Rough ride on new suspension - biggest contributor?
 

Around 5,000 miles ago, I did a full rebuild of the suspension:

Bilstein B6 shocks
Front and rear H&R Sway Bars
H&R Sport Springs
15mm ECS Tuning wheel spacers
New control arms, tie rod ends, spring perch bumpers
Aleu Kreutz cross member
Recently added ECS Tuning adjustable sway bar end links (to see if that would help, no avail)

If you're wanting a SUPER tight ride that is amazing at speed and cornering, this car has it! BUT, it's super bouncy on normal roads. I'll even miss my mouth when trying to take a sip while going over a small bump.

Any advice on what is contributing the most to the harsh ride?



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I'd say biggest contributors to ride quality would be the springs and shocks. Other contributing factors would be the tires and control arm bushings.
Especially if you're sitting at lowered ride height than stock - the springs and shocks have to be stiffer to not bottom out.
Tires - larger wheels means thinner tires, thinner tires mean less sidewall to flex and absorb road impacts.
Control arm bushings - high performance suspension setups tend to have more rigid compounds in the bushings .
All these factors combine to deliver sportier handling at the cost of increased ride harshness.

I'd recommend you try to modify your spring/shock setup that has:
- ride height closer to stock
- softer shock (slower rebound)
- softer (or taller) spring

The Billsteins should have been fairly close to stock dampening. The springs I would say gave it the stiffened ride. If you have the pogo stick ricer bounce going then you have a problem with the shocks not matching the spring rates for the springs.

Sway bars should not impact ride quality significantly, they mostly help with roll in the corners.

These were all super helpful responses. It led me to two choices:

1) Replace springs with OEM-sized springs (any good manufacturers with replacement springs? True OEM are expensive!)
- or -
2) Wait for my H&R springs to "soften" up a little....but I'm thinking this may take years.

I decided I don't want to replace the shocks, since they are very expensive; plus I'm not do-or-die on the lowered stance and was just as happy at stock height.

larger swaybars absolutely affect day to day comfort, as their entire job is resisting twisting, thus giving the suspension less independence side to side.

The springs would certainly contribute a lot, but the first thing to do, is start playing with tire pressures

All of the parts you have replaced are excellent, but all sway toward sport. All will contribute to a stiffer more harsh ride.

However, with aggressive driving, the car should handle better.

Alright...as our daily driver, this super sport ride is just too much. I'm going to put in new, OEM springs.

Now a new issue! What springs should I get? When looking for the official part number, I'm presented with six possible springs, which are distinguished by number and color of dots -- but no mention of what the mechanical/technical differences are.

FRONT SUSPENSION. STRUTS & COMPONENTS.. 2014 Audi A7 TDI Prestige Hatchback 3.0L TDI V6 DIESEL A/T Quattro | Audi of America, Inc. (audiusa.com)

Based upon my photos of the initial replacement, I believe mine were two violet dots. However, I didn't really get good photos and want to be sure I order the right OEM springs for front and rear.

Any help is much appreciated!

UPDATE: I sent a few dealerships my VIN to get the part numbers that are specific to my exact car. Very helpful!

What I recently noticed, when I replaced my engine mounts, my ride comfort improved very noticeable.
Even when my old one was still in place, and only had some cracks in the rubber.
My car drives mush more smooth now.