Bilstein Questions

[Black Magic]

Perhaps a good day to ponder some Bilstein questions:
1. B6 shocks are designed for cars with standard factory suspensions. Should we consider them the appropriate choice for cars with factory mildly lowered suspensions such as BMW M Sport or Audi S series? Or should we chose Bilstein B8 for any lowered situation?
2. Are B6 and B8 shocks valved the same for a given application?
3. What are the consequences of using a B6 in a vehicle that has been lowered either mildly say 5-10mm or more significantly say 15-25mm? Or on the other hand what about using a shorter B8 in a situation where the car has not been lowered at all?
4. Is there any way to know whether a B8 shock (being shorter) is designed for a base model or is it designed for a sportier model such as with an M sport package? Or does it not really matter for a mild drop?

Thanks for the thoughts.

[RBNetEngr]

The B6 and B8 are supposed to be valved the same for a given application. The difference is that the B8 has shorter total damper travel than the B6.

That said...shorter springs need to compensate by being stiffer. So, if the B6 are correctly valved for a standard length spring, and the B8s are valved the same, but used with a shorter, stiffer spring, will the damping be enough to properly damp the stiffer spring rate?

The other issue is that the perch that holds the lower end of the spring is fixed on the Bilstein dampers. So, depending on the length of your spring, you may end up with the damper being too compressed at static ride height, thus limiting the total travel that the damper has before contacting the bump stops.

Many years ago, I put Bilstein Sports (B8) and Eibach Pro Kit springs, on my E30 318i. I think the dampers spent a lot of time on the bump stops, and the ride was pretty crappy on bumps. There was much discussion about shortening the bump stops, that Bilstein screwed up with the bump stops, that there were revised versions with ‘proper’ bump stops. Blah Blah Blah.

All that was said to say that lowering springs, and fixed length/height dampers, are a compromise. If you want to properly lower your car (not SLAM...that’s another world), and stiffen up the suspension for better handling, while still having the suspension operate in the proper range of motion, your best bet is to get a good set of coilovers, which allow them to be finely adjusted in length, ride height, damping, etc., for your application.

Also, if your car is fairly old, and the suspension is worn, the cost of new dampers, springs, bump stops, possibly strut/shock mounts, will equal the cost of a decent set of reasonably priced coilovers. And you will be much better off with the money spent.

-rb