| Author | Message | ||
     Mountainstorm |
Last time this started happening the rotor was shot. Replaced the rotor and all was well. Rotor seems fine still...no pulsing lever movement if I apply it while moving, stops smoothly. But just now under hard baking as I was entering a turn the front end "juddered" and seemed like it was "pogoing" or "pumping" best as I can describe. A bit unsettling. I had been riding hard and braking hard for an hour or so before that with nothing of the sort occurring. I asked this once before, but never got an answer on it. Could this be caused by the suspension settings or some failure or need for maintenance in the front forks? | ||
| Jdugger |
Do two things for me: Put a zip-tie around the slider part of one fork leg. It should be tight enough that it doesn't slip easily, but moveable with modest finger force. Put it at the top of the travel. Go do a braking exercise that generates the shudder you describe above. Is this braking level/pressure roughly as has as you would ever brake? Send me a picture of your rotor and of the position of that zip tie on the fork leg. | ||
| Kicka666 |
Sounds like you are using all your fork travel & your tyre is doing the work at the end of the fork stroke, zip tie it like Jd said, if you are bottoming out the fork its set to soft for your riding style. | ||
| Dannybuell |
The smoothness is gone? When was the last time you changed your fork oil? Been a while? Sludge behaves quite differently with the valving in the forks and shocks. | ||
| Thefleshrocket |
+1 to Dannybuell. I had a blown fork seal on my 5200-mile '08 so I changed both seals and filled the fork with fresh Spectro 15wt. I've got the damping settings just about the same as I had with the factory fork oil (maybe backed off a little bit--half a turn to one turn--since the 15wt should be thicker than the 10wt that I believe the factory oil is) but the fork action feels smoother overall. Fresh fork oil will probably result in a noticeable improvement in smoothness of the fork travel. The zip tie trick is a good way to test how much of your fork travel is being used. Admittedly, I haven't done it on my 1125 because the fork springs are so stiff that even if I set down a wheelie a bit hard, the fork still doesn't bottom. That's with the preload completely backed off. (Message edited by thefleshrocket on August 03, 2011) | ||
| Hughlysses |
...I've got the damping settings just about the same as I had with the factory fork oil (maybe backed off a little bit--half a turn to one turn--since the 15wt should be thicker than the 10wt that I believe the factory oil is)... Yep, the HD Type "E" fork oil for Showa forks is supposed to be 10 weight. I was researching fork oil a couple of weeks ago and found this interesting page on the subject: http://www.peterverdonedesigns.com/lowspeed.htm Basically, this guy claims there is little consistency between the fork oil ratings of various manufacturers. One brand of 10W may have the same actual viscosity as another brand of 15W. That said, if you can find a brand and weight of fork oil that works for you, it makes sense to stick with it. If you switch brands, even if you stick with the same weight, you may have to completely change your settings to make your suspension work like you like it. | ||
| Mountainstorm |
Thanks guys. Jdugger I will do exactly that in a little bit. It really felt like the forks had run out travel. When I first got the bike the dealer did not bother to set it up for my weight and I bottomed out the stock muffler on an off camber bump in a curve...very unsettling...and later on bottomed out the front fork hitting a pothole. I followed the manual and set it up to my weight and never had those issues again. Could be I need a tad more preset up front. | ||
| Mountainstorm |
    | ||
| Thefleshrocket |
Hughlysses, thanks for the link. I like the chart that has the viscosity at 104F and 212F. Theoretically best fork oil would have the smallest viscosity difference between 104F and 212F, meaning that it would hopefully have the least difference between 104F and 0F as well. (IE when it's cold outside, the damping adjustments wouldn't have to be backed off THAT much because the oil wouldn't have gotten as thick as an oil that is rated at a larger difference between 104F and 212F. For example, the Spectro 15wt I'm using is rated at 45.6 at 104F and 7.2 at 212F. That's a VT (viscosity threshold?) of 6.33. (Some of the oils have a VT as low as 2.xx) The Spectro Golden Light (which I've never heard of) is rated at 47.27 at 104F and 16.76 at 212F, for a VT of 2.82. The rating at 104F means that on a hot summer day, it should perform comparably to the Spectro 15wt, but since the VT is much lower, it should hopefully not thicken up as much as the Spectro 15wt when cold. Or, again, so I am theorizing. Is my logic faulty, or is it safe to extrapolate the viscosity at 0F as I have? | ||
