pug Posted January 29, 2006 Share Posted January 29, 2006 I was surfing in the RaceTech site and I was thinking which bike is similar to XX? ZZR1200 right? So the std fork spring rate for the Kawi is 1.15 kg/mm (XX is 0.89 kg/mm). The most critical dimension (fork tube dia) I think is the same (43 mm), so interchangeability is possible. I checked Kawa's online parts diagramm and the spring collar lenght is 115 mm (I think XX's is 200mm - Tim already gave me this info in the past). So the only info I am missing is the spring free lenght (which I suspect it will be longer than XX's) and weather is a progressive wound or not. Until now I have tried WP springs (slightly heavier than std - no increase to bottoming ressistance, I have arranged with the local importer to test them and the OEM on his spring dyno but I didn't have time so far), and Hyperpros which are very hard for anything less than a perfect road (yes no bottoming and better brake control but very harsh). So before going to the ZZR forums, does any of you have the info I am looking for? Quote Link to comment Share on other sites More sharing options...
rodantking Posted January 29, 2006 Share Posted January 29, 2006 I sure would like some one to explain to me what changes with spring length. In my small little mind, the sorter spring get harder quicker when compressed. Pug not sure why you going from .9 to 1.15. Seams like a big jump Quote Link to comment Share on other sites More sharing options...
Redbird Posted January 29, 2006 Share Posted January 29, 2006 So the only info I am missing is the spring free lenght (which I suspect it will be longer than XX's) and weather is a progressive wound or not. Free spring length isn't really a factor, assuming the spring is of sufficient length to handle the travel of the suspension. You'll find that aftermarket springs are not the same length as the stockers- this is corrected for with the spacer. Can't tell you whether the ZZR's springs are progressive wound or not. All that said, 1.15kg/mm springs are going to be waaaay too heavy unless you're a truely massive individual. It sounds as though you may be attempting to compensate for damping problems with the springs, that's not going to work. Get you rider and static sag set, using whatever springs are appropriate, then address any damping issues you might have independant of the springs- using methods as simple as changing fork oil weight or as complex as modifying the shim stacks. If you're the particular type, just swapping springs is never going to do it. It's just a step in the process. Quote Link to comment Share on other sites More sharing options...
pug Posted January 29, 2006 Author Share Posted January 29, 2006 I sure would like some one to explain to me what changes with spring length. In my small little mind, the sorter spring get harder quicker when compressed.Pug not sure why you going from .9 to 1.15. Seams like a big jump If the spring is of the linear type, it doesn't get any harder. Is the same for all the fork's travel. If I remember well the fully progressive wound Hyperpros I am using right now, are 1.25 kg/mm (ok, just before full compression but you get the idea). On the other hand, the WPs should have been 10 to 15% heavier than stock, but practically I felt no difference. As I said when I'll find some time I am going to test them and the stockers on a spring dyno. But if the WPs are really close to 1.0kg/mm , then 1.05 springs are not sufficient. That's why I am looking at the 1.15 of ZZR. Tim, at 108kg I am not lightweight, but I am sure that there are people in this board which are way bigger than me. Free spring length isn't really a factor Well, if we assume that ZZR's springs are equal length with XX's but the XX's spacers are longer, you end up preloading the springs as much as the XX's spacers are longer. And when you start whith a 30% stiffer spring, that won't be nice. Right now the only uknown is the ZZR's spring length, if I ''l find this , then I can compare the 2 systems and decide whether I'll have to shorten/lengthen the spacers. address any damping issues you might have independant of the springs- using methods as simple as changing fork oil weight I am doing this regularly, even with the stock springs I tried many oil weight/level combinations. as complex as modifying the shim stacks That will be the final step but for now I do not have the time or the means to do it. Quote Link to comment Share on other sites More sharing options...
HERBXX Posted January 29, 2006 Share Posted January 29, 2006 As long as the spring has enough coils to not become coil bound (coils close to touching ) in the required distance of movement the length dosen't really matter as the spring is rated as whole not by each coil. BUT . If you take two identical springs, material ect. and put one on top of each other (end to end) the rating of the whole system will be halved. So if you put 2 1.0kg.mm springs end to and apply 1 kg load the system of 2 springs will move 2 mm as each spring still sees a 1kg load so you end up with a 1kg/2mm system = .5kg/mm system . So if you do something to a spring to decrease ist effective coils the rate goes up. One way to do this is cut coils off if there is stilll enough movement left. I have aways wondered about the use of some thing like the 'spring rubbers ' use by stock car racers to change the spring rate the pit stops. I'm thinking some thing could be machined ot out plastic or cast out of urathane that would fit inside the springs (between the damping rod and springs and extend into the space between the coils) , to effective eliminate a coil or two from the system and raise the rate of the spring. any thoughts ????? Quote Link to comment Share on other sites More sharing options...
rodantking Posted January 29, 2006 Share Posted January 29, 2006 It sounds like you been in there enough to know changing the spacer lengh is the cake. You did it with the W.P. so why are you so worried about it? You are also not limit to kawi spring. Some one has listed a supplier of 1.1 and 1.2 for the bird in the last week. I think it was in the garage. Also have you tried less air gap? What is your rider sag set at? Quote Link to comment Share on other sites More sharing options...
