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Author Topic: Shock Setup for mx or xc  (Read 81 times)

Offline rablack21

Shock Setup for mx or xc
« on: April 11, 2018, 03:28:18 PM »
This information came from GT Thunder. Thought I would save it and pass it on. I know it works for mx. I think it works for xc as well but not certain.


Note: The information below will work on any ATV suspension that has the correct extended shock length with the correct wheel travel. Do not ride your ATV till it has been setup correctly!!!

 

Please take the time to read through this shock setup sheet and follow instructions to ensure the best possible performance.

 

1.        Carefully install your suspension components.

2.        Measure your race ride height in the rear.

3.        Set your race ride height in the front.

4.        Measure your rear race sag.

5.        Verify that you have the correct crossover gap in the front.

6.        Measure your front main spring length at race ride height.

 

1.       Carefully install your suspension components.

 Please have a qualified and knowledgeable technician install your components checking for all the correct clearances and that all your suspension components are moving freely.

 

 

2.       Measure your race ride height in the rear.

 Make sure your quad is race ready with tire pressures set and anything else that will affect the height. Then stand on the foot pegs and have someone measure to the bottom of the frame in the foot peg area.

 

3.       Set your race ride height in the front.

Now measure your front ride height 22 inches forward of the foot peg area and adjust the front ride height up and down by adjusting the preload on the front shocks till the front is 0 - 1/4 inch higher in the front for most applications. Feel free to contact us for exact settings for your quad.

 

4.       Measure your race sag.

 Place your quad on a stand that is tall enough so that your wheels are suspended off the ground and the rear suspension is fully extended. Now make a mark on the subframe or other suitable place straight up from the axle. Measure from the axle up to the mark. Next set the quad on the ground and stand on the foot pegs and have someone measure from the axle to the mark again. The difference in the 2 measurements is your race sag. We run 4-5 inches depending on the application and the rider. You can make small adjustments to this by turning your preload nut 2-3 turns and you can make large adjustments by install stiffer or softer springs. For best performance you need to have between 1 and 3 turn of preload. NEVER RUN MORE THEN 5 TURNS OF PRELOAD.

 



5.       Verify that you have the correct crossover gap in the front.

 Your crossover gap is the distance between the crossover and what ever it contacts as you move further down in the travel. The gap needs to be checked at race ride height. It needs to be 3/16  - inch. The smaller the gap the stiffer the ride and the better the cornering. The larger the gap the plusher the ride. The crossover gap can be adjusted by adding or changing crossover spacers.

 

6.       Measure your front main spring length at race ride height.

 Measure the front main spring length at race ride height. On a dual spring setup – 7 – 7 1/8 inches is a good balance of plush ride and good cornering. If the length is less you will need to install stiffer front springs. If it is longer then that you need to install softer front springs.

 

Notes:

1.        Feel free to adjust the compression adjusters to your liking but do not run them fully closed as it will cause a harsh sensation and can damage chassis components due to pressure spikes.

2.        Shock covers on the front shocks are needed to avoid main seal damage, shaft damage, and crossover sticking.
« Last Edit: April 11, 2018, 03:31:02 PM by rablack21 »

Offline rablack21

Re: Shock Setup for mx or xc
« Reply #1 on: April 11, 2018, 03:49:02 PM »
First lets take a look at each one and how it effects you ride quality.

 

1. If you have too little up travel of the front wheels - your quad will hit the bumper (on the shock) to early and you will need to compensate by running a much stiffer setup due to the lack of front wheel travel.

If you have too much up travel of the front wheels - your frame can hit the ground.

If you have too little up travel of the rear wheels - your quad will hit the bumper early and kick the back end up very easily.

If you have too much up travel of the rear wheels - your frame will hit the ground.

 

2. If you have too much down travel of the front wheels - your quad will roll to much in the corners - the front end will come up to high in the front when accelerating giving you poor steering control of you quad since it is transferring too much weight to the rear tires.

If you have too little down travel of the front wheels - you will need to compensate for the lack of travel with with a very stiff front end to keep from bottoming - the front end will then dance over the rough terrain instead of tracking the ground nicely.

If you have too much down travel of the rear wheels - your quad will roll on down hill corners as the rear comes up to high and transfers to much weight to the front - the back end will also swap side to side when braking in rough terrain as the back comes up to high and will not track the ground nicely.

