Fred advocates a different method of balancing Rates than I do. We both wind up at the same place and are in agreement. I have to thank Fred for his participation in this thread, because he is the reason I got started doing this sort of work.

There is an optimal FR balance (both weight and spring frequency) for your chassis layout and the type of track surface you run on. This is why stock cars run their movable ballast all the way forward at plate tracks like Daytona, and all the way back at a short track like Martinsville.

My method requires doing the calculations to determine what the wheel rates are, then calculate the wheel frequency (which is changed by the amount of un-sprung weight on the axle).

When you start calculating the wheel frequency, you discover how far off most of the setups that "work" are. Mayfields base SC10 2w setup is off by like 35%! My point is moving the battery 0.060 can make a big difference in weight transfer and YES it is making two changes at once but it's effect on spring selection is pretty minor.

At least, in my experience of doing the calculations and then ground truthing the results, it's not a big deal to make a change that will modify the wheel frequency 1% when everyone else around you unbalanced FR, off by 30% or 70% or, in the case of one popular SC10 4x4 setup floating around, 150%.

I hope I didn't sound too critical, because I did want to use this method. So I went back and tried again, bingo I found a problem with one of my shockies. Yah it worked.
Next question. I would like to try springs at different positions. The B44.1 has two upper mounting locations and two lower ones. Its the same front and back. So I have four options for each spring.
Outer Bottom / Outer Top (Longest position)
Outer Bottom / Inner Top (Most Horizontal position)
Inner Bottom / Outer Top (Most Vertical position)
Inner Bottom / Inner Top (Shortest position)

Can sombody put these in order of softest to hardest.

Now does any of these positions react more progesively or more linear than another. Is there other handling that I should be aware of or avoid by using one position over another.

I hope I can find a series of mathcing resonance springs and give me a few options to try out at the track

Thanks in advance.

Inner Bottom / Inner Top (Shortest position) softest/ low freq
Inner Bottom / Outer Top (Most Vertical position)
Outer Bottom / Inner Top (Most Horizontal position)
Outer Bottom / Outer Top (Longest position) stiffest/high freq

the arm is coarse adjustment, the tower in fine tuning

Cheers for that.

Fred,

I love your thought process first and foremost. TY for your priceless contribution to this thread. The above makes sense, but i would like to ask is this concept based on being in motion under forces or simply sitting still. Said another way and applying similar concept as a-arm. Moving the cg further back by shifting weight to the rear and getting more steering is because of the leverage is increased as such in the mounting of the shock further in. Actually that would be the reverse right? By moving cg further back the effect of traction is more realized on the rear because of fulcrum position or am i mixing to different logics that should not be. Otherwise. It makes more sense to move weight to rear because on decel/brake, you have more weight to shift. However, i would think it would have opposite effect on exiting/throttle giving more understeer. Balance balance balance. Hit me ob1

Thanks in advance!

Ok so I know it was said don't read to much into the process, just do it and learn. I am all for that, but as I read I get confused on something.

Part 1 of the process says empty oil and bounce car to see which end rises first and adjust to the slower side if possible to get a balanced "spring rate".

Part 2 says drive car once you have balanced "spring rate" without oil to see if you have balanced spring frequency as I understand it. If you don't have balanced spring frequency, do I have to go back to square 1 with looking for a spring rate with the same spring frequency?

If I understand you can adjust the remaining frequency out with the shock mounts? if this is correct then Sweet! But if it is correct then isn't it bad too? Making adjustments say to the front shock mount locations to get the spring frequency to match the rear also altered the droop right? How so I get my droop back in line front to rear?

My point in asking this is I want to be balanced through and through like Freds entire approach is based on.

Balanced Spring Rate, Spring Frequency, Camber turnbuckle length, droop, arms, etc. I don't see how I can maintain this approach unless I have a room full of springs from the get go. I could absolutely be missing/mixing something on this and hope that I am. The alternative says chance of truely balancing is extremely rare if at all.

Said another way.

One would like to think that if you had a set of front and rear springs that were 1.2lb that the frequency would match. So you have rate and frequency match. But we know based on the data at this point we won't be using 1.2lb springs front and rear due to weight bias front to rear. So if I go 1.2lb front and 2.1lb rear, isn't that automatically going to tell me that the frequency will be different? Rates are definitely different but become balanced due to load (my reverse thinking). Does that mean frequency also comes into balance?

Thanks in advance!

Fred,

When and why do you move weight or the battery in your car?

I have been reading some of this thread and like it. I have been racing RC cars from 1985 and am a regular guy. I try to place the battery in my 2wd to balance the cars weight as best as I can and then set up my car. I have a clear understanding that there is a adjustment/setting for every thing you need to do to get the car to work. I have grown up moving my battery to the rear to gain more traction when the other setting's did not do it for me. And it has always worked. The same go's for more steering if all else fails move the battery forward. So my question is do you ever move your! battery? I know if I needed more steering I would not move my battery back. If I had no choice but to move my battery back there would be more rear grip, If at that point the car needed more steering you can make changes to the set up. If a new driver at the track tells me he needs more steering and we have done what we could do to the lack of him or her having tuning parts at that point I move the battery forward to gain more front grip and less rear. Moving the battery in a 2wd to the front and back is a fast way to fine tune the way the car drives and if it is the only option you have back = more rear grip less front and vice versa.

The way I understand is you have to start at some base setup,like out of box.Then with shocks emptied proceed to tune F-R spring balance,I start at middle hole on tower and out on arm then fine tune shock position,replace springs only if you can't reach balance through shock position.Then start at a medium pack shock piston with a medium shock fluid let's say 25wt and then fine tune to track conditions.When you finish this process your car should be absolutely balanced.

HTH

Thank you Fred!

Im on page 68 of reading this excellent thread and I finally have something to contribute.

