Suspension Setup Info

LONG TRAVEL versus STANDARD TRAVEL:

This question has been asked so many times that I feel a need to explain - which of course opens the flood gates. If this is too lengthy, I apologize, not easy to explain quickly.

There are two different issues that can be affected
First Long Travel and increased wheel travel can be two different things.

Increase wheel travel (Extra Travel, extended travel) is any modification that increase the wheel travel over stock travel. For example the stock 05 TRX450R wheel travel is roughly 9 5/8". This is the amount of wheel movement of both compression and extension which are dictated by the max extended length of the shock and minimum compressed length of the shock (including the bottom out bumper fully compressed). If we remove the shock, then measure wheel travel then the limiting factor of wheel travel become the BIND points of the upper and lower ball joint, mechanical interference with tie-rods, etc. or bind of the tie-rod end itself, this is all obviously BAD NEWS. Given this, we want the SHOCK to control the maximum travel so we don't have a ball joint failure etc.. This would be a pretty crappy day especially rolling through the woods in any gear as the trees never seem to move out of my way, go figure. I'm sure the surgeons don't mind, but I sure do.

LONG TRAVEL is increasing SHOCK travel which will allow or not allow any increase of wheel travel. This is accomplished by the A-ARM manufacture moving the lower shock mount from its stock location and relocating it out towards the spindle, which will require a longer shock. This does give the ability to increase wheel travel, but we can still be limited by the BIND POINTS of the ball joints. This is why the angle of ball joint mounting on the a-arm or type of ball joint is so important. This is also why each a-arm manufacture has their OWN specs on shock length. Again the SHOCK should be the limiting factor of compression and extension length. I can elaborate alittle more on this with a future post if you have specific questions. This is where we get into motion ratio - which is the amount of wheel travel compared to the amount of shock travel. If wheel travel is 10" and shock travel is 5", this would give us a motion ratio of 2 : 1. This also points out the mechanical advantage or leverage ratio. So the long story short, can std travel do the same as long travel and the answer is YES. the mechanical ratio can be duplicated from a long travel to std travel and vice versa. A longer shock travel does move more oil and gives more control of the shock tuner. The cross over position is easier to obtain but still can be done with std travel. Long travel will typically lead to aftermarket shocks and there lies another advantage on a few fronts. However, when someone is asking is long travel better, the answer is it can be if wheel travel is gained, can also be NO if there is no wheel travel gain. Keep in mind, that many aftermarket shocks have their inherent advantages in part design, adjustment range, piston oil flow etc..

Do the a-arms change the ride height? Two items affect this, which is width and lower shock location. If the springs on the shock are not changed and simply change the a-arm width, then YES it will put more torque on the spring stack and will sag more lowering the ride height. However, this is not the way to develop spring rate!

Should I get Long travel or Std travel? I can't answer this for you, only give you the information to make your own informed decision. Biggest factor is obviously cost. As stated above the are advantages to long travel versus std travel.

Can std travel feel the same as long travel if wheel travel is the same? Yes, you can duplicate the SAME spring rates on a standard travel as a long travel, but the crossover position must be more precise.

Lets move on to LT REAR suspension.

If the same question is asked for the rear if LT is an advantage, then that is another discussion. I have no issue with increasing rear wheel travel but there are three things that i look for in a linkage and shock combination; amount of progression, ride height and down travel. Increasing the up travel or rear shock fully extended can be a detriment. There are way more ill affects on have a long extension length. This can be very unnerving on a down hill especially try touching the front brakes...enjoy or you feel like your falling over the front on corner entry. Long travel rear requires an aftermarket shock and will typically be a dual rate. Long travel links have less progression and allows the shock builder to build the spring rates to become the progression of the rear suspension versus a mechanical and therefore FIXED progression. If the progression is controlled by the spring stack, then we can adjust and fine tune the progression, the crossover position and spring stack instead of being mechanically stuck to the progression of the link. This decision can also come down to cost. I don't want to make a stand on a particular link versus the other here, but obviously based on the items I look for in a link, this leads me to work with some specific links and not others. There are numerous links on the market and truthfully I haven't tested all links, so just because I don't offer them doesn't mean I like or dislike them.

Will post more if you like and if I can get the time, but by all means I am not implying that I know everything and I make it appoint to always learn, test, try new tricks, and basically try and screw with every portion of suspension to see if we can find an advantage, which means i'm not afraid to answer I DON'T KNOW, but lets see if we can figure it out!

Nick @ JET

JET Suggested Settings

Before you ride, please do these four items in order. The JET conversion kit will allow the suspension to work and provide much more down travel than stock. WARNING! You will break an air-box if you don't raise the air-box! Once the air box is moved, the next point to contact will be the rear brake caliper on the tool compartment on the rear plastic.

Put air the tires (Rear 5 to 6.5 lbs & Front 5.5 to 7lbs) before you tackle the following settings.

Setting ride height.

1. First set ride height. The following is a suggested starting point, if you talk to 5 different tuners, you may wind up with 5 different answers. Of course I have my own opinion as well, but I will tell you, if you are trying to get this on the money, then you are spliting hairs. This isn't an Indy car on a 2 mile flat track with ride height +/- .030", come on now. Plus or minus 1/8" is resonable (however, I don't want to be + 1/8" off in the front and - 1/8" in the rear). Some things to keep in mind, the lower your center of gravity, better cornering ability and reduce amount of body english. The higher, better side bite and better bottoming resistance for rough tracks.

Cross Country - the tree huggers:

Ride heights for XC can be between 6 3/4" to 8 1/4" in the rear with between 1/4" and 1/2" of rake (front higher than the rear). I prefer to start with the rear at 7 1/4" in rear unless rough track, then you can raise to 7 1/2 ~ 7 3/4". Front ideally will be 3/8" higher.

