| Author | Message | ||
     Mke |
I've never really liked the way my 1125r front end felt on the street. And by street I mean crappy city streets. So, I'm thinking about rebuilding the front suspension. Right now they click under braking, and seem to not have much in the way of compression damping or pre-load, regardless of what the settings are. I vaguely recall that there were some changes to the 08' spring rate during the production run, so I don't know which springs I have, but I do know that the preload is completely maxed out and regardless of the damping setting, the front end often bottoms out while riding in the city. So... I want to rebuild my front forks, but I want to rebuild them specifically for street riding on crappy streets. I never take it to the track, but I do like to rip around the poorly paved canyons in Southern CA. I'd appreciate any input into oil weights, spring size/rate, the fork position in the triple tree, or anything else that would make my R ride smoother on rough roads. p.s. I'm about 200 lbs | ||
| Fresnobuell |
@mke....I took the liberty of copying your post to the General SUspension Tuning thread. That thread had died (maybe with the change of seasons)....perhaps we can resurrect it. | ||
| Thefleshrocket |
I've got an '08. I put the '09 springs in the fork but honestly can't tell a difference. I'm about 225lbs in gear. The biggest improvement with the stock fork was dumping the oil and putting in some 10wt. The factory oil (either 2.5wt or 5wt) just isn't thick enough to allow the range of adjustment required for those who prefer firmer suspension. So, change out the springs if you really want to, but I'd recommend that you start by just putting in some heavier oil. Keep in mind that one manufacturer's 10wt fork oil might be thicker or thinner than another's. If you're experimenting with different weights of fork oil, make sure you stick with the same brand to minimize those variations. I generally use Spectro because it's available locally. | ||
| Oldog |
Mke, before you drop a bunch of money on your forks, consider an oil change and some adjustments, I presume that you have the owners manual with adjustment guides? I recently changed the oil in my front end it makes a difference, if the springs are too soft you know that you can adjust the preload? I weigh in at about 300# with my gear on and the ride quality for normal street riding is great | ||
| Ceejay |
When I had an XB, I put in some Buell offered race springs (1.0 kg IIRC) and heavier oil (10wt I think it was Motul) and that little simple mod did wonders…I'm working on 7 yrs of memory, but I do remember it was cheap, easy, and made so much of a difference that I started to look into fixing the rear shock - then I got hit by a car…tinkering with the front suspension and putting the stock exhaust can back on were the best things I ever did to a bike... | ||
| Blake |
>>> if the springs are too soft you know that you can adjust the preload? Hard to believe, but preload does next to nothing to spring rate; it merely raises or lowers the bike. In fact, by increasing preload the air volume inside the forks is increased which will reduce the effective spring rate. Best to follow the owners manual for suspension tuning. See www.traxxion.com Corrected bad URL. (Message edited by blake on November 12, 2014) | ||
| Stirz007 |
If it's an '08, it's likely due for a full rebuild. That might be all it needs. The stock suspension, adjusted correctly, isn't a bad one.. | ||
| Blake |
Bad URL in my previous post. See Traxxion Dynamics (Message edited by blake on November 12, 2014) | ||
| Thefleshrocket |
This is my layman's understanding of preload: Preload doesn't change spring rate, but it affects where the spring is in its travel and how much weight is required before it will move. For example, if you have a 500 lbs/in spring (that doesn't go through any linkage) and you put 500 lbs of pressure on it, it will compress one inch. But if you put 1" of preload on it and then put 500 lbs on it, it won't compress at all. If you put 1000 lbs of weight on it, it will compress one inch. I upgraded my Speed Triple's shock from a 700lb/in spring to a 1000lb/in spring, along with a revalve. With no preload, the back end of the bike would still compress too much when hitting bumps under load. (This despite compression damping set to the point that it got harsh and the rebound damping maxxed.) Dialing in about an inch of preload got it mostly sorted out--in fact, I was able to back off the compression damping a little bit as well. I think in order to be "right", it needs a 1200lb/in spring and a revalve to match, but as-is, it's "good enough". | ||
| Oldog |
Hard to believe, but preload does next to nothing to spring rate; True but it adds tension to the existing spring, the 1125 appears to have about 25 mm of adjustment perhaps less. it merely raises or lowers the bike. I respectfully disagree, it also as a previous post explains it adds a load to the spring so more force is required to compress it Presuming the fork spring does not coil bind before reaching maximum travel, The shock springs cam collar on the 1125 is a common method to change the preload on a spring to control ride height and compression actions. In fact, by increasing preload the air volume inside the forks is increased which will reduce the effective spring rate. True, but the net effect will be negligible, if not why are air forks ( I had them on my '79 suzuki ) not common? vs preload adjusters , the air pressure is not that great the oil fill level is full to with in 94mm of the top with the tubes completely bottomed thats perhaps 10 cuin likley less, so while the pressure will go up as the fork compresses the pressure and its benefit is minimal, also consider that as you pressurize the fork the seals are forced onto the tubes causing a force called "sticktion" a resistance to movement by the oil seals,. For the op's stated need, perhaps a small preload adjustment, oil change, and an adjustment per the owners manual should be tried before ripping the front end apart and throwing new parts at it, the op states his weight as around 200 IIRC I weigh almost 300 in gear and the book adjustments done by the crew at Bumpus still work quite well I just changed the oil in the front end and it made a noticeable difference, and I just put HD type e back in.... YMMV ..  } (Message edited by oldog on November 12, 2014) | ||
| Mke |
Thanks for all the great info guys! I'm definitely going to start by changing the shock oil and see where it goes from there. I'll report back... but it may be a while. Cheers! | ||
| Oldog |
just re-read your Post Mke, when you change the fluid check the adjuster position in the cap to confirm the max preload, consider pulling the springs and checking free length Mine was 14 5/16" my bike has 20K miles on it. | ||
| Ceejay |
another thing to note, be careful about how much oil goes back in, if yours is feeling incorrect it might be too low with oil and the oil volume can have a huge effect on the feel…I don't know much about 1125's but it should state it in the manual, or ask someone here. | ||
| Oldog |
I just did it they do not list a volume but they prescribe a fill level, In essence, collapse the legs, all the way with the springs out and the dampers apart fill to 94 mm or about 3.7" of oil from the top then re-assemble, post up for a write up on this. you need about 3 pints of fluid you will have some left over. | ||
| Tbowdre |
I think the consensus is more air less oil delivers a better feel, more progressive. 100mm or 4inches | ||
| Adambomb |
Sorry to bump this from the dead, just stumbled across it via Google and it saved my butt for my fork oil change on my 09 CR (long story short my Buell is disassembled in Alabama and my factory manual is in Kansas...). Also I'm surprised I didn't have an account here already...guess I've just been a lurker.  One thing to add regarding fork oil: according to the factory service manual, the 1125 calls for Harley Type E oil. According to Bel-ray, HD type E is equivalent to their 20W. So assuming all that is true, 10W should soften things up. http://www.belray.com/sir_tech FWIW when I got the bike the adjustments were all 75% max, and it was a hair skittish for 200lb me. I started by screwing everything to 50% and it was much more stable. Although once I get this fork oil change done I'm setting it to the settings given for my weight in the owner's manual and tuning again. I'm no pro rider by any means, but at least for my '09, the suspension setup was definitely supervised by Erik Buell, not Harley (I'm not even sure Harley would know what to do with an inverted fork), so it would appear that "moar stiffness" might not be the fastest solution. |
