| Author | Message | ||
     Rfischer |
I had seen this link posted before; I doubt any of the Buellers who have been so hotly contesting the BMC O.E.M. solution have read it. It clearly puts paid to all the aftermarket claims being batted around in this thread; is the documented, factual underpinning to the 2nd post at the beginning of the argument. Everything since has been gratuitous. And, for what it's worth, IMHO a couple folks here owe Anony an apology. | ||
| Jaimec |
I posted that link two weeks ago: http://www.badweatherbikers.com/buell/messages/290 431/310654.html?1191265321#POST979986 Some people just love to argue. | ||
| Al_lighton |
"Not necessarily Al. When you change a stock XB to a chain drive you obviously have to have a lot more slack in the driveline, yet don't suffer any handling. driveline lash or drive problems at all, even using the stock swingarm." But don't all the XB chain conversions still have an idler, just not one that takes out ALL of the slack? With the XB swingarm geometry, wouldn't NO idler result in a seriously drooping chain? And wouldn't that seriously drooping chain have to result in substantial driveline lash? Al} | ||
| Spike |
I've read the article in the link, and personally spoke with one of the XB platform engineers about the idler pulley. The topic of the thread presupposes that the claims in the article are wrong, yet no one has posted any real numbers to contradict anything in the article. Until those numbers are posted, everything else remains subjective. | ||
| Trojan |
The article in the link is hardly unbiaised and objective, given that it is written and published by Buell in their own magazine. It gives no regard to alternative solutions or to any problems that may be present with the stock ider system. But don't all the XB chain conversions still have an idler, just not one that takes out ALL of the slack? With the XB swingarm geometry, wouldn't NO idler result in a seriously drooping chain? And wouldn't that seriously drooping chain have to result in substantial driveline lash? I agree that all of the aftermarket chain drive systems that use the stock swingarm use some kind of idler for adjusting the chain. I can't remember if the 'factory' chain drive kit includes a fixed idler though. I've never tried running a chain without the idler assembly, as it would mean making up a chain length just to see what would happen, and I have never felt the need to do that to be honest. Without the adjustable idler you would have to have a new chain for every gearing combination. In 2003 I did have an idler failure when using a chain drive. This was when we were experimenting with different solutions, and I had used a stock idler assembly with the upper hole slotted to allow adjustment. The idler slipped and ended up giving no tension at all. The bike ran fine although there was a lot of chain lash purely because without the idler assembly the chain length was just too long. I suspect that with the correct chain length an idler would be uneccesary though. | ||
| Zac4mac |
Wait a minute. Belts don't stretch(appreciably)and therefore don't NEED an adjuster. Design the driveline, get a length and stick with it. The idler's, either static or sprung are there to make changing a belt easier and possibly to kill harmonic oscillations. A chain WILL stretch and needs some kind of adjuster to compensate. A chain will in fact be different lengths depending on temperature so that adjustment is always a compromise. Off the top, it sounds to me that a belt would be well suited to a static idler, if the suspension is properly set up, and a chain, with its dynamic length more suited to a sprung idler tensioner. God how I would hate to have to adjust chain tension by adding/removing links. Z | ||
| Paintballtommy |
if you reread the article the idler is there because it makes the effective belt path variations throughout the suspensions range of motion very very small therefore eliminating the need for slack. the article claims belt path length changes of less than .01 inches | ||
| Midknyte |
The tensioner has the disadvantage of its name (which leads to these kinds of arguments) - it's really just a slack taker upper | ||
| M1combat |
But on deceleration the spring loaded is a slack giver upper... THAT is the problem (and that it would do absolutely nothing for you under acceleration). "I suspect that with the correct chain length an idler would be uneccesary though." What? You apparently don't understand the point of the belt drive or the engineering behind it and the suspension geometry Matt. Please correct me if I'm wrong. The swinging arm angle is always on one side of parallel to the line created from the pulley to the pivot point. That means that with a chain that has no tensioner you would need a lot of slack at full droop and it would only tighten as it goes into compression. No good. Other manufacturers have a setup (that isn't optimal for handling) that goes above and below that line. The path is at it's greatest length when the swingarm is in line with the pulley/pivot. Buell doesn't do this. The Buell system needs a "tensioner". A better name for it would be an idler pulley... Oh wait... That's what they called it... (Message edited by m1combat on October 08, 2007) | ||
| M1combat |
