Bilstein Suspension. B4, B6, B8, B12.

[kis]

So I've been trying to figure out what to get. Haven't really got anywhere :? Lol.

So fare as I can tell B4 is equivalent for SE suspension
B6 is M Sport
B8 is M sport but lowered?
B12 is an upgrade to M sport?

Mine is M Sport speced so really want to know what the difference between them are. I'm not looking to lower the car really as I think with the roads and driving I do, I'd either break my back or the car!

I think I also heard the shocks are the same in a few of the variations? But the springs are different? I've got fairly new suplex springs and could just buy the shocks and swap my current springs into the new shocks? Help :?

 

[Phoenixboy]

Whilst I have little knowledge on this subject, I seem to read numerous stories of people getting it wrong and simply making the car awful on our crappy roads.
unfortunately a lot of theses mods are only really suited to super smooth road surfaces or on track.
and there seem to be a lot of companies that will happily take your money if you don't do your research and get it right.
if its anything like the bike market, what works well on track, will not work well on the road.
Not suggesting your doing this, but important to get the right set up for your driving.

 

[Chris1981]

I originally bought B6s thinking they were M-Sport replacements, they are not! They are the firmer version of the B4 which is SE spec. B8s are the same damping as B6s but lower so closest to M-Sport. I believe the recommendation from Bilstein is to use B8s to replace M-Sport as M-Sport is factory lowered. I would hazard a guess that B8/B6s are slightly firmer than factory M-Sport.

So...
B4s - SE spec.
B6s - increased damping, similar dimensions to SE.
B8s - increased damping, similar dimensions to M-Sport.
B12 - a full set of B8 dampers and Eibach lowering springs.

If you don't want to adjust the height and simply want a firmer dampers to improve handling then you're best off getting a set of B8's as these are the recommended replacement from Bilstein for M-Sport.

 

[ben g]

PM MACK. He's really knowledgeable with this stuff.

It's literally a minefield if you try and research it online :lol:

I went for B4's on my Sport suspension specced Z4. Ride seems fine, very tight and handles great. Just some knocking issue's I'm having an issue with after replacing it all.

 

[mjennings23]

Replaced my M Sport dampers with BE, work perfectly well and a very flat car through corners so I'd consider them an ideal replacement.

Just some knocking issue's I'm having an issue with after replacing it all.

Did you swap out top mounts on the rear? I had the same issue when installing Meyle HD top mounts, swapped back to new Lemforder ones and problem gone.

 

[DaveD]

I have SE springs and went for b6 dampers. Firms the ride up noticeably but not uncomfortable. But the shock control is miles better than stock and you retain the travel. This set up does deal with bumpy B roads well

 

[ben g]

Replaced my M Sport dampers with BE, work perfectly well and a very flat car through corners so I'd consider them an ideal replacement.

Just some knocking issue's I'm having an issue with after replacing it all.

Did you swap out top mounts on the rear? I had the same issue when installing Meyle HD top mounts, swapped back to new Lemforder ones and problem gone.

It's the front I'm having problems with. Replaced all top mounts with Lemforder ones, so should be fine.

 

[kis]

I seem to read numerous stories of people getting it wrong and simply making the car awful on our crappy roads.

As have I! Which aids to the confusion, they need replacing but what to get!

PM MACK. He's really knowledgeable with this stuff.

I think I saw a post where he went for B4's as well? But yeah I'll give him a PM. Thanks for the heads up

Replaced my M Sport dampers with BE

What's BE mate? You mean B4?

 

[mjennings23]

What's BE mate? You mean B4?

That’s the one! Seems my phone decided B4 was incorrect :roll:

 

[ben g]

I don't believe I can feel any difference between the Sport shocks and Bilstein B4's (with eibach springs on both) in terms of handling.

The only major difference is the ride is now a bit more comfortable. Don't get me wrong, it's no Rolls Royce, but it's more manageable than when I had the Sport shocks and eibach springs on.

