Bilstein B4 shocks & struts

[Swdollar]

Searching on various forums I have not found anyone reporting on the installation of Bilstein shocks & struts without lowering springs, bigger wheels or other mods. I wanted to know how they impacted the ride and handling in an otherwise stock car with 19” wheels.

Well, I just had Bilstein B4 shocks and struts installed on my 2017 94ah REX and it is a noticeable improvement. Although my car has only 33k miles, the previous ride seemed bouncy and I got nearly bounced out of my seat on some roller coaster-like humps on Hwy. 680 in San Jose (the asphalt sinks next to concrete overpasses, leading to dips and humps). Overall ride was moderately unsettled with side to side rocking and front-to-back rocking motions. It wasn’t always severe, but I knew it wasn’t the 101 inch (short) wheelbase that some auto writers blamed for the nervous ride - I have owned several sports cars with far shorter wheelbases (as short as 89.5”) that were more settled and stable. My experience with other BMWs has been that they are sometimes over sprung and under damped and new Konis or Bilsteins help.

Anyway, if you have over 30k on your car and feel the ride is bouncy, unsettled or under-damped, you may be pleasantly surprised by what new shocks and struts can do. By the way the front strut boots were cracked and torn, attesting to all the bouncing. The ride is no firmer, just more controlled.

 

[SuperPoly]

I have been toying with the idea of changing these out. Thanks for posting.

Would you say that they improved stability at highway speed to the point where spacers/lowering/etc aren't necessary?
Any negative changes to NVH?

This looks like a great deal: https://www.shocksurplus.com/products/bilstein-b4-oe-replacement-strut-shocks-set-for-2014-2019-bmw-i3-rwd

 

[Swdollar]

The new shocks & struts definitely make the car feel more planted and stable at highway speeds, especially on bumpy surfaces. I no longer feel the need for a death grip on the wheel at 80 mph. I am very picky about ride/handling issues and feel no negative impact on ride or NVH at all. I was concerned enough to ask the mechanic to give me old shocks just in case the ride was too harsh. I am now discarding them. The key is well matched springs and shocks and these fit the bill.
I don’t know how lowering springs would alter the equation. I have ridden in cars with lowering springs (not i3s) and I felt the reduction in spring travel ruined the ride. The tires on i3s do not have much air volume to provide the cushion that larger tires do, so you do need some suspension compliance for a comfortable and controlled ride.

 

[SuperPoly]

This sounds like a great alternative to lowering springs, spacers, etc. for highway stability! Lastly, any harshness over very rough roads?

 

[Swdollar]

The ride is no more harsh on rough and bumpy roads than before - but it is where there is the least improvement. Based on changing tires, wheel size and shocks on various cars over the years, my experience is that the harshness of broken pavement, potholes, etc. seems to relate more to wheel size, tire pressure and tire choice than suspension (maybe unless you changed spring rates or travel range).

With the i3, I can’t go to an 18” wheel or a nice Michelin tire, so there is a limit to what you can do. On my 986 Boxster, switching from 35 series tires (rear) on 18” wheels to 17” tires with 40 series tires (rear) made a big improvement in ride quality. With the i3 such changes are not an option (look at those brake calipers crowding the wheels). On slow bumpy roads the main improvement of new shocks is a reduction of rocking and bouncing - it feels more settled. Ideally Koni would offer their ST.R (formerly FSD) shocks for the i3 - those really smooth over harsh cracks and bumps, but no such luck.

 

[SuperPoly]

Thanks again! This is great info.

 

[1960euroVWbug]

Thanks for the detailed info.

 

[Arm]

Searching on various forums I have not found anyone reporting on the installation of Bilstein shocks & struts without lowering springs, bigger wheels or other mods. I wanted to know how they impacted the ride and handling in an otherwise stock car with 19” wheels.

Well, I just had Bilstein B4 shocks and struts installed on my 2017 94ah REX and it is a noticeable improvement. Although my car has only 33k miles, the previous ride seemed bouncy and I got nearly bounced out of my seat on some roller coaster-like humps on Hwy. 680 in San Jose (the asphalt sinks next to concrete overpasses, leading to dips and humps). Overall ride was moderately unsettled with side to side rocking and front-to-back rocking motions. It wasn’t always severe, but I knew it wasn’t the 101 inch (short) wheelbase that some auto writers blamed for the nervous ride - I have owned several sports cars with far shorter wheelbases (as short as 89.5”) that were more settled and stable. My experience with other BMWs has been that they are sometimes over sprung and under damped and new Konis or Bilsteins help.

Anyway, if you have over 30k on your car and feel the ride is bouncy, unsettled or under-damped, you may be pleasantly surprised by what new shocks and struts can do. By the way the front strut boots were cracked and torn, attesting to all the bouncing. The ride is no firmer, just more controlled.

This is the major issue with the suspension on this car...the rebound is all wrong. How BMW got this wrong is beyond me as they usually tune their suspensions pretty well.

How much did you end up spending all in? I have an i3s and there is a decent setup for lowering the car with AST springs and spacers I believe?

https://www.youtube.com/watch?v=BQ9A9gUuh4s&ab_channel=Carbonwurks