fork tuning for enduros

Taffy said:

well that means to me that the simple bush in the BCs should infact be a seal? i'm convinced that although we have oil submerging the BCs from above and a full chamber below, we need to maintain the high vacuum and pressure figues in the top of the MV and the best way to do that is to have a seal on that 2" bush running through the BCs.

THAT IS WHERE PRESSURE IS ESCAPING!

i once damaged a cartridge rod and gave it a bit of a clean, i wish i'd replaced it and the bush in the BC. i can see no harm in a small 1mm bleed INTO the cartridge. it'll really help the rebound.

maybe that's why i haven't cupped any shims yet? coz i have a dodgy leg!

BTW it's not a quality to right incomprehensible science. i have already reported you to the "speak plain english" society and it's chairwoman, 89 year old nora bloodthirsty is on her way around to see you!

have a nice day!

tonight i've done the following
i have removed the 16 and 17 that i put in the Bv.
24, 14, 24, 24, 22, 20, 18, -, -, 15, 11, [email protected]

beefed the MV with this 13 so:
23, 23, 22, 20, 18, 16, 14, 13
so the float is now 0.95mm

the idea is that i'm back to as was before last weekend (ok i have gone from a 13 to a 14 splitter on the BV) but have now got a HS 13 in the MV and a smaller float.

i can add 15cc of oil from here and put anything on the Bv i want. not sure when i'm out though...

regards

Taffy

Click to expand...

Base-valve stack is WAY too soft especially considering you drilled a bunch of holes in the piston. The best thing you could do is toss those forks in the garbage and buy a set of 07 XC model KTM's. Put a set of .46 springs in them, set oil height to 110mm and LEAVE THEM ALONE!!!

You have gone completely nuts with "un-necessary" mods... :roll:

well i guess i'll be adding a lot of BV shims then won't i!!!!

closed fork - yeh i'd like them but i am working with the original gear to see what can be done with them. i don't have the money.

thanks for your interest. the 13 is still awaiting fitment.

regards

Taffy

Taffy said:

well i guess I'll be adding a lot of BV shims then won't i!!!!

closed fork - yeh i'd like them but i am working with the original gear to see what can be done with them. i don't have the money.

thanks for your interest. the 13 is still awaiting fitment.

regards

Taffy

Click to expand...

The 07 XC fork is an open chamber. Only the SX/SXF had CC for 07.

There was a set of 07 XCW 400 forks on the board today for $600.00. Main advantage is the 12mm cartridge rod but you also get the latest flex characteristics of the 07 tubes...

If you put enough shims in your forks to control the damping correctly you will be able to run the correct fork springs too...this is all "hinging" on the shock working correctly.

I would think on a Berg you would need (3)24x.10 of the face of the base-valve, especially with your drilled pistons. This should be a good start...and put the damn .46 springs back in with 5mm preload you fool!

(3)24x.10
14x.10
(2)24x.10
20x.10
18x.10<adjust for rocks/roots>
16x.10<etc
14x.10<etc
9.5x.30
12x.10

I try to build something that is too soft and then work back the other way...you are about 20 kilometers past soft...try the stack above and then manipulate the sizes of the ones with an < to tune for rocks/roots. DO ONE THING AT A TIME!!!

Set the oil level to 130mm and leave it alone. Once you get it to dive in corners to suit, mainly controlled by mid-valve, then CONTROL bottoming by adding oil if needed.

Forget all the theroies...fix your forks & then buy a spare set of forks to play with if you must...

i have to learn as i go lew! you may have done it years ago and you're down to small and subtle changes. i have to learn. what i will say in my defence is that we have early darkness, poor weather and nowhere to practice up here. if i was near an acre of scrub down in the mid-west all would be roses in the garden! ok cacti!! but you get ma drift donchya!

it would appear that if i had two more face shims as you suggest and i put one of my 16/17 back in we are not so far apart - but only on the BV! but you wouldn't be lew if you weren't controvercial!!!

the problem as i see it with the ZP3 mod is that he himself started with 23, 23, 18, 13. now if you think i'm very soft he was 'left of field' as you septics call it! i have also got to say that Per, (viking) who i respect completely as a suspension tech, has said that less than 1.4mm float and i was going to suck shims through.

so far i have not even bent a shim so the float is still going down, the MV is getting stronger, oil level going up and in general so is the BV. tom might be a part timer like me but he has come to the conclucion also that a 2-stage BV is needed, especially with the ZP3 mod.

a lot of people cheat by looking at other forks and then pretend to be some kind of guru! or wait until someone who has put up a nugget of info, has passed on, and then re-introduce it as their own wise words of wisdom.