It's lovely and tight down country lanes and it feels like I can chuck it into a bend and it will stick, whereas before I was always a little hesitant.

Of course, I'm comparing used vs new, so it isn't very fair. But I bought my Z4 with 65,000 miles on the clock at 9 years old, so maybe the shocks were due replacement even back then?

 

[MACK]

Here's my understanding of the Bilstein shockers.
B4 are a twin tube shocker (like 99% of all cars leave the factory with) and are a direct replacement for SE spec OEM shocks. They give a similar ride quality etc to the standard SE shock and are recommended for use with the SE springs, although Bilstein also state you can use them with the M Sport and lowering spring up to 40mm. Which is what I have currently done on mine.
For those who might not know. Pre-facelift 3.0 SE cars don't have SE suspension at all, they have M Sport as standard (just to confuse things) Where as pre-facelift 2.0, 2.2 and 2.5 SE do have SE suspension from the factory.
The B6 and B8 shockers are a superior monotube design (which is why they cost a lot more than the B4) but unless your tracking the car etc twin tube ones are more than adequate for normal road use, hence why virtually all cars on the road have them. The B6 and B8 are basically the same shocker, the only difference is the rod length to suit different spring configurations. The B6 are recommended for use with SE springs and the B8 are for use with M Sport ones or lowering springs such as Eibach etc. Indeed Bilstein themselves pair them with the Eibach springs to form the B12 kit. The B6/B8 are a much stiffer shocker than the B4, they're uprated approx 20% over the M Sport suspension which is already uprated over the SE stuff, so are quite hard riding etc.
This (rather than cost) was why I chose to pair my Eibachs with B4 shocks, as I wanted a better ride than my knackered 12 years old M Sport stuff gave me. The reason I used Eibachs springs was not for the lowering/look, but the fact that they have a softer initial spring rate than the M Sport ones which firms up to about the same as the M Sport ones under greater compression. This makes things a bit more comfortable over smaller bumps etc. I have to admit I'm currently toying with the idea of trying some SE springs just to see how these compare with the Eibachs when paired with the B4 shocks

 

[Ducklakeview]

I've just fitted B8's with lowered Eibach springs to replace my Msport setup. I believe this is sold as the B12 kit by bilstein? The car feels completely different now, yes it's firmer and lower, but feels tight and planted. I also poly bushed the lollipops and front arb at the same time. I did notice when fitting that the Eibach springs were a fair bit easier to compress by hand than my old ones which worried me, but apparently their variable rate means they are supposed to be like that.

Going in for alignment in the morning, but more than happy with it.

Also looks quite mean lowered. I'd say it's dropped about another 20mm over M Sport, so about 50mm over SE. Have to say that parked next to the 3 SE cars I have in at the moment it looks slammed

Here it is on M Sport...




And Bilstein/Eibach combo



Still running 15mm spacers on fronts and not had any rubbing..

Mike

 

[MACK]

Replaced my M Sport dampers with BE, work perfectly well and a very flat car through corners so I'd consider them an ideal replacement.

Just some knocking issue's I'm having an issue with after replacing it all.

Did you swap out top mounts on the rear? I had the same issue when installing Meyle HD top mounts, swapped back to new Lemforder ones and problem gone.

It's the front I'm having problems with. Replaced all top mounts with Lemforder ones, so should be fine.

Ben have you checked the ARB droplinks? That would be the first thing I would be thinking it could be, seeing as they were disturbed as part of the suspension overhaul. Beyond that I would checking the usual ball joints/track rod ends etc and even the brace bars between the suspension turrets and the bulkhead, they may have loose bolts.

 

[ben g]

Replaced my M Sport dampers with BE, work perfectly well and a very flat car through corners so I'd consider them an ideal replacement.



Did you swap out top mounts on the rear? I had the same issue when installing Meyle HD top mounts, swapped back to new Lemforder ones and problem gone.

It's the front I'm having problems with. Replaced all top mounts with Lemforder ones, so should be fine.

