I have a '06 cbr600rr with a ohlins out back. At my last track day I paid someone to help me set up the suspension since the bike was new to me, the shock (bought used) was just installed, and I had the forks reworked with racetech valving and springs, etc... Anyhow, the guy said I needed a different rear spring since he was unable to get the desired sag out back with the spring preload adjuster maxed. Based on the racetech web site I got the following rates: Recommended Spring Rate for Racing: 11.29 kg/mm (use closest available) Stock Shock Spring Rate (measured): 11.0 kg/mm (stock) With that, it seems that the stock spring is pretty close given my weight (200lbs). .. Is there anything wrong with using a stock spring on a Ohlins given the, what seems to be, correct spring rate for the stocker?
In 4 wheel land they sell springs in 2 inch length steps (free length) for similar reasons. Do they not sell different lengths in 2 wheel land?
Ride height correct? How "outta wack" was your rear sag? What was your total sag with preload "maxxed out" (presume you means 'stiffened'/tight).
your desired sag is usually in the range of 5 to 10 mm free sag (from unweighted to just bike weight) and 30 to 40 mm rider sag (from unweighted to bike + rider). If you have the wrong spring it's hard to get both of those numbers to match. you don't mention what rate you have in now, and not matching is too general for us to help further. ... more details please I belive you are referring to the ohlins hydraulic preload adjuster, which you mean is at the maxed setting. You can shim the spring if this is the case.. but you would only want to if you have the proper spring back there. It's important to match your front and rear spring rates (not the same duh, I mean the equivelent when all the suspension and ratio math is done).
Thanks for your thoughts so far. I have a data sheet at home with the sag measurements and settings that I need to reference. I'll post up the #'s to better explain where I'm at. I haven't done my suspension research and am basing my problem on the comments of the "suspension guy" at the STT trackday (can't recall his company name). While he could not get a view of the spring ID to tell me its rate, he told me based on the fact that he could not achieve the desired sag that my spring was not heavy enough/too soft. He even said I would have been better off leaving the stocker on I have 1.0k/g racetech springs up front with compression gold valves. I was also advised that I would have been better off doing the rebound valves if I was only doing one, or best would have been to do both compression and rebound. HIs comment was that with the heavier springs in there for my weight, I overwhelmed the stock rebound valving setup, which he described as grossly inadequate. It was my first time riding the bike, and I was coming from a superhawk (vtr1000f) that I was able to do 1:04's at the beav.. Best I could do with a couple dry sessions on the cbr was 1:07, but man what a difference this bike is and it usually takes me a bit to feel comfortable on a new bike. again, thanks for the thoughts so far, I'll post up more data when I get home.
. . . and you are what, 5' 7"? Your suspension woes would be cured be making to 2 or 3 less daily stops at the donut shop.
this from the guy who blew out the ass of his leathers at the last trackday... slicks in the rain Hey Rodg I'll take a boston cream donut please (and I'm 5'9 dammit!)
hey bro, it seems that not only do have the wrong rear spring, but that your springs are horribly uneven. A 1.0 Kg is a reasonably stiff spring for a track bike on a guy your weight, I don't know what to recommend for a rear cbr since I never swapped suspension on a Honda. Shimming or otherwise using preload to get sag numbers on a too-soft spring is ok to get you through the day, but not good for the long run anyway, so a rear spring should be on your order list. A lot of the Race tech guys seem to recommend not re-shimming the rebound valves, they told me that...then I rebuilt the rebound valve after the next track day. Rebound is more important handling wise than compression, so you should definately rebound those valves to match the spring. The shims to rebuild a rebound stack are quite cheap, paying someone to do it can cost $200 dollars. in my opinion, skip a track day and invest in a proper rear spring and suspension valving that works and you will be back in 104's.
I need to double check when I get home... they may be .95's ... but I'm still wondering if the oem spring is a good or bad idea on the ohlins shock assuming the rate of the stocker is correct.
ok, referencing the sheet from the suspension guy I do have .95kg springs up front. Up front my rider sag is 39 and free sag is 21 (seems high). The rear rider sag was 36 and this is with the spring pre-load knob turned all the way in, free sag for the rear is 12. Setting-wise the Fork Compression is 1.5 turns from max, Fork Rebound is 0 turns from max. Shock Compression is 12 from max, Shock Rebound is 18 from max. He recommended a different rear spring, hence my question about using the oem spring since it seems to be a match based on the racetech website based on my weight. (11.29 recommended, OEM measured to be 11.0 based on RT website) Thanks again for your assistance.
