Suspension Set Up For Track - Suzuki GSX-R Motorcycle Forums Gixxer.com

 
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post #1 of 11 (permalink) Old 05-26-2002, 07:22 PM Thread Starter
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Suspension Set Up For Track

Can someone tell me what is a good set up for my suspension for my 01 gixxer 600 for the track like summit point or VIR?
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post #2 of 11 (permalink) Old 05-26-2002, 09:28 PM
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Re: Suspension Set Up For Track

Quote:
Originally posted by atrain282:
Can someone tell me what is a good set up for my suspension for my 01 gixxer 600 for the track like summit point or VIR?
<font size="2" face="Verdana, Arial">heres an article on setting sag and such
..................
Suspension and Springs
What's all this ruckus about suspension these days? It seems everyone is clued in that suspension setup can be a key to riding fast and safely, but how do you do it? No matter what shock or fork you have, they all require proper adjustment to work to their maximum potential. Suspension tuning isn't rocket science, and if you follow step-by-step procedures you can make remarkable improvements in your bike's handling characteristics.
The first step to setting up any bike is to set the spring sag and determine if you have the correct-rate springs. Spring sag is the amount the springs compress between fully topped out and fully loaded with the rider on board in riding position. It is also referred to as static ride height or static sag. My company, Race Tech, (909/594-7755) has an advanced method of checking spring sag that I'll describe.

If you've ever measured sag before, you may have noticed that if you check it three or four times, you can get three or four times, you can get three or four different numbers without changed anything. We'll tell you why this occurs and how to handle it.

REAR END
Step 1: Extend the suspension completely by getting the wheel off the ground. It helps to have a few friends around. On bikes with sidestands the bike can usually be carefully rocked up on the stand to unload the suspension. Most race stands will not work because the suspension will still be loaded by resting on the swingarm rather than the wheel. Measure the distance from the axle vertically to some point on the chassis (metric figures are easiest and more precise; Figure 1). Mark this reference point because you'll need to refer to it again. This measurement is L1. If the measurement is not exactly vertical the sag numbers will be inaccurate (too low).

Step 2: Take the bike off the stand and put the rider on board in riding position. Have a third person balance the bike from the front. If accuracy is important to you, you must take friction of the linkage into account. This is where our procedure is different: We take two additional measurements. First, push down on the rear end about 25mm (1") and let it extend very slowly.

Where it stops, measure the distance between the axle and the mark on chassis again. If there were no drag in the linkage the bike would come up a little further. It's important that you do not bounce! This measurement is L2.

Step 3: Have your assistant lift up on the rear of the bike about 25mm and let it down very slowly. Where it stops, measure it. If there were no drag it would drop a little further. Remember, don't bounce! This measurement it L3.

Step 4: The spring sag is in the middle of these two measurements. In fact, if there were no drag in the linkage, L2 and L3 would be the same. To get the actual sag figure you find the midpoint by averaging the two numbers and subtracting them from the fully extended measurement L1: static spring sag = L1 -[(L2 + L3) / 2].

Step 5: Adjust the preload with whatever method applies to your bike. Spring collars are common, and some benefit from the use of special tools. In a pinch you can use a blunt chisel to unlock the collars and turn the main adjusting collar. If you have too much sag you need more preload; if you have too little sag you need less preload. For road race bikes, rear sag is typically 25 to 30mm. Street riders usually use 30 to 35mm. Bikes set up for the track are compromise when ridden on the street. The firmer settings commonly used on the tract are generally not recommended (or desirable) for road work.

You might notice the Sag Master measuring tool (available from Race Tech) in the pictures. It's a special tool made to assist you in measuring sag by allowing you to read sag directly without subtracting. It can also be used as a standard tape measure.

Measuring front-end sag is very similar to the rear. However, it' much more critical to take seal drag into account on the front end because it is more pronounced.

FRONT END
Step 1: Extend the fork completely and measure from the wiper (the dust seal atop the slider) to the bottom of the triple clamp (or lower fork casting on inverted forks; Figure 2). This measurement is L1.

Step 2: Take the bike off the sidestand, and put the rider on board in riding position. Get and assistant to balance the bike from the rear, then push down on the front end and let it extend very slowly.



Where it stops, measure the distance between the wiper and the bottom of the triple clamp again. Do not bounce. This measurement is L2.

Step 3: Lift up on the front end and let it drop very slowly. Where it stops, measure again. Don't bounce. This measurement is L3. Once again, L2 and L3 are different due to stiction or drag in the seals and bushings, which is particularly high for telescopic front ends.

Step 4: Just as with the front, halfway between L2 and L3 is where the sag would be with no drag or stiction. Therefore L2 and L3 must be averaged and subtracted from L1 to calculate true spring sag: static spring sag = L1 - [l2 + l3) / 2].

Step 5: To adjust sag use the preload adjusters, if available, or vary the length of the preload spaces inside the fork.

Street bikes run between 25 and 33 percent of their total travel, which equates to 30 to 35mm. Roadrace bikes usually run between 25 and 30mm.

This method of checking sag and taking stiction into account also allows you to check the drag of the linkage and seals. It follows that the greater the difference between the measurements (pushing down and pulling up), the worse the stiction. A good linkage (rear sag) has less than 3mm (0.12") difference, and a bad one has more than 10mm (0.39"). Good forks have less than 15mm difference, and we've seen forks with more than 50mm. (Gee, I wonder why they're harsh?)

