Understanding Tuning: Let's break it down...
 

Ok I've been thinking about this one for a while and I really felt it was a good idea to get this all into one place. I realize we have some great minds here on RCTech and after reading the "Tune with Camber Links" thread that fredswain contributing BOAT loads too, I thought it would be nice to continue that trend.

What it all means...

If you don't notice the theme, I'm a bit put off by too many generalizations. I like to break things down into their very basic forms and figure that out. That's why I think it's so important to get a discussion going and break some of these tuning tips down to these most basic of levels. It really helps to avoid confusion in the long run.

Lets start the discussion and try to keep it as organized and easy to interpret as possible on an interweb forum. I will do my best to update a summary post as well to keep everything in some kind of order. Again I really think this can help us all out. At least those of us who want to learn and not just copy other people's setups.

Compiled Data so far (will be updated as thread progresses and discussions are had)....

Intended goal = More rear traction
Add more rear toe in
Thinner rear shock oil
Softer rear shock springs

Notes: This is for overall rear traction. See the below options for the break down of side bite and forward bite. Use these options first, and then fine tune with the TYPE of rear traction you want.

Intended goal = More rear side bite (lateral traction)
Shorten rear camber links
Lower rear link on tower side and/or raise link on hub side
Add more negative rear camber (up to a certain point)
Lay down shocks more (in on tower, out on arm)
Decrease anti-squat

Notes: Side bite helps with initial to middle corner traction and keeping the rear end locked in, instead of sliding or drifting out. As you tune for more side bite, you'll usually find forward traction reduced. You'll also most likely find that steering (especially turn-in and mid-corner) increases.

Intended goal = More rear forward bite (straight line traction)
Lengthen rear camber links
Raise rear link on shock tower side and/or lower the link on the hub side
Reduce negative rear camber
Increase anti-squat

Notes: Forward bite helps square you up as you exit a corner, and also straight line speed. As you add forward bite you'll usually see less side bite. You'll also may find that steering is decreased.

Intended goal = More overall steering
Reduce rear toe
Softer front spring/stiffer rear spring
Add a small amount of front toe out
Thinner front shock oil (mainly for low speed steering)

Notes: These adjustments are to add general steering. For more in depth break down, see them below.

Intended goal = More off power steering
Shorten front camber links
Lower front link on tower side and/or raise link on hub side
Reduce front caster/front kick up
Add more Ackermann angle
Move front shocks out on the tower/rear shocks in on tower


Notes: As you tune for off power steering you'll likely see a reduction in on power steering. Also remember that off power steering is only when you're not on the throttle or braking.

Intended goal = More on power steering
Lengthen front camber links
Raise front link on tower side and/or lower link on hub side
Add more front caster/front kick up
Increase anti-squat
Reduce Ackermann angle
Move front shocks in on tower/rear shocks out on tower

Notes: As you tune for on power steering you'll likely see less off power steering. Also a car with lots of forward bite is going to progressively have a harder time maintaining on power steering as the rear wheels will fight to push straight forward.

Intended goal = Better/Further Jumping
Add more anti-squat
Add more kick-up
Add more droop (preferably on the front)
Thicker shock oil in all shocks
Stiffer shock springs on all dampers
Stand shocks up, more vertical ---> |
Add more pack (smaller piston holes/less holes)

Notes: Keep in mind that making the above changes will affect more than just jumping. They will affect your handling as well. To see the other effects these changes will have, reference the rest of the tuning guide and cross reference.

Intended goal = Better Handling on Rough Tracks
Add ride height
Add more droop
Add more caster
Add more kick-up
Adjust anti-squat (smooth drivers usually prefer less, aggressive drivers usually like more)
Thinner shock oil on all shocks
Softer springs on all shocks
Lay shocks down, more horizontal ---> \
Decrease pack (bigger holes on pistons/less holes)

Notes: Keep in mind that making the above changes will affect more than just handling in rough sections. They will affect your handling as well. To see the other effects these changes will have, reference the rest of the tuning guide and cross reference.

