| Author | Message | ||
     Foximus |
So lets say you were Forced to do an extended swing arm... What would be the longest you would go? Or shortest? I dont like the idea of a extended swing arm, however In this new project I'm doing I may be forced to extend. And that being said... are longer belts at custom lengths available at all? | ||
| Guell |
why would you be forced to do an extended? Not a fan of any extended swingarm on a streetbike. | ||
| Foximus |
I am not either... However the end result might be worth it. Uber cool project underway. Right now without major machining to what I'm building I will be at 7" extended. I dont like that at all... I might be willing to accept 1 or 2 inches. And I'm trying to avoid going to chain drive. | ||
| Guell |
I remember seeing a link to a site that had different length belts. Ill see if i can dig it up again | ||
| Foximus |
I know ulyses has 135, and the 1125 has 139... (though I'm not 100% sure its the same 14mm pitch...?) | ||
| Hybridmomentspass |
Fox, without more info its hard to speak about what our opinions would be on the arm length All youre saying is you dont want to go long, but you have to go 7, I dont know, we need more information | ||
| Foximus |
I apologize... you are right. Let me rephrase it this way. Those of you who have experimented with longer swing arms on these bikes.... Is there a magic number that makes the bike ride really sweet... or is anything longer than stock just take the bike down a notch? I myself find the rear wheel incredibly shakey at anything over 70 when letting off throttle... | ||
| M2typhoon |
Wouldn't you also need a stiffer rear spring since the leverage being increased from the longer swing arm? I've designed suspension systems for race cars and that tends to be the case. | ||
| Foximus |
Yes... but thats not a problem. Would just get that worked out by racetech. I'm out taking measurements in the shed quite fervously seeing if I can get away with chopping 7" out. | ||
| Sdecp |
Dude, Fox, what happened to the Duc arm? | ||
| Littlebuggles |
Suggest going over your suspension and making sure it's in good shape before you start looking into extending the swing arm. If it's adjusted properly and working as designed to it should not cause stability problems. Is the bike getting skittish just from rolling off throttle? If so you need to rework the front end and perhaps put some heavier springs in there (kinda depends on body weight and how aggressively you are using that front brake). If you are just grabbing a handful of brake as you roll off - making the back end light, well, that's different. Trying a different technique would prolly help that  55" is the wheel base these bikes are designed to perform best at. | ||
| Foximus |
sdecp. shh. | ||
| Littlebuggles |
Ahhh. Seems like MAYBE the wheelbase got a bit longer with the XB swingarm on Joesbuell's bike, like maybe an inch, up to 56"(???). I'm too tired to try and find the thread, and all the data points at the moment. Will be a good project for me when I'm nice and sharp near the start of the shift tonight though. There are plenty of sportbikes out there with 56+ inch wheel bases. | ||
| Hybridmomentspass |
Yeah I think maybe its something else, not the swingarm Im on the stock arm on my dragbike (for now, by saturday it'll be different) and I go from WOT to zero throttle on every run on the big end, never have an issue with the rear getting out of control (over 110 mph when getting out of it) If racetech will already be doing work for you then you need to tell them of the problems youre having and ask their advice. | ||
| Foximus |
I'm not going to divulge yet, but I'll say its not an XB swingarm... ;] | ||
| Hybridmomentspass |
Yeah, we know, Ducati arm, the other guy already said it, cats out of the bag, just spill the beans | ||
| Foximus |
... sigh... So much for surprises. VFR swingarm.... Ducati 1098 hypermotard wheel  | ||
| Sdecp |
Sorry Fox.  | ||
| Littlebuggles |
Sounds like a cool project, I hope it goes well. I say do it and worry about wheel base if the handling turns ...sucky. Just make sure the ride height stays same to keep the front end geometry (rake and trail) stock. VFR's have a 57.4" wheel base if Wikipedia is to be believed. | ||
| Foximus |
Well that will be the hard thing to do, as the way you adjust a single sided swing arm length is through an eccentric bearing, so the height in the rear will always change some... | ||
