Para045 Posted March 29, 2008 Share Posted March 29, 2008 Hi I have done a bit of a search but found nothing conclusive? I am in the process of putting some newer (04) forks on my 98XX, they have Ohlins valves and I am putting 1.2kg/mm Sonic Springs in them with Motul 5w oil What I want to know is roughly what sort of preload should be on the springs when assembling them? From looking at the old forks with the OEM springs there is ~9.5mm (3/8") between the top of the fork tube and the lip on the cap The Sonic Springs are 80mm longer so should I cut the spacer down to leave the same sort of gap on the tube-cap or should I cut the spacer longer and then assemble and set sags and go from there Well finished putting in the 04 forks with Ohlins valves, 1.2kg/mm springs and 5w oil on the front and new tapered bearings, went out for a 300km ride in the country with the missus about a week ago and no more pogo-ing/seesawing or harshness through the front and that was without having set my sags and probably a bit too much preload on the fork springs The missus said that it felt a a bit funny like the back end was "slipping" or moving about although I never really noticed it It certainly changed direction easy and cornered quickly but overall not too bad, most of the time we were cruising along at ~110kmh with a couple of spurts up to ~180kmh and no real problems Fast forward to yesterday and I went for a ride by myself and took her up to 200kmh and she started to weave around in the back end from around 180kmh Now the setup is this rear - Rebuilt CBR 900RR shock with 1100lb Eibach spring and a total of 8mm spacers, tapered head bearings, front - 04 forks with Ohlins valves, 1.2kg/mm Sonic Springs with ~20mm preload, 5w Motul oil at stock levels and I also moved the fork legs up ~4mm in the triple clamps and fitted a PP front and PR2 rear tyre :icon_think: Now any idea's what could be causing the weave? Could I just have the geometry too far out with the 8mm shim and lowered front? It never did this with the old forks and springs or when I had this tyre combo previously (well PPf+PRr) so I am leaning towards too much "loading" on the front with the dropped front added to the 8mm shim Also seems to be a lot harder to get the front wheel up as well Quote Link to comment Share on other sites More sharing options...
Iceman_40 Posted March 29, 2008 Share Posted March 29, 2008 Now any idea's what could be causing the weave? Could I just have the geometry too far out with the 8mm shim and lowered front? It never did this with the old forks and springs or when I had this tyre combo previously (well PPf+PRr) so I am leaning towards too much "loading" on the front with the dropped front added to the 8mm shim Also seems to be a lot harder to get the front wheel up as well I'd bet on that.... 8mm in the rear is quite alot and dropping the front only puts things farther out. Stock setup is about the most stable for speeds, adding the 6mm shim makes it turn quicker but not as good at high speeds. Quote Link to comment Share on other sites More sharing options...
tomek Posted March 30, 2008 Share Posted March 30, 2008 When messing with suspension the most basic thing is getting a measurent of ride hights front and rear before and after mods. Ride hight effects chassis geometry,it is alwayes nice to know what changed what.Without that knowledge troubleshooting of handling problems can be really fucked up. Quote Link to comment Share on other sites More sharing options...
airborneXX Posted March 30, 2008 Share Posted March 30, 2008 Check the preload on the steering head bearings. I set mine to the factory torque spec and the 'bird had a feeling similar to what you describe. There's instructions in the manual on using a pull scale to measure the force it takes to move the bars. Set them using this spec and don't worry about the preload torque. Quote Link to comment Share on other sites More sharing options...
EVLXX Posted March 31, 2008 Share Posted March 31, 2008 Now any idea's what could be causing the weave? Could I just have the geometry too far out with the 8mm shim and lowered front? It never did this with the old forks and springs or when I had this tyre combo previously (well PPf+PRr) so I am leaning towards too much "loading" on the front with the dropped front added to the 8mm shim Also seems to be a lot harder to get the front wheel up as well I'd bet on that.... 8mm in the rear is quite alot and dropping the front only puts things farther out. Stock setup is about the most stable for speeds, adding the 6mm shim makes it turn quicker but not as good at high speeds. Bingo. The 6 mm shim in the rear and stock front is abot the Max for keeping some kind of high speed stability.. 8 is too much.. Quote Link to comment Share on other sites More sharing options...