| Thefleshrocket |
According to this chart, it looks like Spectro 15wt is very close to Harley Type E. http://www.spectro-oils.com/pdfs/techsheets/Shock_ Fluids_Comparison_Suspension_Oils_Chart.pdf I set my rebound damping to 2.75 turns out from full stiff after changing the fork oil, and I have been periodically adding rebound damping in .5 turn increments after riding. I used to have the rebound damping set to .25 out from full stiff (I like a lot of rebound damping) and since Harley Type E (38 at 104F) and Spectro 15wt (47 at 104F) are rated so close at 104F (which is really close to ambient during the day), I'll probably end up back at .25 out from full stiff again. After reading that chart a bit more, it looks like the shock oils are the ones that have the least change in viscosity between 104F and 212F. Anyone have any idea why? Would it be "bad" to use shock fluid in a fork? | ||
| Mountainstorm |
Any chance, while you are discussing the finer points of fork oil could someone please tell me the minimum distance I should be looking for? What's a good number for that cable tie to be at? | ||
| Jdugger |
For someone not braking very hard (can tell by color and deposits on your rotor), you are using up a LOT of travel. You probably shouldn't be getting that close to the bottom. Definitely setting the springs so that you are closer to the center of the range of the suspension while doing normal things, and at the kind of travel usage we see above when doing extreme braking would help... | ||
| Mountainstorm |
Or losing about 40 pounds...whichever comes first  Damn this Middle Age! | ||
| Kinder |
Hehe... I just lost 30... Every 7lbs= 1hp right?  | ||
| Mountainstorm |
That might be the biggest motivator yet. In a bit I'll see what a few turns of preset and touch more damping and rebound do for the travel. I have a feeling not much. These bikes are "one size fits all" the problem is the size is "Erik Buell" and he aint 6'-4" | ||
| Captjoe |
This happens on my 1125r also. Coming out of the garage I have to pull a 90 degree right turn at slow speed. When I hold the front brake through the beginning of the turn, I "sometimes" feel a shudder coming off the front wheel. I don't really consider the braking to be hard or aggressive as I'm not doing more than 10 mph. It never does it when braking in a straight line. The front wheel has to be at least a bit turned. My suspension is set to the firmest. I've never given it much thought other than the pads might be skipping a bit. Maybe there's more there to worry about than I'd thought.... | ||
| Mountainstorm |
What's happening for me is not brakes but too much weight for the factory springs. If you look in the owner's manual around page 97 in the 08 there's a chart that tops out at 250-270. At that weight there's not much more adjustment as far as more compression or more rebound before the valves are closed...and more preload is not really the answer. I followed the manual and then I added 1/2 turn more preload up front to 8 turns from full soft, 1/4 turn more Compression for 1 turn from full hard and the same for the Rebound. On the rear shock I am already at 8 of 9 notches of preload. I turned the compression in one click leaving 9 to full hard and I left the rebound at 1/2 turn from full hard. I'm 250 pounds with gear. Those settings are working for me. After 300 Miles the bike feels much different. Flatter during braking and acceleration, more feedback from the pavement, and more solid in sweeping bends. I did not detour off into any really tight twisty roads so no impressions about that yet. It seems a little more predictable and I can see getting used to it. I still want a properly set up suspension...but fiddling about with it did help. | ||
| Dannybuell |
Mountainstorm - I am a big guy @260lbs. Right after I purchased my CR the bike went to gpsuspension.com where I set them loose. I was told that too much preload was bad, it was going to cause the spring to bind sooner than the shocks actual potential range of motion. I was not going to be getting full suspension travel. If you are more than 2 clicks of preload on the rear I would consider a stiffer rear spring with the appropriate valving. | ||
| 99buellx1 |
Set the sag properly to your weight as a start, not by the manual. That should get you a good starting point. | ||
| Mountainstorm |
Thanks guys! Getting resprung is on my list. | ||
| Ratgin |
Same .. cept im well north of you flyweights. Guys checked out my suspension said i have no free sag in rear due to preload maxed out. Said i need to loosen it off and get a much better spring. After the shock gets replaced since something is messed up internally. |
