E86 Suspension - Help me understand the options

[Fred Smith]

I have been trying to read up on this forum and elsewhere, and here's post of what I think I know - the key options for suspension replacement and upgrades on E86 Z4s (and I think E85 is pretty much the same). I would love any corrections and additions, and I will have questions later. Prices mentioned are approximate as of my quick googling today.

Notes – Price are approximate as of May 2024. I have tried to cover the main options. I have tried to note cheapest prices, but I have not searched that hard. Prices of shock / coil combos are there as an approximate guide if you are refreshing the suspension front and back and want get an idea of how much more you will need to spend to upgrade to the next “better” level (by which I mean less comfortable, more sporty). Also combo prices exclude sundries such as top mounts, and fitting of course.

OEM Suspension

All the UK E86s are SI, the difference is the Sport models had the M-Sport suspension that sits 15mm lower and is a bit stiffer than the SE.

Dampers / Shocks

Sachs are probably the go to OEM option, but the rears no longer seem to be available

Bilstein are the ones to go for if durability is the primary aim, but Koni’s are probably a bit more comfortable. B4 are the go to option if not Sachs.

Bilstein B4 dampers – standard dampers for E86 suitable for SE or M-Sport Setups AND eibach lowering springs (but see Eibach specific notes elsewhere). Rear £140 for 2. Front £260 for 2. Seem to be a bit better than Sachs and very much the go to option. Seem to be more reliable than Koni. Total - £400.
Comments
“B4s and Suplex M-sport size springs, works well for me”
“I've got Bilstein B4 dampers with the Eibach springs on my E86. It now sits about 30mm lower than the M Sport set up. Is it more comfortable than original? I'd have to say no, it's still a bumpy ride but, it handles better and looks better than it did.“
“Bilstein B4s, Suplex springs (sport). These wont lower the car car but the handling is much improved better cornering less roll etc.”
“Been running B4s for 4 years now with initially SE springs, then MSport and now back on SE springs again. My spine just cannot get on with MSport springs. Absolutely no complaints with SE/B4 combo”

Bilstein B6 dampers – up-rated / firmer dampers for standard ride height. Not suitable for SE springs, give a noticeably firmer ride than B4 or OEM. Rear £280 for 2. Front £440 for 2. Total - £720
Comments
“If you want firmer dampers then get the B6's, if you want to maintain OE ride-comfort, I'd go for B4s.”
“I’ve run B6s with SE springs and sport springs. The B6s very noticeably firm up the ride on either - I actually think the sport springs are better balanced with the B6s, as the SE set up felt under springer but over damped.”

Bilstein B8 dampers – up-rated / firmer dampers, same damping spec as B6 but designed for lower ride height. Rear £340 for 2. Front £450 for 2. Total - £790.

Bilstein B12 Suspension kit - B8 dampers + Eibach coils. £1,200 for everything front and rear incl. coils.
Comments
“I went for the B12 kit and found it not suitable for pot holed road of Brighton so I eventually went back to standard springs (m-sport). Kept the Bilstein dampers though.”
“I had the sports suspension and changed it to the Bilstein B12 Pro Kit with Powerflex Rear Shock Top Mount Bracket and Bush 10mm. 30mm lower than the Sports Suspension. Firmer ride but better that the V4's it had. Corners like it's on rails.”

Koni Sport aka Koni Yellow dampers - £450 front and £360 rear, or Total £870 including springs for full set. Lowers car about 35mm front and rear. [Broadly equivalent to a Bilstein B8]
Comments
“I'm running eibachs with Koni Yellow Sports dampers on 19 inch wheels fitted with 245/35 tyres. The ride quality is definitely improved over the original, tired MSport dampers.”

Coils / Springs

Coils seem to be advertized as the amount they lower from the standard (SE Level), not the M-Sport level. On this basis it seems like one of the two Einbach options only lowers the car 20mm at the rear, which – by my calculations – seems to mean only a 5mm lowering if your E86 already comes with the 15mm lowered M-Sport set-up.

Suplex 06252 (SE level Manual) - £100 for 2. Front. Length: 290mm.
Suplex 06228 (SE level) - £150 for 2. Rear. Length: 229mm.

Suplex 06248 (M-Sport level Manual) - £120 for 2. Front. Length: 270mm.
Suplex 06231 (M-Sport level) - £190 for 2. Rear. Length: 229mm.

Suplex 06253 (SE level – automatic) - £100 for 2. Front. Length: 288mm.
Suplex 06249 (M-Sport level – automatic) - £105 for 2. Front. Length: 276mm.

