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Old 10-08-2003, 12:31 PM   #31
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Okay, a kind of summary:

1: Simplicity! Eliminate as many parameters as possible.

2: Use the stiffest springs possible, without sacrificing grip, and without the car jumping over eventually bumps.

Starting point:

Tires, track and motor/gearing (=brake, which affect weight transfer) are given.

I've choosed to start out with a one-way diff - even though I might regret it later - but the goal is to find a proper setup with a one-way, rather than re-work a traditional-diff-setup.

Loosen down travel screws and use light shock oil. Dismount anti roll bars.

All other settings in stock position.

Now find the spring combo.

And then comes the tricky part: I like running anti roll bars.

Take a car with a certain spring rate. Now take some softer springs and add anti roll bars, so the roll is close to the setup with the harder springs. I find this makes the car more predictable.

There is a couple of bumps on our track, but they are 90 degree to the driving direction, so the front wheels will hit them at (almost) the same time.

So the tricky stuff: Should I add the proper shock oil or the proper anti rol bar first?

Gotta think about that...
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Old 10-08-2003, 12:49 PM   #32
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One more question: How big/small differences do you guys find appropriate in front/rear springs? With and without one-way?
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Old 10-08-2003, 01:37 PM   #33
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Cole Trickle;

In general, you will find that softer Springs are needed when switching over to a Front One-way.

My suggestion should be a good basic starting point for either, but is based on Asphalt experience. For Carpet, I am assuming better traction, so a change to a stiffer all around set-up may be needed.
Remember as you go stiffer with the Springs, they now have more energy/force to overcome the Oil dampening, so a change to thicker oil might be nessesary.

Problem with the HPI Swaybars is that they are not very effective when compared to some other Brand of Cars.

Anyways, follow your current plan for a set-up as it seems to be sound. Then we can work on the little things one at a time.

Last edited by popsracer; 10-08-2003 at 07:43 PM.
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Old 10-08-2003, 05:05 PM   #34
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Quote:
Originally posted by Cole Trickle
Hi sosidge

I dont understand this example?
To quote from your own setup - you say a #3 piston and 60 wt is equal to a #5 and 80wt.

Now, by the "10wt per piston" theory, if you had #3 piston and 30wt, it would be the same as #5 piston and 50wt.

BUT we can see that, since 30wt is half 60wt's viscosity, for the damping to be the same in the second example, you would need a #5 piston and 40wt.

Your summary of "simplicity" is a good one - but also stick to changing one thing at a time. If you find a good setting with springs only, DON'T fit anti-roll bars and a softer spring at the same time to compare - fit the anti-roll bars only, then you will know their effect alone (in fact, fit the anti-roll bars one at a time, not both straight away).
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Old 10-09-2003, 12:49 AM   #35
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Good point about sway bars and one thing at the time.

Plan is to start out with piston #5/50 wt oil all around. Green springs (480) front, red (432) rear.
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Old 10-10-2003, 12:38 PM   #36
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The wheel rate thing

Okay, I tried pressing front and rear seperately by hand; Felt quite similar. So I tried placing big soda bottles with water on front and rear respectively. The front required 1425 grams, to be pressed accurate enough to touch the ground. The rear required 1230 grams.

Now, a little dividing:

Front: 1425 / 2 (each spring). Next divided by 6 mm ride hight. 119 g/mm.

Rear: 1230 / 2 / 6 = 103 g/mm.

If it can be done this way (I cant see why not), then front and rear are pretty close to each other.

So the experiment should be to set downtravel to 3 mm and the rear camber link to stock position, and see what happend. To ensure, the total system is not overdamped, shock oil could be set to piston #5 + 50 wt oil.

There's just one little thing, that is a torn in the eye: Dr. Diff's spring suggestion (approx. 298+351) was way closer to each other than mine 480 gF/mm and 272 gF/mm.

Comments are appreciated.
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Old 10-10-2003, 01:04 PM   #37
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By the way, I've checked a lot of old Pro2 setups. Some are quite difficult to understand, since they are described with "HPI Green springs" and HPI Yellow springs". Today, there's 3 greens springs and 4 yellows in the HPI program. However, setups with equal springs front and rear were well reprensented. On the other hand, setups for carpet and rubber tires, went from gold springs (147gF/mm) to purple (670gF/mm) (not on the same car ), so there's no clear figure in which area the springs should be. So I'll stick with the "as-stiff-as-possible-idea" !
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Old 10-10-2003, 06:50 PM   #38
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Cole Trickle;

Even in the Days before the Pro-linear Springs I alway kept no more than 1 step difference between the Front and Rear. With the new Springs the rates are even closer together, so this is better yet.

