Suspension

[Lamprey]

Hi Gang,

I’ve a bit of a novice when it comes to suspension, but I’ve been going to a bit a research and I’ve learned a fair amount.

A couple of thread is particular were/are very helpful for me:
http://audirevolution.net/forum/index.php?topic=2796.0
http://audirevolution.net/forum/index.php?topic=2669.0

I’m looking to upgrade my suspension a little bit. As background I have a 2013 S4 with ADS and sport diff. I’m going to keep the stock dampeners (at least until someone come out with an adjustable set that plugs into the Audi and I can adjust with the stock Audi controls). I don’t plan to track the car.

My goal is to reduce the “push” (Hopefully, that is the right term) on corner entry and reduce body roll.

My plan, for now, is to start with some Eurocode items: Alu Kreuz, Sways and, maybe, the end links (not 100% sure if I need those).

That leads me to springs. I don’t have a great desire to lower my car, perhaps an inch or so, if at all. Naturally, with ADS the popular springs are the KW HAS. However, in my readings, it appears that the KW HAS rear springs are softer than the stock springs.

Assuming that is the case, would that increase the “push” affect I’m trying to reduce? That is my understanding from what I’ve been reading. But, that’s where I’m turning to some more knowledge people to help me understand or, at least, validate my assumption. I realize, that suspension is a multi-faceted game with trade-offs at every turn (no pun intended). Perhaps, the sways help counter act the softer springs? As you can see I’m a little overwhelmed. So, any advice or insight would be appreciated!

Cheers!

[drob23]

First step in my opinion is absolutely bars + links. You will be directly affecting the roll stiffness, and by changing the settings from front to rear, you move the understeer gradient up or down (but effect your ultimate grip). Negative effect is your “head toss” will be worse, because any travel on one side of an axle will be less isolated…so you’ll feel it.

Changing springs but keeping stock ads system (what I’ve done) can have a pretty big hit on ride comfort. The only big beit of lowering springs is you move the cg closer to the roll center, implying the car will roll less under similar lateral acceleration. But if you really wanted to do this right, I’d say fully adjustable suspension like pss10, kw v3 or h&r ss coilovers would be nice. You can also change handling by changing static alignment.

[Lamprey]

First step in my opinion is absolutely bars + links. You will be directly affecting the roll stiffness, and by changing the settings from front to rear, you move the understeer gradient up or down (but effect your ultimate grip). Negative effect is your “head toss” will be worse, because any travel on one side of an axle will be less isolated…so you’ll feel it.

Changing springs but keeping stock ads system (what I’ve done) can have a pretty big hit on ride comfort. The only big beit of lowering springs is you move the cg closer to the roll center, implying the car will roll less under similar lateral acceleration. But if you really wanted to do this right, I’d say fully adjustable suspension like pss10, kw v3 or h&r ss coilovers would be nice. You can also change handling by changing static alignment.

Thanks for the feedback!

You mentioned in another suspension thread about the S4 plowing into corners (slow-entry, fast-exit). I’m trying to reduce that, but I’m leery that the KW HAS springs would make that worse. I’m I right that, assuming the KW HAS has softer rear springs, that that will exacerbate the problem?

[drob23]

Sounds like something Boro said…Lol

The ads spring in the rear also has a small spacer there. The rear sway bar is extremely small on the ads cars…I believe to allow for a big deference in feel going from dynamic to comfort.

But yea I’m no expert of changing springs in relation to high speed handling…however, changing the rear spring to something softer will most likely have an effect on ride. You want the rear to be stiffer than front (factoring motion ratio) to maintain the proper up/down and pitch movement when driving over bad roads. I believe some off the “bouncy” complaints have to do with this when going to aftermarket springs/dampers.

[Lamprey]

Doh, maybe it was Boro. ;D

At any rate, I appreciate the info!

[westwest888]

The first thing I would do to eliminate push is alignment. Get adjustable upper control arms and dial in the front camber and caster. The Alu Kreuz seems to stiffen up the feel. I thought the sways had a minimal effect, before and after.

