2008 fork springs help - 600RR.net
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post #1 of 18 (permalink) Old 05-15-2017, 05:35 AM Thread Starter
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2008 fork springs help

I want to buy springs, so I need you advice.
I'm 165lbs (75kg),drive most about street 85% ,15% track, and I looking for RaceTech springs 0.9 or 0.95.
Please give me your advice,which springs to buy.

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post #2 of 18 (permalink) Old 05-15-2017, 07:01 AM
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I'm 80-85 with gear on. went with .95 springs

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post #3 of 18 (permalink) Old 05-15-2017, 01:14 PM Thread Starter
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It's like my weight I think... how much you tight preload?
on race tech calc for street is 0.9, for track 0.95... I check it now

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post #4 of 18 (permalink) Old 05-15-2017, 08:43 PM
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.90's.
I'm supposed to run the same spring rates as you for my F4i, and I went with .85 springs because the bike is 99% street and I wanted somewhat comfy still. If your going to do track at all, then run at least .90's.

06 F4i- Yoshimura RS-3C, Racetech springs and valves, Ohlin's rear shock, steel brake lines, 520 conversion. 82k miles and counting.....
08 600RR- Stripped trackbike. CRG shorty brake lever, goodridge front brake lines.
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post #5 of 18 (permalink) Old 05-15-2017, 11:07 PM
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I weigh about 170 w/all gear and am using 0.90 springs i bought from GP suspension Seattle.

Love the 0.90's and don't think 0.95's would be better for me.
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post #6 of 18 (permalink) Old 05-16-2017, 03:13 AM
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Quote:
Originally Posted by RRdriver View Post
It's like my weight I think... how much you tight preload?
on race tech calc for street is 0.9, for track 0.95... I check it now
I'm 8 turns in.

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post #7 of 18 (permalink) Old 05-16-2017, 03:51 AM Thread Starter
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Tnx guys , I try 0.9kg.
I contact Dave Moss and he told me to try 0.9kg with 10w oil at 140mm.

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post #8 of 18 (permalink) Old 05-16-2017, 02:50 PM
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I'm 165 lbs (without gear) and am running 0.95's right now, and I think they're a bit too stiff.. 0.90 kg/mm would probably be perfect.

Also, 140mm seems like too little oil. GP Suspension recommended 115mm and I was still close to bottoming so I added more. I messed up, though.. used too light an oil on the initial fill. I outsmarted myself trying to blend my own mix of Red Line Medium and Light. So I drained and refilled with more Medium and now it's pretty good. If I could do it over again I would just use the shop oil (Motorex 5wt) or even better Silkolene RSF 5. Actually if I could really do it all over I'd probably get full on cartridges instead of just revalving the stock ones (GP Suspension 20mm piston kit). I had Matris 20mm cartridges on my Triumph and once you've tasted the nectar of the gods there's no going back..
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post #9 of 18 (permalink) Old 05-16-2017, 04:32 PM Thread Starter
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I buy race tech 0.9kg from ebay (oemcycles),and now w8 to come.
Dave told me 140mm and it's sound too little oil for me but... race tech recommended 110mm I think. Need check again this with Dave.
Oil is Motul 10w.

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post #10 of 18 (permalink) Old 05-17-2017, 01:08 AM
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IIRC I used 110 mm oil level and 10wt ( Drake at GP suspensions recommendation)

riding i do, (canyons) I 'm about 15-20mm from bottom out.

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I've got the GP 20mm suspension valves/0.90 springs, I understand the "nectar of the gods" comment.
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post #11 of 18 (permalink) Old 05-17-2017, 02:42 PM
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Quote:
Originally Posted by RRdriver View Post
I buy race tech 0.9kg from ebay (oemcycles),and now w8 to come.
Dave told me 140mm and it's sound too little oil for me but... race tech recommended 110mm I think. Need check again this with Dave.
Oil is Motul 10w.
I just saw Dave last weekend at Buttonwillow. He was really busy both days, but did make a couple adjustments for me.. I probably should have bugged him some more, i.e. given him more feedback. My setup was already pretty good.. the Penske 8987 is beyond reproach, and the GP 20mm kit is quite good now with the proper oil viscosity. My tire wear was fine all weekend. The front end just wasn't giving me good feel and feedback.. had a nervous, jittery feeling and I didn't feel confident on the brakes, especially on bumpy entries. I believe now I may have diagnosed it as loose steering head bearings. Will tighten them up tonight and see how it feels.

Anyway, he might remember my bike (Red/Black 2011) and my oil level is roughly 110 mm.. and as he saw the forks were about 3/8" from bottoming. These forks have a soft rubber bottom-out bushing (sits on top of the inner tube) and a hydraulic lock (although mine has been partially disabled by drilling a drain hole) so even if you underfill you're not going to break anything. And it's easier to add oil afterward than subtract. Now that I'm getting proper compression damping with the thicker oil, I probably don't need the extra 5 mL/5 mm I added. Will see if I can drain out that amount through the compression adjuster assembly.
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post #12 of 18 (permalink) Old 05-17-2017, 03:06 PM
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Quote:
Originally Posted by tary preisser View Post
IIRC I used 110 mm oil level and 10wt ( Drake at GP suspensions recommendation)

riding i do, (canyons) I 'm about 15-20mm from bottom out.