HERBXX Posted January 29, 2006 Share Posted January 29, 2006 traxxion has 1.2kg/mm in stock Quote Link to comment Share on other sites More sharing options...
pug Posted January 29, 2006 Author Share Posted January 29, 2006 As long as the spring has enough coils to not become coil bound (coils close to touching ) in the required distance of movement the length dosen't really matter as the spring is rated as whole not by each coil.BUT . If you take two identical springs, material ect. and put one on top of each other (end to end) the rating of the whole system will be halved. So if you put 2 1.0kg.mm springs end to and apply 1 kg load the system of 2 springs will move 2 mm as each spring still sees a 1kg load so you end up with a 1kg/2mm system = .5kg/mm system . So if you do something to a spring to decrease ist effective coils the rate goes up. One way to do this is cut coils off if there is stilll enough movement left. In sort the coil spring stiffness formula is: K= Gd4 / 8D3 N where G= shear modulus (assume the same for all springs) d(to the power of 4) = wire diameter D (cubed) = coil mean diameter and N= number of working turns (coils). So yes if you halve the coils, you double the stiffness. In cars is common practice to cut coils in order to increase stiffness but do not forget that car springs don't have a finish at the end of the coil like bike fork springs Quote Link to comment Share on other sites More sharing options...
shovelstrokeed Posted January 29, 2006 Share Posted January 29, 2006 Now we are getting somewhere. The forks are a system, and a relativly complex one at that. Changing spring rate changes the way the fork tubes accelerate inside the sliders which impacts the damping. Changing fork oil level impacts the peformance at the end of the compression stroke. Spacers and preload impact ride height and, along with spring rate, determine the position range at which the fork will work. All these things are inter-related and have to be approached in a systematic way. The normal sequence is spring rate, sag, oil level and damping. To change one, you will have to make changes in the other factors till you finally realize an optimum setting. The needs of the street rider differ a bit from pure track bikes as a rule, requiring a good deal more compromise. As my HP increase program progresses, from 107 to 95kg so far, I am finding the stock suspension on my bike to be more and more to my liking. When I reach my target of 86kg, I expect that I will only need a .95 spring and maybe a little lighter fork oil for the front. The rear is still gonna need a good quality shock. I suspect my riding technique, with a lot of slow in, fast out applied as well as a pretty smooth transition with the throttle hand keeps my demands on the suspension pretty low. I am unwilling to compromise the freeway ride of my bike to gain some incremental speed through the twisty bits as more than 80% of my riding is there. Quote Link to comment Share on other sites More sharing options...
rodantking Posted January 29, 2006 Share Posted January 29, 2006 --------------------------------------------------------------------------------HERBXX wrote: As long as the spring has enough coils to not become coil bound (coils close to touching ) in the required distance of movement the length dosen't really matter as the spring is rated as whole not by each coil. BUT . If you take two identical springs, material ect. and put one on top of each other (end to end) the rating of the whole system will be halved. So if you put 2 1.0kg.mm springs end to and apply 1 kg load the system of 2 springs will move 2 mm as each spring still sees a 1kg load so you end up with a 1kg/2mm system = .5kg/mm system . So if you do something to a spring to decrease ist effective coils the rate goes up. One way to do this is cut coils off if there is stilll enough movement left. In sort the coil spring stiffness formula is: K= Gd4 / 8D3 N where G= shear modulus (assume the same for all springs) d(to the power of 4) = wire diameter D (cubed) = coil mean diameter and N= number of working turns (coils). So yes if you halve the coils, you double the stiffness. In cars is common practice to cut coils in order to increase stiffness but do not forget that car springs don't have a finish at the end of the coil like bike fork springs I think you missed the part about my small little mind :oops: If they cut the spring they would also have so have to add preload or it would be softer. So lets say they do, where it becomes stiffer is near full compression? If that is the case why are aftermarket springs longer? Aren't you looking for soft on the front end and stiff on the compressed end for street use? Quote Link to comment Share on other sites More sharing options...
HERBXX Posted January 29, 2006 Share Posted January 29, 2006 Not all after market springs are longer, but if they are longer they will work for more applications most likely. I'm not really recommending cutting springs in a bike, but i was just trying toillustrate how they work. If they cut the spring they would also have so have to add preload or it would be softer. So lets say they do, where it becomes stiffer is near full compression? The length of the spring doesn't really effect the amount of preload needed , it does significantly effect the length of spacer your need to get that preload. As long as your still within the operating length the spring the rate of the spring wont increase that much when its getting close to fully comressed. Of courcs if the spring is too short and coils actually start touching the rate be infinit and then u have a problem. I found getting rid of some of the compression damping made the most improvement in ride quality. As for the merits of staight vs progressive rate springs that being going on for decades . Noe if cpould just find a way to 25kg of the rider part of my system everything would be good! :? I find this discussion much more interesting then dealling with my flooded laundry room. :helpsign: Quote Link to comment Share on other sites More sharing options...
