Okey dokey. To start, I'd like to say I've searched like hell through every thread I can find on the subject. If some of my questions are answered thoroughly in a thread and you know of it, please don't hesitate to link it here.

So my 210 pound (naked) self has decided to go the F3 shock route for my 2007 919. I know it's got as many haters as lovers, and that's fine. I'm not buying a Penske or that Other brand, so there.
While we're on it, I'm not even all that keen on buying the RT Gold Valve kit. Might happen, but I wanna play first.

So anyway: I bought an F3 shock a month or so ago, and have finally gotten to start in on it. I've got it all apart, and have some questions and some interesting notes regarding disassembly and stock shims for posterity. For the notes, skip Section 1 and go to Section 2.

Section 1: So since I'm rebuilding this F3 shock for the 919, I'm planning on sticking on an Eibach spring (6.00" long, 2.25" I.D, 1100lbs). I'd also like to fool around with the shim stack, but am not so sure what to do here. I suppose I'll buy the ReStackor program, but I think I'll need a little bit of an idea of what I'm shooting for before I can use that effectively. So question time:
Anyone got the relevant ReStackor measurements/profile for the stock or aftermarket 919 shock?
If that's a no-go, wanna help me define exactly what am I looking for? I figure the 919 needs a bit more low-speed compression damping (LSC) compared to the F3, but how much more? And how much of that necessary additional LSC will be negated with the heavier spring?
Same thing for rebound: I assume the heavy spring will require a bit more rebound damping to balance, too. Any thoughts here? I know shim stacks are a black art; I've done a lot of looking around on the web, but it seems like one would do well to have a baseline. To be honest, I'm not entirely convinced I'll be able to feel the difference anyway. (I'm a regular ol' street rider; probably with a couple track days a year) So yeah, if you've got a thought or ten about stacks, I'd happily listen. This goes for shock oil, too. I figured I'd play in ReStackor, but if you've got a suggestion. . .


Section 2: Notes: First, my shaft nut wasn't peened (preemptive TWSS). The second thread, however, was wider than the rest. I mic'd this to be sure. I could get the nut off fine, but the shims and piston didn't wanna go past the thread. So I put the nut back on, filed that thread down a bit, and took the nut off. This method allowed the threads to get "re-shaped" when I took the nut back off. It's fine.

Also, there seemed to be no nitrogen in the remote can when I drilled it, and the shock oil was absolutely disgusting. Like, disgusting. It looks like used gear oil. It's gross. It would have been a mistake to simply mount this shock without a rebuild or re-fluid.

Stock spring measured 6" long, 2.5" I.D. on the bottom, 2.25" I.D. on the top and coil diameter was .505" .

Shock eye-to-eye was 11.5", or 292mm.

The stock shim stack was as follows, working from the end of the shaft (rebound stack) downward. All shims have 12mm I.D.

Washer: 25.75mm O.D., 3.05mm thick
Shims:
O.D.mm Thickness mm
25.2 .60
25.2 .60
21.96 .20
15.4 .19
32 .60
32 .51
32 .51
32 .51
32 .51
32 .52
PISTON
34 .21
34 .20
34 .21
32 .21
32 .20
32 .20
30 .51
30 .51
16 .20
26 .41
26 .41
WASHER 37 4.0

I polished the crap out of both piston faces up to 2000 grit then went in with some pastes. I used a glass plate to keep it all even. I guess this is supposed to help with the shims sealing, but somehow I doubt it's the limiting factor in this shock.
Also chamfered the intake ports for compression and rebound. You know, for "turbulence reduction" or whatever. Basically, I like motorcycle becasue 1) they're awesome and 2) because I like to tinker around. Chamfering a shitty stock piston counts as tinkering around.

-B

It would be awesome if you posted some pics of this in a step by step fashion.

I can't offer any help with stacks, but I wonder if there's some way that can help test the results.

Is there any way the effects of the shim stack could be made externally adjustable? I know that's probably a long shot.

What about getting a chart from a builder and using that as a starting guide, so at least you could have a guide that would indicate the changes you should expect with each stack change.

"I'm not buying a Penske or that Other brand, so there."

Clearly you are new, the only way to fit in is to purchase a shock that is worth at least 1/4th the value of your bike.

Not really... He stated that he enjoys tinkering and that was the main reason why he took on this project, if I read it correctly. Kudos to him, he'll have a lot of fun tinkering as there will be plenty of opportunities.

It would be a different story if he was convinced he could do a quality rear shock for cheaper by rebuilding the f3 and expect it to perform on par to a penske or ohlins.

Is there something special about the F3 that makes it a good choice for this? I understand some are more adjustable that others, but is the F3 more rebuildable than others?

