Handling questions - CE indoor high bite clay

[Charlie don't surf]

I'm not condoning or condeming your set-up style, but man......that's a different approach.

[fredswain]

I actually do it that way because it was the way I would setup my RX-7 for track events. It's all a matter of scale and not physics. It still applies. Figure out the cars natural suspension frequency and balance it out. Then go from there. By doing it this way, any preconceived notions about how something should be setup go out the door. It wouldn't matter if the car was 2WD, 4WD, rear motor, mid motor, etc. The same technique yields the same end result even though the setups may end up very different.

What I used to do was to just set the roll centers as low as possible (tie rods all the way in) like everyone else did and then rely on camber, shocks/springs, and tires to do all the tuning. The problem with this approach was that I'd get the car setup to handle the jumps well but then it may not corner. So you fix the cornering issues by adjusting the shocks but then you don't handle the jumps well. This was trying to do too many things with too few components.

The way I tune the car gives a pretty neutral balance. That's the initial goal. Once it is all balanced, then you can go make changes to suit your particular track. Once the car is in a neutral state, you actually don't have to do much to adjust it for different tracks. Some tracks warrant running more understeer, some more oversteer. It's not hard to dial these in once you know where neutral is. That's the whole goal of how I start tuning the car. Find neutral so you know how to easily adjust to suit your needs. It is establishing a reference baseline.

Many people may not like my technique and here's why. Most people, at least around here, want to go flying toward the inside of a corner at full speed, slam on the brakes, let the rear end slide out, and then power their way back straight again. Basically it's a motocross approach to driving. Very low roll centers favor this driving style. The suspension will grip and then suddenly just let go. I setup the car for a more realistic line where you hold more speed through a corner and try not to slide the rear end out as much. Then again I tune RC cars like I tune real ones and use the throttle accordingly too rather than only full throttle and full brake. I actually suspect that I'd love a mid engined car if I ever drove one. I tune for more predicability but it requires careful throttle control as opposed to all or nothing. If you are an all or nothing driver on the throttle, you'll hate my car setup!

Yeah it's different. I'm not famous either so maybe I'm a complete idiot!

[JHarris]

So using your method, what's your current setup and on what surface type? I'm curious how close or far it is from the setups found using traditional methods.

[fredswain]

The old RC10's have an interesting problem. When you get the front/rear spring rates set to bring the front and rear suspension frequencies together, suddenly the front end doesn't get front end weight transfer in corners and it understeers. When the spring rates are set to get the same front and rear grip in corners so that it turns well, the suspension is then in the middle of an imbalance that causes it to "porpoise" (uneven front and rear oscillations). This has always been a problem. You'd either have a car that turned well or one that was very stable in the rough stuff but it was difficult to get both. The JRX2 cars were generally always more stable but the RC10's were generally more aggressive in corners.

Where does the problem lie and how do we fix it? One problem is the front end rake of the old car. It is 30 degrees. The swept back nature of the front a-arms is also an issue but I'm not going to deal with that now. When the weight transfers sideways in a corner, the front end rake makes it tough for this weight to transfer in the front. Fortunately most of the time we are in a high rate of brake when we need it and the downward angle of the car rear to front when braking helps this problem out. This problem shows up as understeer in long fast corners but in tight ones we can grip just fine. By reducing the front end rake a bit we can get a better balance in weight transfer front to rear in corners of all speeds. If you'll notice, the newer cars went down to 25 degrees from the 30 of the old RC10. The new 22 comes at 25 degrees with an optional block to bring it back to 25 if desired. I'd be a fan of going to 20 degrees with the option of adding more later. Since the 22 can move the front caster blocks front and rear a bit, it can adjust for varying amounts of rake. We can't. I'm not here advocating the 22 of course. I don't have one on order. I am using it as an example of suspension design because once you understand the old suspension issues of the old RC10, you can see that it is in fact being addressed in modern designs.