Para045 Posted March 31, 2008 Author Share Posted March 31, 2008 Now any idea's what could be causing the weave? Could I just have the geometry too far out with the 8mm shim and lowered front? It never did this with the old forks and springs or when I had this tyre combo previously (well PPf+PRr) so I am leaning towards too much "loading" on the front with the dropped front added to the 8mm shim Also seems to be a lot harder to get the front wheel up as well I'd bet on that.... 8mm in the rear is quite a lot and dropping the front only puts things farther out. Stock setup is about the most stable for speeds, adding the 6mm shim makes it turn quicker but not as good at high speeds. Bingo. The 6 mm shim in the rear and stock front is about the Max for keeping some kind of high speed stability.. 8 is too much.. I put the extra 2mm on when I had the previous set of Shinko tyres on as they were very slow to turn in and thought it would help, didn't make much difference Didn't have the weave or any vagueness before I replaced the forks, springs, oil and lowered the triple on the forks and put on the PPf/PR2r so I am thinking just TOO much of a good thing Didn't get around to pulling the extra shims today as had other shit to do and it was pissing down rain so not really conducive to "high speed test rides" Will hopefully get the extra shims out tomorrow and get out for a test and see how she goes then look at setting the sags and going from there :icon_think: Quote Link to comment Share on other sites More sharing options...
Para045 Posted April 1, 2008 Author Share Posted April 1, 2008 Will take the 2mm of "extra" shim out tomorrow and see how she feels, can't spin the rear tyre for lubing etc now anyway without a piece of 18mm MDF under the CS 8O EDIT: Will definitely do the sags this week as well Well took out the 2mm washer on top of Blu's shim and went for a ride and she feels a smidgen better but still weaves around from ~180>220kmh Will take the forks back to stock position and try that then set up my sags Quote Link to comment Share on other sites More sharing options...
EVLXX Posted April 1, 2008 Share Posted April 1, 2008 Will take the 2mm of "extra" shim out tomorrow and see how she feels, can't spin the rear tyre for lubing etc now anyway without a piece of 18mm MDF under the CS 8O EDIT: Will definitely do the sags this week as well Well took out the 2mm washer on top of Blu's shim and went for a ride and she feels a smidgen better but still weaves around from ~180>220kmh Will take the forks back to stock position and try that then set up my sags ... another curious question, do you have saddle bags, or a Loose coat on, or do you have a top box mounted ? (I see your Avater...but I just don't know if it's acurate to your current riding) Reason I ask is because Bad Aerodynamics can also give you this same effect. But I still think your need to go with the 6mm and set your Sag. Quote Link to comment Share on other sites More sharing options...
airborneXX Posted April 1, 2008 Share Posted April 1, 2008 And check the preload on the steering head bearings. Quote Link to comment Share on other sites More sharing options...
cbrxxquad Posted April 1, 2008 Share Posted April 1, 2008 Ok, I have been watchin and learnin. But, since I don't know anything about adjustable forks I have been messin with the zxxx adjustments. All the way one way and see, and all the way the other and see. Well I got this 100 mph weave about the same time as this post started and wanted to tell you what or rather where my settings are when it started or rather did it. I started out: No shim, zx forks set as on the zx when I got it. comp and rebound and preload in the middle. (The distance from axle to bottom of frame unloaded on the zx is 1.5 " shorter than the xx is.) Compaired to the one xx I have rode, turnin quicker, had to pickup on exit. cranked preload all the way in. Felt xx ish cranked all the preload out and opened all the dampening smooth, quick turnin, power pickedup on exit, highspeed weave. I think I am two low in the front with all the preload out and the lower front than the xx had. Going back to mid way on preload and see. Quote Link to comment Share on other sites More sharing options...