Motocross - the aerial artists:

Ride heights for MX can be between 7 1/4" to 8 1/4" in the rear with between 1/4" and 1/2" of rake (front higher than the rear). I prefer to start with the rear at 7 1/2" in rear. Front ideally will be 3/8" higher.

Desert - the sand people:

Ride heights for Desert can be between 7 3/4" to 8 3/4" in the rear with between 3/8" and 5/8" of rake (front higher than the rear). I prefer to start with the rear at 7 3/4" in rear.

TT - the ground pounders:

Ride heights for TT can be between 5 1/2" to 6" in the rear with between 1/4" and 3/8" of rake (front higher than the rear). I prefer to start with the rear at 5 1/2" in rear. Front ideally will be 1/4" higher as you start to increase your rake, the front will lose grip and steering suffers, especially in the center of the corner.

Camber - (Not adjustable with most stock a-arms unless you have our JET camber modified upper a-arm). First take a couple of tie-downs and hook from the handlebar grips to the rear plastic or grab bar and measure to center the handlebar. Once this is complete, you don't have to worry about knocking the tires out of place. Now take an L square and butt up against the front tires and measure the gap at the top (pay attention to the raised lettering or knobbies, this can really mess you up). I don't worry about someone sitting on the quad to adjust camber or toe since it is a very small change unless your stem and rod end setup creates a lot of bump steer. On my quad, it only changes by less than 1/16". Now adjust the ball joint in or out until you reach 3/8" ~ 1/2" and make sure both sides are equal. Also, take special not to rotate the ball joint out of place when tightening down or you could break a ball joint. Make sure the top of the ball joint is parrallel to the top of the spindle or SNAP, when you least expect it!

Always set camber first because this WILL change toe, if at some point camber is adjusted, you must go back and re-adjust toe!

Camber and toe

Camber

You can see there is enough air pressure.

Matt Sillery with a camber and roll issue, stock 450R a-arms

The purpose of camber is for the tire to provide maximum foot print and therefore GRIP in the center of the corner. During cornering, suspension components flex and the tire's sidewall rolls. This results in a tire that rolls over on it’s side losing traction. Leaning the top of the tire in towards the frame (or “negative camber”) compensates for this “tire roll”. Make sure that your not comensating low tire pressure with camber. If the side wall of the tire is rolling over, then compensate with increased tire pressure or less side wall (shorter tire, like 21" fronts versus 22"). Check out the LF tire of #45 - camber issue. You can see the difference in the #705 which is low tire pressure AND camber issue.
Amount of change: set it and don’t mess with it.
Starting point: 3/8" ~ 5/8” -- negative camber

Amount of handling change you will feel: medium
Importance level (should I mess with it or not?): medium
• Lower tire pressures will require more camber
• See “TIRE” section (below) first, and run the correct tire and tire pressure.

You can see the tire rolling over on entry. This tire had 5lbs of pressure!

Justin Lewicki with air pressure and camber issue

The end result is you want the front tire to be straight up and down through the corner to provide the best turning traction. Parts bend and tires flex under load; there is play in rod ends, ball joints, etc. All this causes the tire to roll up on its side under cornering which decreases the foot print and kills steering traction. Check out an Indy car, Formula one or NASCAR. At times, they are running as much as 10°.
1.    However, make sure the air pressure is correct before leaning the tire in further.
2.    Always set camber before setting toe and obviously after changing camber, toe must be reset.
3.    A good starting point is ½” from the bottom of the tire to the top of the tire. This is easiest measured with an L square set up against the outside of the tire.
4.    The more camber the more difficult it is to steer.
5.    Too much camber will cause a "darty" feel in the bumps.
6.    A great way to check is to have someone take a picture in the center of the corner at speed and look at the outside tire.
7.    Oval track racers will run negative camber on the outside tire and positive camber on the inside tire. In this instance both tires should be straight up in the center of the corner as listed above, providing maximum traction.

With oval track racers, correct camber can be fine-tuned by checking tire temperature across the tread. TT Racers will be determined by the turns in the track.

Negative Camber

Tires

Obviously, the issue of tire choice is extremely important. Track conditions are critical in that choice. Many racers have a few sets of rear tires mounted up and they will make the selection based on the track and conditions. A tire's #1 affect is to provide traction – pretty obvious I know, but there are several other items that tires affect, which if not chosen correctly, will cause other parts of the suspension to suffer. You may find you are adjusting your suspension and not realize that you are band-aiding how the vehicle feels because of a certain choice of tire, wrong pressure, or wrong size. A secondary tire affect is to provide a lack of traction.

Too tall a tire will cause a high ride height and poor cornering. Example: an ATV racer was running too tall of a tire. Not realizing this, he compensated by reducing his spring preload to lower his ride height. This made it corner better, but now his race sag was off and the quad was too soft to take the bumps. How many springs did he buy in order to run those 22” rear tires? After several spring purchases and handling problems, he was finally convinced to run 20” rear tires (XC).

If you are not sure what tire to use, at least start with a tire that you know works. Do you mean run what the pros are running? Yes, there is a reason they are running those tires. If people are winning on them, they work. Use them!

Once you have chosen that tire, find a tire pressure that works. Take a good ride on a tacky track and have someone take a picture of you in the middle of the corner on the gas...and look at the rear tire.

Is the tire rolled over too much?
Does it look like it is biting good?
Is the rim about to hit the ground?
Is the tire still straight up and down?
Are the tires spinning?

Wesley Fruits -- Indiana GNCC

Hmm...the track is even dusty. Do you think the quad is pushing in the center of the corner?

Some points to consider:

•    Correct sizing
•    Correct rim width
•    Sidewall height (8”, 9” or 10” diameter)
•    Using tire balls
•    Air pressure
•    Whether or not to groove

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