Eibach Performance (Progressive) Springs - £150 for 2, £225 to £300 for 4.
Version 1 – Lowers front 30mm and rear 20 mm.
Product code: F11-20-010-01-VA (front)
Product code: F11-20-010-01-HA (rear)
Product code: E10-20-010-05-22 (full set) Total - £255
Version 2 – Lowers front 30mm and rear 30 mm.
Product code: (front)
Product code: (rear)
Product code: E10-20-010-01-22 (full set) Total - £255
Comments
“I have Eibach Performance springs and Koni dampers which now give a controlled more compliant ride.“

H&R Lowering Springs Kit [29269 1] – The manufacturer’s blurb “H&R lowering springs are the ideal solution if you want to optimize the handling of your car and achieve a sporty look while maintaining the standard driving comfort. The springs are compatible with both standard and retrofit dampers and are available with ABE or parts certificate.” Lower the car 35mm front and rear. Total - £230

Vogtland Sport Lowering Springs – Lower the car 30mm front and rear. Total - £140

Coilovers

Stance+ Coilovers – £290 full kit – Lowers by 15mm to 40mm (rear) and 20mm to 45mm (front). Definintely available for E85 – TBC whether it also works for E86. Coilovers at this point are likely to be UTTER TRASH.

Max Speeding Rods Coilovers – £685 full kit – Lowers by 10mm to 30mm. The manufacturer’s blurb “MXR-SNA coilovers are designed as an entry level for street use. It features with full length height adjustable and adjustable camber plates (applicable for some vehicles),  which offers you a lowered stance, improved performance  for your daily use vehicle.”

BC Racing Coilovers – £1,000 full kit –

Bilstein B16 Coilovers – £2,250 full kit –

Intrax Coilovers-

KW V1 Clubsport Coilovers - £1,500 full kit

KW V3 Clubsport Coilovers - £3,000 full kit – look superb, but maybe too sporty for UK roads?

Nitron NTR R3 Coilovers / Suspension Kit - £5,500

Top Strut Mountings

Lemforder – Decent and thought to have supplied the BMW originals.
Lemforder Top Strut Mount and Bearing - Front, pair – Part Number – 27309 01
Lemforder Rears – are they available anywhere?

Febi Bilstein – OK?
Febi Bilstein 21091 Top strut mount. Rear Axle, with attachment material, without ball bearing, Elastomer. Kit includes : 1 no. top strut mount (Article No. 21090); 1 no. seal, suspension strut bearing (Article No. 12701) – £25 for 2

PowerFlex Rear Shock Top Mount Bracket and Bush 10mm.

Meyle – DO NOT USE Meyle HD top mounts on the rear! Terrible design allows metal on metal and they knock like mad.

The cost of Dampers and Coils Front and Rear

Interesting to note that the cost of the main parts is basically £650 to £700 for SE / M-Sport Level, lowered or standard. Price has to be secondary - get the set-up you want.

SE Level - Bilstein B4 dampers with Suplex Standard coils - £650

M-Sport Level - Bilstein B4 dampers with Suplex Sport coils - £710

Basic Level Lowered - Bilstein B4 dampers with Eibach Performance coils - £700

A Budget Sports Option - Koni Sport aka Koni Yellow dampers - £870 including springs for full set.

M-Sport Plus Level - Bilstein B6 dampers with Suplex Sport coils - £1,020

M-Sport Plus Plus Level - Lowered - Bilstein B8 dampers with Eibach Performance - £1,090

M-Sport Plus Plus Level - Lowered - Bilstein B12 kit - Bilstein B8 dampers with Eibach Performance (includes extras?) - £1,200

[Special Kay]

Sounds very well researched to me

[Fred Smith]

My E86 is an SE, currently with 19" wheels. Might switch to 18" some time if anyone wishes to comment on how wheel size affects things.

The front currently has Sachs dampers and unknown coils. Both are allegedly reasonably new, and a visual inspection suggests this is almost certainly true. The ride height is not at all low and I would be very confident that the coils are relatively budget and like for like replacements for the SE originals. I am slightly concerned that the ride height is not the same on each side.

One rear coil is broken and the dampers look OLD.

Lemforder top mounts, plus Bilstein B4 dampers, plus Suplex standard coils will - at £300 or so in parts - be the best option by a mile if my priority is keeping the costs low (both short and long term), and the car original. Will also ensure a relatively comfortable ride.

If I want a more "M-Sport" level ride I could spend £470 on B6s and Suplex Sport Coils for the rear. But if I do that then I need to spend another £560 on B6s and Suplex Sport Coils for the front as well. Just over £1,000 in parts (plus sundries).

If I want a more "M-Sport" level ride AND a lower ride height then switch to the Eibachs instead of the Suplex Sport Coils, and that'll cost about the same.

If I'm spending £1,000 on parts then I might as well consider the full Koni Yellow kit which would work out a bit cheaper compared to B6s with Suplex or Eibachs.

[enuff_zed]

I think if it were mine, wanting it at a Sport ride height I would put the B4s on the back with the 06231s.
Put 06248s on the front, but run the risk of finding the shocks aren't as good as you thought and then having to wait for replacements.
Or bite the bullet and get Sachs front shocks at the same time.
New top mounts, bump stops and the two front knuckle bolts (31306779487)
Possibly wortynh picking up new front drop links at the same time.

Did exactly this on the 180k coupe thread and parts were around £750 with a decent autodoc discount.

[Special Kay]

I think it all depends upon how you intend to use the car. If you do intend to track the car at some stage, I would definitely fit a more purposeful suspension set up. If your just using it on the roads, then I'd probably just opt to do a refresh with some B4s, and maybe a set of Eibachs for a slightly lower look, or suplex springs if I wanted the OE setup. It's decision time, but I think you can make the correct choice with alot of confidence. Good luck

[Fred Smith]

Thank you so much for the reply.