I'm probably not helping you to determine a proper setup but hopefully I am making some people aware that our old beloved cars had some flaws in design (gasp!) that cause us to choose which areas we want to compromise in and which we don't. This is where modern car design can have an advantage assuming their designs don't have the same mistakes in them. If designed well they'll have fewer compromises for each type of track which means that while the old cars may be able to hang in some portions of a track, they may not be able to in others. At some point I'll do a thorough writeup of fixing the suspension issues on the old cars as much as possible while still leaving them the vintage cars that we all love.

[JHarris]

You didn't answer the question. Discussing suspension theory is great, but the method of setting up a car that you described is so far from anything I've seen in 27 years of hardcore racing I just have to know where you ended up using your method. I'm curious how far off the rest of us are just using the way we've always done it. Please, tell us your camber link locations, pistons, oil, springs, shock locations and so on.

[fredswain]

I'm a technical person. I'm going to talk tech. It's my way. I don't believe in instant gratification but rather knowledge as to why things work the way they do. I don't copy. My setup may not work for you at all but here it is.

I'm going to change things up a little bit still but it is currently a stock black chassis 90-94 team car. The front shocks are mounted on the inner holes on the arm, the top on the upper middle holes on the shock tower. End links are mounted all the way in but that is probably going to change soon. 15 degree caster blocks. Green springs, #2 pistons and 30W oil. Level ride height.

In the rear the shocks are mounted on the inner holes on the shock tower and the next to outer holes on the arms. End links are mounted all the way in currently but I may end up drilling a completely new location directly below it. Running blue springs and 30W oil. I may change the rear though. #2 pistons. Our track is hard packed clay and even the straights are fairly rough due to flaking of the surface. Corners can be a bit soft. My biggest problem is that with my old stock Lightspeed motor, I don't have enough power.

Keep in mind that the farther in on the arms you run the shocks, the lighter the effective spring rate becomes. Farther out makes a stiffer effective spring rate so don't compare my setup vs another based solely on the spring color. Look at locations too. They both matter.

I'd like to try the world's suspension setup. My friend is currently building one so when he gets it done we'll work on his. I was looking at a B4 yesterday at the track and watching him run around and that car does have a very improved suspension geometry as it should.

EDIT: I had to go back and edit my spring settings. I originally stated blue springs all around. This was incorrect. I am running greens up front and blues in rear. All blues makes the car porpoise.

[m_vice]

pics please...

[Lonestar]

Interesting setup theory

Likewise - does anyone have a starting setup for CE/TeamCar with old-school, shorter shocks? HEre's what I found, I was wondering if JHarris and such top-notch racers would agree with this (source rc10b4.com)

thanks
Paul

Front:
30wt
#1 pistons
Black Springs
25 degree caster
1-2 deg camber
0deg toe
Middle shock tower hole
Outer hole on arm

Rear:
25-27wt
#1 Pistons
Green Springs
Std toe in
1-2 deg camber
Std anti squat
Inner Shock tower hole
Outer hole on arm
Rear arms level, front of chassis slightly higher than rear when viewing from side

This setup will work on 95% of the tracks I ran on with up to 3 thin limiters in front and rear for smooth, high bite tracks, and no limiters for rough tracks. Varied limiters for in between tracks. Other tuning done with tires and shock angles.

[JHarris]

Lonestar,

That setup will work for most racers and on most tracks. If someone is building a racer/runner, that's the perfect starting point.

As for the setup posted by fredswain, I'll have to try it after the Spring Fling this weekend just to see the difference.

[fredswain]

I'm still working on my upper link locations and caster block selection but the spring rates are perfectly balanced. I am 100% positive that having the front upper links all the way in on the shock tower mount is a bad idea. The upper links should never be longer than the arms! My front and rear roll centers are drastically different as a result and it shows. If I wasn't aware of this problem and didn't know how to balance the front and rear suspension frequencies, I might be tempted to fix this issue with shocks and springs rather than dealing with the actual problem. The links are set where I always ran them as a kid which is where everyone else ran them and I always had a problem with the car setup as a result. I started with the old setup and am now tuning from scratch on this car to get it where it should be. My XX is dialed in and it is nice.

Keep in mind if you do try this spring selection that you have to use my exact upper and lower shock mount locations too. By moving the shocks on one end over a hole, you'll throw the suspension balance off between front and rear again and spring selection will once again have to change. You can't just run blues in back and greens in front in any location and expect it to work well. Remember this isn't the only spring combination or shock location that works. This is just what I'm using right now.