i sat infront of the fire friday night going through all 23 sheets of fork info trying to work out WTF happened at the beginning for me to not to get full travel? i had 155 air gap, hardly any shims in anywhere and still had 2" unused. and this was with the 46s!

i can't tell you how i got to gradually use that space up? all i can say is that i added some oil, i opened the compression clickers, drilled the BCs and over three weeks i used 5mm more each week. weird! is it any wonder that your shimming is all over the show when suddemly someone says: "drill your bottoming cones like this..." you do it and suddenly your raison d'etre is accomplished! shimming o yeh! now let's get back to shimming!

if someone handed me forks with the 17cm mod done, the right BCs, the right, TOs the three drilled holes in the BPs and the right preload YES I WOULD CONCENTRATE ON THE SHIMMING. but why do you think that valentino rossi is always testing suspension? it's because everytime he nearly gets there they give him a grippier tyre and more power just to phuq it up again! so i'm never gonna have just shimming to do am i?

you say do one thing at a time and it's true to say that at the beginning i didn't but i am now! i was miles off so i made big changes, then i got into the zone and i'm slowing down as i get nearer.

the reason at the moment i run 1 x 24 at the face is so that i get some dipping on braking and entering (for which i got a 6 month suspended sentance! LOL!!!) so you should in a way say; 'ok what's happening from after the 14? maybe 3 x 24 here would be good?'

it's only in this past two rides that i have been really happy with the forks and feel i'm getting close. i did feel that way last year and then rode a fast track and they were awful. lesson learnt. i then was chuffed again with them and then changed the frame and had to start all over again!

the free mods, as they were done have all done something for the bike. something better! and surely 'suspension'' and dip' can be seperated slightly?

in the absense of any greater knowledge i'm afraid we have to find these things out for ourselves and if i did EVERYTHING you've suggested above i would, quite frankly, give up. i'm not starting again! i am where i am and each time i ride i get a different result, come up with different problems, have to find different solutions.

last week, i added a 16 and 17 to the BV and i felt that i lost 'dip' entering corners, i rode over the berms but i was riding in 10" of wet mud and couldn't trust the front tyre. were my results valid? not sure. do i carry on trying to suspend the bike better whilst this problem remains unsolved or do i try different settings to get the front down a bit for corners whilst maintaining what i have?

so during this week i swopped out the 16 and 17 and added a 13 to the MV. if i get about the same suspension and have the dip back then i have done the job and learnt something.

could go straight to NOST or gold valves but i'd rather try my best with the original stuff. it appears that the BV pistons can REALLY be replaced yet there are still plenty that continue to use the OEMs. PMK for instance. is he doing it so that he continues R & D for his customers or because the OEM can be made to work?

i am hard up, i'll admit it. and my money goes on many things lew. my bike started with 28bhp and is now on 42 with more to come. i am a man of many talents!

so i won't be throwing the baby away with the bathwater mate.

ok?

regards

Taffy

Taffy,

the reason at the moment i run 1 x 24 at the face is so that i get some dipping on braking and entering

Click to expand...

With those hard springs I bet you need every help available to increase the efficacy of rider input, in that view it makes sense.

And now over to something completely different: The silicone grease in the seals is not only a lubricant, try some on the kitchen floor! it is not like any grease, it is also a good release agent. Maybe if it is only humus drying in on your chrome it doesn't matter, but if you ride on clay and it dries on the chrome it is almost guaranteed that you will soon spring a bad leak. The silicone will help the scrapers do their job a lot.

Thinking of it, why would wp start using pressurized closed cartridges in forks? To increase total pressure to reduce the risk of cavitation I think. Then they can start using relatively heavy MVs and weak BVs without getting cavitation. The use of a check valve, like what you described, in the open chamber would allow the same to an extent, I think that you are right there. And the fork would still be relatively easily serviceable for us amateurs.

Regards

Deltas=Deltas is NOT true!

Aaah! Didn't get it until now! Newer delta shims in the rebound stack are more deltaed than those in my 2000 fork. Old deltas are nibbled to 10 mm from the center and newer deltas are nibbled to 9 mm from the center.
Instead of bellmouthing the MV piston ports I could simply have replaced the deltas with new ones and gotten the open port area enlarged whith that simple move.

Also, comparing older and newer rebound stacks is more difficult since the older deltas (like mine) are probably a bit stiffer than the newer deltas.

RE: Deltas=Deltas is NOT true!

i have been testing with the bottom pistons drilled. i flipped them over and drilled into each port once with a 1.5mm drill bit.

it brought the forks back to having plenty of 'dip' on entering corners. the idea is that you increase the free bleed under breaking where the bike is slower to compress than when it hits a bump. some of the problem waas that the float is now down to .95mm.

the bike also seemed to glide over bumps and gave just a little less feedback. i'll let you know about the shimstack i've been trying since soon.

regards

Taffy

You flipped them AND drilled?
Are you getting more checkplate float now?
This will be exiting...

