General thoughts on rebound,alignment and ackerman?

[Zwaf]

Well, recently got installed Koni dumpers with rebound adjustment. So far I'm pleased with results but still wanna to understand better what is the egsact after effects when changing rebound.

Here is my thoughts:

-When you increase rebound (make it harder) your dumper slows down in extension and put more control on spring oscilation.
That can control bouncing of the vehicle and after that can improve handling.

But! How does affect on grip?

-To stiff rebound can slow down the spring to a degree when your wheel don't manage to reach the ground after several road bumps = loosing tire contact/no grip.
-To loose rebound allows the spring to bounce off to a degree when whole car bounce up = loosing tire contact/no grip.

Am I missing something or I'm completely off the track?

Next thoughts is about suspension geometry:

Having alignement done and man managed to set all parameters intoo "green" errior despite lowering and spacers.
I sensed after installing spacers car is somewhat slower in reaction with steering wheel. I got two concerns:

-Does spacers affect Akerman effect? If so, in what manner? Is my feeling about slower reaction on steering wheel somewhat connected with changed akerman?

-Does spacers affect active camber (when on full lock) and how? Increasing it or decreasing?

Copy/paste for initial explanation of Ackerman:
Ackerman is the term used to define the steering geometry where the inside tire needs to turn tighter than the outside tire. This allows both tires to roll around a common point in a corner or curve.

Hope my english is good enough to clear out what I wanna know and hope it is not dumb questions!

 

[HDi fun]

You're not at all off track mate. Suspension setup is always based upon a suite of compromises. Firmer damping is something that appeals to me. I like it. Lower ride height is not always better than standard. Though using progressively wound springs the results can be good.

I am not a fan of overly stiff roll bars. All these do is reduce the lateral independence of the suspension. Thus compromising ultimate grip and steering feel.

 

[Zwaf]

You're not at all off track mate.

Thanks! Got no experience, but trying to think logically having in mind common known physics.

...Firmer damping is something that appeals to me...

You mean dumping in general, or you are talking about rebound? Quite now I'm more interested in rebound control because that is what I can change with my Koni's.

...Lower ride height is not always better than standard. Though using progressively wound springs the results can be good.

I see logic in that! In one hand you can go to low for unperfect road conditions, and in other hand you change angle of your "shoulders". (don't know egsact word. Hope you can imagine "shoulders" on which" entire front lies). Also you can not avoid messing the suspension geometry.

I am not a fan of overly stiff roll bars. All these do is reduce the lateral independence of the suspension. Thus compromising ultimate grip and steering feel.

Thank you for mentioning that! I was contemplating about roll bars and all I could conclude without practical proficiency is why would someone try to cancel independency after ingeneers put the effort to make oure suspension independent. Steering feel doesn't come to my mind at all! Good to know!


- What about my Ackerman suspicions and active camber suspicions posted in initial post?

 

[jarrus]

Hmmm, my 306's front suspension is bouncey, I have the same shocks so maybe I need to firm them up a bit, however this means dismantling the whole strut....not something I fancy doing again....

Are all of your suspension bushes ok? When my ball joints went my steering was unresponsive and sloppy, maybe check those, also make sure you tyres are inflated to the correct pressure.

 

[Zwaf]

My front dumpers can be set without dismantling, but rears need to be of the car for adjustment. So i understand what you mean - me to need to adjust rear ones soe more.
In my guessing if you got bouncy behavior it means that dumpers do not entirely control your springs when they moving upwards or in other words they let them to oscilate. If you make rebound harder you will slow down upward movement and therefor put the oscilations under control. If you add to much firmness you can experience situation when your wheel wont reach road surface quick enough and sense it like sliding cause of no grip - understeer if we talking about front suspension. If that hapens just pull of a little rebound on your dumper and you should be there. Without bouncing and suspension fast enough to cope with road unregularities.
.............

