Z4 Coupe Bilstein B8 vs B4 (again, sorry)

Zummerset · Post by **Zummerset** » Sun Jan 28, 2024 3:15 pm

Hi all,
Hoping to get a bit of advice/confirmation of my proposed way forward please.

My newly acquired Coupe came with a recently fitted Bilstein B12 suspension kit which I believe consists of Eibach progressive lowering springs and B8 dampers. It also has non run-flats.
I'm finding the ride rather firm, it's not crashy but firm and jiggles you about quite a bit!

From researching on here I think the following will improve matters:
1) Keep Eibachs as they are progressive,
2) Fit Bilstein B4 dampers,
3) Add thicker spring pads to bring the ride height back to MSport height. (For extra ground clearance rather than ride quality)

Can anyone confirm this will likely improve matters as I think it will?
There may well be a set of 5k miles old Bilstein B8's for sale soon!

Thanks.

Ed Doe · Post by **Ed Doe** » Sun Jan 28, 2024 3:18 pm

B4 are designed to be an oem replacement, so deigned for the oe ride height. As such it won't be the ideal pairing for lowering springs. If you want to increase ride height too anyway then why don't you just get standard sport springs with B4 dampers. You'd probably get more money selling the b8s with the eibachs too as they're paired together anyway.

Ed Doe · Post by **Ed Doe** » Sun Jan 28, 2024 3:19 pm

Also as I'm sure you know b6 are the same as b8s but designed for oe ride height so I'd avoid them if you're finding the b8s and eibachs too firm...

Zummerset · Post by **Zummerset** » Sun Jan 28, 2024 4:21 pm

Hmmm, thanks for your thoughts.
I was under the impression the B4 was OK for lowering up to 40mm which obviously I'm within that range.
The only reasons for keeping the Eibachs was due to their progressive nature and that they may well be of better quality than the standard ones which seem to have a habit of snapping.

Completely agree about B6's and B8's being the same level of damping just different lengths.
You make a good point that the whole B12 kit including the springs would probably sell for more than just the dampers alone.
I wonder what they would be worth second hand?

Decisions, decisions.....

Pic of current ride height for info.

Dubbedown · Post by **Dubbedown** » Tue Jan 30, 2024 2:38 pm

Sell the B12s, they’re not for everybody. I too find them too jarring. Go back to stock springs and B4/B6, you’ll be much happier with those imo.

tomscott · Post by **tomscott** » Tue Jan 30, 2024 2:54 pm

One of the main reasons the OE springs snap is because the standard dampers are also not great they have a habit of leaking and if they don't leak the gas often escapes so the car is pretty much relying on the springs to do all the work and is one of the reasons the ride is so poor.

Part of the crashyness is the fact the driver sits over the rear axel and as stock there wasn't much give in the rear dampers and springs, best thing to do is get a kit that can be adjusted then you don't have one trait or the other and depending on your endeavours you can change it without much work.

Zummerset · Post by **Zummerset** » Tue Jan 30, 2024 6:27 pm

I guess that's one reason why you feel so much whilst driving, you are pretty much sat on the rear wheels!

I've ordered some B4's and will try them with the Eibachs first. If still not happy I'll pop a set of Suplex springs on. It isn't too much of a job to change the springs so will see how it goes.

Thanks for your thoughts.

MikeyH · Post by **MikeyH** » Tue Jan 30, 2024 7:22 pm

When I bought the car it had B4's with sport Suplex springs all round. At the MOT it was found that the nearside spring had gone so had both rear springs replaced and the garage used Sachs sport ones. Can't notice any difference at all. Still a bloody awful ride

Zummerset · Post by **Zummerset** » Tue Jan 30, 2024 8:03 pm

sounds about right.
Just had a brainwave, get a memory foam cushion for the seat. Sorted.

MikeyH · Post by **MikeyH** » Tue Jan 30, 2024 11:56 pm

I tried different cushions I had in the house and considered having more foam adding to the seat but in the end I spent some time adjusting the seat and got used to it

Rockhopper · Post by **Rockhopper** » Wed Jan 31, 2024 7:53 am

Broken springs are common across all makes of car these days. Lightweight suspension designs with thin coils is the reason. Once the coating gets damaged and rust starts to take hold then they are weakened even further.
Standard shocks will last an absolute maximum of 50,000 miles in my experience. At 105,000 miles the rear shocks had no damping left and they’d been replaced at least once before!
I have B4’s with Suplex springs on mine and I’m very happy with the.

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