The Good, the Bad, and the Ugly

Now that I've covered some changes you can make to try to reach your intended goal, let me talk about some other things. As always with tuning, when you tune for one specific area you're usually seeing a trade off in another. I explained that above in many of the notes, but I want to delve into it a bit more specifically here.

Camber Links Position and Length

I know above many of the suggestions involve camber link lengths and positions. Just keep in mind that you can often overtune with these. Making small changes and testing is the best way. If you're tuning with these and you find your car not responding well, it's best to go back to a baseline and start again.

Going too high on the front link (tower side) or making it too long can cause your car to hook while entering a corner. Going to low on the link or making it too short can make the car flip over in a corner.

Going too high in the rear (tower side) or making it too long will probably cause a lot of steering push. Making the link too low or too short will cause you to lose traction in the rear very quickly and unpredictably.

Note: When trying different rear link locations, and you get it spot on, it feels like the car does everything better. The rear link will mainly determine the amount of traction the car has, and how it slides when cornering.

Toe Adjustments

Adding rear toe in is going to take away from your top speed. The more rear toe you add, the more violently the rear will break free when it does. Adding front toe out can cause your car to wander on the straights or in bumpy sections. It's usually not suggested to run more than 1 degree of toe out in the front.

Ride Height and Droop

Be careful when adding too much ride height or droop. Small changes can make a big difference. While a little higher ride height or more droop can help on bumpy or loamy tracks, too much (especially droop) can cause you to traction roll and smoother or high bite tracks. Less droop and/or ride height will lessen body roll, which helps on smoother tracks.

Camber

In a straight line adding camber reduces forward traction slightly, but you will gain cornering grip. Starting at about -1 deg is your best, and working from there. Too much camber can result in losing grip (even in corners), because your tire ends up missing the optimal contact patch on the track.

Caster

When adjusting caster keep in mind that less caster is generally better for smaller, more technical tracks. More caster is usually better for bigger tracks with wider turns. Too little caster can make the car feel very twitchy and too responsive where as too much caster can make the car feel like it has little steering and lots of push.

Anti-Squat (rear)

More anti-squat is usually better for a high traction, smooth track, while less is better for a bumpy rougher track or a track without much traction. Drivers with aggressive driving styles tend to prefer a lot of anti-squat, while smooth drivers may prefer less. Too much anti-squat can cause excessive push entering corners and loss of traction exiting a corner as you brake and accelerate respectively.

Kick-up (front)

Less kick-up is usually preferred for a high traction, smooth track. More kick-up works better for a rougher track and/or can help if you want to slide the rear around sharp turns under braking. Less kick-up usually makes the car more responsive, especially with steering.

Akermann Angles

With the link towards the back (reduced Akermann), you'll get more responsive steering and more turn in. With the link moved forward (increased Akermann), you'll get more mix to corner exit and on power steering. The more Akermann angle you have, the later you'll notice the turning response geared towards corner exits.

Overall Suspension (damper) Tuning Notes

Why shocks get their own section? Because they are a very complex thing to talk about. There is different components involved (fluid, springs, pistons) and also different mounting positions to talk about. The most important thing to remember about shocks is that the dampening (pistons and fluid) and spring rates should always be tuned in unison. This even goes for the shock positions, because as you move them, you're affecting your suspension rates as well. I'll try to do my best to explain all of this, but here's the basic break down.

When it comes to tuning suspension setups, it's usually something most racers do first before anything else. Once you find a good suspension setup for your track and driving style it will likely stay almost untouched as you fine tune other adjustments. Even on different tracks you can usually make small adjustments and achieve the results you're looking for without retuning the entire suspension. In most cases it's best to start with the manual specific setup and then tune from there.