Ben have you checked the ARB droplinks? That would be the first thing I would be thinking it could be, seeing as they were disturbed as part of the suspension overhaul. Beyond that I would checking the usual ball joints/track rod ends etc and even the brace bars between the suspension turrets and the bulkhead, they may have loose bolts.

Droplinks is a good shout. I replaced them with Meyle HD ones a couple of years back, but I guess they could either have failed or my dad may not have tightened one back up correctly (it's only the drivers side front).

It's definitely not right in terms of noise. In terms of handling it feels great.

Cheers for the heads up. If it is the droplink, my dad will never hear the end of it :lol:

 

[MACK]

It's the front I'm having problems with. Replaced all top mounts with Lemforder ones, so should be fine.

Ben have you checked the ARB droplinks? That would be the first thing I would be thinking it could be, seeing as they were disturbed as part of the suspension overhaul. Beyond that I would checking the usual ball joints/track rod ends etc and even the brace bars between the suspension turrets and the bulkhead, they may have loose bolts.

Droplinks is a good shout. I replaced them with Meyle HD ones a couple of years back, but I guess they could either have failed or my dad may not have tightened one back up correctly (it's only the drivers side front).

It's definitely not right in terms of noise. In terms of handling it feels great.

the track rod end is probably the next best place to look thinking about it, as that will have been disturbed and possibly heated when you had the alignment done after fitting the new suspension

 

[kis]

Some interesting reading guys. Thanks for the updates. I think I've got my head round it all now!

Ducklakeview do you feel the car is much more stiff and harsh now (planted and good handling aside)? Not sure what sort of roads you have? But everytime I go over a unavoidable pot hole I cringe slightly as I know it comes with a bit of a bang. My shocks will definitely be tired but trying to decide if the B8/B12 combo will be a bit too unforgiving, factoring in our fairly poor road conditions / maintenance programs.

At the moment I'm thinking that my OEM shocks will be worse than the B8 shocks. So even if I fit the B8's there will be an improvement?

 

[ph001]

There's some pretty good guidelines that might help you identify your knocking issue Ben:

1) Knocking from worn drop links will nearly always go away as you go around a corner. This is because the body roll 'loads up' the anti-roll bars and hence puts tension/compression on the drop link and stops the knocking.

2) Knocking caused by worn tie rod ends (or track rod ends if you like) tends to be heard as you waggle the steering from side to side when stationery. Almost feels like the steering rack mounting bolts are loose. If you get someone to waggle the steering while you feel the road wheel, you can feel the 'knock' transmitted to the road wheel quite easily with worn tie rod ends.

3) Easy check for the wheel bearings is to see if there is any play in the wheel when holding it at 6 o'clock (jacked up with wheel off the ground).

Suspension bushes etc usually need a crowbar to apply pressure (leverage) to show up any movement. Of course there is also the loose strut brace bolts to check too (need to torque them to proper setting).

Kis - I would not be thinking of fitting anything other than B4 shocks to go with suplex springs if you want the ride to be at least as foregiving as oem.

 

[Clarkie]

Boy - am I confused. If B6 is an uprated B4 and B4 can take a either an SE or msport spring - why cant B6 also take an Msport spring?

FWIW - I am about to put B6s on with an msport spring - just wondering if that is a huge mistake

 

[mjennings23]

Boy - am I confused. If B6 is an uprated B4 and B4 can take a either an SE or msport spring - why cant B6 also take an Msport spring?

FWIW - I am about to put B6s on with an msport spring - just wondering if that is a huge mistake

The B6 will work fine with sport springs, but it will be firmer than the factory Sachs shocks.

 

[MACK]

Boy - am I confused. If B6 is an uprated B4 and B4 can take a either an SE or msport spring - why cant B6 also take an Msport spring?

FWIW - I am about to put B6s on with an msport spring - just wondering if that is a huge mistake

The B6 will work fine with sport springs, but it will be firmer than the factory Sachs shocks.

The shorter rod of a b8 would be the better choice with m sport springs. Other than the rod length the b8 and b6 are identical