Part of the problem is that I don't really know what I want! Presumably I have no real idea how the stock set-up should feel given I have only driven it in the month run-up to a broken coil, let alone different set-ups

I am conscious that I have no track plans and with 19" wheels and crap roads I want every bit of comfort I can get. On the other hand the car is more comfortable than I feared it would be, and sits very high IMHO (40-50mm or more between top of tyre and wheel arches) and it's a sports car - it should be sporty!

Would there be an issue with installing B4s on the back with 06231s, and then leaving the car for a while before putting 06248s on the front?

Do you prefer the Sachs or B4 dampers (not that we seem to have a choice at the rear any more)? Would you put B4s on the front of a Z4 or would you always go Sachs for the front?

Are the Sachs and B4 dampers both equally suitable for M-Sport level coils?

Do you have a problem with Eibachs / lowering? Am I right in saying that the Sachs and B4s are both suitable for lowering with Eibachs (subject to the caveat that shorter coils increase the risk of dampers bottoming out and breaking, and that this risk can be reduced or eliminated with some sort of spacers?!?!!)

[Fred Smith]

I think it all depends upon how you intend to use the car. If you do intend to track the car at some stage, I would definitely fit a more purposeful suspension set up. If your just using it on the roads, then I'd probably just opt to do a refresh with some B4s, and maybe a set of Eibachs for a slightly lower look, or suplex springs if I wanted the OE setup. It's decision time, but I think you can make the correct choice with alot of confidence. Good luck

Thank you - road mainly, so I should go sensible.

Further to my question just above. Would there be an issue with installing Suplex 06231s, and then leaving the car for a while before putting 06248s on the front? And same question but with Eibachs? Or would it be utterly insane to change the ride height at the rear and waiting to do the front?

[Special Kay]

This is just my personal opinion, but I think a happy medium would be to get a firm but comfortable ride. Spring wise opting for either the m sport Suplex option or the Eibachs will lower your car, with the Eibachs being slightly stiffer, and slightly lower than the M Sport Suplex option.

[Special Kay]

I think it all depends upon how you intend to use the car. If you do intend to track the car at some stage, I would definitely fit a more purposeful suspension set up. If your just using it on the roads, then I'd probably just opt to do a refresh with some B4s, and maybe a set of Eibachs for a slightly lower look, or suplex springs if I wanted the OE setup. It's decision time, but I think you can make the correct choice with alot of confidence. Good luck

Thank you - road mainly, so I should go sensible.

Further to my question just above. Would there be an issue with installing Suplex 06231s, and then leaving the car for a while before putting 06248s on the front? And same question but with Eibachs? Or would it be utterly insane to change the ride height at the rear and waiting to do the front?

I honestly couldn't answer that question for you. I'm sure someone more qualified will be along shortly and put you straight. But from my limited knowledge, I think you'd need to bear in mind that once all the parts are fitted, you'd need a geometry setup, whether or not you decide to do the whole or part of the car. Just to make sure the car runs true. That's just my 2pences worth

[fredej]

Sachs are the standard, go-to option, but rears no longer seem to be available.

I did also notice when searching Autodoc (and similar websites) that rear Sachs dampers for the E86 3.0si were not available. However, selecting E85 3.0si instead shows Sachs 312 468 as available. Is the specification of dampers for the E85 different to the E86? Or are those dampers suitable for the Coupé as well?

Do the rear Bilstein B4 dampers differ in specification between the E85 and E86 3.0si?

[Fred Smith]

I honestly couldn't answer that question for you. I'm sure someone more qualified will be along shortly and put you straight. But from my limited knowledge, I think you'd need to bear in mind that once all the parts are fitted, you'd need a geometry setup, whether or not you decide to do the whole or part of the car. Just to make sure the car runs true. That's just my 2pences worth

Probably a stupid question to be honest... do a proper job is always the good advice (and sell the car if you can't afford to!)

[Special Kay]

To be honest Fred, I think you've done the sensible hard work by researching your options. Most people would just send it to the nearest garage and let them decide on the (usually the cheapest) option. Good luck

[Ed Doe]

B6 dampers are uprated/firmer dampers for standard ride height
B8 dampers are uprated/firmer dampers, same damping spec as B6 but designed for lower ride height
B12 is a kit comprising B8 dampers and eibach lowering springs.

B16 are coilovers (if you're interested) lol

Edit:

There are also various other coilovers options including intrax which I have with true rear coilovers.

I believe nitron a kit too.

[thecremeegg]

I went with the B4 dampers and eibach springs and I think it's a great setup for daily use

[Fred Smith]

B6 dampers are uprated/firmer dampers for standard ride height
B8 dampers are uprated/firmer dampers, same damping spec as B6 but designed for lower ride height
B12 is a kit comprising B8 dampers and eibach lowering springs.

B16 are coilovers (if you're interested) lol

Edit:

There are also various other coilovers options including intrax which I have with true rear coilovers.

I believe nitron a kit too.

Thank you - I will research everything you mention and update my first post.