My bushes are good, some of them are new. Other parts are also in great condition.
My questions is in form to fill out blankness in common understanding what hapens with active camber and ackerman angles when you put spacers in equation. My initial feel is steering is somewhat slower (but not to a degree i can not recognise my car anymore) and in other hand i can fell car leans on outside wheel with some more confidence.
I am trying to avoid common trap called confidence sense - when you got wider, lower and stiffer suspension you got more confidence to drive fast. Pretty good in declaring what is grip and what is handling and what is steering. I am aware manny call that just handling, but to me it is 3 different things.
About tire pressure you ara certainly right. Gains with proper choosen front and rear tire pressures should be pronounced.
Right now I still experimenting with pressures.

 

[Prince]

Spacers shouldn't affect the camber because they are hubcentric (meaning they sit flat against the hub).

In terms of how stiff the damper/shock is think of it like this. Track cars use stiff setups because they don't have to cope with speed bumps or pot holes. The firmer the ride, the more uncomfortable normal roads can be (trust me on this!) which is why road cars tend to have softer settings.

ARBs will again stiffen things up and allow less roll in the corners, but you can gain a compromise with these by fitting adjustable ones.

If you want more steering wheel response then up the castor a little. This should increase cornering speeds.

 

[Zwaf]

Spacers shouldn't affect the camber because they are hubcentric (meaning they sit flat against the hub).

I think when you make you're arm longer and don't change the point where the arm is atached, object on the end of that arm will change its angle to the ground.

In terms of how stiff the damper/shock is think of it like this. Track cars use stiff setups because they don't have to cope with speed bumps or pot holes. The firmer the ride, the more uncomfortable normal roads can be (trust me on this!) which is why road cars tend to have softer settings.

Of course!

ARBs will again stiffen things up and allow less roll in the corners, but you can gain a compromise with these by fitting adjustable ones.

Manny report increased understeering with firmer Front ARB, than they cure that up with adding rear ARB. I do not know does ARB increase or decrease grip? I mean, people put the balance in cars behavior, but is that balance result of increasing grip on problematic side or decreasing grip at oposite side?
Manny diff opinions around the net about that and I can not make conclusion without a doubt what is what.

If you want more steering wheel response then up the castor a little. This should increase cornering speeds.

So, with more castor wheel responce will increase? Can you tell me does castor impact on initial steer? In other words, around center point of steering wheel I got somewhat slower and undefined steering feel (range between 11 and 1 o'clock). When further adding steering - things improve themself. Can castor make some difference here?

 

[Prince]

I think when you make you're arm longer and don't change the point where the arm is atached, object on the end of that arm will change its angle to the ground.

Again, because the spacer is hubcentric and sits flat against the hub the camber will not change. It's effectively the same as just putting a wheel on.

Many report increased understeering with firmer Front ARB, than they cure that up with adding rear ARB. I do not know does ARB increase or decrease grip? I mean, people put the balance in cars behavior, but is that balance result of increasing grip on problematic side or decreasing grip at oposite side?
Many diff opinions around the net about that and I can not make conclusion without a doubt what is what.

ARBs are basically a bar (like a strut brace). The thicker the bar, the stiffer the car becomes. If you fit an uprated ARB to the front, then you should do the same at the back to keep the balance. I would go with an adjustable setup so you can alter it to your own preferences because not everyone likes such a stiff setup. You can also experiment with what suits you.

So, with more castor wheel responce will increase? Can you tell me does castor impact on initial steer? In other words, around center point of steering wheel I got somewhat slower and undefined steering feel (range between 11 and 1 o'clock). When further adding steering - things improve themself. Can castor make some difference here?

This explains it better than I can (but also means you need adjustable top mounts): See here.

 

[Zwaf]

Thank's Prince!
Apreciate your time and will to explain!:idea:

 

[Prince]

Thank's Prince!
Apreciate your time and will to explain!:idea:

Quite alright mate! We're all learning.