Audi A4 Suspension Upgrade

Hello,

I could use your help.

Yesterday, my brother and I tried to modify the suspension on my dad's A4 2.5 TDI (model 2000, sedan).

He bought a suspension system from an S4 and wanted us to install it for him.

However, we are not sure if it will fit. It is from a 2000s S4 sedan.
Does anyone know if this is a good fit? / Does anyone know if this works?

Second problem: While we've already converted suspension systems on some cars (Golf II & III, Toledo, Audi coupe), we have no idea how to do it on an A4. Does anyone have a guide or instructions for this?

First, we couldn't remove the set screw on the upper control arm assembly (it seems to be stuck); second, the screw at the bottom of the shock absorber won't come out because it's hitting the rear suspension. Why isn't this screw accessible from the front? The front is clear... That Mr. AUDI is crazy...

Unfortunately, we have no idea whether we are even on the right track.

I would appreciate any tips you can offer.

I didn't find anything relevant using the search function.

Regards,
Nick (A4 2.5 TDI)

Here you will find instructions:

http://home.arcor.de/turboschubser/Fahrwerkseinbau/Beschreibung.htm

If the A4 2.5 TDI model from 2000 is not a Quattro, the suspension from the S4 will not fit. The rear axle on the S4 and Quattro models is completely different.

Regards,
Thomas.

Thank you, Thomas...

With the help of this guide, it should be possible to do it; however, we no longer have a chassis that we can install.

The shock absorbers from the S4 should fit on the VA (front axle).
Question: Would it make sense to buy two new rear shocks and use the springs from an S4? Is there a difference between the springs from an A4 and an S4?

Regards,
Nick.

What's going on? Does nobody have a clue?

I've already figured out which abbreviation on the type label in the trunk refers to the suspension.
1BA = Standard Forwarding.
1BE = Sports-FW
1BB = Enhanced Forwarding.

My dad's car has a 1BE engine, which means it's a sporty front-wheel-drive model.

Now I'm wondering, what's actually inside the S4???
Are the feathers actually stronger?
Would the springs fit, considering there's no Quattro?

I'm grateful for any advice you can offer.

Regards,
Nick.