Preload problem...

[veteran_80]

Tried a search but couldnt really find the answer... I tried adjusting my sag today, rear went fine but when I tried to adjust the forks I couldnt get enough preload....

Even with it all the way tightened I was still about 3/4" to much sag. Its an 05 gsxr 600 with just over 8000 miles. Im right about 200 lbs...

Possible problems? Solutions? Thanks in advance.

[Bueller]

You should probably present your method of, and actual measurements, so we know what #'s we are talking about. But the quick answer would be a different spring.

[rybo]

Without numbers it's hard to diagnose, but the likely problem is that you don't have the right springs.

[veteran_80]

I bought the bike used last august. I assume they are stock springs. Im just trying to get about 1 1/4 sag. I woulda thought that stock should be able to accommodate that...

[OUTLAWD]

stock suspension and 200 lb riders rarely go together...I have some spare .95's that should work in your forks...

[Bueller]

So you want 1 1/4" or ~32mm total sag (with you on bike), and you are not able to get better than 2" or 50mm?

What is the static sag?

[veteran_80]

@bueller exactly... Forks fully out with no weight on them were 10" from bottom of fork to upper edge of dust guard... With me on the bike it sits at 8.5".... Not sure if that answers ur question...

@ outlawd... That would be awesome if you think that would help my prob... How much for em?

[Bueller]

Ok according to my math you are at 1.5" total sag, which is not as far off as you were first stating, although with full preload that is still off. What I am after in addition would be the amount of sag you have (W/full preload) with just the weight of the bike. As this will also tell you if your springs are the wrong rate. But since you can't get total sag within the desired range even with max preload I would say your springs are too light.

http://old.racetech.com/evalving/menu/searchstreet.asp

[cbrjohnny]

what is a good shop for us csc peeps to take our bikes for a suspension adjust?

[matt2778]

what is a good shop for us csc peeps to take our bikes for a suspension adjust?

Dave Rose. STM Suspension.

[rybo]

Dave Rose. STM Suspension.

+1

STMsuspension.com

970-222-9597

Dave is an expert in this area, possesses a degree in mechanical engineering AND has done extensive studies in vehicle dynamics. There is no better person to set up your bike than him.

s

[veteran_80]

May be a dumb question but..... I just topped off my fuel. Should the sag setting be done with a full tank or may that be part of my problem?

[Bueller]

Spring rate is the problem

[veteran_80]

Cool. So a stiffer spring oughta fix me right up. Thx for all the insight. Much appreciated...

[Zach929rr]

Quit being a fatass.

[veteran_80]

Damn I'm just big boned! Lol

[Zach929rr]

I have no room to talk in the fatass department, which is half the reason I said it :)

[TransNone13]

May be a dumb question but..... I just topped off my fuel. Should the sag setting be done with a full tank or may that be part of my problem?


Curious about this too. Full tank right?

[Bueller]

210# on a ninja 250, now top that :lol:

As far as the fuel weight, don't get too anal about a few pounds, use the calculator I linked to and you can see the effect on different bike and or rider weights. You usually don't end up right on a specific rate so they have you round to the closest. The key is to get the rate that puts you into the range of your static and total sag, then you can adjust the preload to your specific needs. Sometimes you set it up according to the #'s but a specific problem may require more or less preload (small increments) to compensate. A tank filled or empty is not going to make any noticeable difference.

[veteran_80]

:up: Yeah checked out the calculator. Looks like i need 1kg springs. Learning more everyday. Thx for the help! Now time for a cheeseburger and a search for a DIY spring rate change thread...

[Bueller]

When I put your numbers in I think it came up with .95 for street, 1.0 for race.

[Zach929rr]

Changing the rear spring isn't too hard on most bikes. Honda made my 929 a real pain in the ass.

[OUTLAWD]

I'll look up the numbers of the springs I have when I get home...swapping them is no biggy...you will most likely have to cut down the spacer, but total job can be done in an afternoon.

[veteran_80]

I'll look up the numbers of the springs I have when I get home...swapping them is no biggy...you will most likely have to cut down the spacer, but total job can be done in an afternoon.

Man that would be great. Really appreciate it!

[veteran_80]

When I put your numbers in I think it came up with .95 for street, 1.0 for race.


Didnt catch that... Thx!

[OUTLAWD]

RT is spec-ing a FRSP S3825095 38.2x35x250 .95kg, which is what they spec for the 00-03 GSXR 750 and the 04-05 600. When I ordered them they sent 3827095, which is ~272mm long instead of 250mm, which is why you need to cut the spacer to make up the difference

[veteran_80]

Ok is that relatively easy to do? Really new to this stuff but deff wanna get my hands dirty

[OUTLAWD]

the spacer is just a piece of thin-walled steel tubing, cuts like butter with a hack saw. or you could make a a new spacer out of tubing of a similar size...

The first time I had them apart, it was good to have a second set of hands there to make sure I didn't make a mess of things, the factory service manual should have a section on spring replacement.

[veteran_80]

Alright I'm in.What do you want for them?