If you want to try my setup, try just the spring rates and keep the oil fairly close in weight front to rear. Use your own caster and camber settings if they work for you. If your track is smoother, you may want a higher suspension frequency (stiffer springs). If the track is rougher you may want a lower frequency (softer springs). The key is balance.

The reason I balance out the suspension frequency rates front to rear is because if you don't, all tuning after that point is done to an inherently unbalanced car and everything is a bandaid from there.

[Lonestar]

Lonestar,

That setup will work for most racers and on most tracks. If someone is building a racer/runner, that's the perfect starting point.

Thank you - this is exactly what I'm doing, so off to checking my stock of springs and pistons I go

Cheers!
Paul

[kaiser]

that setup would work for most cars too. very similar to the fatory b4 setup, rb5 too.

i guess what works....works! lol

[fredswain]

I worked on the roll centers tonight and the changes I suspected worked exactly as I thought they would. The roll centers with the links all the way in at all 4 corners puts the roll centers too low. Yes it adds stability but I suspect that most people do not have proper suspension f/r frequency equilibrium so they are fixing an unstable spring setup but using a bandaid elsewhere which slightly offsets it. Once my spring rates were balanced, I still had some issues. It can't be the springs so the next logical place was the roll centers. It was.

The front upper links were originally all the way in on the shock tower. I said this was too long. It is. The team car towers have 3 link mounting locations. The far inner ones and 2 outer ones, one high and one low. I am now using the upper outer hole.

In the rear I was running the inner most hole directly underneath the wing tubes. I have now drilled a hole directly below them inline with the middle holes on the outer locations. The upper links are still just as long. They just are mounted slightly lower inside. This combo between front and rear is perfect. I know some would think that with higher roll centers that the car is less stable but this hasn't proven to be the case. It is because the spring rates are balanced and now the roll centers are too. At even ride heights front and rear, the rear roll center is slightly higher than the front. This means slight high speed understeer which is a fairly stable setup. The car is quite neutral now. The front arms are 2" long and the upper links are now 1-3/4" long. The rear arms are 2-1/4" long and the upper links are 2" long. That's a decently equal ratio front to rear as it should be. Close enough.

If anyone is going to try my spring combo and locations, you must also use my link locations. You will hate it if you don't and you'll think I'm nuts if you don't already. Maybe I am! At the very least use the front upper link location I am and the inner most in the rear. It's close but not quite right. I want someone to try this out. I'd like the feedback. The difficult thing now is that if one end of the car needs to be loosened up, you don't touch the springs, only the shock oil weight. You can adjust the shock collars as necessary but if you change spring colors at one end or arm mount locations, you must also change the other end somewhat as well to balance it. Balance is absolutely critical. If you are going to change lower shock mounting holes at one end, you also have to change something at the other end to bring it all back equal again. Oil weights front to rear can vary quite a bit though. Also play around with the rear arm mounting locations. Don't be afraid to use the rearward location on the chassis that pushes the arms backwards and slightly lengthens the wheelbase. Just make sure the shocks don't bind. Try both. Each has an advantage and disadvantage.

I'm tempted to go play with a bone stock B4 at the hobby shop now. I'm curious if the springs are balanced from the factory or not. Then again shock locations on the bottom can make the exact same spring rate either balance or unbalanced based solely on mounting location so it isn't only about spring color. It's far easier to set it up unbalanced than balanced. Be careful claiming something looks similar to another car's . Looks can be very deceiving.

[Lonestar]

that setup would work for most cars too. very similar to the fatory b4 setup, rb5 too.

i guess what works....works! lol

well, yes and no the spring-oil combo might be the same, but the b4 geometry is really different... check a-arms length for a start

built the shocks yesterday nite - will try to finish the car today!

Paul

[fredswain]

The spring/oil combo can be identical and the suspensions can be identical but if the shocks aren't mounted in the exact same locations on the arms, then it's different. Depending on where the front and rears are mounted on each car could be the difference between one car being completely balanced and one being completely unbalanced even with the exact same springs and oil.