after reading this, i wonder how your methods apply to real cars when i doubt you drop them from 5-6 inches without the shocks attached. do you use a crane to do this?

also the spring force equation is f= -kx where k is the spring constant and x is the distance. f is obviously force.

http://en.wikipedia.org/wiki/Hooke's_law

This will affect your rebound, which is where your shock oil comes into play, which will then affect your compression again too. I do agree with finding a balance first, as it is a good base to set everything else up from.

With a real car such as a track car, you may have several spring options available to you. If you are a person who uses Tokico Illumina shocks or Koni's and then decide to use an Eibach spring, you aren't going to have a high degree of tunability. You hope they matched spring rates to each other well and usually they do. It doesn't mean you have the ride frequency that will give you the best performance for every application though. A street car requires a higher ride height and a lower suspension frequency than a dedicated track car. Tokico and Koni shocks add a nice degree of flexibility for a street car and the casual driver who occasionally wants to go out on a track but you can't adjust shock and rebound independently of each other. I take that back, Koni does make a true race shock that is double adjustable but you won't use it on your street car. On a single adjustable shock such as the ones I listed, when you adjust shock, it adjusts the rebound as well. On better, dedicated track coil over type of setups you can adjust both though and can get it to compress at a different rate than it rebounds. Since you don't go into those shocks and change your shock oils you change the shock and rebound settings for your track. In the r/c world, we can change shock oils although we can also go in and change the pack through different pistons. RC cars are the most tunable performance vehicles in the world and due to their small size should seem obvious that there are some techniques that are possible that aren't on a full sized vehicle.

You can feel if the front and rear of a real car are going up and down at the same time. You don't need to drop the car. You don't even need to go off roading. Just pick a street. You can tell the cars that have worn out old suspensions. Just watch the way they bounce over a hump or a dip in the road. A big old Cadillac pops in my head when I think of this. You are watching it bounce at it's ride frequency. This thread deals with r/c cars that weigh a few pounds that fit in your hand. It's obvious that you can pick it up. If you drive an rc car with no shock oil, you can also observe the rates at which each end bounces. It is far easier due to it's size to just do it on a bench. You fine tune it by running it. Onroad rc cars with very high suspension frequencies and short suspension travel distances can get very hard to observe.

On a real car it is pretty apparent when the car is porpoising and when it isn't. Keep in mind most real cars are quite well balanced but typically have a slightly higher ride frequency in the rear as they assume you may be hauling cargo of some kind. A good passenger car is designed with about 5 cyles per second (5 hz) higher rear frequency than front. You typically don't have the option of moving shocks around on real cars to determine spring rate like you do r/c cars either but again only serious track cars will ever worry about doing this in the real world.

I'm actually surprised it has taken until page 4 for someone to start quoting technicalities and calling out their doubts. Typically on forums, this happens far sooner and the thread goes downhill pretty rapidly. Usually when one person starts, others waiting in the woodwork will suddenly appear. Either try it or don't. It's as simple as that. People are always asking for a setup for their car and then go on blind faith that the exact setup they were given will work for them. I don't believe in this. I'd rather teach people how to arrive at their own setup and you don't easily do it through guessing.

BTW: I forgot to mention that I don't believe that any of us can ever know everything or ever stop learning so if you have a better or easier way to do things that this, speak up. I'm all ears and would love to learn it. I'm only passing on what I was originally taught and it has seemed to work well.

The RC world has a lot of "Boasting" in the knowledge arena (funny enough). I think people are becoming less interested in looking good and more interested in driving good. With that we need a decent set up vehicle. You have had some very helpful advice. I think most of us recognize this. I wouldn't let the boasters or doubters get you down Fred. You have quite the audience right now whom are paying close attention and trying their set up's out as you are recommending. I'd very much appreciate you continuing with your set up lessons --- I believe we are onto shock oil now.

Perhaps once we are done start to finish with set up's we can create a single consolidated post with all of your pointers for easy reference. Until then, I, as well as others are all ears. Lets not get deep into a debate and loose focus.

I'm open to this as well.... lets just not get hung up on one concept. I'm 100% interested in moving forward with your suggestions as I have my shock oil sitting at the ready

I'm definitely not here boasting. I guarantee there are smarter people out there than I am! I don't have an impressive list of accomplishments in the rc world to brag about either. For all intents and purposes I'm just an ordinary guy passing on what he was taught and you'll have to decide if you want to believe it and try it or not.

haha, nobody said you are Fred.
Although I can't say the same for Mr. Spring Formula guy

I appreciate the time and effort you're putting into your posts. Looking forward to phase II >

2 things:
1 Its interesting this thread is called "tuning with camber links" and correct me if I'm wrong but have we even talked about camber links yet? Lol!

2 are you of the belief that these RC car companies do not do a lot of testing to make sure their baseline setup is close and then a driver can get out and race faster. Meaning just tune from there. Because I used the baseline setup and it worked good. I just had a slight problem with chassis slapping after landing causing the buggy to spin out. So my answer would be to change pack. It doesn't seem like a band aid fix to me.
Fred keep it up I love talking about theory
Jake

Mr. Bubonic - X:

It is funny the name of this thread is "tuning wtih camber links" isn't it . I would suggest going to page one and start reading. That might clear any questions you have regarding titles.