Regards.

oops! sorry! i merely turned them over so that i was drilling the side with the small triangles 'proud'.

sorry to disappoint.

actually i'll carry on here and explain what i've been doing.

i was running
24, 24, 14, 24, 24, 22, 20, 18, 15, 11, [email protected]
23, 23, 22, 20, 18, 16, 14
float 1.05mm
120 airgap

tried the drilling and the bike was like velvet with nice dip at the corners. bike was superb, almost using too much travel for a woodland circuit and almost too good as tiny bumps were completely unfelt.

i removed one of the first two 24s and added 17 and 16 between the 15 - 11. this stiffened things nicely!

then added a 13 to the base of the MV which also lowered the float to .095mm. this gave the heels of my hands a thump so i've pulled that. travel is fully used.

so i had the taps machined and now have removed the 22 from the MV as well (kinda copying dangeroo0 here) but the float is still .95mm as a start. i've lowered the air gap to 115mm as well.

to finish
24, 14, 24, 24, 22, 20, 18, 17, 16, 15, 11, [email protected]
23, 23, 20, 18, 16, 14
.95mm float
115mm air gap.
2mm preload

sags are 46mm and 68mm front.

i really like this setup and will see how it goes as it differs little from a previous (just a MV 22 removed and 5mm added to oil level) test.

regards

Taffy

Taffy,

Can you really notice the single face 24 shim in your 24, 14, 24, 24, 22, 20, 18, 17, 16, 15, 11, [email protected] stack? Isn't it totally masked by the free bleeds?

Would you be able to notice the difference at all if you used 14, 24, 24, 24, 22, 20, 18, 17, 16, 15, 11, [email protected] instead?

Also, and this is only a reflection, you seem to experience special joy in bottoming the fork. But I guess every man have got the right to have his own preferences... :twisted:

Regards

h yes sir!

i really enjoy the full travel ....

i'm learning as i go?

regards

Taffy

i'm learning as i go?

Click to expand...

Not everyone does so I guess there is hope.
Good to see you at it again.

i think that i may haver the MV about where i want it now. the BV may well need stiffening. the thing i find difficult is the fact that i'm only riding my bike competitively and have nothing to compare it too. i'm by no means the guru of suspension just someone looking to share information and improve things as i go.

i get the feeling that one 46 spring might help but i can honestly say that i rode far quicker when i fitted the 48s. one could argue that the fork damping was too soft and therefore the springs covered a basic mistake but it did feel far quicker with them and that was good enough for me.

i get the feeling that it'll require 24, 24, 14, 24, 24 before too long. my problem is a lack of money and the fact that i'm racing far more infrequently now than just two years ago. then you put in that i'm 46 near 47 and it makes the testing that much tougher.

i'm suprised that there aren't a few other members here at UHE testing and trying things out though.

regards

Taffy

Taf,
I could never get away from cavitation with less than 3 shims in the 1st stage BV, cavitation from the 1st stage with anyhing less than 3 shims fokt op the rebound.
Maybe with the 14 splitter your 2 shim 1st stage is somewhat stiffer than my 2 shim 1st stage was that did not work because it was too weak. But should be close to it and pose a risk of cavitation?
What about 24, 24, 24, 14, 24, 22, 20, 18, 15, 11, [email protected] then?, it would better separate the bleed "lock point" from the BV 1st stage coming to its end. Maybe then you'd have a true advantage from your free bleed in combination with the two stage stack. And with the splitting of the active stack maybe an even a heavier 2nd stage can be put in without the overall stiffness going overboard?
Or, to really see what happens with an extended range of the 1st stage, 24, 24, 24, 24, 14, 22, 20, 18, 15, 11, [email protected] !

There is a risk that with too much free bleed or a too weak 1st stage in the BV, that you are in effect running a single stage stack. 1st stage allowing itself to be masked by the bleed. Better to run a too heavy BV 1st stage, it can never get worse than a BV that is in effect, or in fact, whichever, a single stage BV.

I understand the problem with competing only, while great fun you need to piddle around too, for balance training, and for making all these little adjustments, if I had lived nearby I would have picked you up and we could have taken the bikes somewhere to just piddle around. That would have been fun.

You may be old, but you are not dead yet, are you?

Regards

Smorgasbord said:

You may be old, but you are not dead yet, are you?

Regards

Click to expand...

ha! ha! not the last time i checked anyway!!!!!

i have to check what i have done first. i'm a believer in

finding out for myself
learning the whole picture
then going for the right answer

so i'm not panicking! i do absorb all that is said.

funnily enopugh it#s not the shims that are interesting me but the float gap.....

regards

Taffy

Taffy,

finding out for myself

Click to expand...