If you have too little down travel of the rear wheels - you will need to compensate with excessive spring preload and a stiff shock to keep from bottoming due to the lack of wheel travel.

 

3. The front spring curve can be built with various combinations of springs, spacers, and crossovers. A few things to look for in a good spring curve -  lift up on the front of the quad till the shocks fully extend - now push down on the front of the quad - it should be a nice smooth transition thru the down travel with no distinct changes as the springs crossover into the next spring - push down on the front of the quad several times and then let go - the upper spring should be supporting the weight of the quad without hitting the crossover point - now have someone the same weight as the rider stand on the pegs and do this again - the extra weight will let you push the front end down further into the travel so you can feel more of the spring curve - everything should still be smooth - push down several times and let go again - the top spring should now be 1/8 - 3/8 inches close to hitting the crossover point - again the top spring should be able to support the quad and the rider.

The combination of the center spring, if there is one and the main spring is the next thing to check - with the rider on the pegs - push down on the front bumper until you have most of you weight on the bumper (150#) - now look to see how far the body or seal head is from hitting the bumper - bounce down on it gently and then recheck - you should have a distance of 3/4 to 1 inch before it contacts the bumper when you have about 150# on the bumper and the rider standing on the pegs - you should also be able to gently bounce down and almost hit the bumper without hitting any harsh spots in the spring curve - if there is harsh spots in the spring curve.

If you spring curve is to progressive - it will be to soft at the top of the travel, to stiff at the bottom of the travel, and will give you a harsh ride. If the spring curve has to little progression - it will act like a single spring and bottom easily on any hard hits - it will also roll a lot in the corners.

 

 

FAQ#1: What is a crossover??

A: The crossover is a part that makes contact with another part and transfers the remaining increase in pressure to the main spring. That can be different looking parts on different shocks. The first photo is of the crossover that is used one one stock shock conversion. The second photo shows how the crossover fits on the shock. The third photo shows the shock and crossover with the spring installed. The fourth photo shows the shock compressed to the point that the crossover is 3/16 inch from hitting or crossing over. The last photo shows the shock compressed to the point where the crossover contacts the collar above it and all the remaining pressure is going into the main spring.

PICT0034.JPG (149421 bytes)PICT0035.JPG (142545 bytes)PICT0036.JPG (165652 bytes)PICT0039.JPG (170221 bytes)PICT0040.JPG (182693 bytes)

 

FAQ#2: What should my ride height be??

A: That is a loaded question that does not take into account how your shocks are built. If the compressed and extended lengths of your shock are correct for you quad, application, and components - then your race sag should be around 4.5 inches for XC, 3 inches for dunes, 3.5 inches for TT, and 5 inches for MX - depending on the track or terrain you are riding on. If you setup your quad by ride height alone - you can take a perfectly good set of shocks and jack up the quad so bad it will never handle right. Measuring ride height is essential as a reference especially when calling in for technical support.

 

FAQ#3: How do I measure my race sag??

A: Have someone lift up on the front and back of your quad till all the suspension is stretched out to its max. Then measure the distance that the bottom of you frame is from the ground, both front and back. That should be from 11.5 to 12.5 inches on an XC quad, 12 to 13 inches on a MX quad, and 7.5- 8 inches on a TT quad. Then have the rider stand on the pegs and measure the frame to ground measurement again. The difference of those 2 measurements is your race sag.

 

FAQ#4: What should my distance to crossover be??

A: First off the race sag needs to be set where you be be riding it before you worry about the crossover distance. Adjusting the race sag will effect the crossover distance. Be sure to measure your distance to crossover with the rider standing on the pegs. The crossover distance should then be 1/8 to 3/8 inch. The lower the number  - the better it will corner and the stiffer the shock will feel - a longer distance will give you a plusher ride.

 

FAQ#5: What do I do if my quad rolls to much in the corners??

A: First make sure you race sag is set correctly, then verify that the crossover distance is within range. You can then either install a longer crossover or run the next stiffer main spring.

 

FAQ#5: How much progression do I want in my front spring curve??

A: Your front spring curve must work in conjunction with the shock valving to provide the plushest ride possible without bottoming harshly. If the spring curve and valving combination is to stiff - you will not use all your travel and will have a harsh ride quality. You want the combination of valving and spring curve to allow you to use all your travel yet still provide good cornering and bottoming resistance. It is a balancing act and what works for you may be too soft or stiff for someone else.