1stGenCRXer
11-08-2010, 05:15 PM
Alright, we've gotten some more of you guys hooked on the RC :crack: habit, and I've been getting some of the same questions. So here's a how-to, and then we can get into special requests and specific questions.
I won't be covering shock building at this time, but I promise to take some pictures for a future how-to the next time I need to rebuild some of my shocks.
On to the info!
For this thread, I'll be using a Nitro Sportwerks Mayhem 1/8 Buggy, but the "basics" I'll cover here apply to any off-road vehicle.
http://www.lazermotorsports.com/Photos/RadioCPics/Suspension/DSC_1281.jpg
Here's the front and rear suspension when I very gently set the vehicle on the table. This is the highest the suspension will ever set with the tires touching the ground, and doesn't mean a thing. You'll never see the ride height this high naturally, nor should you try to get the suspension to ride at this level.
http://www.lazermotorsports.com/Photos/RadioCPics/Suspension/DSC_1282.jpg
http://www.lazermotorsports.com/Photos/RadioCPics/Suspension/DSC_1283.jpg
To get a true indication of "settled" ride height, push on the center of the chassis until the chassis bottoms out on the setup surface.
http://www.lazermotorsports.com/Photos/RadioCPics/Suspension/DSC_1284.jpg
If this is difficult at all, STOP! There is likely something else going on that needs to be looked at, which I'll cover in a bit.
If the chassis will bottom out fairly "normally" release the chassis and let it "pop" back up to it's normal "settled" ride height.
http://www.lazermotorsports.com/Photos/RadioCPics/Suspension/DSC_1285.jpg
Now we can see what the true ride height is. Since this buggy is already set up and handles well, these pictures are also what a good final or starting result should look like.
A lot of times you'll hear people refer to off-road ride heights in terms of lower suspension arm or drive shaft angles. This is close to "arms level" on the rear suspension. On this particular buggy, the drive shafts follows almost the same angle, so it could also be considered "bones level".
http://www.lazermotorsports.com/Photos/RadioCPics/Suspension/DSC_1286.jpg
http://www.lazermotorsports.com/Photos/RadioCPics/Suspension/DSC_1287.jpg
When in doubt, on any chassis, arms level in the rear is a good starting place.
On the front, you usually want the ride height a little higher, to help transfer weight to the rear on acceleration, and limit some weight transfer to the front so the vehicle doesn't spin out under braking as much. This is arms "above level" since the chassis pivot point is higher than at the wheel hub.
http://www.lazermotorsports.com/Photos/RadioCPics/Suspension/DSC_1288.jpg
http://www.lazermotorsports.com/Photos/RadioCPics/Suspension/DSC_1289.jpg
Once you have a ride height you're happy with, compress the front and rear, and make sure the springs don't compress 100%. If they do, that puts you in a situation known as coil bind, which pushes the effective spring rate to infinite, and WILL BREAK PARTS. If you find yourself in this situation, you'll have to back off the spring preload, and settle for a slightly lower ride height, or go to a higher spring rate to get the ride height you want, without getting coil bind at full compression.
http://www.lazermotorsports.com/Photos/RadioCPics/Suspension/DSC_1290.jpg
http://www.lazermotorsports.com/Photos/RadioCPics/Suspension/DSC_1291.jpg
If that checks out, make sure the suspension arms drop to even levels left/right when the suspension is unloaded.
http://www.lazermotorsports.com/Photos/RadioCPics/Suspension/DSC_1292.jpg
http://www.lazermotorsports.com/Photos/RadioCPics/Suspension/DSC_1293.jpg
If the arms don't come down to the same levels at full extension, some chassis have downstop screws you can adjust so that they do. This is more important for tuning a vehicle for racing than bashing, but everything adds up.
Here's the downstop screw on the rear suspension.
http://www.lazermotorsports.com/Photos/RadioCPics/Suspension/DSC_1308.jpg
http://www.lazermotorsports.com/Photos/RadioCPics/Suspension/DSC_1307.jpg
Which rests on a special place on the chassis to limit down travel of the suspension arms.
http://www.lazermotorsports.com/Photos/RadioCPics/Suspension/DSC_1309.jpg
Then make sure the spring preload is even left/right for the front and rear.
http://www.lazermotorsports.com/Photos/RadioCPics/Suspension/DSC_1294.jpg
http://www.lazermotorsports.com/Photos/RadioCPics/Suspension/DSC_1295.jpg
After that is Camber. You don't need anything fancy [unless you're racing] to measure camber, but you should try to get them even. You generally will run more camber in the rear than the front on off-road vehicles to gain side-bite.