| Palmer |
I would go for a singlesider. http://www.ram-italia.net/modelli-buell-con-telaio -tubolare-p-155.html?zenid=6c2ebulg4563vbru76011cc cd3 | ||
| Foximus |
Well I am doing a single sided swing arm... thats why I have a $1300 ducati wheel on my bench. I actually have been in the talks with Ram Italia, they still have all the molds, and would take about 8 weeks to do all the castings for me. However that translates to roughly over $4000 USD. I'll make 10 for that price. | ||
| Palmer |
Foximus, If you can build a pretty singlesider like the one of RamItalia for 400$.. I'll buy two. Anyway, I think you will enjoy this bike:     that should be an inverted 916 singlesider. | ||
| Maru |
WITH 7 INCHES ADDED TO THE WHEELBASE YOU WILL BE OVER 60 INCHES. That is longer than any sportbike I have ever seen this side of a drag strip. Modern sportbikes use very long arms but the front half is shorter. Wheelbase is not the only consideration. You need a certain amount of swingarm droop or the bike will squat like mad when driving off the turn. This gets amplified with a long arm. At a given angle of droop, your steering head angle will steepen with the longer arm. When building with a clean sheet, the swingarm pivot is raised to compensate. | ||
| Maru |
If you run the arm flat, the bike will squat from the apex out on high throttle settings and the bike will want to run wide. If you roll out the bike will pitch and you will be constantly feeding in steering input to make corrections. An interesting project but your really going to be changing the way the bike responds to steering and throttle inputs. I think you might, with an emphasis on might be able to handle the steeper steering head angle that would result from such a long arm when coupled with a reasonable amount of droop but you might have to make special triple clamps to keep the trail within reason. | ||
| Maru |
I would consider going with the Ducati arm and linkage because some of those have an adjustable rod that allows for ride height adjustments. This would make it possible to increase or decrease ride height/swingarm droop over a pretty broad range and evaluate its impact on handling. Good luck and post progress reports. | ||
| Maru |
The higher you can make your pivot point (within reason) the better off you will be geometry wise, also try to keep the pivot point as close to the countershaft sprocket as possible. | ||
| Rick_a |
The Buell Pro Thunder tuber racebikes back in the day ran 1" extended swingarms, raised the rear ends 1," and most had the front ends dropped 5-10mm. That's what I did. Steering is faster, it is still very stable, with much better manners at corner entry and exit. The S1's, M2's, and S3's ran pretty conservative steering geometries. The X1's were more aggressive, yet most were similarly set-up. Mines a bit twitchy at low speed (below about 30mph) on sh*tty roads, but that's the only negative besides a typical sportbike-like seat height. | ||
| Maru |
Yes these bikes are really sweet set up like that. They turn in nice and finish the turn as well. Run that same swingarm angle with 7 inches of extra arm length and you will have quite a bit more ride height in the back which will stand the bike on its nose. You can raise the front some to get the front geometry back in line but that has the effect of reducing droop so you start chasing your tail. Fox will have to think this stuff out at the deign phase if he wants to minimize the negatives of that long wheelbase. He should raise the pivot as high as he can, this is limited by belt or chain rub on the nose of the swingarm. The higher pivot point will allow for more swingarm angle without added ride height. He should also get the pivot point as close to the countershaft as possible. This reduces the amount of squat which is what you are trying to negate with the added swing arm angle. | ||
| Foximus |
Agreed on all aspects. I Know i wont be running 7". I just know I wont. However 1 or 2, I might find acceptable. That is another otpion i was t hinking of, as to raising the rear swing arm, is making eccentric cam mounting blocks instead of the standard centered ones. That would allow for perhaps up to 1" of height change in the rear. I'm still deciding if I should try to use this VFR swing arm, or make one from scratch using VRF bearing blocks. |
