We've received lots of questions lately on the Bilstein B6 and B8 dampers, so I thought I'd do a rundown on these two fixed perch shocks. I just got a set in for my own car (because I really like them!) so I thought it was good timing.
Short version
The Bilstein B6 (formerly called Bilstein HD) dampers are an OEM fitment replacement, fixed perch, monotube damper with inverted front strut. The Bilstein B8 (formerly called Bilstein Sport) have a few differences and are specifically intended to be used with lowering springs, but have the same valving as the B6 dampers. I recommend the B6 even with lowering springs. We'll talk about that more later.
These are excellent as a replacement for your high mileage OEM suspension or as a performance upgrade with lowering springs. Both work with lowering springs. They ride well and they're durable.
Is a monotube like the Bilsteins better than a twintube?
Sometimes. Monotubes and twintubes each have their advantages and disadvantages, and either one can be good or bad. Monotubes are generally more responsive and sometimes better on bigger bumps, sometimes at the expense of a "busy" ride over smaller bumps. Bottom line, Bilsteins are good and the valving is really nice.
What is an inverted strut?
An inverted strut is upside down. This means that inside the Bilstein front, the base of the damper is actually up at the top inside what looks like the massive shaft. The actual shaft is down at the bottom inside the yellow body. This reduces unsprung weight slightly and improves resistance to side loads. So, it's a little more durable. Nice for high grip track cars and rally cars. The rear is a conventional shock, not a strut, so they don't see the same side loads and you don't usually see them inverted. You also don't usually see twintubes inverted.
Where are the bumpstops in the front?
Since it's inverted, the bumpstop is inside the lower part of the strut body. Yes you can open these up and have a look, but I don't really recommend replacing the internal bumpstop. The non-inverted rear uses a regular bumpstop you can see (you reuse stock).
Are these better than coilovers?
It depends! The Bilstein damper itself is very high quality and certainly better than what's in most low end coilovers. You're limited in that you can't easily run coilover springs, so your choice in spring rates and overall drop isn't the same. If you don't need stiff springs or a bigger drop, these make a lot of sense. If you want more than 300 lbs/in spring rates or like to make adjustments, I'd consider coilovers. But these ride great, are still good on track, and are a lot more simple than an adjustable coilover.
Are these rebuildable/revalveable?
Yes! You can send these to Bilstein (and a few other places) and have them rebuilt to factory fresh or revalved to custom specs.
What kind of springs can I use with these?
Stock works. Our RCE Yellows are great too and the combo with Bilsteins is fast, fun, and simple. Other lowering springs work (Swift, STI, Eibach Prokit), but I'll always recommend a relatively mild drop.
Should I get B6 or B8?
Bilstein B8 are supposed to be paired with lowering springs...but we still recommend B6 instead. The difference between B6 and B8 is NOT in the valving. That's identical. The B8s have slightly less droop, or extension travel. The idea is that shorter lowering springs don't need the droop travel or wouldn't be fully secure with longer travel. In reality, all lowering springs for this car are designed around the OEM dampers dimensions so this simply isn't needed and actually droop travel is good. So, get the B6s. The B8s are still very good if you have them.
- Andrew