Matt... You seem to have a hard time grasping the fact that Buell engineers solutions that are correct for the street. I'm certain that you understand that the street is a different place and has different needs than those of the race track. If you "need" to change the gear ratio... Go with a chain. If you don't "need" to change the gear ratio... The belt is a better solution when done right. Buell did it right. Can you explain to me the physics behind why the spring loaded tensioner would either prevent a belt breakage or help the suspension? I'm just not seeing it. Maybe I'm dumb. Here's how I do see it... On deceleration the wheel will be driving the engine. This force acts through the lower belt path (the one where the spring is). The spring will compress. This will generate slack in the upper path. No good. On acceleration we're exerting force along the upper belt path. The only thing we want in this situation is no slack on the lower belt path. The stock system only has .010" of length change in it when compressed vs. in full droop. Of course when we're on the throttle we are using out anti-squat. We aren't fully compressed. Either way... .010" is negligible. So... The question is... Where does Buell set the belt length to be at their desired tension? At full droop or full compression? | ||
| Trojan |
You apparently don't understand the point of the belt drive or the engineering behind it and the suspension geometry Matt. Please correct me if I'm wrong. OK, take a look at pretty much every other sports/touring/utility bike on the planet that uses a chain drive. With just a few notable exceptions the vast majority do not have drive sprockest that are concentric with the swingarm pivot. This means that chain tension will inevitably alter to a degree with suspension movement. The longer the suspension movement and the more the distance between the pivot point and the sprocket then the more tension will be affected. Now take a look at just how few bikes use a chain tensioner of any description (fixed or sprung). Almost none is the answer, even amongst sportsbikes with some pretty extreme suspension geometry. The exception is long travel suspension bikes such as dirt bikes etc. Yet all these bikes manage to cover many thousands of miles without the chain developing such slack that it jumps off the sprockets or breaks. Even a badly adjusted and lubricated chain will last for a long time before suffering from enough wear for the rider to notice. If Honda, Yamaha, Ducati, Triumph (the list goes on) do this why is it wrong, and Buell right? The suspension works perfectly well enough for GP racers right through to despatch riders and commuters. In fact the CBR66RR suspension works a lot better than the XB does in spite of having a system that Buell seem to think shouldn't work. It is only Buell who have decided that chain drive is a problem to suspension movement and that they will be the ones to solve it by the methods that they use. Others, like BMW, have come at it from a very different angle and have come up with system on their new 450 dirt bike that is amazingly simple yet addreses the problem without the need for any tensioners or belts. Matt... You seem to have a hard time grasping the fact that Buell engineers solutions that are correct for the street. I am not saying the Buell engineers do not have A solution, but I and many others do not believe that they have THE solution. | ||
| Ratbuell |
"It is only Buell who have decided that chain drive is a problem to suspension movement" I think this is a mis-statement. Buell does not state chains are a problem for suspension movement; they state they have lowered unsprung weight by using a 1 lb belt instead of a 6 lb chain. | ||
| Jaimec |
Not only Buell. The whole reason for the existence of ATK is because of inherent problems the founder noticed in chain drive systems and motorcycle suspensions... | ||
| M1combat |
I'm not so sure I ever heard Buell say that they thought that chains weren't "up to the task" that they were currently doing. I think their premise is that when done right a belt can remove a lot of issues that come with a chain. Slack, adjustment, mass, friction, oil, compromises in suspension geometry (not movement as such)... The fact seems to be that Buell did it right. Other manufacturers (with chains and belts) have not. To address point one and two specifically... For one... Uhhh yeah. Agreed. For two... Who says they're doing it correctly? I understand they're using a system that works. I also understand that they have slack in the chain because they didn't realize how/where to put an idler so that their path length wouldn't change OR they decided that the advantages of such a system weren't enough to justify the research and development required to do it right. Buell decided that the advantages are indeed worth it and I agree (unless you have an '03, then I think Buell or Gates should owe you a pulley system and a belt...). For point three... Agreed there too. BUT... Why have slack in your drive system when you don't NEED to? It makes for a smoother transition from coast to throttle and the other way. It's smoother. Once you've created an environment like that one would realize "Hey... We just created an environment that a belt should thrive in... Hmmm... Lets