Longer swingarm on a 15

[2and3cylinders]

Curious what year FJ/Tracer/FZ/XSR with longer swingarm (I presume 18~20?) will be a direct bolt on to a 15 but will shock angle / bottom mounting location change (I have a Razor R) and how many more chain links will be needed (total # links)?

Want a bit more stability (have .95 springs & custom comp & rebound cartridges), as it now dives into turns great but almost too quickly; plus straight-on cruising stability could be better.

Then of course does anyone have a suitable longer swingarm for sale?  LOL

Thx

[betoney]

16 minutes ago, 2and3cylinders said:

Want a bit more stability (have .95 springs & custom comp & rebound cartridges), as it now dives into turns great but almost too quickly; plus straight-on cruising stability could be better.

Bret, before spending money on a longer swingarm, have you tried altering your ride height ?  Your Razor-R should be ride-height adjustable and most members here report raising their forks up as much as 10mm in the triple clamp, I personally found that to be too much, I am closer to 5-6mm on the forks and maybe 3mm on the shock.

If you do actually go through with a longer swingarm, I am very curious to hear how the handling changes.

If I remember correctly, the longer swingarm came on the '19 900 and '19 and '20 900GT.

[ilanr1]

I just want to remind you that longer swingarm requires longer chain , longer tube for the rear caliper..

 

[draco_1967]

The aftermarket shocks don't list a separate option for 19+ Tracers vs. 15-17 FJ-09 (or the MT-09, XSR), so I would assume the linkage distances are the same. I think they just added length to the wheel end of the swingarm. 

[roadrash83]

Didn't the Japanese police FJ model come with a Longer swing arm? 

[2and3cylinders]

2 hours ago, betoney said:

Bret, before spending money on a longer swingarm, have you tried altering your ride height ?  Your Razor-R should be ride-height adjustable and most members here report raising their forks up as much as 10mm in the triple clamp, I personally found that to be too much, I am closer to 5-6mm on the forks and maybe 3mm on the shock.

If you do actually go through with a longer swingarm, I am very curious to hear how the handling changes.

If I remember correctly, the longer swingarm came on the '19 900 and '19 and '20 900GT.

I thought the swingarms on the 18s were also lengthened; as well as on the FZ/XSR?

I appreciate your input but have the following related comments based on my experience and understanding of suspension; feel free to comment thereon.

1.  Raising the forks will steepen the rake (reduce it numerically, as well as lower the front), and reduce trail'; unless matched by lowering the rear by reducing shock length, and less effectively, shock preload.  Reducing rake and trail will then have the opposite affect I desire by speeding up turn-in.

2.  Lowering the rear by reducing shock length will help but also reduces ground clearance which can be offset somewhat by increasing preload but that effects response of the rebound and compression damping settings.

3.  Lengthening the swingarm should shift the Cg rearward and take load off the front (not necessarily desirable even when offset by softening front preload and compression damping; usually with less than optimum results), as well as change the swingarm angle and effect drive chain tension and it's effect on suspension action under acceleration and deceleration (anti-jacking effect).  An extended front-rear sprocket center-to-center length can often have positive affects, and the longer wheel base should also slow down turn-in; which is what I'm after.

As I have things set-up and adjusted now, I could try shortening the shock length and see how it correspondingly lowers rear ride height and reduces ground clearance.  I have foot pegs (without any feelers) that are about 19 mm lower and 10 mm more forward but I have not had issues with them or my boots grounding to date.  This is likely due to me not being in good enough shape to push all that hard on the comparatively not the tightest, fastest, twistiest roads I frequent; I don't challenge the suspension.  With the rear lowered I could stiffen compression and increase rebound to compensate for the reduced ground clearance, which will reduce responsiveness and comfort somewhat on the unfortunately comparatively much longer distances I must traverse to get out to the "twisties" (this term must be used loosely in my locale).  I can always go back to the longer than stock height rubber covered foot pegs (with very short feelers) if more ground clearance is then needed but like the extended leg room from my custom Sargent saddle (+0.60" taller than standard) in the high setting.  Consequently, high speed (+80 mph) stability is very important here.  At least the rapid wear on the center of the rear tire does lower the rear :-)

While I like the almost telepathic steering response I have now that requires minimal counter-steering, upper body lean /movement and peg loading, I find myself often running too quickly to the inside of the turn and centerline.  I also think my moderately loaded Shad SH46 topcase raises the Cg and moves it rearward, somehow speeding up turn-in but not nearly as much as a pillion would.  I still should experiment deleting the topcase and running instead my Shad SH36 panniers, or a pillion seat bag.

