| Author | Message | ||
     Jersey_thunder |
who has experience with extending a S2 swing arm? T | ||
| Lynrd |
I have some experience in general in extended swing arms in rubber mount frames, but nothing specific to the Buell S2. Generally, be prepared to change your shock spring as you have a longer lever to control. Stock spring could be too light. The isolators are sort of sensitive generally to having correct loads on them, and the loads fed from the correct direction.. None of this theory is as good as a healthy round of jumping in and finding out - I will be extending the swing arm on the "Black lightning" project , but I am moving the shock(s) as well, and so already have to recalculate the springs Simply extending the swing arm, from a weldment standpoint, is straightforward- I'm planning on using a spud inside the stock rectangle tubing, and cutting where I can move the brake anchor slot on the left side. You could simply butt weld it and probably never have a problem, but anything worth doing is worth overdoing, I always say. There is at least one drag racer on this board who altered his wheelbase that way. My S2 was drag raced by a former owner and did consistent 12.00, but did so with stock wheelbase. | ||
| Jersey_thunder |
thanks, i'm not racing it, just looking to build a head turner for my shop... i'm picking your minds and using all your R&D to help me out T | ||
| Jersey_thunder |
are there neoprene isolators? | ||
| Hybridmomentspass |
got extended arm on my s3 | ||
| Jersey_thunder |
COOL,got pics? | ||
| Rick_a |
My S1 has been extended a full inch. Yup. An inch. Makes all the difference. | ||
| Rick_a |
In street cred...  | ||
| Kc_zombie |
"Are there neoprene isolators?" I don't know about neoprene, but once upon a time someone manufactured solid isolators... | ||
| Tll130 |
All this talk about extending swingarms makes me wanna shorten my swingarm. Talk about a head turner   | ||
| Hybridmomentspass |
jersey - yep, what you wanting to see? | ||
| Midnight_rider |
 | ||
| Midnight_rider |
not mine found on web | ||
| Hybridmomentspass |
see if this works....  | ||
| Spiderman |
head turner? Really? Is the bike not stunning enough without resulting to cheap after affects that a ricer would use to make the bike more 'gangsta' If you plan on putting an extended swing arm on an S2 for other than drag racing and even then I would suggest bastardizing another Buell such as an S3, I suggest you sell said motorcycle to someone who will love the S2 as she is and not change her in such a cheap and trampy way... | ||
| Lynrd |
An extended swingarm isn't an irreversable mod - there are lots of 95-98 swingarms around. He just got the bike, and want's to personalize it to himself. So long as he isn't cutting the frame or chopping up original fiberglass, well, if that's what you want, I guess. That said, I don't even get why this is considered a cool thing to do. I can't see why you would do that on a street bike as lengthening the wheelbase impacts the cornering ability. For a show bike, maybe. I don't think it looks all that cool, myself, and would not gain you any points in a show (Might be able to move the bike into a "Modified" or "Mild Custom" class, I guess...) but , as they say in the customizing biz..."There's an ass for every seat". | ||
| Lynrd |
I just noticed both of the bikes pictured have the shock replaced with a strut. That makes a lot of sense - like a I said before, the rubbermount system is really picky about how the rear suspension is set up. By immobilizing it, you should be able to keep the factory isolators. | ||
| Hootowl |
The rear isolators are not involved in the rear suspension on a tuber. The stresses from movement of the rear wheel are transmitted through the shock to the mount at the front of the motor. and through the swingarm mounting block to the rear of the engine/transmission. Never through the isolators, which simply isolate the frame from the vibrating drivetrain, and there are no rear suspension loads carried by the frame. | ||
| Lynrd |
I will go ahead and disagree here. Those sort of isolators, which are common to the FLT/FXR as well, have a twist to them and setlle in when load is placed on the suspension. IF you feed that twist from the wrong direction, or change the loading, the isolators fail shortly. I know this because I was involved in not 1, not 2, but THREE "Rubbermount Softail" designs (One at Ness, two at Gambler) and at Gambler, we eventually solved the problem just in time for HD to make it irrelevant by introducing the 88B Engine. The short lever (rear swingarm anchor) used on a Softail initially used on the first version (the failed Ness rubber mount softail from around 1991) coupled with FLT/FXR/Buell isolators and the spring rate made necessary the short lever would twist those things out and apart in no time. Lengthening the axle-pivot length has the same mathematic affect as shortening the pivot/rear shock mount arm. THe first generation RubberMount Softail at Gambler (Which I didn't design but was brought on to fix), they had initially ditched those isolators for polyurethane bushings. That definitely solved that isolator twist problem but the bike transmitted way too much vibration through the polyurethane and was a failure. In the three generations of prototypes for what became the Gambler G-2000, we went back to FLT Isolators, and spent far too much time studying how the isolators reacted to