Postby GMP » Sun Jan 05, 2014 12:59 pm

The stock Marzocchi oil is made by Spectro and is 26cSt @ 40 deg C. This is sold here as Spectro Cartridge Fork Fluid 125/150. I have a race car shop nearby the uses and stocks a lot of Redline synthetic products(American) and a 2 to 1 mix of the medium(10w) to light(5w) is a perfect 26cSt. You can do this with any brand oil to get what you want. Too light an oil makes the sloppy rebound valving seem worse, oil affects rebound more than compression.

Yes, extremely disappointed in this situation. For the price I expected a lot better. The internal anodizing is not a hardcoat either, just the same thin red as the external surface. I'm not 100% positive what the cause was so I'm not putting any serious $$ back into it. I have my suspicions. I'm going to put it back together with new bushings and ride it until performance degrades then scrap it for a KYB SSS. While I like this forks action, I have never had or worked on Zokes without a problem. Maybe it's just bad luck on my part, but 30 hrs is not long enough. I want to see what the internal surfaces of a larger population of these forks look like after some hours. My GG version had somewhat dirty outer oil on service but I never broke it down completely for inspection. If you see grey mud, its your anodizing and base metal.
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Re: Stock shim stacks for the Marzocchi Shiver 48 on 4Ts

Postby Leon_RR250 » Sun Jan 05, 2014 1:15 pm

Sorry again to hear that about your fork after only 30 hrs of use.

Thanks for the advice on Redline oils because I can really get them from a local shop here! I just put fresh 2,5W Redline oil to the Sachs forks of the RR250 (after cleaning the seals) before changing it. I should get the letter with the shims this coming week so I will give it soon a try if I am not still very happy after tomorrow's ride.

BTW, no internal issues with this Marzocchi on the Factory 400 after 76 hrs except this funny issue with the PFP screw stuck fully open on both tubes... I will have one more go at it soon when I open again the internals...

Best,

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

Postby twowheels » Sun Jan 05, 2014 9:28 pm

Leon_RR250 wrote:Sorry again to hear that about your fork after only 30 hrs of use.

Thanks for the advice on Redline oils because I can really get them from a local shop here! I just put fresh 2,5W Redline oil to the Sachs forks of the RR250 (after cleaning the seals) before changing it. I should get the letter with the shims this coming week so I will give it soon a try if I am not still very happy after tomorrow's ride.

BTW, no internal issues with this Marzocchi on the Factory 400 after 76 hrs except this funny issue with the PFP screw stuck fully open on both tubes... I will have one more go at it soon when I open again the internals...

Best,

Leon


Leon: I'm not sure that I follow the "PFP screw stuck open" comment. The PFP adjuster is just to preload the PFP spring, and unless the fork cap is stripped you should still be able to turn it back in. I have seen them almost 'take a set' though - it seems like a lot of force on the threads may cause them to gall together.
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Re: Stock shim stacks for the Marzocchi Shiver 48 on 4Ts

Postby GMP » Mon Jan 06, 2014 6:22 am

There is a circlip that stops the adjuster from unscrewing and sets the minimum preload. Perhaps the adjuster is jammed into this. I have seen a pic of a PFP adjuster unscrewed through the top from a broken or missing circlip. Both sets of my 48s were greased up pretty good, no seizure.
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Re: Stock shim stacks for the Marzocchi Shiver 48 on 4Ts

Postby Leon_RR250 » Mon Jan 06, 2014 12:15 pm

Thank you for all for trying to help me!

I had a hell of a drive today. Very slippery, very demanding, several rock gardens between whoop sections, etc. The fork was ok with 3rd gear through stones but still harsh in the tighter going with 2nd through roots and up and down big rocks. Through whoops with 3rd and 4th was really good. I settled quickly at 15 clicks out for compression and 23 (full) out on rebound. I need to check the mid-valve setting and the rebound stack next time, very soon, when I open it. It feels that my comp shim stack is really ok but the harshness comes from the "pro" level midvalve. The problem with the fork started when it was borrowed by a pro rider for a race and it was returned back to the previous owner without changing back the stock settings (and both the PFP screws stuck open). At least this is what I understood from this story... And I am unhappy that I got finally this bike or, better, this fork... It feels that my comp shim stack is really ok (and it will get better with the correct oil) and the harshness comes from the "pro"-level midvalve.

The picture shows the shim stack I found. On the system, on the long 14mm nut on the right after the cap I could see the lock-ring for the max preload on the PFP. So, you say there is another lock on the other side of this nut that probably the 22mm nut or the system it pushes on is jammed. On my hand I had the big cap assembled with this long 14mm nut and through the long nut the clicker needle. Spring, axis, etc were off. After that step I could not disassemble any more to solve the problem. I need to recheck it soon.

Thank you again for trying to help!

Leon

Image
Last edited by Leon_RR250 on Mon Jan 06, 2014 11:40 pm, edited 1 time in total.
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