use one." So they did because there are plenty of inherent benefits to a belt in the right conditions. They are not the be all end all of drive systems in every situation but I do believe that they are that on the street. With point four... If you have to ask that Matt you'll just have to keep looking for the answer yourself because I just can't explain it. It's pretty close to the same reason that no one ever figured out how to do a perimeter mounted rotor correctly until Buell did. Maybe it took a revision to become track worthy (And yes I put "maybe" in there for a reason) but it is and it's different AND better than the other solutions on the market. I have the same question that you do... Why don't the rest of the manufacturers do it? I have a feeling that you and I approach that question from opposite directions though. Would you mind doing me a favor though? Would you explain the physics of why a spring loaded idler would either make a belt last longer or allow the suspension to travel in a more desired fashion wrt traction? Also... Would you mind listing (just a list, not an explanation as such) all of the advantages of the belt as implemented by Buell? I'm not looking for Buell's diatribe on why they think it's better but I would like to hear from you what you think the advantages are. So far you haven't been able to bring any evidence to the discussion that helps the spring loaded tensioner to make sense other than "Buy it and you'll see". No thanks. I considered it years ago when they came out, put some thought into it and what it would actually do and decided that it is detrimental to belt life in certain situations and does diddly squat in all of the others. Please prove me wrong and I'll most likely buy one. I don't think you can but I'll be the first to admit that I'm wrong if I am. Testimonials do absolutely nothing for me. Everyone who has spent money likes to feel that they spent it on a worthy product so they'll convince themselves that there's an advantage when there isn't. I need for someone to explain why it works. | ||
| Trojan |
M1, there are lots of advantages to a belt over a chain in theory, and on street bikes it is a very attractive option I agree. Just some advantages are: 1. No lubrication needed 2. Theoretically smoother drive (not always the case) 3. Lower weight than a chain (although see point below) 4. Theoretically longer life. However, there are also some disadvantages and some claims that need to be examined a little closer. 1. With modern cush drives and slipper clutches, chain drive can be just as smooth as belt drive. 2. Belt life is very inconsistent, and although you don't like anecdotal evidence you will find horror stories on every Buell forum. 3. The belt saves weight over a chain, but what about the sprockests needed. Modern chain drive sprockets weigh a fraction of the Buell front & rear sprockets, redressing the balance somwehat. 4. No choice in final drive gearing. 5. Limited vendors for replacement belts. If you have a chain you can buy one in any motorcycle shop wherever you happen to be. I also think that the sprung belt tensioner has been misunderstood by some people on this board. The total movement of the tensioner is around 1/4", and rather than move through an arc it just moves enough to absorb the shock when the suspension goes through suden movements (particularly in extension). It does not alter the angle of the belt and there is not enough movement for the spring to release significant amounts of energy back into the belt to cause damage or to cause any 'lash' in the belt. I know you don't like testimonials or anecdotal evidence, but this is what we have to draw upon. We know from 4 years experince using & selling these and from the experience of our customers that these do not damage belts, that belts don't break as readily as with the stock tensioner and that suspension quality is improved. Of the hundreds and hundreds that have been sold I have never heard one person come back to us or Free Spirits to say that his ride has not improved or that the tensioner does not work better than the original. Most importantly, I have never been told by anyone of a broken belt when using this tensioner. Everyone who has spent money likes to feel that they spent it on a worthy product so they'll convince themselves that there's an advantage when there isn't. Normally if people spend money and then don't like a product they have bought they will be on the phone within days, believe me. We have always encouraged feedback from our customers, and so far we have had nothing but positive on these parts. In the end the choice is yours, if you don't want one then nobody will force you to buy it  | ||
| Vagelis46 |
'We have always encouraged feedback from our customers, and so far we have had nothing but positive on these parts. ' OK, here it is : BRAKING pads, I really do not like them. EBC GFA are much-much better in braking power and overheating issues. I would not recommend them. Also I find the EBC GFA much better than the OEM Nissins. BRAKING wave rotor. It improves noticably the handling, since it is 300gr lighter, but it gives serious overheating problems. I would not recommend it to any rider that pushes the bike hard. I recommend the OEM rotor. FREE SPIRITS spring tensioner. It improves the rear suspension, and the stability of the bike at hard braking. I strongly recommend it. It makes a big improvement, regardless of what the factory, and other people that have not tried it, say. All the above have no theoretical data, and is only anecdotal evidence, based on the 30.000 km / year, I ride the XB12R. This is what this forum is all about, sharing our experience and ideas. | ||