Tuning your suspension is a very important part of any race vehicle setup. Learning how to watch the car react on the track, how it jumps and lands, how traction is, and how it steers all give you input on how to tune the suspension. A well tuned suspension will mean that the wheels are on the ground as much as they can be without losing contact, which equates to loss of grip. The better you get your setup dialed in, the more time your wheels stay on the ground and the better your car will handle in pretty much ALL of the areas I covered above.

Aggressive drivers or smoother tracks usually favor a more stiff overall suspension, while smoother drivers or bumpier tracks favor a softer suspension. A stiff suspension will make the car feel more responsive and quicker to driver inputs, but also could be more twitchy for smoother drivers. A softer suspension will usually be better for a driver who is more smooth and will probably feel more consistent.

As a rule, the pack, spring rate, and oil should all be tuned together for the same basic feel. For example if you're running a heavier oil, you should reduce pack and decrease spring rate to "align" these three areas. Likewise a thinner oil usually works best with more pack and a stiffer spring rate. Basically all of these parts work together and should be tuned as such. Big differences can cause your suspension to be very unpredictable if all the components are fighting with each other as you drive. You can always make small changes to each of these components independently, but try not to end up with large variances.

Shocks Positions

Always remember that by moving the shock positions you're also affecting your suspension rate as well. As you have a shock that's more horizontal, your suspension rate will increase at the wheel (feel stiffer). As you put the shock in a more vertical (upright) position, the suspension rate at the wheel decreases (feels softer). This is why changing these positions affect your handling in different ways, and why you should also remember that it can affect your overall suspension balance of oil, pack, and spring rates. As a general rule when you run the shocks very upright you'll want to run less pack, softer springs, and heavier oil. The opposite is true for shocks that are laid down a lot (horizontal).

When adjusting shock positions the lower arm adjustment is going to be a more noticeable adjustment. The upper (tower) mount is usually used to fine tune after that. The following is good to keep in mind as well. I took it from the buggy setup guide.

When the front shocks are more inclined than rear: Steering feels very smooth, you'll see a little more mid-corner steering. When the rear shocks are very upright it can result in the rear end sliding in the middle of the turn, especially in high-speed turns.

When the rear shocks are more inclined than front: Feels aggressive turning in, the car has a lot of side traction in the rear, and the turn radius isn't very tight.

Springs, Pistons (pack), and Oil

Springs are rated usually by weights and/or stiffness. They are pretty easy to figure out based on how they are sold or labeled. Most racers usually have a range of springs to choose from when tuning.

Pistons are a bit more complex to understand. In their most basic form though, they are controlling how much fluid (oil) can get through them in a given time. The bigger the holes (or more holes of similar size) and the more fluid that can be pushed through the piston with less resistance. This is referred to as less pack. The smaller the holes (or less holes) the more pack you have. Think of it like drinking out of a straw. Less pack would be like drinking out of a big diameter straw, where as more pack would be like drinking out a coffee stir straw. More pack is good for aggressive drivers or smooth tracks because it reacts to inputs faster and keeps your car basically handling the same in most areas. Less pack allows the suspension to "work" more and travel quicker and more smoothly. That's why it's good for a bumpy track or a smooth style driver.

Oil is sold in weights. The higher the weight, the "thicker" the oil is. As you add weight to the oil, it moves through the piston inside the damper slower. The lighter the oil, the faster it can move through the piston. Again, this changes how fast your suspension can react, so should be tuned based on track conditions, driving style, etc.

Springs, pistons, and oil all sort of work the same way. As you change these to make your suspension more stiff or soft it will react as stated above. Just remember that usually a stiff spring usually works good with a thinner oil and more pack, and vice-versa.

Some other things I'd really like to delve into.

Steering - different types (turn-in, off power, on power, etc) and how to tune them
Shocks - damping, spring rates, etc and what it affects when changed
Shock Mounting - what do the different holes do???
Caster - How it affects EACH facet of turning
Anti-Squat - How it affects the car when your breaking or accelerating and where on the track

There's lots more, but I'm just throwing out some ideas I have been pondering and trying to get figured out in my brain.