I too agree it seems the manufacturer does set a good baseline. I ran my RC8be on a baseline set up all the way around and got a great lap time for the day. I'm ready to go beyond that and tune further --- but I think the manufacture baseline is "their set up" baseline.... not the baseline you should start with all tuning. They just decided on a simplistic baseline tuning to cover an array of driving conditions I'm sure that's not over complicated.

We'll get to camber links someday! First we have to get past shock oils and packing.

Hopefully the manufacturers provide a good setup. They should. It should be a good baseline average taking into account what most people will be using the vehicle for. It doesn't mean it's optimal for any one particular track or location though. How would the average person know where to begin if they wanted to dial it in though? That's where generalizations really start to confuse things.

Well you should be this information is brilliant.

Maybe this is true however they're not here talking to us in the simple well described method you are. Thank you for being smart enough though.

Yea because you using all your spare time helping us out and not on the track practicing

OK on to shock oils. This part is actually quite easy but VERY time consuming as you will be replacing the oil in your shocks many times. First off if you have multiple piston options for your shocks, pick one somewhere in the middle. If you don't have any options then obviously use what you've got.

First off, go drive your car without shock oil at all. Pay attention to how the car bounces up and down. You don't need a track for this. The street or a parking lot will work just fine. Notice how it bounces up and down on the springs since there is nothing there to dampen it. I merely refer to this as "bouncing on the springs" so when I say that, you know what I mean. The rate at which it bounces is your suspension frequency. Hopefully at this stage, the front and rear of the car move up and down together in harmony without one end bouncing at a different rate or opposite the other. If you don't have a match here, you aren't done with your spring rates yet.

I start with a light oil. What you consider light may vary from what I do depending on your scale, pistons, etc so use something that you know is inadequately light. It sounds weird I know but we can't find what works without first knowing what doesn't.

Use the same shock pistons all around. Don't use something different in front than rear. Now fill your shocks up with the same lightweight oil all around. Be careful to bleed them well so we don't mess up our results. At first you can perform the shock oil tests in the street or a parking lot. Later on you fine tune at the track.

If you just drive around with this light oil, you'll notice that the car is probably still bouncing on the springs, just not as quickly. Your goal is to keep increasing the oil weight until this stops happening. It will happen at each end at different rates with the rear being a bit more obvious as there is typically more weight there. Once you find this point, it doesn't mean you've got the perfect weight. There may be a range. You may be able to keep increasing the weight for a while. You'll know it's too stiff once the wheels start trying to bounce off the street. Make note of where you stop bouncing on the springs and start bouncing on the tires. This is the usable range for oil at that end. Do the same for the front and rear. I've found that typically the front requires a heavier oil than the rear, sometimes by up to 20W different or more.

What you are basically doing is driving the car, and you can do this at the track if you are fine tuning, and are adding oil weight until that end of the car stops effectively dampening the bumps and starts wheel bouncing. Then you back it off. If the rear hits this point first, stop changing things and keep going in front until the same happens. You get the idea.

If you find balance and good dampening and you are having no problem at all with the bumps but are bottoming on landing from the jumps, you need to go up in packing in the shocks. This will mean a decrease in shock oil of course but just start low again and repeat the process until you get it where you want. If you have a very bumpy track and have no problem with bottoming on landings from jumps, go with less pack and heavier oils. Maybe what you have is good. Leave it alone.

This technique is going to take lots of time, trial and error. You may get frustrated or think you aren't making progress. Stick to it. Remember the shocks are being used to control suspension chassis movement. Don't worry too much about the affect of oil weights on cornering at this point although when you get the shocks done it should be pretty good. The car should still maintain pretty neutral handling. Cornering will come into play when we get to roll centers and tire selection.

What happens if you are still somewhat bouncing on the springs but never get to a point where you get fairly smooth and it goes straight to bouncing on the tires? Your spring rate is too high.

I suspect this step is going to get some interesting feedback, good or bad, so just get to work using the steps and find the sweet spot. Remember you'll have a shock oil range front and rear so there really is no one right combo here. Just a range to stay within although the range could potentially be large or small depending on your suspension frequency and track.

I know it's weird but it is systematic, although very time consuming.

I know I will be watching for updates as well. I have some understanding of setup but never understood where to start! Thanks

Fred I'm loving your articles. I've been in to RC racing for about a year now and this is the most complete guide to setting up a RC car that I have found. Thank you so much for taking the time to do this. I'm still setting up my springs so i'm a little behind. Here is my question, I have a Hyper 9e and the stock springs with out any shock oil allow the car to just sit on the ground. I'm assuming I need stiffer springs correct?

Thank you Fred for having such a logical method to setting up a buggy. I have always hated just fiddling with different things to try and "fix" bad handling habits when as a whole I figured it was the entire set up. I have gotten my car to work well but I know its filled with band aids like you said.

I will be redoing my entire set up fairly quickly here, once a few parts come in and my new batteries show up, that way I wont be wasting my time by setting it up with batteries I wont even be running. lol

I assume using the factory recommended set up as far as the caster / camber / toe and roll center starting points would be ideal. Correct?