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Basic Suspension Tuning

4K views 4 replies 1 participant last post by  hankster 
#1 · (Edited)
Here are a few basics on RC car suspension. It will give you information on what the different items of the suspension are, what effect it has on handling and guidelines on where to start your setup if you do not have the manufacturer's recommendations.

Ride Height
[IMG-LEFT]http://www.hobbytalk.com/bbs1/attachment.php?attachmentid=12961[/IMG-LEFT] This refers to the clearance between the ground and the chassis, both at the front and the back of the vehicle. The proper ride height should be noted in the manufacturer's instructions.




[IMG-LEFT]http://www.hobbytalk.com/bbs1/attachment.php?attachmentid=12962[/IMG-LEFT] If you have an off-road vehicles, drop it from around 6"-12" above flat ground, making sure it drops flat. Check where the suspension arms come to rest. If you do not have the manufacturer's instructions, you want the rear "A" arms horizontal and the front "A" arms slightly higher where they attach to the vehicle. This will get you close to the recommended setup.






[IMG-LEFT]http://www.hobbytalk.com/bbs1/attachment.php?attachmentid=12963[/IMG-LEFT] You can adjust ride height by moving the spring adjusters on the shock (which are at the top of each shock spring) until the appropriate height is achieved after the drop test.

If you have an on-road vehicle, you should place it on a flat hard surface, compress the suspension a few times by pressing on the chassis and let it return to it's normal position. Set the ride height according to the manufacturer's suggestions. If you do not have the manufacturer's instructions available, you normally want to set it so the chassis will not rub the ground while being used and for the chassis to be perpendicular to the ground.



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#2 · (Edited)
Toe-In/Toe-Out
[IMG-LEFT]http://www.hobbytalk.com/bbs1/attachment.php?attachmentid=12964[/IMG-LEFT] This refers to the angle of the front tires when viewed from above when the suspension arms are level. If the fronts of the tires angle in, it is called "toe-in" and if the fronts of the tires angle out, it is called "toe-out. This is adjusted by turning the steering rods - the rods that run between the front hub and the steering linkage that is mounted on the chassis.

The linkage is normally turnbuckle type, which means you do not have to remove the rods to make adjustments in length. Turning the rod in one direction will lengthen, turning the rod the opposite direction will shorten. Normally a small amount of toe-in is used to make your vehicle track straight at high speed. Too much toe-in will make the vehicle difficult to turn as well as reduce the overall top speed because of tire scrub. Sometimes a small amount of toe-out will be used to help the steering. As a general rule use a small amount of toe-in.




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#3 · (Edited)
Camber
[IMG-LEFT]http://www.hobbytalk.com/bbs1/attachment.php?attachmentid=12966[/IMG-LEFT] Camber is the angle of the tops of the tires when viewed from the front. Negative camber is when the tops of the tires are angled towards the center of the vehicle. Positive camber is where the tops of the tires are angled away from the center of the vehicle. Positive camber is very rarely used, if ever.

A small amount of rear negative camber is helpful to increase traction in the rear. Negative camber at the front will increase stability. Camber adjustments can be made on most vehicles by turning the “camber rods," which are the upper links on the suspension. The camber links are also turnbuckle type. Lengthening the camber rod will add positive camber and shortening the camber rod will add negative camber.
 
#4 · (Edited)
Shocks
[IMG-LEFT]http://www.hobbytalk.com/bbs1/attachment.php?attachmentid=12967[/IMG-LEFT] Changes in shock oils, springs, and pre-load on the springs can dramatically change the way the vehicle handles. A thicker shock oil will make the vehicle turn faster but reduces overall traction and handling over bumpy surfaces. Thinner oil will increase traction at the expense of steering response and the car will tend to roll more. In general, shock oils between 20 and 40 weight will be best for off-road vehicles and 40 to 80 weight for on-road vehicles.

You should experiment some to see what oils work best for your vehicle, track and driving style. Shock springs affect the rate that the suspension rebounds from a bump. Optional springs are available from most manufacturers. Pre-load on the springs means that the springs are already compressed some so that the suspension will rebound faster. Sometimes you will want to pre-load one side when the track has turns all or mostly in one direction, for instance an oval track. Preload will also increase the ride height.

The information contained in this article is based on information from the DuraTrax MT Pro manual and is used with their permission. You can find DuraTrax at www.duratrax.com
 
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