I helps too, when you have at least one each of all the relevant Springs in your Pit Box.
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Old 10-13-2003, 02:18 PM   #39
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Default More wheel rate thing

Preparations almost finished; Piston #5/50 wt oil all around. Green springs (480) front, red (432) rear. Sway bars removed. Just need to change rear camber links, re-adjust ride hight, camber and toe - do it at the track, where the setup system is.

Plan is changed slightly: One-way diff is replaced with a graphite ball diff.

The rear definately feels harder than the front by know.

Anyway, I look forward to try it out.
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Old 10-13-2003, 08:42 PM   #40
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Default Piston #5/50 wt oil all around

Cole Trickle;

What is your reasoning behind the #5/50 wt set-up?
This is going to be like having 200 wt Oil in the Shocks with #3 Pistons

If the Green/Red Spring combo is too stiff, put the REAR (Red) Springs on the FRONT and the next step softer Spring back on the Rear until you come up with a workable set-up.
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Old 10-14-2003, 05:18 AM   #41
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Yep, this spring change method, is excatly what I'm going to do.

There's several reasons for the piston/shock oil setup.

The main idea, is to use a shock oil, which is too soft. This is for simplification, so I see the springs result, and nothing else. I dont want to choose a wrong spring, as a result of overdampning.

Next reason: There's some bumps in our track, so I use piston #5, to avoid packing.

Last reason: My shock oil collection is Associated, in 50, 60, 70 and 80 wt.
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Old 10-14-2003, 12:40 PM   #42
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Default Hey popsracer;

I got your mail:

"You know your Car/Track better than I do, but I think you will be happier by starting off using a HPI #3 Piston all around. With 45-50 wt oil, this should be a very good starting point for Carpet."

I dont expect the 50wt/piston #5 should work. Plan is to find a proper spring combo, afterwards I will use thicker and thicker oil to find a good combo.

One problem about oil wt, is that not two brands are equal.

Chances are that I end up with what you suggested, but at least I try out a kind of method to find the proper spring/oil combo. So there's two purposes: Find a good steup for my car/me/the track, and maybe find a method to setup a car in general.
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Old 10-14-2003, 01:50 PM   #43
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Default Cole Trickle;

Could you hurry it up so you can let us all know how things worked out !
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Old 10-14-2003, 05:21 PM   #44
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Some of the previous posters are right on with the returning the car to a more balanced setup. I saw a little on pack and may have missed any comments on camber links.

Here goes:

Specifics on pack:

If you take a fluid dynamics class and read up on what a reynolds number is, you'll get the real answer. Short one is that smaller holes on the piston will make the effective damping rate much higher at faster rates of shock compression. The smaller the holes, the sooner this happens. The bigger the holes, the faster the shock needs to compress before it packs. If your car bounces on the high speed sections, but is good at low speed, increase the oil weight and go to bigger piston holes.

Camber links:

It always amazes me how much an impact one hole away change will make the the performance of the car. Essentially the end with the longer link will want to roll more and transfer more weight, hence more grip. This is why you needed to have a much heavier rear oil then front. To slow down this weight transfer.

A more angled link will limit the amount of body roll, and will make that end transition faster. It will have more initial grip becuase it will lean over faster, but will tend to not lean as far. So that end will have less grip once the car has settled down in mid corner.

Playing with both front and rear camber links will alter where in the turn which end has more grip and how fast the grip comes on and leaves. This assumes that all of your other settings are ideal. Typically camber link changes is the last thing you want to do. Get tires, sauce, damper rate, damper location, damper angle, droop, spring rate, ride height, toe, kick, anti-dive, roll bars, weight balance, chassis tweek, motor gearing, caster and camber right first, then do camber links last. (did I miss anything? LoL)

I suggest you return your camber links to the recomended factory setting and get the springs and dampers right first. Don't forget the other basics too.

Sands
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Old 10-15-2003, 05:48 AM   #45
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Quote:
Originally posted by sands
If your car bounces on the high speed sections, but is good at low speed, increase the oil weight and go to bigger piston holes.
This is excatly what I experienced, and therefor I use heavier oil and higher piston number.

Quote:

Camber links:

I suggest you return your camber links to the recomended factory setting and get the springs and dampers right first. Don't forget the other basics too.

Sands
Yep, that's the plan.

In addition, I find that changing camber links, change the handling a lot. In this point, I find the Pro2 has too little adjustment options. That's a demand for my next car....
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