suspension load. This was before you could model this sort of thing inexpensively in a computer, so we did it the hard way - we built prototypes, and racked a couple of spectacular failures before coming up with a workable design. The final design did indeed look like a Softail, and rode like an FLT. There were several keys to making the isolators work - one of them was the angle of istalation (you know, the reason there is a dowel pin in them to keep them in correct orientation) and one was correct spring rate for the critical dimensions. I can still ratlle off the critical variables: Pivot to upper (or rear) shock mount Pivot to lower (or front) shock mount eye to eye shock length pivot to axle. Change any of those and you need to recalculate spring rate. I think we built about 100 or so G-2000s before I left the company (and the industry). Sadly, I didn't keep the prototype frame that finally cracked the code - I wish I had it today, it was a great bike while it was together. I did recently find a picture in a old issue of HotBike for a frame we comped to them in exchange for ink. Note the shocks/battery trey were covered by a sheet metal cover that simulated an oil tank, and we bult for the later FLT transmission to move the oil tank under the transmission.  and here are some detail shots showing off the hidden isolators, courtesy of the Internet Archive.   | ||
| Kevmean |
The difference with that design is that the shock is mounted between the swing arm and the frame NOT between the swingarm and engine as per the Buell. On the Tubers the rear suspension has no direct link to the frame.Changing the length of the arm on a Buell will alter the leverage against the shock itself and also probably the front engine mount. | ||
| Hootowl |
Yup. You obviously didn't read what I wrote about load path on Buell tubers.  Neat story about your experiences with those frames though. The diversity and depth of experience on this board is amazing. | ||
| Lynrd |
No, the increased leverage on the swingarm pivot will twist the isolators out, no matter what the spring is anchored to, if the suspension is under sprung. The rear suspension does, in fact have a "direct link to the frame". We call them "engine isolators", and they also form the outer edges of the swing arm pivot point. They are picky little bitches and have a pretty narrow tolerance for what sort of load they will take. Increase the load on the rubber pivot point by lengthening the lever trying to twist them, and they go away. In this case, where the spring in anchored is really immaterial. Increase spring rate to balance that twist, and everything works again. If you really believe that the isolators have no involvement in the suspension - go look at your bike, find the isolators, and ask yourself "If I remove those, will the bike collapse?" Of course it will, because the swingarm pivot would then only be supported by the rear motor mount casting and pivot bearings. If the swingarm pivot was not also a rubber engine isolator that is sensitive to being mounted in precise orientation (the reason the hole is off center and they all look "Slanted"), I would agree with you. You could get away with this on something like a late sportster or Dyna where the engine mount and pivot are two separate things. You'd still need to recalculate spring rate for the longer lever, but you wouldn't be risking collapsing the bike when you get it wrong the first 3 times. BTW - I LIKE the isolator/pivot design in our Buells an awful lot. I consider the design a real thing of beauty, and it is the main reason I own tubers. <later> ...Wait - OK, I get your point, and yes, that front shock mount DOES make a difference. I retract all attempts to make this about FLT/FXR. THe longer lever, however, is still a longer lever, and still needs a stronger spring. but the isolators, yeah, would not have the tendency to twist as they would in a FLT/FXR based design. (Message edited by Lynrd on October 03, 2013) | ||
| Jersey_thunder |
An extended swingarm isn't an irreversable mod - there are lots of 95-98 swingarms around.  | ||
| Jersey_thunder |
NOW WE HAVE A DISCUSSION, trying to take all this great info and process it...lmao...  | ||
| Hootowl |
"If you really believe that the isolators have no involvement in the suspension - go look at your bike, find the isolators, and ask yourself "If I remove those, will the bike collapse?" Of course it will, because the swingarm pivot would then only be supported by the rear motor mount casting and pivot bearings." On a Buell tuber, the only thing that will happen is the frame will fall down onto the back of the engine/transmission. The rear suspension will be unaffected. <later> I read your addendum. Absolutely the spring needs to be stiffened to compensate for the longer lever. (Message edited by hootowl on October 03, 2013) | ||
| Lynrd |
OK, ok - I get it. You're right. But you still need a stronger spring. Damnit. | ||
| Jersey_thunder |
ok, so increasing swing arm lenght and spring rate... would be a ok mod ..Not stressing the isolators? t | ||
| Hybridmomentspass |
ditching the shock for a strut is essential on a bar bike, otherwise you kill some of its advantages | ||
| Jersey_thunder |
THANKS HYBRID.. | ||
| Hybridmomentspass |
Jersey - if you arent racing it then it wont matter to you but please keep us updated on how this goes and if you have any questions I'll do whatever I can do help you out man |