KarlJay: There are several tutorials on the web about disassembling this style shock. Peter Verdone's site Peter Verdone Designs - 2005 CBR600RR Shock is pretty awesome, and Borynack's guide is quite helpful. http://www.borynack.com/xr650r/KYBShowaShockService.htm
As far as shims go, any stack is quite specific to bike, piston, oil, spring weight, and rider preference. There seem to be very few "rules of thumb" for their setup. Unfortunately, it's not as simple as seeing what one shock builder does, as it's likely not at all relevant. Thus my intent of getting an idea of what the 9er needs in comparison to the F3's valving. For instance, the LSC damping: Since the F3 is a linkage'd bike, it probably has less LSC damping than the 9er requires as a non-linkage'd bike. But putting such a heavy spring on the F3 fork on the 9er will require a setup with slightly less LSC damping, as the spring is holding more of the load.



pvster- I think we're all on the same page. I definitely read jnich's post as sarcasm, but thanks for hopping to defend my little project.


So. . . anyone got any ideas? I'm questioning whether I'll even ride my bike again for the rest of the year. Maybe it's time to pull the 9er shock and see what it's running myself.



-B

The F3 shock is close to the same length as the 919 (292mm vs the 9er's 282mm). It also has rebound and compression adjustments, both of which supposedly actually work.
There have been several folks who have swapped to the F3 shock, and a couple have done spring swaps as well. Some guys have had their shocks (both F3 and 9er stock) revalved/rebuilt by a dealer/servicer/pro, but I'm not aware of any who have done the work themselves. A little searching on this here (and other) forums will turn up quite a number of posts on the subject.

-B

I think your biggest challenge will be two fold: the first is using a linkage shock on a non linkage swing arm which will create some difficulties. The other is the 919's tendency to squat. Combine the two and you're in for a challenge

Might be best to pick mcromo's brain. Surprised he hasn't chimed in yet. He must be buried in 10 ft of snow by now.

Yeah; I was thinking this would be right up his and Rob T's alleys. I know McRomo doesn't like to talk specifics about the F3 shock stuff as much since he's never fooled with it. But the linkage and damping requirement, on the other hand. . .

So my understanding is that a shock's a shock, and it's the valving and stroke that make the difference for linkage/non. So by adjusting the valving appropriately. . .

-B

True story, I put a Penske on my bike for about 6th months. Just swapped my old shock back on that I had rebuilt. Despite what everyone believes, the Penske was not worth the money for how I use my bike.

Lies

Cool story bro

I spoke to a few shops about having an F3 shock valved and resprung for my 919. Every one of them had nothing but encouraging feedback and the price was a big advantage over an aftermarket shock.

I ended up buying a used Penske that was sprung for a190lb rider ( I am 170) from a member on here. I never could get it to ride like I wanted it to. When I looked into swapping the spring, the cost difference was not worth it when combined with the purchase price of the used shock. I ended up selling it for what I bought it for and wrote it off as a learning experience.

In the end, I had the 919 shock resprung and new seals and crap put in it and am much happier. I definitely wish I had kept the F3 shock and went with that route rather than pissing away money based on internet folklore.

Kudos to you for doing it yourself and not following the herd.

My contribution to "internet folklore".

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Nice man!

I'm curious, was that my triple clicker you bought?

As long as the shock is properly configured for what the bike is, its use or uses, and the rider's butt sense matches his "brain wants", a Penske will bring joy and a huge improvement over stock. So will an Ohlins. The Ohlins that LDH sells from DK's shop is a can't go wrong shock, all it needs is the correct spring and the right adjustments and a good and much improved result is guaranteed. That is not the case with Penske's, at least not in my opinion. Based on the experience I had, as later mirrored by Arctic, when ordering a Penske for one's particular requirements, piston selection also has to be part of it, not just spring rate, installed preload and clicker settings. Mine came from Jim Lindemann about 8 years ago in two way build. The catalogue called up standard build with 900 # spring so Jim upspringed me to 1000. Later I figured out the shock body was common with that for a Triumph 1050, in other words a linked suspension, let alone the swing arm angle re squat/antisquat forces. I wanted a very track friendly build, and after a full blown development project with a local whiz on first name basis with Penske, I ended up with a digressive piston, 1200 # spring and longer free eye length.
At least I learned lots as a result of the frustration I had with the Penske until I got it all sorted out.
If I hadn't bothered to learn, it'd have been akin to having the best ever two stroke bike forever sticking engines and not bothering to find out why.

Yeah, I'm careful on stuff I've not dealt with at all. But I'd expect that an F3 shock could be reconfigured to get it to acceptably work on a 919 if economy is major driver and it can be done cheap enough in comparison to a good aftermarket unit. (I always keep in mind what zaq did with his 919 unit some years back, stupid cheap and it sounded as though he liked the results and I'd say he's a fairly savvy and picky guy that assesses well)

Below is from your earlier post, I have interlaced some comments within, hope this helps you at least a bit.