[betoney]

18 minutes ago, 2and3cylinders said:

"I thought the swingarms on the 18s were also lengthened; as well as on the FZ/XSR?"

I believe that is correct but since neither an FJ or Tracer were offered in North America in 2018, I didn't mention that specific year since it could be cost prohibitive finding one and having it shipped from a different country.

"1.  Raising the forks will steepen the rake (reduce it numerically, as well as lower the front), and reduce trail'; unless matched by lowering the rear by reducing shock length, and less effectively, shock preload.  Reducing rake and trail will then have the opposite affect I desire by speeding up turn-in."

I might not have been clear in my previous post but that is what I was suggesting, lowering the forks in the triple clamp, raising the front.

 

[OZVFR]

The longer swingarm places more weight on the front wheel which is what the 15 lacks. 
Lowering the front by 15mm (done it on both ends of mine as I’m short, with no issues with ground clearance as long as the stupidly soft stock front has been addressed) also helps. 
The rear shock is also soft if you’re on the heavy side which makes front wheel loading even worse. 
I’ve also removed the hand guards and stock screen as I found them to only induce buffeting and not much else. 
And if you’re always running into the inside of the corner, you’re turning in too early. 

Edited December 18, 2021 by OZVFR

[2and3cylinders]

You may be correct about lengthening the swingarm loading the front more (I'm not quite yet all there, as they put me out for my surgery Tuesday), and that indeed may improve stability but I have to check Paul Thedes suspension bible (https://www.amazon.com/Techs-Motorcycle-Suspension-Motorbooks-Workshop/dp/0760331405).

As far as lowering the front & back, if they are balanced properly, and the damping and preload is correct, going down should not matter at the speeds we can realistically achieve frequently & safely; i.e., under 120.  If I were going to Bonneville, then yes, lowering helps streamlining and stability but not with my mass & girth on top.

I'm not removing my KTM Adventure hand guards.  I ditched the rubbish stock screen immediately (along with the saddle), and two of my AM screens, one an OEM size DB & the other the Givi Tour barn door, both with adjustable top edge spoilers, I believe actually help more than hinder depending on ambient wind speed & direction (other than adding drag, reducing top speed) because I can actually tuck in better behind them.  I also have a opaque black bikini screen for really hot weather which basically only keeps the instruments & my cell clean.

I know my front hoop is a bear to balance adequately and it may be a big factor here, as vibration, particularly in the vertical plane, can induce headshake, etc..  So I was planning on re-balancing the front tire and adding more weight.

[PhotoAl]

I was thinking that there was a longer swingarm before the lengthening one in the 2019/2020 swingarm.  It is about 1" longer.  If the mounting is the same then I don't see why one shouldn't work on a 2015 bike.  Wit the same shocks used sounds like they extended the swingarm behind the shock mount.  

I dropped my triples 7mm which helped my 2020 GT.  More weight on the front and more stable cornering.  

[2and3cylinders]

On 12/18/2021 at 10:54 AM, PhotoAl said:

I was thinking that there was a longer swingarm before the lengthening one in the 2019/2020 swingarm.  It is about 1" longer.  If the mounting is the same then I don't see why one shouldn't work on a 2015 bike.  Wit the same shocks used sounds like they extended the swingarm behind the shock mount.  

I dropped my triples 7mm which helped my 2020 GT.  More weight on the front and more stable cornering.  

I agree about it being more stable cornering after raising the forks in the clamps but I'm looking for a bit more stability at high speed (i.e., in a straight) and am willing to slow down turn-in to obtain it.

Again, they lengthened the swingarm on the 18~20 and again more in 21, and also in 21 they dropped the steering head height significantly and tilted the engine more vertical to obtain stability while improving turn-in.

A couple ways I've done this before was to add 2 chain links to lengthen the wheel base, as well as reduce my 2-way (comp & rebound + preload of course) adjustable shock's overall length to lower the rear (without reducing preload).

I contacted someone I know at Race-Tech for his opinion.

[2and3cylinders]

My contact at Race Tech got back to me with the following

It mirrors exactly what I was saying and he concurs with my assessment..

Running the forks lower in the clamp to make the bike taller will increase high speed stability, if it makes turn in lazier you can always raise the rear just a little to get it back.

I prefer to leave the forks as long as possible and adjust the rear to get it to do what I want.  That way it can be stable and turn.

 Mike Crow

Tech Support

 I told him I shouldn't have doubted myself I've been doing this too long...