GSXR REAR WHEEL MOD

[Arnie]

  I have been putting off this mod....havent been able to determine,for sure, how much gearing and maybe more importantly,to me, how much ride height will drop? ...i run a 160/80/16...and i read that the 180/55/17 is shorter. dropping a few teeth on back is no big deal but the rear susp.on the 89s wont allow the shorter dogbone trick as the shock will hit the swingarm when raised  so...the back end will be lower,affecting handling.

Assuming the tire sizes are accurate.....

Your overall rear wheel diameter with a 160/60x16 is 26 inches.    (160*.80*2)/25.4 + 16 =
Your overall rear wheel diameter with a 180/55x17 is 24.8 inches. (180*.55*2)/25.4 + 17 =

So, your axle and ride height will be 1.2"/2 = 0.6 inches lower with the new wheel and tire.

Your gearing will be 81.68/77.91 = 1.048 times shorter than before.
So, if you were turning 4000 rpm @ 60mph originally, you'll be turning 4000*1.048 = 4192rpm.

HTH,
Arnie

[Dan Filetti]

The one downside you forgot?

Raise it too much, and the front needs a steering dampener to prevent tank slappers etc.  Probably not such an issue for the uber-stable FJ, but I bet you could make it one if you tried hard enough.

Dan

[turbocamino]

  Bama< my shock (Hagon) is maybe an1/8", or less, away form the s/arm as well...but as i raise bike any, it contacts the  arm....if yours is this close as well,,how can it be raised more?      Arnie, thanks for the gearing info...actually, my Michilin pilot is an 80 (aspect ratio) making gearing even shorter than the 60 you ran #s on.. for a total gearing difference of maybe 200 rpm?    As i think of it...the 160/80/16 ,being so tall, helps handling some..but that tall sidewall can flex more...a bit of a trade-off...i run 40 psi to reduce flex....the bike does handle very well.  I really would like the wider cross section with less sidewall..but if i cant raise the bike i dont want to reduce ride height with the 17" wheel... i cant find a 180/60/17 which may be closer in height to the 160/80/16.  I wish the 18" fz conversion didnt sound like such a pain in the a**.  Does anyone know of anybody that can do all nessasary machining,fit bearings etc. if sent all needed items? 

[Pat Conlon]

There's some downsides to raising the bike, but they're all pretty minor.  

Biggest one is that you may have to modify the kickstand so the bike doesn't lean as far (isn't a problem unless it had been modified or worn a bit already).

Makes it harder to launch the bike hard from a stop.

Makes it harder to touch the ground if you're short and uncomfortable on tall bikes.

The one downside you forgot?

Raise it too much, and the front needs a steering dampener to prevent tank slappers etc.  Probably not such an issue for the uber-stable FJ, but I bet you could make it one if you tried hard enough.

Side stands and steering dampeners? Sheesh, you guys are pole vaulting over mouse turds....Bummer if the Hagon shock does not allow shorter dog bones.

[Dan Filetti]

Pat-

The Gixxer has (and seems to need) a dampener.  Never actually had a tank slapper, but I've felt the front want to develop an oscillation once or twice.  The FJ and the Gixxer are different yes, but not THAT different, they're both motorcycles after all.  My only point was that lifting the back too much could cause such issues, although I don't think I've ever read where someone has actually done such a thing to an FJ. 

Then again, if they HAD done it, and wiped out and died, and simply dropped off the forum, we may never know.  Hell, maybe his last post would have been something like 'jacked the back sky high, with my new 1/4" dog bones -man, does the front feel twitchy.  Going to take it for a longer test ride this afternoon...'



Can you tell I'm board?

Dan

[andyb]

Bigger pisser if you're enjoying the new handling only to find the bike laying on its side when you come out to it, eh?

Don't think a damper would be required until you got way, way up high.  I suppose arguably they get pretty weav-y at stock height once the tire cup a bit though.



Like anything else, it's just a compromise.  Worth it for some (most!) but downsides are downsides.

[Harvy]

TurboCamino, When I did the 18" Genesis rear wheel mod, I just had the local engineering shop do the machining. I told them how much I wanted off each of the pieces. Worked out just fine.
Bearings are easy do it yourself.........

Its really not that difficult.

Harvy

[Arnie]

The one downside you forgot?

Raise it too much, and the front needs a steering dampener to prevent tank slappers etc.  Probably not such an issue for the uber-stable FJ, but I bet you could make it one if you tried hard enough.

Dan

The chain will cut through the swingarm way before the FJ gets twitchy enough to need a dampner.
I've got the rear high enough that I had to extend the sidestand over an inch and its not twitchy.
I think Frank has his up in the air much higher than that. :-)

Cheers,
Arnie

[SILVERGOAT]

 You guys give me the giggles talking' about all your big rear tires. I used a 17x5 off a 95 YZF600R with a 160/70r17(which could actually run a 170/60) which adds one more inch to my circumference (81") instead of stock (80") effectively lowering my overall gearing. The bike is pretty light on its feet and I have never had a stability problem. I actually prefer this to the way my '03 FZ1 handles with the 180 out back, not that it's a slouch by any means, just different.
  P.S.I am using a Race-Tech modified FZ1 rear shock which puts a sliver of light between the rear wheel and the ground, setting ride height at maximum.

[bama1]

TURBOCAMINO
The FZR wheel mod is a breeze.If I can do it you can.The machine work is easy for someone that knows what there doing.I havent fooled with trying to raise the back anymore.I will work on that when I do the GSXR mod.You can do any mod that you want it just takes doing it.I was told you could not put a 89 FZR front wheel on but I did it with having the bearing housing machined for the FJ bearings.It works great.
THANKS BAMA

[bama1]

  Bama< my shock (Hagon) is maybe an1/8", or less, away form the s/arm as well...but as i raise bike any, it contacts the  arm....if yours is this close as well,,how can it be raised more?      Arnie, thanks for the gearing info...actually, my Michilin pilot is an 80 (aspect ratio) making gearing even shorter than the 60 you ran #s on.. for a total gearing difference of maybe 200 rpm?    As i think of it...the 160/80/16 ,being so tall, helps handling some..but that tall sidewall can flex more...a bit of a trade-off...i run 40 psi to reduce flex....the bike does handle very well.  I really would like the wider cross section with less sidewall..but if i cant raise the bike i dont want to reduce ride height with the 17" wheel... i cant find a 180/60/17 which may be closer in height to the 160/80/16.  I wish the 18" fz conversion didnt sound like such a pain in the a**.  Does anyone know of anybody that can do all nessasary machining,fit bearings etc. if sent all needed items? 

uSE gsxr wheel bearings no machinig except for spacers and brake arm.BAMA