Bilstein B12s

[NE Marlon]

Just a quick query folks.

I recently had a new set of Bilstein B12s installed on the S3. Every changeable part was renewed with genuine VAG parts and I had the bushes changed for LCR ones. Unfortunately, I didn't have the time to do this myself so farmed it out to a VAG tech friend of mine to sort it.

Now I know suspension takes a while to 'settle' but I'm a little concerned that the fronts are sitting higher than expected. The original dampers were 95K/14 years old but didn't really have a huge amount wrong with them, they were just a little tired and I dare say had sagged by a few mm.

As I didn't have chance to see the parts to compare before it was done, I was wondering if anyone else had had the same issues and how/if they'd overcome it. It was suggested that the LCR bushes are slightly taller than the S3 ones...

Thanks in advance

 

[Gazwould]

So you've gone from stock suspension to a B12 Pro Kit ?

It doesn't look like level ground , a slight slope backwards will have the front up .

 

[Ben jah min]

The gamble of buying a fixed drop kit - risk of reverse rake :S

Could you not get just a set of front springs with a lower rating to resolve it IE if this is a 50mm kit get some 60's just for the fronts?

 

[s3_trev]

Most obvious question to ask here first is does your friend know what hes doing.

 

[NE Marlon]

Yep, stock to the B12 pro kit.

The whole point of buying the 'kit' was I wouldn't have to split it and mess around with alternatives, so I'd be reluctant to alter brand new springs.

He's a VAG master tech so I'm hoping he knows what he's doing! I trust very few other people with my cars, he's one of them.

I was just wondering if others had found a similar issue after fitting...

 

[Gazwould]

Ok they're ment to have a specified height, but the increased damping from a B6/ B8 would make it sit higher than a B4 on a Eibach Pro kit.

 

[NE Marlon]

Ok they're ment to have a specified height, but the increased damping from a B6/ B8 would make it sit higher than a B4 on a Eibach Pro kit.

Surely they would be level front to back though???

I'm not overly fussed about it being super low, I just want it to be right. I'm more than happy with the actual handling now, a more positive 'turn in' etc etc. I'd just like it to be level...

 

[tomjol]

Think the front sitting slightly higher than the rear is normal with the Eibach springs?

 

[NE Marlon]

Just have to use it as an excuse for some new 18s!!!

 

[Lavis89]

Is it actually sitting higher at the front or does it just look that's way due to the lower rear arches.

 

[NE Marlon]

I think it's a 'settling' issue...

It SEEMS to be sorting out over the days since. Give it another couple of hundred miles and we'll see

 

[Alex C]

the increased damping from a B6/ B8 would make it sit higher than a B4 on a Eibach Pro kit.

the damping force has nothing to do with the ride height. It's the springs that carry the weight of the car and the car's height is determined by the initial spring length and the spring rate (k) and where the spring perch is on the shock.

The shock absorber's job is to critically damp the spring oscillation with the damping force being inversely proportional to spring velocity; a car in a static state with 0 spring velocity means the damping force is also 0 therefore not affecting ride height

 

[NE Marlon]

That's what I figured. The car seems to be VERY sensitive to angled ground now (I'm sure that sounds ridiculous!), far more than it did on stock shocks. It seems to take the smallest amount of angle to make the car seem lopsided front/back or offside/nearside.

I guess that's down to more movement at minimal input. However, when the input is increased, either when driving or pushing down on the car, the damping seems far more. Surprisingly so actually...

 

[newbster]

I wonder if the suspension bushes were torqued up with the car still up on the lift, this will preload the suspension in the fully extended position, the "settling" is the bushes working their way back to the correct position
the bolts through the bushes should be tighten with the weight of the car on the suspension

 

[NE Marlon]

How long do you reckon this would take if they were torqued incorrectly?

 

[Gazwould]

the damping force has nothing to do with the ride height. It's the springs that carry the weight of the car and the car's height is determined by the initial spring length and the spring rate (k) and where the spring perch is on the shock.

The shock absorber's job is to critically damp the spring oscillation with the damping force being inversely proportional to spring velocity; a car in a static state with 0 spring velocity means the damping force is also 0 therefore not affecting ride height

I disagree Alex , I tend not to work off theories as life has taught me differently.



I had already fitted the Eibachlowering springs but wasn't happy with the handling using the standard SE shockers, especially on track, so bought a Bilstein B12 pro suspension kit.
This includes a set of Eibach springs and matched Bilstein B8 shock absorbers.
The springs are identical to the ones I already have on the car so will be going on Ebay in the near future.



The shock absorbers are completely different to the standard one fitted. The standard shockers take about 30 seconds to fully extend if compressed. The Bilsteins are high pressure monotube ones and I put the shocker on a scales and it requires over 30Kg of force to compress and hold the shock compressed. They have a significantly greater amount of damping than the standard shocks.
The result is when fitted the car ride height has increased by about 6-8mm front and back which is not really a major issue for me.


Post #191 http://www.audi-sport.net/xf/threads/karls-3-0-tdi-build-thread.204785/page-5

 

[Alex C]

@Gazwould so do shocks have some sort of 'preload' in them; do they have internal springs? I honestly thought they worked by pushing a plunger with a small channel in it and some shims through a viscous fluid

 

[superkarl]

but the increased damping from a B6/ B8 would make it sit higher

That's not how shocks work and not what governs height at all


Edit: and I didn't read all the replies and now realise Alex is on the ball

 

[superkarl]

I wonder if the suspension bushes were torqued up with the car still up on the lift, this will preload the suspension in the fully extended position, the "settling" is the bushes working their way back to the correct position
the bolts through the bushes should be tighten with the weight of the car on the suspension

What bushes are you referring to??

 

[Gazwould]

So why did Karl's sit 6 - 8 mm higher on Bilstein B8 dampers ?

 

[superkarl]

So why did Karl's sit 6 - 8 mm higher on Bilstein B8 dampers ?

Old vs new shocks
Oem vs completely different design shocks

 

[Gazwould]

So if he had used oe Bilstein B4 shocks he could be lower than using the shorter Bilstein B8 shocks ?

 

[newbster]

What bushes are you referring to??

the ones in the lower arm, I meant the bolts that go through the bushes.
the one at the front of the arm can impart a preload if torqued when the suspension is at full droop