adjust to softer = compromise traction?

[Shaun]

Re: adjust to softer = compromise traction?

It's been specifically said that he took the turn at triple digit speed.

If you read my reply again, you will see that I described a turn and surface that would be the exception to what I had wrote about. This sort of turn (the exception) is not taken at triple digit speeds in a street type car with street type travel and spring and damping rates (lest it pack down). So the turns and surfaces he is driving fit within the near absolute rule (for street cars) written about earlier.

 

[Shaun]

Re: adjust to softer = compromise traction?

Exceptions to damping affecting total degree of roll above are short duration small vector change turns where a car never has time to reach steady state. These are not so much turns as they are high speed kinks. Locally we don't even have these types of turns - neither PG nor SIC... well actually running race cars or extreme street-sedan-type cars (high avg. speed, high grip) 2 or 3 turns (out of 12) at PG may qualify, but still not any at SIC.

Further exception to statements on tire loading / heat would be a vehicle with a very low tire loads for a given contact patch and mass. This would require low vehicle mass, and/or low power and low downforce. Street cars (even sportscars) don't fit this set because they run relatively narrow tires and are heavy. Almost all race cars don't even fit this set because they are high powered and run more aero load and the compounds are very soft relative to street tires.

So nearly without exception tire management is always a consideration and softer damping within the range of minimum springing to prevent bottoming at highest fuel load in combination with highest aero load (if any), or excessive CG height, or excessive roll with associated forms of geometry change, helps this - keeping average grip higher, over a longer period of time - double positive.

 

[Shaun]

Re: adjust to softer = compromise traction?

more dive = less braking effectiveness? i think it doesnt as the brakes still have to stop the same amount of rotational force.. but i'm inclined to think it had a harder time as the car dived, hence more weight transfer to the front wheel?

As with degree of lateral weight transfer where CG and track width are the only factors, degree of longitudinal weight transfer is only affected by wheelbase and CG, not damping changes. Speed at which weight transfers to the front is affected by damping. The more compression damping (load receiving end) and the more rebound damping (load sending end) you have, the quicker the weight transfers and the quicker you can roll on the brakes. In a long travel low compression damped vehicle, you have to roll on the brakes a lot more.

Dive is not wanted more for reasons of suspension geometry change (eg. camber loss reducing decel. ability, roll center changes affecting balance under lateral accel. ), and pitch sensitivity on aero cars. Dive does not affect degree of weight transfer, only speed of transfer.

 

[Rastaman]

Re: adjust to softer = compromise traction?

Bro - so the jist of it is what ??? can u summarize pls

 

[adliz]

Re: adjust to softer = compromise traction?

thanks shaun.. for this, and for all your help all this while..

anyhow, u explain like u are a physics lecturer lah.. really!! unless i sit in a class, with u explaining on a white board what u r saying, i cannot compute lah..

can pls explain in simpler words? thanks shaun!!

adam

 

[TripleM]

Re: adjust to softer = compromise traction?

thanks rasta..

jack, can u not just change the springs? somehow..

Perhaps I could but then again, who makes the proper fit for PSS9 coilover ?
I dont want to mess ard with it. Besides, PSS9 springs are progressive springs. I prefer the constant type like GC and TCK set ups.

 

[Shaun]

Re: adjust to softer = compromise traction?

Simple words... bodyroll and dive have next to nothing to do with weight transfer.

============

You can't go with intuition on these things, neither can you go with popular press, or press releases and magazine articles all designed to make quick money.

The other thing is that the mechanical efficiency of a car will always reflect the detail and accuracy of the information and processes it was put together with. You can drop 2 seconds of laptime with 10K, or you can drop 10 seconds with 2K worth of equipment. You just
cannot jist your way into anything good.

 

[chickenbackside]

Re: adjust to softer = compromise traction?

Stiff springs and/or damping aid driver confidence via speed of response to inputs, and confidence alone can yield speed within the physical limits of that setup, but talking strictly in terms of grip (the physical limit), there is almost always a reduction as stiffness increases. Building confidence and ability to control a softer car is tougher but yields the best speeds by providing the most average grip through a turn or round a track. The physical limit here is higher, and all that's left is for the driver to build confidence based on true ability to manage the car.

This coincides with a comparison of lap times between a set of Koni coilovers and a set of Koni FSD's with Koni springs installed on identical cars (BMW 330) driven by the same driver. I read the comparative review somewhere on the net when I was researching for suspension upgrade options.

The review said that although the Koni FSD's (standard non-adjustable damper) rolled the car around more, the lap times were actually significantly quicker than the coilovers set on a hard setting.

 

[DreamDriver]

Re: adjust to softer = compromise traction?

Simple words... bodyroll and dive have next to nothing to do with weight transfer.

Ok I'm confused. I read your earlier post and you seemed to say that in dive and bodyroll, the AMOUNT of weight transfer remains constant (with CG, track width and wheelbase held constant), but just that the RATE of weight transfer is changing (i.e. higher rate of transfer = less roll/dive). Then now you say these have next to nothing to do with each other? Would you be able to clarify a little?

 

[adliz]

Re: adjust to softer = compromise traction?

You just
cannot jist your way into anything good.

understood, but as a rule of thumb (for the exact same car) wud these be true?

1) bigger tyre, better traction.. but more straight line drag?
2) harder springs, less roll?
3) harder abs, faster and sharper recovery?
4) wider track and longer wheelbase is better in weight distribution, hence more neutral handling?

I accept that it's not easy to achieve the 'perfect / right' setup, but surely there's a clear guideline on the basic fundamentals?

 

[Shaun]

Re: adjust to softer = compromise traction?