Redbird Posted April 1, 2008 Share Posted April 1, 2008 Stan, sounds like you're adjusting ride height with the preload adjuster. Set your sag, then adjust ride height to your liking by moving the fork tubes up and down in the clamps. Your final results will be much better, IMO. If you keep the front end that low, you're probably going to need a damper sooner or later Quote Link to comment Share on other sites More sharing options...
cbrxxquad Posted April 1, 2008 Share Posted April 1, 2008 Stan, sounds like you're adjusting ride height with the preload adjuster. Set your sag, then adjust ride height to your liking by moving the fork tubes up and down in the clamps. Your final results will be much better, IMO. If you keep the front end that low, you're probably going to need a damper sooner or later I agree, the only thing I am changing is ride height, and the effect is related to that. I don't have a sag mesurement to go off of. Most of the shocks I have set are about 30% of travel. I doubt it is the same for this. Got a place to send me for the front and rear? I am really toped out as far as legs with the way my seat and suspension are now. And I am not ale to tell much difference just standing. But, I am going to have to start getting some mesurements. And make some decisions... Quote Link to comment Share on other sites More sharing options...
Redbird Posted April 1, 2008 Share Posted April 1, 2008 30% total sag is the range you'll want to be in. Front travel is 4.6" on the ZX14. Get that set, then play with ride height. If seat height is an issue and ground clearance isn't, you can alway drop the rear a little? Not via preload, but different spacing on the holes in the shock mounting plates. You're probably a little taller out back due to that 190, anyway. Quote Link to comment Share on other sites More sharing options...
cbrxxquad Posted April 1, 2008 Share Posted April 1, 2008 30% total sag is the range you'll want to be in. Front travel is 4.6" on the ZX14. Get that set, then play with ride height. If seat height is an issue and ground clearance isn't, you can alway drop the rear a little? Not via preload, but different spacing on the holes in the shock mounting plates. You're probably a little taller out back due to that 190, anyway. Don't think the rear is taller with the wider wheel, but that is just my impressions, have not checked. And the height is fine but Porters had the shim and I was tippin. A change in level or a dip, could run out. Still want to do the rear swingarm, some day. Quote Link to comment Share on other sites More sharing options...
EVLXX Posted April 2, 2008 Share Posted April 2, 2008 (The distance from axle to bottom of frame unloaded on the zx is 1.5 " shorter than the xx is.) There's your problem.. On my bike... I have a 3mm shim in and the front is dropped 10mm, and the bike is stable at speed.Turn quick but still stable. In order to achieve the same result... you need to Drop you tubes down inside your triples about 20mm. (raise the triples), can you do that ?????? , I don't know. If not you need to Lower the rear. (how much I can't tell you, because I forgot the relationship numbers) ... Then the next Huge thing is to set your Sag... and the most important thing with that is, makeing them even, Front and rear, irreguardless of how far it is. That way the geometry of the bike stays the same while riding. Quote Link to comment Share on other sites More sharing options...
Para045 Posted April 2, 2008 Author Share Posted April 2, 2008 another curious question, do you have saddle bags, or a Loose coat on, or do you have a top box mounted ? (I see your Avater...but I just don't know if it's accurate to your current riding) Reason I ask is because Bad Aerodynamics can also give you this same effect. But I still think your need to go with the 6mm and set your Sag. No loose coat but have a top box mounted and there is rack for the panniers but they weren't on when the weaving started Also the bike never weaved before with the TB or Panniers on only since I have done the forks Backed off the bearing preload and dropped the forks back to stock so will test ride again tomorrow and see Quote Link to comment Share on other sites More sharing options...
Para045 Posted April 3, 2008 Author Share Posted April 3, 2008 Backed off the bearing preload and dropped the forks back to stock so will test ride again tomorrow and see Well that made fuck all difference so will cut down the spacers and reduce preload on the fork springs Quote Link to comment Share on other sites More sharing options...
EVLXX Posted April 3, 2008 Share Posted April 3, 2008 Backed off the bearing preload and dropped the forks back to stock so will test ride again tomorrow and see Well that made fuck all difference so will cut down the spacers and reduce preload on the fork springs Glad to hear it... Now which part did you do ? Bearing Pre-load, Ride height, or Sag ? Or did you do all three ? I know you changed the ride height, but I thought I would ask anyway. If you have a Angle gage... I believe I found 22.5 degrees to be the Maximum, and any steeper than that and you start getting the instability. Which, if I can remember correctly, is about 25mm of drop (front) or rise (rear) from stock, or some combination there in. Quote Link to comment Share on other sites More sharing options...
cbrxxquad Posted April 4, 2008 Share Posted April 4, 2008 I got some numbers, but I don't know if posting in para's is apparopate. But, it is on the same subject. And the solution, transferable. I will let you decide. Quote Link to comment Share on other sites More sharing options...