It's important to stress that there is no magic number. If you like the feel of the bike with less or more sag than these guidelines, great. Your personal sag and front-to-rear sag bias will depend on chassis geometry, track or road conditions, tire selection and rider weight and riding preference.

Using different sag front and rear will have huge effect on steering characteristics. More sag on the front or less sag on the rear will make the bike turn more slowly. Increasing sag will also decrease bottoming resistance, though spring rate has a bigger effect than sag. Racers often use less sag to keep the bike clearance, and since roadraces work greater than we see on the street, they require a stiffer setup. Of course, setting spring sag is only first step of dialing in your suspension, so stay tuned for future articles on spring rates and damping.

-Paul Thede

--------------------------------------------------------------------------------

Magazine: Sport Rider
Issue : August 1995

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post #3 of 11 (permalink) Old 05-26-2002, 09:30 PM
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Re: Suspension Set Up For Track

Is there something about the suspension the way it is now, that you don't like..? there's more info. needed if your answer is yes..your weight, how hard you ride. For riders over 175lbs..most gixxers are under sprung..There's really no magic set up..try looking at these 2 websites that deal with suspension..see if that doesn't help.. [img]images/icons/grin.gif[/img]

www.circuit1.com
http://members.ozemail.com.au/~kenru...sion/setup.htm
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post #4 of 11 (permalink) Old 05-27-2002, 03:51 PM Thread Starter
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Re: Suspension Set Up For Track

thanks for the help.
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post #5 of 11 (permalink) Old 10-28-2018, 10:18 PM
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Re: Suspension Set Up For Track

What are people doing for ride height front and rear? My bike had lowering links which I am guessing need to be swapped out for stock to bring the height back up but curious what height people normally run on the track?
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post #6 of 11 (permalink) Old 10-29-2018, 02:04 AM
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Sixteen years and 5 months, that's gotta be some sort of record.
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post #7 of 11 (permalink) Old 10-29-2018, 11:57 AM
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Re: Suspension Set Up For Track

Quote:
Originally Posted by SethGixxer View Post
What are people doing for ride height front and rear? My bike had lowering links which I am guessing need to be swapped out for stock to bring the height back up but curious what height people normally run on the track?
You may have resurrected an old thread, but these things are always applicable. You definitely do not want the bike lowered or you will be dragging all sorts of hard parts and the steering will be heavy. I even run a 1/4" spacer in the rear, which raises the ride height around 5/8" to quicken steering.
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post #8 of 11 (permalink) Old 10-29-2018, 02:57 PM
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Re: Suspension Set Up For Track

MadViking - really appreciate the response on this, that was my guess but I will be new to the track set up (in the past mostly street riding) so wanted to check with those with more experience. The previous owner lowered the front and rear so I am going to get the stock dog bones to put the rear back and stock height. What's a good setting for the front height (measurement top of mounting bracket to the top of the shock tube). I read the stock setting is 5mm; my bike is currently like 1in down. What height are you using for the front?
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post #9 of 11 (permalink) Old 10-29-2018, 03:18 PM
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Re: Suspension Set Up For Track

Quote:
Originally Posted by SethGixxer View Post
MadViking - really appreciate the response on this, that was my guess but I will be new to the track set up (in the past mostly street riding) so wanted to check with those with more experience. The previous owner lowered the front and rear so I am going to get the stock dog bones to put the rear back and stock height. What's a good setting for the front height (measurement top of mounting bracket to the top of the shock tube). I read the stock setting is 5mm; my bike is currently like 1in down. What height are you using for the front?
Use the stock settings in the manual as a baseline, then adjust from there. Or, bring it to a suspension guy.
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post #10 of 11 (permalink) Old 10-29-2018, 04:03 PM
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Re: Suspension Set Up For Track

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Originally Posted by Just_Nick View Post
Use the stock settings in the manual as a baseline, then adjust from there. Or, bring it to a suspension guy.
Agreed. I always start off with what is called for in the manual. As stated above, sag needs to be set first. One thing I was always told and may be missing from the instructions on setting sag is to begin with you want to completely back out damping in both directions. Maybe that is a moot point since they suggest averaging the dimensions to account for drag/friction/striction. But if you leave the damping settings stiff, it will affect your spring movement.

I am probably +5 in the front over what is called for on my track bike. I like a quicker turning bike, but to some people that may be too twitchy.

There are typically suspension gurus at most track events and you can have them work with you for a pretty modest fee ($60?). They will set a baseline based on your class, weight, etc. and then consult with you and look at your tire wear.
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post #11 of 11 (permalink) Old 10-29-2018, 09:18 PM
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Re: Suspension Set Up For Track

Quote:
Originally Posted by MadViking View Post
Agreed. I always start off with what is called for in the manual. As stated above, sag needs to be set first. One thing I was always told and may be missing from the instructions on setting sag is to begin with you want to completely back out damping in both directions. Maybe that is a moot point since they suggest averaging the dimensions to account for drag/friction/striction. But if you leave the damping settings stiff, it will affect your spring movement.

I am probably +5 in the front over what is called for on my track bike. I like a quicker turning bike, but to some people that may be too twitchy.

There are typically suspension gurus at most track events and you can have them work with you for a pretty modest fee ($60?). They will set a baseline based on your class, weight, etc. and then consult with you and look at your tire wear.
Good tips, and this really helps. Thanks guys!!
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