So since I'm rebuilding this F3 shock for the 919, I'm planning on sticking on an Eibach spring (6.00" long, 2.25" I.D, 1100lbs). 1100 # IS THE LIGHTEST I’D SUGGEST FOR YOUR INTENDED PURPOSES.

I'd also like to fool around with the shim stack, but am not so sure what to do here. I suppose I'll buy the ReStackor program, but I think I'll need a little bit of an idea of what I'm shooting for before I can use that effectively. ONE DAY I’LL BUY IT AND PLAY WITH IT BUT WHEN IT COMES TO VALVING, PISTONING AND STACK BUILDS I PAY THE LOCAL WHIZ FOR WHAT HE KNOWS BETTER THAN I’LL EVER KNOW.

So question time:
Anyone got the relevant ReStackor measurements/profile for the stock or aftermarket 919 shock?
If that's a no-go, wanna help me define exactly what am I looking for? MY OPINION IS DIGRESSIVE COMPRESSION DAMPING FORCE CHARACTERISTIC CURVE SHAPE.

I figure the 919 needs a bit more low-speed compression damping (LSC) compared to the F3, but how much more? YES. LOTS MORE. F3 IS LINKED, 919 IS NOT, SO IN NOMINAL TERMS 919 SEES TWICE THE FORCES JUST BY THAT ALONE. I THINK THE F3 HAS A BETTER SWINGARM ANGLE WITH MORE FAVOURABLE SQUAT/ANTISQUAT RELATIONSHIP. AGAIN, THE 919 NEEDS MORE DAMPING FORCE. 919 HAS MORE TORQUE AND LOTS OF IT RIGHT ACROSS THE REV BAND. AGAIN, THE 919 NEEDS MORE DAMPING FORCE. 919 IS GEARED FOR A SIGNIFICANTLY LOWER AERODYNAMICALLY LIMITED TOP SPEED, IN OTHER WORDS HAS A HIGHER TORQUE MULTIPLIER. AGAIN, THE 919 NEEDS MORE DAMPING FORCE.
And how much of that necessary additional LSC will be negated with the heavier spring? THE HEAVIER SPRING HELPS BUT COMES NOWHERE NEAR DOING IT ALL AND SEE ABOVE RE THE OTHER FACTORS.
Same thing for rebound: I assume the heavy spring will require a bit more rebound damping to balance, too. Any thoughts here? REMEMBER THAT TOO MUCH REBOUND PUTS YOU ON YOUR HEAD. YOU WILL NEED MORE FOR SURE. THE REBOUND CIRUIT ON MY PENSKE WAS NEVER CHANGED, IT WAS FOR A 650 # SPRING, AND WITH A 1200 ON IT IT’S ONLY IN THE MID RANGE OF ADJUSTMENT. I CAN’T COMMENT ON THE F3 BUT GUESS IT HAS MORE BUILT IN THAN YOU THINK. GET YOUR GUY TO DO A SHOCK DYNO TEST, THEY ARE CHEAP AND YIELD GOOD INFO.
I know shim stacks are a black art; I've done a lot of looking around on the web, but it seems like one would do well to have a baseline. REALLY GOOD STACK BUILDS COME FROM SMARTS/EXPERIENCE/SKILL. A GOOD PROGRAM SHOULD YIELD PREDICTABLE DAMPING FORCE CURVES SO THE QUESTION BECOMES WHAT CURVE SHAPE AND MAGNITUDES DOES ONE WANT ?

To be honest, I'm not entirely convinced I'll be able to feel the difference anyway. (I'm a regular ol' street rider; probably with a couple track days a year) YOU WILL BE ABLE TO TELL THE DIFFERENCE. ON THE ROAD AND ON THE TRACK.

So yeah, if you've got a thought or ten about stacks, I'd happily listen.

This goes for shock oil, too. I LEAVE SHOCK OIL TO THE SHOCK BUILDER. ALL I KNOW IS MINE HAS A SILKOLENE IN IT AS RECOMMENDED BY PENSKE, DON’T KNOW THE WEIGHT.

A bit more on my Penske.
It came with a piston that was categorized by my local guy after testing it, as having a characteristic that was half way between Penske's manual depiction of "Linear/Linear" and "High Flow Linear/Linear".
Another piston he had on hand was tried, the particulars I never bothered to ask for, as upon test it was obvious the compression characteristic was not what he was looking for. So a "Digressive(comp)/Linear(rebnd)" was ordered in and fitted. The specific part number is DL 005, 2 degree dish. It's worked quite well, although I've not yet got the shock dyno test done for it.

Also, in terms of damping force magnitudes, the chart that came with my shock when new, was scaled 0 to 400 # for the Compression, and 0 to - 1400 # for the Rebound. In terms of Penske's "initial settings", the Compression force peaked around 200 # but under 100# up to 4 in/sec velocity. The use of the digressive piston significantly increases the damping force available in the low velocity zone, which is where squat force resides.