| Bombardier |
Correct me if I am wrong but I believe the tensioner is there to spread the load as it were. It keeps the maximum amount of teeth engaged at the strongest part of the belt/teeth marriage. If there was slack it would put a lot of strain on the thinner part of the teeth and cause them to snap off. This is something I have seen on the timing belts of various engines over the years when the tensioner has not been adjusted to spec. | ||
| Hootowl |
I believe the tensioner is there so that swingarm movement does not change the path length of the belt. My X1 has no such tensioner, and while I have broken two belts, neither one broke because of stripped off teeth. Interestingly enough, and germane to this topic, both belts broke immediately after riding over railroad tracks. Both belts were run loose, no tension at the midpoint of swingarm travel. | ||
| Spatten1 |
Here's a good one: Last night I was sitting next to one of the Goodyear belt engineers from Lincoln on a flight to Dayton, OH. We had plenty to talk about. He thinks highly of the Buell powertrain staff. He used the words "smart" and "aggressive". We did discuss the sprung tensioner. He said Buell designed the tensioner the way it is. He worked on the XB belts soon after the Gates issues. He has not worked on the "Helicon project", as he called it. He did speculated that under decel if the spring compressed, and there was slack on the top side of the belt, it would slap around a bit too much (he used hand motions of it flexing sideways while bouncing). Don't worry anony, the discussion was completely above board with no controversial content whatsoever. I told him that I get my bike rolling, rev it to the limiter and dump the clutch. He said that is very bad for belts.... | ||
| Djkaplan |
The whole reason for the existence of ATK is because of inherent problems the founder noticed in chain drive systems and motorcycle suspensions... I agree with this statement, but the inherent problems the founder noticed in chain drives (and resolved with the AMP link) also present themselves with belt drives. It's probably not going to make anyone feel better, but Husqvarna used a similar concept on their offroad bikes in the late 70's. They used a nylon rubbing block instead of a roller to keep the chain slack relatively consistent throughout the swingarm's range of motion. There was no logical reason it would have hindered or altered suspension movement and braking. No one complained about it back then. | ||
| Rfischer |
I think what we have in the context of the present Buell-related discussion is a solution in search of a problem, aka "marketing". | ||
| Rick_a |
I fashioned a spring loaded chain tensioner for my S1 out of one made for a Harley. The only benefit was a lack of driveline snatch, which felt incredibly smooth. Unfortunately it broke off after a few weeks whilst jumping a railroad crossing. It flew so far I was never able to recover it. Running a belt I don't see one being necessary. The belt naturally has some elasticity. Most belt breakages I've seen are due to rocks/debris or with earlier belts improper service procedures. Shock loads seem to be a weakness, too, such as popping the clutch, banging downshifts and such. I don't think anything will change that. | ||
| Spatten1 |
Most belt breakages I've seen are due to rocks/debris or with earlier belts improper service procedures. Shock loads seem to be a weakness, too, such as popping the clutch, banging downshifts and such. I don't think anything will change that. I hope that is not true anymore (other than the improper handling). If a belt breaks due to any of those normal riding/sporting activities, it does not belong on a motorcycle. | ||
| Fresnobuell |
+1 Spatten. I have being popping the clutch, banging downshifts and generally abusing my 06 xb for nearly 20,000 miles and the belt is absolutely fine. I believe Buell made some great strides from the original belts. I mean, if there were issues with the belts, no way in hell would they put them on the 1125r. | ||
| Xbolt12 |
It's pretty simple if you think about it. Dirt bikes had struggled with chain tension ever since a Maico mechanic figured out he could get more suspension travel by moving the shocks forward on the swingarm. The real issue is that unless the counter shaft sprocket is on the same axis as the swingarm pivot, then chain (or belt tension) will vary as the suspension moves because the length will need to change. This is why most track organizations look at chain tension during tech inspection. Basically a chain must have enough slack to prevent binding and damaging the counter shaft bearings when the suspension is compressed enough that the axle, the swingarm, and the counter shaft are all in a straight line. Early dirt bikes used to use spring loaded tensioners, but those caused a lot of problems, especially if mis-aligned and