Ok I'm confused. I read your earlier post and you seemed to say that in dive and bodyroll, the AMOUNT of weight transfer remains constant (with CG, track width and wheelbase held constant), but just that the RATE of weight transfer is changing (i.e. higher rate of transfer = less roll/dive). Then now you say these have next to nothing to do with each other? Would you be able to clarify a little?

Next to nothing to do with weight transfer in the context that many look at degree of roll or dive and think that weight transfer must by large, when in fact they should be looking at track, wheelbase, and CG to find that.

If you want you can disregard that confusing statement since it involves subjective "next to nothing". We can keep it simple and leave the distinction between amount of weight transfer, and rate of weight transfer.
====

Chicken, it is possible to go soft too, but most enthusiasts go too stiff especially on street driven cars.

 

[Shaun]

Re: adjust to softer = compromise traction?

understood, but as a rule of thumb (for the exact same car) wud these be true?

1) bigger tyre, better traction.. but more straight line drag?

Bigger tire doesn't necessarily lead to better traction or more straight line drag.

Bigger tire doesn't automatically mean larger contact patch. If and how the contact patch grows dpeneds on tire construction, rim-to-tire-width ratios, inflation pressures and camber setting.

Bigger tire generally means wider but shorter contact patch, which is generally good for steering speed, and lateral grip, not necessarily traction (longitudinal grip, straight accel.)

The wider and more square a tire is, the more sensitive it is to camber setting. Again this depends on factors listed in line 2 above.

2) harder springs, less roll?

Yes

3) harder abs, faster and sharper recovery?

Abs?

4) wider track and longer wheelbase is better in weight distribution, hence more neutral handling?

Wide track and long wheelbase reduces sensitivity to mass placement affecting weight distribution and reduces dynamic weight transfer. By themselves they don't have anything to do with weight distribution. You can have a really long and wide chassis, yet it you place the engine, transmission, gas tank, and driver in the front left quadrant of it, you're still going to end up with a very unbalanced car.

I accept that it's not easy to achieve the 'perfect / right' setup, but surely there's a clear guideline on the basic fundamentals?

Yes, you can pick up the basics from books by Carroll Smith, Paul Van Valkenburg. If you can, find articles by Peter Elleray, Mark Ortiz.

 

[kurqa]

Re: adjust to softer = compromise traction?

Shaun>> are you even human??? youre virtually a walking wikipedia! RESPECT.

 

[Shaun]

Re: adjust to softer = compromise traction?

Kurqa, if it's what one does for a living, one better have it down to some degree, at some kind of depth. In any case, outside of those who do not exert even base level effort, almost always strength in one area means weakness in another. Even apparent exceptions can't be confirmed because there are more intelligences than a single group or individual (even those at the peaks) can define, assign importance to, or identify in an individual. Inability to prove anything will lead the weak to hide in that fact and stagnate, whilst the driven keep striving - even if it is entirely private and personal.

=====

]3) harder abs, faster and sharper recovery?

Just figured out you meant ARBs. By itself it has nothing to do with recovery since it will resist roll from the very start. Although now rebound involves inner wheel rebounding along with to greater degree because of stiffer couple (bar), the inner wheel shock is still adding its rebound damping to it, also because of couple.

In the case of pure spring change leaving the dampers as they were, you are not changing compression to rebound damping ratios. What you are doing though, is increasingly taking the dampers out of the equation. The effect is underdamping since you are putting more energy into the springs due to lack of compression damping (from reducing damper shaft speeds [stiffer springs - imagine a pure strut]), and then on the rebound (recovery), you are still underdamped and alot of that energy is returned. Recovery indeed will be fast and sharp, but to the point of upsetting the car. You end up reducing roll but tend towards overwhelming the outer wheel damper since the inner one is not forced to work harder along with it, unlike with the ARB solution.

You always have to match dampers. If you are happy with how the car handles as it is except for roll recovery , then you can leave both bars and springs the way they are and adjust (reduce) low shaft speed rebound damping by adjusters (if they still have adjustment range) or valving (send to manufacturer) if either is an option with whatever damper you currently run.

 

[adliz]

Re: adjust to softer = compromise traction?

no, i really meant abs as in stomach!! hehe.. u r right, arbs.. thanks for all the explanation, tho ill have to really re-read everything to really imagine what u r saying..

anyways, for all these variables, can u pls summarised which wud be 'better' for handling, simply by considering them independantly (no combination and effect with another)

1) tyres width
2) tyres profile
3) suspension hardness
4) spring hardness
5) spring height
6) arb's thickness/tightness
7) strut bar thickness/tightness
8) rims and tyres weight

others, pls feel free to add any other common variables re your suspension setup.. cheers!

 

[Shaun]

Re: adjust to softer = compromise traction?

anyways, for all these variables, can u pls summarised which wud be 'better' for handling, simply by considering them independantly (no combination and effect with another)

1) tyres width
2) tyres profile
3) suspension hardness
4) spring hardness
5) spring height
6) arb's thickness/tightness
7) strut bar thickness/tightness
8) rims and tyres weight

others, pls feel free to add any other common variables re your suspension setup.. cheers!

They're all connected in real life. Separating them means too much qualifying to be done and will require too much time. Best you read some books.

The only ones that are fairly straightforward are strut bars and rims. You always want the lightest, strongest, and stiffest ones. Everything else is too dynamic.

Sorry and cheers

 

[Racebred]

Re: adjust to softer = compromise traction?

street adjustable coilovers set for a harder setting will definitely wear out faster than if set softer. so if u want it to last longer, dont set at the hardest setting if u dont need it.