Nice work, tuning guides are always a bit obscure for newcomers, this one is crytal clear!

http://www.rctech.net/forum/electric...reat-info.html

here is one i did awhile back.

Thanks slim jim, I just used some of the information from your guide and added it to my compiled data. I think what I'm trying to do differently is really differentiate between the different types of traction, steering, etc. Then I want to lay out HOW to achieve these types of things. Most guides I see tend to be like the one you posted. They go through each of the components (caster, camber, toe, links, etc) and tell you what each one of them does. What I'm trying to do is make a guide that kind of works the opposite way. I want one that first asks the question "What do you want to do?" and then answers that for you with suggested tuning options.

I hope that makes sense... :p

Anyway, I hope this thread takes off a bit. The more people we have contribute, the better.

Ok so I added rear toe in and camber to the equation. Since I want to also explain why these changes work, I'll give my explanation for how toe and camber affect rear bite.

The reason toe in affects the car is because it's actually angling the rear tires more in towards each other, or more parallel with each other. More toe aids in more forward bite AND rear bite because the rear tires work more in unison at all times.

Camber works by changing the angle at which your tires are touching the track. It's commonly referred to as "static" camber because when your car is sitting at ride height, that's usually what you adjust camber for. As your car turns or squats, the toe angle changes. More rear toe helps with side bite because your tires have a larger contact patch with the track as you put more pressure on the outside wheel. Adversely less rear toe helps with forward traction because as you move in a straight line, you have more contact patch with the track.

I love this as I am one that struggles with knowing what my changes are doing to the car. After reading this I am still a little confused as to which rear traction I need. I have a sc10 and have always struggled with rear traction. I have too blindly thrown any setup changes regarding rear traction into it and consequently have a car that tends to be out of whack. My truck is very very loose on throttle (specifically mid corner to exit), no tire changes or setup changes I have done have every really solved it. Now I realize 2wd in nature has limited rear traction, but mine is unbearable. Now also if I am coasting through a corner or lightly on the throttle (entry to mid) I have quite a push.

My guess is I have probably added/taken away side or forward bite with all my changes. What I am guessing I need to do based on what you say is add forward bite to help with the exit and straightaway rear traction, and perhaps reduce some side bite due to my push when coasting (and perhaps add some front traction which I never do out of fear of making my rear more loose). Let me know if I am understanding you correctly.

Overall, I really appreciate a thread on this. Great info!

This is exactly what I intended for this thread. I'm not an expert by any means, so I think collectively we can figure this out.

It sounds to me like you're needing more forward bite in the rear. Just to clarify I'm assuming your back end wants to break lose as you accelerate coming out of a corner? If so, then you need to make changes to add more FORWARD traction. Doing so will likely lower your side bite and probably affect steering as well. Since I haven't gotten to the steering bits, focus on the rear traction for now.

If I'm wrong please some one correct me. They way I see it, when you're on power coming out of a corner you want the car to square up better (ie. go straight). That to me says forward bite all the way.

I also just edited my notes to better describe the difference between rear side/forward bite and where they come into play on a track. Should help with clarification.

I believe you are correct as it makes sense to me. I'll give it a whirl for my next track day tomorrow and let you know how it goes.

I like this thread. Good Job

Subscribed! Cheers,

I just subscribed! Thanks for the help!

So, on a medium to high bite indoor clay track, My B4 seems to nose-up off a triple. Short of adding weight, what can I do?

With the RB5 I was able it dial it out by adding pack. I think raising ride height helped too. But, since RB5 and B4 setups look completely opposite of each other, I thought maybe some B4 guys can tell me how to bring the nose down...short of adding weight. Ballast and 5 grams under the front tower is all I want to run. because body and chassis wrap is heavy.