Para045 Posted April 4, 2008 Author Share Posted April 4, 2008 Glad to hear it... Now which part did you do ? Bearing Pre-load, Ride height, or Sag ? Or did you do all three ? I know you changed the ride height, but I thought I would ask anyway. If you have a Angle gauge... I believe I found 22.5 degrees to be the Maximum, and any steeper than that and you start getting the instability. Which, if I can remember correctly, is about 25mm of drop (front) or rise (rear) from stock, or some combination there in. I removed the 2mm shim first, then dropped the forks in the triples back to stock and I also took a little tension off the head bearings (stock is 20lb/" I went down to ~18) Today cut my spacers back down by 10mm so I should have ~ 11.5mm of preload on the springs (OEM springs had ~9.5mm), will try and get out tomorrow but the forecast is rain, will be Sunday if not tomorrow I will do the sags after I try this EDIT: Don't have an angle gauge, what do they look like and what do they do Quote Link to comment Share on other sites More sharing options...
EVLXX Posted April 6, 2008 Share Posted April 6, 2008 Good. ... as for the Angle Finder... I use one of these... http://www.lowes.com/lowes/lkn?action=prod...&lpage=none ... but I want to point out, you don't need to run out and buy one.... because It's not going to tell you your bike is set up right... only you can do that from trial and error... which you've already done. Keep up the good work. Quote Link to comment Share on other sites More sharing options...
XXTi Posted April 6, 2008 Share Posted April 6, 2008 Since you guys are talking about suspension set-up, I thought I'd post this old link. It has some good info. Suspension Set-Up Guide Quote Link to comment Share on other sites More sharing options...
Para045 Posted April 30, 2008 Author Share Posted April 30, 2008 Well I cut my front fork spacer back two mm for ~9.5mm preload as on the old forks, still have the 6mm shim and the forks are at std height and set my free sag and static sag and they were within the ranges given on various sites I have looked at regarding setup - Static sag ~32mm front and 15mm rear :icon_think: Still has a slight weave around 190-200kmh mark but is better Haven't had a chance to check the rider sag as I was by myself when I did the others and then stuffed my back the next day and have been having trouble bending etc for the last week or so and getting someone else to measure the sags while I am on the bike :icon_think: Just wondering whether the oil levels could be a factor after reading THIS thread :icon_wall: I just checked my manual (as promised months ago, but I got lazy) and the number for 99-03 is 142 MM, or 5.6 IN, not 230 as previously posted. My 97 manual says 154mm Wonder why the difference As I remember, there was a difference in the cartridges inside the forks for the 97-98 models. Hmmm just read this as I haven't been on here for a week or so and am wondering whether the fact I have replaced my original forks with 04 forks with Ohlins valves, 5w oil and heavier springs that the different oil level (I set it at 154mm) could be contributing to the high speed weave I have been experiencing :icon_think: Quote Link to comment Share on other sites More sharing options...
cbrxxquad Posted April 30, 2008 Share Posted April 30, 2008 I replyed in the other thread before I saw this, What I do to measure rider sag alone, is put a tie rap around the tube, slide up to the seal and get on. get off and measure where it moved to. I also when I have help is to use a sharpe to mark on the tube. Quote Link to comment Share on other sites More sharing options...
rhubarbray Posted May 4, 2008 Share Posted May 4, 2008 Ummm, just a thought here,... stock head bearings are balls,....you`ve installed tapered. You can`t use the stock torque figures for the head bearings as the two bearings react differently to preload. I think it was Airborne who said to try checking the force required to move the handlebars with the front wheel in the air. You may find you`ll have to back way off on the torque. Quote Link to comment Share on other sites More sharing options...
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