Agreed, that's the best way.

learning the whole picture

Click to expand...

Will we ever?

then going for the right answer

Click to expand...

Who can say no to that?

BTW, as said by Groucho Marx:" I have my principles and if you don't like it I have others."

funnily enopugh it#s not the shims that are interesting me but the float gap.....

Click to expand...

MV float?

Can you absorb this mad BV stack?:
24, 12, 24, 24, 24, 14, 24, 22, 20, 18, 15, 11, [email protected]
It has a splitter shim for your flexing bleedshim facing the piston, it has a fair 1st stage to provide enough damping and it has a 2nd stage to catch you when you hit the ground hard. Just an idea, you are the boss, as always. I have never tried anything like it if you wonder.

gave the heels of my hands a thump

Click to expand...

Cavitation can be felt like an unexplained thump or someone knocking on your handlebar with a plastic hammer. Especially during drop rebound (high speed). It removes rebound damping during the first part of the rebound. If it is severe you get it at compression too. You have to look for it or it can go undetected, but gives a general harsh feeling that is hard to explain. What really surprised me when experimenting with my fork was that it got less harsh when more shims than oem were used, it even felt smooth. If your BV is too weak or the MV is too hard in ANY speed range you will have cavitaton.

Regards

Smorgasbord said:

Cavitation can be felt like an unexplained thump or someone knocking on your handlebar with a plastic hammer. Especially during drop rebound (high speed). It removes rebound damping during the first part of the rebound. If it is severe you get it at compression too. You have to look for it or it can go undetected, but gives a general harsh feeling that is hard to explain. What really surprised me when experimenting with my fork was that it got less harsh when more shims than oem were used, it even felt smooth. If your BV is too weak or the MV is too hard in ANY speed range you will have cavitaton.

Regards

Click to expand...

smorgy

i said that the only change i made at all was to fit the 13 to the MV. that reduced the float from 1.05mm to 0.95mm AND THAT'S ALL I DID. sorry if i didn't say that the results i offered were in seperate tests!

so, i figure that my MV is where i want it with the 13 out and now also with the 22 out making it very similar to Dangeroo0 who has odds to my evens under the 23s. 24, 24, 21, 19, 17, 15, etc etc.

i consider the BV to be the 'units' and the MV to be the 'tens' as i was taught at school! i certainly don't think it's 10 to 1 but you get my drift!

now, as for the almost '3-stage' stack you offer, i simply wouldn't get involved in that till i understood the 'balance of the shimstack' by testing. that would be a single-stage and at max: a 2-stage.

still can't get over how i phuqed up the float gap. measured at .95 i had .3 removed from the piston's shoulder on the tap. i then removed the 22 and the 13 worth .2 yet ended with a larger gap of 1.0 (i had said .95 to flatter myself) again?????

having rebuilt it i'll live with it. float has grown from .95 to 1.0, MV has lost a 22 and a 13 and finally 115mm air gap.

nice thing is i can"'tie, rope and brand" her at the track from here at just the BV.

ROWDEY YATES WOULD BE PROUD OF ME

GET 'EM IN RAW HHHHHIIIIIIIDDDE!!!!

RAW HIDE!

someone PM'd me and said that i never mentioned the clickers.

that's right. i don't!

if i don't like a fork how it is i change it at the shimstack when i get home. i've found that the only clicker i use is the compression for checking travel 'ability'.

regards

Taffy

Taffy, I found this stack info on Shiver shimming. Nothing new under the sun, all the mad elements of shimming i proposed are here, all in the same shim stack. That does not say that this was a good fork, but it may well be, I wouldn't know...
Anyway, it may serve as an inspirator in your fork shimming adventures, the notes are mine, note how thy use different thickness of shims, I suspect this fork is quite progressive, here you go:
-06 Marzocci Shiver
11x.2 Bleed shim leaving a free flow gap. No need to drill oles...
22x.1 Bleed stage "stack", I think it linearizes the bleed a bit, to stretch it. (?)
11x.2 Split shim for the Bleed stage
19x.1 1st stage stack
17x.1
11x.1 Split shim
16x.1 2nd stage stack
16x.1
15x.15 (the stiffness corresponds to 3.4 x the stiffness of a 15 x .1 shim!)
14x.15
14x.15 (Jeez,.. these two 14s together are as stiff as 7 x the stiffness of a 14 x .1!)
13x.2 (this is getting rock solid...)
12x.2

Regards

smorgy

when you go off at an angle you really do donchya! i can't start in the middle of nowhere again! i'm in serious need of some skiing this weekend in italy and then head down for a few weeks.

regards

Taffy