suspension setup

[dakh]

Stock '03 gixxer 600, stock susp. settings. 140lbs rider. Does it make any sens e to spend cash on pro suspension setup if all I want to do next season is a few track days?

I actually like to mess with gear myself, so if there's a DIY way to tune that actually works I'd be happy to spend time on that..

[CBRmania]

Have Barry @ GP Suspension (he is at most track days and every race weekend) make sure your intial set up (sag and etc.) is set correctly. If your just doing track days now and then there really is no reason to have the suspension re-done unless you cant get it into spec for your weight. At your weight you shouldnt have a problem though.

[Darkside]

even street susspension needs to rebuilt and with an 03 your talking about fluid that is 4 years old and not nearly as affective as it should be. Save yoruself the headache and have GP suspension rebuild them both for you. You will thank them later and your bike iwll handle much better.

[brianm]

The stock suspension is pretty good if you adjust it correctly. I ran an 02gsxr750 with stock suspension all the way into Advanced at nesba. There's no need to change unless you are too heavy for the springs, which you aren't, because sport bikes are designed for a 150 lb rider. Here are a few tricks to help set up your bike.

First, the rear shock off a 01-03 gsxr1000 has better internals than yours, and it's approximately 10mm longer which will increase your rear ride height just slightly. This is important to make your bike handle properly. Whether you keep your rear shock or upgrade to a 1000 shock you will still need to shim the back. You can shim the rear shock with washers at the top shock mount. You're looking for 10-12 mm over the stock 600 shock to get you in the ballpark, so if you use a 1000 shock you only need about 2mm. This adjustment will cause the bike to turn without excessive lean angle.

And second, you need to know what your bike is doing in order to adjust it. Put a zip tie around the front fork tube to show you how much travel you are using. Here's a tip sheet to adjust the bike yourself based on what the bike is doing and where it's doing it:

www.tonedeft.org/cycle/SuspensionGuide-01.jpg

Note: if you don't have the geometry set properly (i.e. the rear shimed) the compression and rebound adjustments will have much less effect.

Also if you are really interested in learning how to make your bike handle to it's potential here's a web site with a few vids about bike set up. www.onthethrottle.tv Click on one of the tool boxes to get the vids.

[Mr Sunshine]

Also if you are really interested in learning how to make your bike handle to it's potential here's a web site with a few vids about bike set up. www.onthethrottle.tv Click on one of the tool boxes to get the vids.

+1 sweet videos.

[justintime2]

How are the GP guys at Pacific when reading tires like that? Great videos!

[Mr Sunshine]

How are the GP guys at Pacific when reading tires like that? Great videos!

It just told me that last year I screwed around too much. Time to be the pig.

[dakh]

Yay, thank you all esp. brianm. I'm on it, armed with good advice now.

[dakh]

Oh yea, Luke who sold me his barely used two sets of DOT michelins was blabbering about the stock front tire being taller than the michelin. But for the life of me I couldn't understand why he insisted on making an opposite fork adjustment to what seemed logical to me. Most likely I just don't have my terminology right.

Would the slightly slimmer (I forgot by how much - 12 mm?) front tire make up for the 2mm that I'd need to shim on the rear shock?

[brianm]

No, a smaller front tire will not make up for the rear ride height adjustment. It will however decrease your trail slightly causing your bike to be more "twitchy". The tire profile can also have an effect which may increase or act against the "twitchy-ness".

The front trail and rear swing arm angle are the two most important geometry settings. Once those have been established the sag, compression and rebound setting of your bike can be turned. If the geometry is not right there is no compression or rebound setting that will help.

The front trail is adjusted by raising the fork tubes in the triple to drop the steering head. The further you raise the forks the more sensitive the bike is to control inputs. Adjust it slowly. Continue to increase the distance the fork tubes protrude from the triple until the bike begins to feel unstable in a straight line and then back off from that point a little. It should be about 1/4 to 3/8 of an inch.

The rear swing arm angle is set by adjusting the shock length with shims. This adjustment affects the bikes ability to turn through a corner. If the angle is too slight the bike will require extreme lean angle to turn, but if the angle is too steep the bike will be unstable under hard braking. The settings I gave you should put you right in the middle. Start with a 10mm shim or just switching shocks and increase until it becomes slightly unstable under braking then back off.

And just to make sure you have the right picture of trail... here's a page with a picture:
http://www.lortim.demon.co.uk/reviews/Foale/Geom.PDF

[Mr Sunshine]

The front trail is adjusted by raising the fork tubes in the triple to drop the steering head.

Please correct me if I am wrong but I thought that the trail is also modified when you shim the rear.

[brianm]

Yes, you are right Thatman. The Front trail is affected by the rear ride height, but to a much lesser extent. So much so, that you can consider them independent initially and only treat them as coupled in truly fine adjustments, much finer than we are talking about in this thread. It's just too confusing to deal with the full complexity of motorcycle handling right off.

If The shims are set at 10mm first, then the front trail adjusted there is little conflict. Certainly none that would be detected during a few track days.

[Ex Presidente]

Dakh -

What I was talking about was the difference in tire height between what tire was on the GSX-R vs. the tires height that I sold you. The difference in tire hright that I qouted was the difference between the Michelin and the Dunlop 209. I wasn't sure what the difference was between the tire that you had on the GSX-r vs the Michelin.
If there is a differnce than you need to divide the difference by 2, and then adjust the ride height accordingly.

Luke

[Mr Sunshine]

Yes, you are right Thatman. The Front trail is affected by the rear ride height, but to a much lesser extent. So much so, that you can consider them independent initially and only treat them as coupled in truly fine adjustments, much finer than we are talking about in this thread. It's just too confusing to deal with the full complexity of motorcycle handling right off.

If The shims are set at 10mm first, then the front trail adjusted there is little conflict. Certainly none that would be detected during a few track days.


Glad I am not crazy.

BTW: Brian I was one of the dudes at the show who confused you and your brother. :)