http://www.lazermotorsports.com/Photos/RadioCPics/Suspension/DSC_1296.jpg
http://www.lazermotorsports.com/Photos/RadioCPics/Suspension/DSC_1297.jpg
http://www.lazermotorsports.com/Photos/RadioCPics/Suspension/DSC_1298.jpg
http://www.lazermotorsports.com/Photos/RadioCPics/Suspension/DSC_1299.jpg
Toe comes next. Here's where it can get a little different between 2wd platforms and 4wd platforms.
On 4wd, you generally run some toe-out in the front, where on 2wd, you'll want close to zero toe [wheels parallel].
http://www.lazermotorsports.com/Photos/RadioCPics/Suspension/DSC_1301.jpg
Both 2wd and 4wd are going to have a significant amount of rear toe-in for stability.
http://www.lazermotorsports.com/Photos/RadioCPics/Suspension/DSC_1302.jpg
Caster can be adjusted by moving shims on most 4wd vehicles. More shims to the rear adds caster by moving the upper suspension arms to the rear. This adds mid-corner and corner exit steering.
http://www.lazermotorsports.com/Photos/RadioCPics/Suspension/DSC_1303.jpg
2wd vehicles usually run a LOT of caster, built into the front suspension arm kick-up, as well as the caster blocks, this helps calm the steering on corner entry, and helps the suspension better cope with bumps on the unpowered wheels.
A 4wd pivot ball front suspension allows for quick adjustments of camber, track width and caster, without replacing parts. The downside is there are more parts involved in the design, so they can develop slop quickly which would require more maintenance.
http://www.lazermotorsports.com/Photos/RadioCPics/Suspension/DSC_1305.jpg
The rear suspension on this buggy shows the basic concept of a caster hub design, where the camber is controlled by an adjustable turnbuckle at the top to control camber. Since this is on rear suspension, toe is fixed by the hub angle and rear arm angle. Changing rear toe requires the hub or inner pivot mounts to be changed.
http://www.lazermotorsports.com/Photos/RadioCPics/Suspension/DSC_1306.jpg
That's all I have for now, if there are some more specific questions, I can take more photos and give more in-depth explanations. :)
I won't be covering shock building at this time, but I promise to take some pictures for a future how-to the next time I need to rebuild some of my shocks.
On to the info!
For this thread, I'll be using a Nitro Sportwerks Mayhem 1/8 Buggy, but the "basics" I'll cover here apply to any off-road vehicle.
http://www.lazermotorsports.com/Photos/RadioCPics/Suspension/DSC_1281.jpg
Here's the front and rear suspension when I very gently set the vehicle on the table. This is the highest the suspension will ever set with the tires touching the ground, and doesn't mean a thing. You'll never see the ride height this high naturally, nor should you try to get the suspension to ride at this level.
http://www.lazermotorsports.com/Photos/RadioCPics/Suspension/DSC_1282.jpg
http://www.lazermotorsports.com/Photos/RadioCPics/Suspension/DSC_1283.jpg
To get a true indication of "settled" ride height, push on the center of the chassis until the chassis bottoms out on the setup surface.
http://www.lazermotorsports.com/Photos/RadioCPics/Suspension/DSC_1284.jpg
If this is difficult at all, STOP! There is likely something else going on that needs to be looked at, which I'll cover in a bit.
If the chassis will bottom out fairly "normally" release the chassis and let it "pop" back up to it's normal "settled" ride height.
http://www.lazermotorsports.com/Photos/RadioCPics/Suspension/DSC_1285.jpg
Now we can see what the true ride height is. Since this buggy is already set up and handles well, these pictures are also what a good final or starting result should look like.
A lot of times you'll hear people refer to off-road ride heights in terms of lower suspension arm or drive shaft angles. This is close to "arms level" on the rear suspension. On this particular buggy, the drive shafts follows almost the same angle, so it could also be considered "bones level".
http://www.lazermotorsports.com/Photos/RadioCPics/Suspension/DSC_1286.jpg
http://www.lazermotorsports.com/Photos/RadioCPics/Suspension/DSC_1287.jpg
When in doubt, on any chassis, arms level in the rear is a good starting place.