UAV Online.....
I've got the GP 20mm suspension valves/0.90 springs, I understand the "nectar of the gods" comment.
Motorex 5W was what they recommended to me.. I attempted to match it, but with better oil.. higher viscosity index: less change in viscosity with temperature. But I neglected to consider the operating temperature of the fork oil. The convention is to test viscosity at 40 deg C and 100 deg C, whereas the fork oil usually operates at ~25 C. [Rear shocks run hotter, about 65 C.] Not realizing this I targeted the cSt@40C of Motorex 5W which meant a roughly 50:50 blend of Red Line Light (5W) and Medium (10W). But since Red Line doesn't thicken up at lower temperatures as much as Motorex, in operation my blend was too thin. In hindsight I should have just used Silkolene RSF 5 since it has the high viscosity index of Red Line but roughly the same cSt@25C as Motorex 5W.

Hopefully you guys will learn from my mistake. This viscosity-vs-temperature curve calculator was the missing link for me: Graph your oils | Widman International

Or you could just use the oil the shop recommends.
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post #13 of 18 (permalink) Old 05-18-2017, 02:51 AM Thread Starter
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Dave confirm
http://pokit.org/get/?736919c90776cc...faaa7dcbbe.jpg

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post #14 of 18 (permalink) Old 05-19-2017, 02:55 PM
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I drained roughly 10 mL from each fork leg yesterday. Only intended to take out 5 mL, but draining through the compression adjuster hole is a bit cumbersome. Theoretically I now have 120 mm of air gap. Anyway, did some hard braking on the way in this morning and I'm now 8 mm from the "bottom out" rubber bumper (engages at ~25mm of chrome showing). This is with 0.95 kg/mm springs with "2 turns in" on the preload adjuster (perhaps 10mm actual preload). The fork definitely feels more plush now, and does seem more composed on bumpy sections.. even under hard braking.

I have my front end lowered ~5 mm, but I moved my footpegs back on the rearsets and the tendency to stoppie is still there but more controllable. Anyway, I think I have enough range on all the adjusters that I feel like I can leave the fork oil alone.. which is a relief. The forks have demanded so much attention I've hardly touched the adjusters on the 8987. I really like how sharply the bike turns in now.. but it might be more balanced if I lowered the rear closer to stock height. Probably raised it 5-10 mm when I installed the shock, by not precisely matching the stock length.

At some point I might swap in 0.90's (might need more oil height then), or maybe if my pace picks up I'll do a stiffer shock spring (currently 600 lb/in) just to get the front and rear more balanced. I believe the GP 20mm valves could be improved as well by adding a face shim to each stack.
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post #15 of 18 (permalink) Old 06-15-2017, 08:26 PM
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Apologies to @RRdriver for taking over your thread, but I've got more results to share. Hopefully helpful to someone out there:

At some point I thought I might have loose steering head bearings, but I checked them and they're fine.

I believe now that jittery feeling with the GP Suspension 20mm valve kit is just due to a lack of high-speed compression damping. It is more obvious at higher ambient temperatures (effectively lower fork oil viscosity) and can be mitigated by further closing the adjuster needles. A softer carcass tire---like the Pirelli Supercorsa SP that I ran at Buttonwillow (in mild weather) and on Day 1 at Chuckwalla (in hot weather) the following weekend---seems to be a better complement to this "looser" damping feel, perhaps because the tire itself will absorb more of the minor imperfections on the road/track. With a few minor tweaks (thanks to AJ at Paradigm Suspension) I was able to really find my flow that first afternoon at Chuckwalla. The track itself had a lot to do with it, I'm sure. It's fairly smooth and much easier to find the fast line compared to Chuckwalla.

By the end of Day 1, though, the Supercorsa SP's were done.. and cheap bastard that I am, did not take the opportunity to move up to the Supercorsa SC's. Instead I switched back to the much stiffer carcassed Dunlop Q3's, and spent another day chasing the right setup. Or perhaps re-calibrating my senses to the different feedback. We also changed directions to CCW, which was interesting. By the end of the day, though, AJ had the bike back in the sweet spot and the final session(s) were really enjoyable.

In the weeks since I've just been commuting, but I've made the geometry even steeper by taking the 8987 length/ride height adjuster to the limit.. and I love it. It seems to have helped settle the front end as well, by shifting some weight onto it. I've also noticed a clear improvement in damping feel when the temperature drops down below 20C. As such I would imagine this kit would perform even better in the typically hot weather at our California desert tracks with an oil that's about 5 points more viscous at 25C, i.e. 100% Red Line Medium. This would jive with Peter Verdone's findings with his 600RR. The GP valve kit (in this application, anyway) utilizes a compression stack on the mid-valve as in the stock setup, so it makes sense that it needs a thicker oil than typical.

Of course, having finally achieved near perfection I was presented with another upgrade opportunity I couldn't resist: another 8987 with upgraded "AMA kit" valving and a set of forks with GP Suspension 25mm cartridges installed. So the folly continues..
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post #16 of 18 (permalink) Old 06-16-2017, 03:44 AM Thread Starter
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Race Tech 0.9 springs are installed,Oil motul factory 10w @ 140mm.
Everything is ok but front of bike is raise.
New springs are little bit longer than stock springs.
It's ok ? :D

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post #17 of 18 (permalink) Old 06-16-2017, 10:55 AM
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Did you not make up new preload spacers​? Race Tech usually provides PVC pipe and instructions.. basically make your [new spring + new spacer] the same length as the [stock spring + stock spacer]. Traxxion provided a pre-cut spacer with my springs, but also instructed me to reuse one of the little plastic collars.. the one above the spacer IIRC.

Sounds like you just reused the stock spacers.. and with the longer race tech springs you'll have too much preload and therefore ride height.
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post #18 of 18 (permalink) Old 06-17-2017, 03:48 AM Thread Starter
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No I only receive 2 springs and 4 washers.
I did not install springs, the mechanic installed it.
Preload is full soft and SAG is ok now I think 31mm-32mm

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Last edited by RRdriver; 06-17-2017 at 04:14 AM.
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