Bilstein B6 and B8 explained

[Ohio Enthusiast]

Originally Posted by Racecomp Engineering

Is there any concern with having the bottom of the shock extend so much below the mounting points? Does it reduce ground cleanrance in some way or might hit some suspension or brake component/inside of the wheel? It looks like an easy way of getting more travel while keeping ride height the same.

[Racecomp Engineering]

Originally Posted by Thefalls

Thats very nice Andrew.

Now go have a nice drive and let us have a nice detailed review from you.

I would have loved red springs, to look like the STI Bilstein kit.

Also, can you post pictures of the car to show the ride height change from stock?

Im curious about the drop and if the forward rake is still maintained.

Thanks a lot.

Can't comment on ride height as these are not OEM springs of any type...they're a prototype spring we're developing. With OEM springs you'll be within a few mm of factory.

As for the ride, the springs we're using are about 20% stiffer than factory and the ride is still better than OEM 2016 dampers. Have a lot more driving to do.

- Andrew

[Racecomp Engineering]

Originally Posted by Ohio Enthusiast

Is there any concern with having the bottom of the shock extend so much below the mounting points? Does it reduce ground cleanrance in some way or might hit some suspension or brake component/inside of the wheel? It looks like an easy way of getting more travel while keeping ride height the same.

The front lower control arm is below the strut and there's still plenty of clearance between the two. A lot of coilovers look like this too (though with a lowered ride height).

- Andrew

[Koba]

Andrew,

Any thoughts on pairing B6s with Ground Control coilover kit?
Very popular mod in the BMW world of track cars - cheap and effective way to get the ability to corner balance.
Just don't see any GC kits on the twins... is there a reason?
Thanks!

[Racecomp Engineering]

Originally Posted by Koba

Andrew,

Any thoughts on pairing B6s with Ground Control coilover kit?
Very popular mod in the BMW world of track cars - cheap and effective way to get the ability to corner balance.
Just don't see any GC kits on the twins... is there a reason?
Thanks!

If you really wanted to do a Bilstein non-damping adjustable coilover, you could just do B14s which aren't that expensive. Then just replace the progressive springs they come with if you want a specific rate (which we've done in the past).

- Andrew

[macuser27]

Originally Posted by Racecomp Engineering

Photo dump from the weekend. Bear with me, lots going on over here.

You can see a few small differences here between B6 fronts and stock. The B6 is kind of shifted downwards, but things do line up in terms of attachment points and where the spring sits. Overall stroke is roughly the same.


I did not take apart the fronts to measure the internal bumpstop.


The rear spring seats for the BRZ are a separate piece.


This is a crap picture, sorry. The rears line up with each other pretty closely. OEM rear bumpstop and dustboot get transferred over to the Bilsteins.


I wish they had the nice blue Bilstein dustboots, but they don't do that anymore.


Installed with some nice adjustable endlinks (OEM work fine too)


- Andrew

Thanks for sharing Andrew!

[ZDan]

Originally Posted by Racecomp Engineering

You can see a few small differences here between B6 fronts and stock. The B6 is kind of shifted downwards, but things do line up in terms of attachment points and where the spring sits. Overall stroke is roughly the same.

My impression is that the front Bilstein B8s have a *lot* more bump travel than the stock PP Sachs struts. With stock Sachs, Swift SpecR springs, and Raceseng camber plates the car would bottom out HARD over the smallest bumps. It was pretty well intolerable. With the B8s, no problems over most bumps, at speed. Even took a speed bump at ~30mph, purposely trying to bottom them. Transformed the car for me! I'd guesstimate at least 25mm more bump travel, the difference feels that profound.

I did not take apart the fronts to measure the internal bumpstop.

I cut one of mine in half before installing and used one half in each strut. Here's the intact one, 65mm long (Hot Wheels Corvette for scale...)

[Thefalls]

Originally Posted by Racecomp Engineering

If you really wanted to do a Bilstein non-damping adjustable coilover, you could just do B14s which aren't that expensive. Then just replace the progressive springs they come with if you want a specific rate (which we've done in the past).

- Andrew

I suppose this would be better for someone looking to go wider wheels and get some clearance.

Otherwise why would you go to this set up with non adjustability when you can get the B6/springs combo for almost same damping.

Im assuming the B6 and Coilover from B14 are about on par?

[ZDan]

I went with with the B8s (in retrospect could have gone B6) and springs over B14s because height-adjustability costs me a point for time trials, or 41 lb. At the softish (for track) spring rates I'm running I don't think there's much benefit to height adjustability and ability to corner-balance.

Also it seems like swapping springs for B14 would be a problem up front as I think they're stock diameter up top and smaller coilover-diameter at the bottom.

[Vital]

Andrew or anyone with that has experience with B6 struts, i know i read some where that it raises the ride height. Just out of curiosity I'd like to know how noticeable is it in reality? I have RCE Yellows, would i notice the raise in ride height if i got the B6's?

[ZDan]

Originally Posted by Vital

Andrew or anyone with that has experience with B6 struts, i know i read some where that it raises the ride height. Just out of curiosity I'd like to know how noticeable is it in reality? I have RCE Yellows, would i notice the raise in ride height if i got the B6's?

For me, no noticeable change in ride height, though I haven't measured. Starting at -1.25" though, so a few mm higher would still look pretty low relative to stock...

[Racecomp Engineering]

Originally Posted by Thefalls

I suppose this would be better for someone looking to go wider wheels and get some clearance.

Otherwise why would you go to this set up with non adjustability when you can get the B6/springs combo for almost same damping.

Im assuming the B6 and Coilover from B14 are about on par?

Yeah the coilovers would definitely be a plus if you need space for wider wheels/tires.

Same technology inside but I think slightly firmer valving with the B14.

As ZDan said, you have to figure out what to do for upper spring perches if switching the B14 to linear coilover springs.

- Andrew

[strat61caster]

Originally Posted by ZDan

Also it seems like swapping springs for B14 would be a problem up front as I think they're stock diameter up top and smaller coilover-diameter at the bottom.

Not really, you can get an adapter for the oe spring perch like what KW provides, swap to a custom spring perch, or if you're going to camber plates a 2.5" or 60mm spring perch is pretty standard.

B14/16 springs clear 17x9 +40 up front with some camber from bolts, can probably get away with higher offset and less camber.
https://www.ft86club.com/forums/show...&postcount=780

[LancePower]

Originally Posted by ZDan

I went with with the B8s (in retrospect could have gone B6) and springs over B14s because height-adjustability costs me a point for time trials, or 41 lb. At the softish (for track) spring rates I'm running I don't think there's much benefit to height adjustability and ability to corner-balance.

Also it seems like swapping springs for B14 would be a problem up front as I think they're stock diameter up top and smaller coilover-diameter at the bottom.

Why B6 over B8?