contributed to excessive drive-line lash (after all, a spring does give). Later manufacturers paid a lot more attention to getting the counter shaft as close as possible to the swingarm pivot in order to minimize chain slack variation. This today is combined with fixed rollers at travel extremes along with a fixed chain guide and is very reliable. Buell and some other manufacturers figured out that if the swingarm is below in-line for most if not all travel, chain torque will not compress the rear suspension under acceleration and so will enhance control. I believe this causes another effect which is not so desireable-an increase in chain path length because suspension travel is not balanced on either side of all the three points in-line (counter shaft, pivot, axle). Buell came up with an ingenious fixed pulley location which compensates perfectly for the decrease in path length as the swingarm moves down-that is increased belt slack. ATK did similar but different control of slack with their A-TRAK system in the 80's. I would think that because Buell XB's have a swingarm that acts below a straight line between the three points and that the drive pulley is a large diameter which means the center is farther away from the swingarm pivot than conventional chain drive bikes, that any chain conversion should at least attempt to replicate the fixed roller relationship to rear pulley diameter when choosing sprockets for both idler and front and rear drive sprockets. Just my two cents... | ||
| Xbolt12 |
It's pretty simple if you think about it. Dirt bikes had struggled with chain tension ever since a Maico mechanic figured out he could get more suspension travel by moving the shocks forward on the swingarm. The real issue is that unless the counter shaft sprocket is on the same axis as the swingarm pivot, then chain (or belt tension) will vary as the suspension moves because the length will need to change. This is why most track organizations look at chain tension during tech inspection. Basically a chain must have enough slack to prevent binding and damaging the counter shaft bearings when the suspension is compressed enough that the axle, the swingarm, and the counter shaft are all in a straight line. Early dirt bikes used to use spring loaded tensioners, but those caused a lot of problems, especially if mis-aligned and contributed to excessive drive-line lash (after all, a spring does give). Later manufacturers paid a lot more attention to getting the counter shaft as close as possible to the swingarm pivot in order to minimize chain slack variation. This today is combined with fixed rollers at travel extremes along with a fixed chain guide and is very reliable. Buell and some other manufacturers figured out that if the swingarm is below in-line for most if not all travel, chain torque will not compress the rear suspension under acceleration and so will enhance control. I believe this causes another effect which is not so desireable-an increase in chain path length because suspension travel is not balanced on either side of all the three points in-line (counter shaft, pivot, axle). Buell came up with an ingenious fixed pulley location which compensates perfectly for the decrease in path length as the swingarm moves down-that is increased belt slack. ATK did similar but different control of slack with their A-TRAK system in the 80's. I would think that because Buell XB's have a swingarm that acts below a straight line between the three points and that the drive pulley is a large diameter which means the center is farther away from the swingarm pivot than conventional chain drive bikes, that any chain conversion should at least attempt to replicate the fixed roller relationship to rear pulley diameter when choosing sprockets for both idler and front and rear drive sprockets. Just my two cents... | ||
| Rick_a |
What constitutes abuse is a very subjective thing. For example, there's guys who've run their bikes "hard" for nearly 100,000 miles and never had the top end off, then guys who do top end rebuilds every 10-15K and replaced crankshafts at under 20K. Who am I more inclined to believe? It'd be interesting to know how belts on those Buell XB stunt bikes out there have been holding up. | ||
| Spatten1 |
What constitutes abuse is a very subjective thing. Yeah, but with chains no amount of abuse will break them, in my experience. It VERY rare for a chain to break. The belts need to hold up to maximum abuse too, or they do not belong on a sportbike. The factory seems very confident that the belts have reached this point of ultra-high reliability. Good stuff. It will be a strong unique selling point. | ||
| Josh_ |
Anyone comment yet on the 1125R that snapped a belt near turn 14 on the last demo session? | ||
| Reepicheep |
Just to keep beating this topic to death... It's anectdotal evidence, but I have broken fewer belts (0) in 57k miles of Buelling then I have broken chains (1) in 500 miles on my Kawasaki. Chains "break" every 6000 to 15000 miles. If they weren't broken, then why am I replacing them? If you priced a $ for $ comparison to chain maintenance on a sportbike, and invested that same amount in belt maintenance, you would probably break belts as rarely as chains break. (Message edited by reepicheep on October 25, 2007) |