rodantking Posted January 29, 2006 Share Posted January 29, 2006 sorry, I worded that wrong. I was thinking increase spacer lenght or turn the preload adjustment (if it has one) up to do the same thing. Quote Link to comment Share on other sites More sharing options...
rodantking Posted January 29, 2006 Share Posted January 29, 2006 If it doesn't change anything, why cut them? Quote Link to comment Share on other sites More sharing options...
shovelstrokeed Posted January 29, 2006 Share Posted January 29, 2006 If it doesn't change anything, why cut them? It does change something, the rate of the spring. It is an inverse function of the number of active coils in the spring. Cut off a couple of coils and increase the length of the preload spacer and you will have a stiffer spring. Getting the end of the spring right again might be another matter. A little heat and a grinder could get you back to something workable so long as you don't embrittle the spring while doing so. A lot will depend on how much travel remains in the spring, relative to suspension travel, after the cut. A coil bound spring is not a good thing.. Quote Link to comment Share on other sites More sharing options...
HERBXX Posted January 29, 2006 Share Posted January 29, 2006 What i meant to say was that the length of the spring has nothing to do with how much preload you need, assuming the long and short springs are the same rate. If you cut coils off of the spring the ratr goes up and this does effect the amount the preload you need (you need less preload) I think in practice cutting fork springs would not be that good of an idea as the flatning of the last coil would be an issure. If you use heat you will effect the rate of the other coils. You might be able flatten the last coil with a hammer and dolly if you really wanted to try . Quote Link to comment Share on other sites More sharing options...
rodantking Posted January 29, 2006 Share Posted January 29, 2006 I have no plans of cutting my springs, just trying to understand how it works. Quote Link to comment Share on other sites More sharing options...
danzig69 Posted January 31, 2006 Share Posted January 31, 2006 For a XX 1999 Stock spring lenght is 232.9mm (9.17). Service lenght is 228.2mm(8.98 ). I found this info in the service manual. Ohlins sold a 237mm part no. 08633-95 for XX 97-00. 4.3 mm of difference. ZZR1200 1999 (edit 2002 not 1999) ohlins Part No. 08685-12 Length 273 mm A Long difference between XX and ZZR1200!! 40.1mm. I think that you will have to reajust your preload. You can use this web site to find the lenght of other spring for different bike. http://www.ohlins.com/cgi-bin/dbsok/newmen...ist&category=mc It can give you an idea. Quote Link to comment Share on other sites More sharing options...
pug Posted February 1, 2006 Author Share Posted February 1, 2006 For a XX 1999 Stock spring lenght is 232.9mm (9.17). Service lenght is 228.2mm(8.98 ). I found this info in the service manual. Ohlins sold a 237mm part no. 08633-95 for XX 97-00. 4.3 mm of difference. ZZR1200 1999 ohlins Part No. 08685-12 Length 273 mm A Long difference between XX and ZZR1200!! 40.1mm. I think that you will have to reajust your preload. You can use this web site to find the lenght of other spring for different bike. http://www.ohlins.com/cgi-bin/dbsok/newmen...ist&category=mc It can give you an idea. Thanks for the info. Only that there was no ZZR1200 in 1999 but this might be a typing mistake. Quote Link to comment Share on other sites More sharing options...
arcticflipper Posted February 1, 2006 Share Posted February 1, 2006 Stock fork spring on ZZR1200: length = 269.3mm service limit is 264mm Quote Link to comment Share on other sites More sharing options...
HERBXX Posted February 1, 2006 Share Posted February 1, 2006 My traxxions 1.1s that just showed up are 315 mm long . My notes show that i am using a 130 mm spacer with the ractech springs so im sure there is room for the 315 long ones in there. I believe the longer spring will be straighter in it real rate (less progressive) then a shorter spring . Herb Quote Link to comment Share on other sites More sharing options...
XXTi Posted February 1, 2006 Share Posted February 1, 2006 FWIW, the Ohlins from Jaws are about 100mm longer than stock with 100mm shorter spacers provided. I have a set of his 1.05's in my bike and like them. Quote Link to comment Share on other sites More sharing options...
danzig69 Posted February 1, 2006 Share Posted February 1, 2006 Pug, you said the truth. I've edited my post ZZR1200 2002, Not 1999. All the other number was OK. Quote Link to comment Share on other sites More sharing options...
pug Posted February 4, 2006 Author Share Posted February 4, 2006 Stock fork spring on ZZR1200: length = 269.3mm service limit is 264mm Thanks arctic for the info. Quote Link to comment Share on other sites More sharing options...
pug Posted February 8, 2006 Author Share Posted February 8, 2006 Today I ordered the ZZR1200 front springs from Kawasaki for 42 Euros each (but I'll get a good discount). Delivery is for next week. Probably they will be cheaper in US , so I guess if they work they will be a good alternative. Quote Link to comment Share on other sites More sharing options...
pug Posted March 1, 2006 Author Share Posted March 1, 2006 Received zzr springs yesterday. Final cost 59 Euros. Free length is 271mm, diameter identical with stock. I guess I have work for the weekend... Quote Link to comment Share on other sites More sharing options...
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