[PsYkHoTiK]

The first thing I would do to eliminate push is alignment. Get adjustable upper control arms and dial in the front camber and caster. The Alu Kreuz seems to stiffen up the feel. I thought the sways had a minimal effect, before and after.

That’s a great recommendation.

A good alignment can help sort some stuff out. A set of adjustable upper control arms can also allow the setup to be dialed in further (if changes are needed beyond the stock arm’s ability).

Alu Kreuz increases turning response - not sure if it does anything for under steer.

Also, tires too (all seasons or squishy winter tires will definitely under steer).

Also, driving technique is another thing that can help alleviate under steer (changing a certain set of inputs). Driving schools are great for that (car control clinics). You don’t even have to track it - but the temptation might exist. It’s not a fix for mechanical grip, but it does wonders too…

[Lamprey]

The first thing I would do to eliminate push is alignment. Get adjustable upper control arms and dial in the front camber and caster. The Alu Kreuz seems to stiffen up the feel. I thought the sways had a minimal effect, before and after.

Damn more to research.

Is there a (general) recommended amount of camber/caster for the B8.5 S4, other than factory specs?

[Lamprey]

Also, tires too (all seasons or squishy winter tires will definitely under steer).

Also, driving technique is another thing that can help alleviate under steer (changing a certain set of inputs). Driving schools are great for that (car control clinics). You don’t even have to track it - but the temptation might exist. It’s not a fix for mechanical grip, but it does wonders too…

I still have the stock (conti) tires. I only have 13k miles the car, but probably going to get some new ones in the next couple of months (PSS mostly likely). So, I’m hoping that’ll help with the overall feel a bit.

Good point about technique. I might have to hook up with a buddy of mine that races and teaches to get some lessons about how I can drive a quattro better.

[westwest888]

The first thing I would do to eliminate push is alignment. Get adjustable upper control arms and dial in the front camber and caster. The Alu Kreuz seems to stiffen up the feel. I thought the sways had a minimal effect, before and after.

Damn more to research.

Is there a (general) recommended amount of camber/caster for the B8.5 S4, other than factory specs?

Read through our whole B8 suspension thread: http://audirevolution.net/forum/index.php?topic=2796.0

[boro92]

First step in my opinion is absolutely bars + links. You will be directly affecting the roll stiffness, and by changing the settings from front to rear, you move the understeer gradient up or down (but effect your ultimate grip). Negative effect is your “head toss” will be worse, because any travel on one side of an axle will be less isolated…so you’ll feel it.

Changing springs but keeping stock ads system (what I’ve done) can have a pretty big hit on ride comfort. The only big beit of lowering springs is you move the cg closer to the roll center, implying the car will roll less under similar lateral acceleration. But if you really wanted to do this right, I’d say fully adjustable suspension like pss10, kw v3 or h&r ss coilovers would be nice. You can also change handling by changing static alignment.

+1 on sway bars.
It was a dramatic difference to the handling of the car. I review it here: http://dreamingin302ci.blogspot.ca/2015/04/eurocode-swaybar-set-review.html

Regarding roll center - not quite. If you lower the car, the roll center drops along with the CG. And the roll center drops more than the CG change does - so any time u lower a street car, you actually make the car geometrically softer & increase the tendancy for the car to roll. The only thing to combat this is spring rate/sway bar/bump stiffness on the shock. A proper suspension setup will have a stiffer spring rate to compensate for this geometric change, however.

If you do not want to drop it, I say don’t drop it. Put the sways on first and enjoy. You’ll find that the car is a different animal with the sways.

West nailed it with the camber arms - though if you are not hitting the track, not necessary. Change the toe.
Try 0 front toe, and if u dont like that, go for 1/8th toe out up front. Both will will make the car turn in much better.
The stock tires are also junk, as the sidewalls are too soft. This isn’t helping the car respond to steering input. Moving to PSS won’t improve this, as PSS is also a soft sidewall. If you are serious, look at a better (more track oriented) tire. AD08, Z2, RE71R, RS3 et al.