Some of you are using AE's spring resistance rating (in lbs) to try to determine spring return rate in order to find a common formula. this is incorrest. AE's springs are not rated in return rates. All of my spring knowledge comes from tuning snowmobile primary clutches.

Two springs of equal length and weight rating will have different return rates based on their number of coils. The less coils, the faster the return rate.

Conversly, a lighter spring with less coils can have the same return rate as a heavier spring with more coils. (same length and diameter)

To apply this to rc simply look at the number of coils of a spring and assume that the one with more coils has a slower return rate.

Look at dual rate coils and see the tight and loose coiling. i believe RC dual rates are set up wrong and shouls be tight coils at the ends with a few loose faster rate coils in the middle.

Higher rate (less coils) springs do not last as long as lower rate (return rate) springs.

All things being equal, a stiffer spring with more coils can have the same return rate as a softer spring with less coils.

This is measureable science, but like roll centers, has floating results.

Everything I know about springs came from Olav Aaen's Clutch Tuning Handbook. There are formulas in his book for you engineer types

my $0.02

Thanks for the awesome information and discussions Fred! Now we just have to get a manufacturer to list weights and rates on our toy car springs!

Having finally gotten to the end of this post from page 1 and I have to say, I have learned a lot and have done my best to attempt the method used here. So to start, I set up my JQ using this method with the CSI Blue pistons. I settled on the White springs, with the Manuals settings. (This is where it ended up being the most closely matched). I went through the process of working up in oils and settled on 45F Losi Front/ 40 AE Rear (This is all I had once I got past the 30s, I plan to use JQ Oils in the near future, they are rated in CST so I will have a more equal determination).

The camber link settings I left as per the Manual Setup. I had driven the car prior to all this and while the setup was better and showed more rear traction then my Mugen MBX-6R, it lacked the mid/ exit, on power cornering, it pushed hard and would not hold a line. While predictable, wasn't as fast as I would like it. So after our local race this weekend I went on to playing with the camber links. I wanted more steering and wanted to get rid of the push so I did the following...

There is a grid of 12 Holes on the JQ shock tower. I started at the inner most row, third highest on tower and farthest out on the hub Carriers (car pushed). I could not move it further down in that row on the tower as it hit the bulkhead. So I moved it out 1 row on the Tower and all the way to the bottom. Testing it showed the rear would break lose a little easier (but in control) and it would now out turn its previous line; however, it was just a little looser then I wanted, so I moved the link up one hole.

So here is what I understood I did...

By shortening the link, I raised the Roll Center, and by moving it down, I raised the Roll Center a bit more... So the result was a bit of slide in the rear, and more steering mid and exit on corner. The negative of this seems to be the rear of the car slides a bit easier than before, a little looser... but drivable and fast.

So given that data, I think I had an understanding of what was going on with the car? My questions first and foremost, does this makes sense to the rest of the community? And second, if I didn't want the car to slide in the rear, but to maintain the grip it had, what are other options I could have tried... Maybe lowering the front roll center? Thicker rear sway bar?

Also some more data... corner wieghed it with 1/2 tank of fuel:

FL 778
FR 784

RL 898
RR 887

Total Weight 3347 (Think it needs to diet a bit)
F/R: 47/53 (Pretty close for being stock)

I noticed while doing this that it was so sensitive everytime I placed it on the scales that some dust would change the reading, or if the suspension settled just a fraction more on one side it would skew the results +-15g, so I will have test again with solid shocks as it was just to all over the place.

The length of your camber link has nothing to do with your Roll Center. It only controls the camber angle throughout your suspension travel.

1. The short the link the greater the camber angle as your suspension compresses. Less traction

2. The longer the link the less your camber changes as your suspension compresses. More traction

So in fact, by shortening your camber link you increased your camber gain and reduced your traction allowing you rear end to break loose in the corners.

Second, by lowering your camber link you also reduced the amount of roll, weight transfer, on that end of the car and further reduced your traction in the rear.

1. The lower the link is on the tower, the less the car will roll and transfer weight, hence reducing traction.

2. The higher the link on the tower, the more the car will roll and transfer weight and increasing traction.

To sum up, your problem was off power steering which has to do with the front end of the car, not the rear. It would have been better to raise your front camber link on the tower, allowing more roll and giving you more steering. If after adjusting the front camber link and you still needed more steering, then you can make the rear adjustment of reducing the traction on the rear end. You might have liked the changes you already made, however what you really did is reduce your rear traction and are allowing your rear end to slide around corner like a drifter. It feels fast, but is not the fastest way around corners. Good luck.

Unless I've completely misunderstood everything I've ever seen, read, or been taught, I believe you have those two backwards.

Lower the link on the tower = higher roll center (more roll / weight transfer and traction, but less responsive)

Raise the link on the tower = lower roll center (less roll / weight transfer and traction, but very responsive).

No, you must have low and high roll centers confused. The previous poster is correct.

Changing the link length does change the roll center. On my Associated products, I created a CAD file that shows the roll center changes with different adjustments to link length and position at static ride height. For my AE stuff, adding a washer under the ball stud in the rear changes the roll center more than changing the link length by 1 hole on the hub carrier. The thing is, with the change in link length, you also get a different amount of camber gain on suspension movement and a different rate of roll center change (instant center) over the movement of the suspension.

Well...

I looked over and copied what had been discussed in this thread about roll centers and camber links. I understood that I was making the car slide, also this was on power mid and corner exit push that I was trying to correct. Was trying to do this without making the rear end slide in order to get the turning I wanted; however, with a change of tires that had more side bite, the slight slide I had was gone, so I know its something in the setup.

So without "drifting" or adding more mechanical steering, and given what I posted above, how can I get a little more steering mid and exit of corner without, like I said "drifting"