On the front, you usually want the ride height a little higher, to help transfer weight to the rear on acceleration, and limit some weight transfer to the front so the vehicle doesn't spin out under braking as much. This is arms "above level" since the chassis pivot point is higher than at the wheel hub.
http://www.lazermotorsports.com/Photos/RadioCPics/Suspension/DSC_1288.jpg
http://www.lazermotorsports.com/Photos/RadioCPics/Suspension/DSC_1289.jpg
Once you have a ride height you're happy with, compress the front and rear, and make sure the springs don't compress 100%. If they do, that puts you in a situation known as coil bind, which pushes the effective spring rate to infinite, and WILL BREAK PARTS. If you find yourself in this situation, you'll have to back off the spring preload, and settle for a slightly lower ride height, or go to a higher spring rate to get the ride height you want, without getting coil bind at full compression.
http://www.lazermotorsports.com/Photos/RadioCPics/Suspension/DSC_1290.jpg
http://www.lazermotorsports.com/Photos/RadioCPics/Suspension/DSC_1291.jpg
If that checks out, make sure the suspension arms drop to even levels left/right when the suspension is unloaded.
http://www.lazermotorsports.com/Photos/RadioCPics/Suspension/DSC_1292.jpg
http://www.lazermotorsports.com/Photos/RadioCPics/Suspension/DSC_1293.jpg
If the arms don't come down to the same levels at full extension, some chassis have downstop screws you can adjust so that they do. This is more important for tuning a vehicle for racing than bashing, but everything adds up.
Here's the downstop screw on the rear suspension.
http://www.lazermotorsports.com/Photos/RadioCPics/Suspension/DSC_1308.jpg
http://www.lazermotorsports.com/Photos/RadioCPics/Suspension/DSC_1307.jpg
Which rests on a special place on the chassis to limit down travel of the suspension arms.
http://www.lazermotorsports.com/Photos/RadioCPics/Suspension/DSC_1309.jpg
Then make sure the spring preload is even left/right for the front and rear.
http://www.lazermotorsports.com/Photos/RadioCPics/Suspension/DSC_1294.jpg
http://www.lazermotorsports.com/Photos/RadioCPics/Suspension/DSC_1295.jpg
After that is Camber. You don't need anything fancy [unless you're racing] to measure camber, but you should try to get them even. You generally will run more camber in the rear than the front on off-road vehicles to gain side-bite.
http://www.lazermotorsports.com/Photos/RadioCPics/Suspension/DSC_1296.jpg
http://www.lazermotorsports.com/Photos/RadioCPics/Suspension/DSC_1297.jpg
http://www.lazermotorsports.com/Photos/RadioCPics/Suspension/DSC_1298.jpg
http://www.lazermotorsports.com/Photos/RadioCPics/Suspension/DSC_1299.jpg
Toe comes next. Here's where it can get a little different between 2wd platforms and 4wd platforms.
On 4wd, you generally run some toe-out in the front, where on 2wd, you'll want close to zero toe [wheels parallel].
http://www.lazermotorsports.com/Photos/RadioCPics/Suspension/DSC_1301.jpg
Both 2wd and 4wd are going to have a significant amount of rear toe-in for stability.
http://www.lazermotorsports.com/Photos/RadioCPics/Suspension/DSC_1302.jpg
Caster can be adjusted by moving shims on most 4wd vehicles. More shims to the rear adds caster by moving the upper suspension arms to the rear. This adds mid-corner and corner exit steering.
http://www.lazermotorsports.com/Photos/RadioCPics/Suspension/DSC_1303.jpg
2wd vehicles usually run a LOT of caster, built into the front suspension arm kick-up, as well as the caster blocks, this helps calm the steering on corner entry, and helps the suspension better cope with bumps on the unpowered wheels.
A 4wd pivot ball front suspension allows for quick adjustments of camber, track width and caster, without replacing parts. The downside is there are more parts involved in the design, so they can develop slop quickly which would require more maintenance.
http://www.lazermotorsports.com/Photos/RadioCPics/Suspension/DSC_1305.jpg
The rear suspension on this buggy shows the basic concept of a caster hub design, where the camber is controlled by an adjustable turnbuckle at the top to control camber. Since this is on rear suspension, toe is fixed by the hub angle and rear arm angle. Changing rear toe requires the hub or inner pivot mounts to be changed.
http://www.lazermotorsports.com/Photos/RadioCPics/Suspension/DSC_1306.jpg
That's all I have for now, if there are some more specific questions, I can take more photos and give more in-depth explanations. :)