[drob23]

Here’s a nice chart, which defines turn in response

http://images.tapatalk-cdn.com/15/05/01/5c7e0dac8be8ae777fec8170f68e429c.jpg

[notarmed]

I had the same car same spec. I tried out the three basic systems out there.

H&R Lowering Springs
Stasis Ohlins non adujustable coilovers
Bilstein PSS10 coilovers

If I were to do go back in time, I would have just installed H&R springs, adj. control arms, wheels/tires and stopped there.

Be aware that adding a lowering spring on the ADS system will cause premature failure. They are not cheap. Pay to play.

[Lamprey]

Awesome information, much appreciated! I guess I’ll be doing some more reading.

Thanks again!

[westwest888]

I’ve had passengers remark how stiff the sidewall feels on my Pilot Sport Cup 2. It’s harder to notice when you have the comfort of holding the wheel.

[drob23]

First step in my opinion is absolutely bars + links. You will be directly affecting the roll stiffness, and by changing the settings from front to rear, you move the understeer gradient up or down (but effect your ultimate grip). Negative effect is your “head toss” will be worse, because any travel on one side of an axle will be less isolated…so you’ll feel it.

Changing springs but keeping stock ads system (what I’ve done) can have a pretty big hit on ride comfort. The only big beit of lowering springs is you move the cg closer to the roll center, implying the car will roll less under similar lateral acceleration. But if you really wanted to do this right, I’d say fully adjustable suspension like pss10, kw v3 or h&r ss coilovers would be nice. You can also change handling by changing static alignment.

+1 on sway bars.
It was a dramatic difference to the handling of the car. I review it here: http://dreamingin302ci.blogspot.ca/2015/04/eurocode-swaybar-set-review.html

Regarding roll center - not quite. If you lower the car, the roll center drops along with the CG. And the roll center drops more than the CG change does - so any time u lower a street car, you actually make the car geometrically softer & increase the tendancy for the car to roll. The only thing to combat this is spring rate/sway bar/bump stiffness on the shock. A proper suspension setup will have a stiffer spring rate to compensate for this geometric change, however.

If you do not want to drop it, I say don’t drop it. Put the sways on first and enjoy. You’ll find that the car is a different animal with the sways.

West nailed it with the camber arms - though if you are not hitting the track, not necessary. Change the toe.
Try 0 front toe, and if u dont like that, go for 1/8th toe out up front. Both will will make the car turn in much better.
The stock tires are also junk, as the sidewalls are too soft. This isn’t helping the car respond to steering input. Moving to PSS won’t improve this, as PSS is also a soft sidewall. If you are serious, look at a better (more track oriented) tire. AD08, Z2, RE71R, RS3 et al.

Great review as always! I stand corrected on the motion ratios, interesting stuff. Funny how dramatic the difference was to you while west said they had minimal effect. I’ve never tracked the car without them, but I found the rear bar swap made a remarkable difference for street driving.

[westwest888]

I set the sways to soft/soft. I suppose I could try stiff/stiff in the future. I did this to try to minimize emergent behaviors at the limit.

[boro92]

I set the sways to soft/soft. I suppose I could try stiff/stiff in the future. I did this to try to minimize emergent behaviors at the limit.

Sent from my iPhone using Tapatalk

You shouldn’t need to compensate with big bars with your current setup any longer, unless you front rates are still soft (under 600lbs on this car is pretty soft).
With your rear springs, you probably want to keep the bar on soft, if not remove it all together.

[westwest888]

I set the sways to soft/soft. I suppose I could try stiff/stiff in the future. I did this to try to minimize emergent behaviors at the limit.

Sent from my iPhone using Tapatalk

You shouldn’t need to compensate with big bars with your current setup any longer, unless you front rates are still soft (under 600lbs on this car is pretty soft).
With your rear springs, you probably want to keep the bar on soft, if not remove it all together.

This makes sense. Perhaps I will try stiff front.

[boro92]

West,

I seem to recall you drilling shock towers to allow for on-car rebound adjustments.
I too have drilled my front shock towers.
However, for the rear…where were they drilled? Do you have pics for reference?
I was peeling away the truck liner but thought I should stop before I take it all apart…