jon dee

Yusss... appreciate the comments and the offer. And I know there are many other options for shocks and springs to suit individual taste and performance goals. Seeing as I am quite happy with the OEM spring rates and ride height, I'm not looking to change springs. For shocks I like adjectives like supple and smooth rather than stiff or firm,  so although I was tempted to go for a "performance shock" upgrade for a while, that really ran contra to my goal of restoring/refreshing the OEM ride.

I have no complaints about the Sachs (steel) OEM shocks and struts. However I see that there seems to be some consensus in the euro car community, that the B4's offer a small step up in performance without affecting ride quality. Several reputable specialist aftermarket parts suppliers claim that the B4's are valved around 10% stiffer (yes I know what I said above) than OEM and that they should be considered as a minor upgrade. There is also a model specific version for the E92 with Msport suspension.

I am also naive enough to believe that Bilstein may have done their homework so that the B4 valving improves handling without affecting ride quality. Twintube construction offers some advantages over inverted monotube in low speed (around town) ride quality, and that is where my car is mostly used. So while my choice may not be to everyone's taste, I'm going to try the B4's and see how I like them. Worst outcome is I have to buy a B12 kit and drive faster

Cheers...

Yeah... well... hmmmm... I gave mum a detailed explanation of all my research and pointed out the advantages and disadvantages of all the different and competing options. When I finished, realising that she had nodded off, I gave her poke in the eye with a sharp stick that I keep handy for that purpose. Upon waking she lobbed her empty glass in the direction of my head and blurted out "Get the black ones you f**kwit !!". I have always admired mother's ability to instantly get to the crux of important technical matters.

So black ones it is

Cheers...

16 hours ago, Bennyboy said:

enough pussy-footing, go straight to PSS10's, you won't regret it!

I'll have to ask my mother first... ?

I was looking at how close the Eibach Pro Kit spring rates were to the E92 rates, and it got me thinking how strange it was that Bilstein did not offer the B8 for the E92 when they offered the B12 kit for the E92. Seemed illogical to me. So I checked to see if the B8's in the B12 kit were any different to the B8's listed for the E90 sedan. Bilstein said nope... they are identical. So then I asked them why they didn't offer the B8's for the E92 with Msport and they said... WUT !!!... but we do offer the B8 for the E92 with Msport and sent me the attached screenshot.

So it seems that 98% of the sales outlets for Bilstein are still working off an old application listing (as I was), one that does not list B8 for the 2011-2007 E92 with Msport. Downside of clarifying this is that now I have to reopen my internal struggle between being sensible and getting the B4's or succumb to the modifiers curse of wanting the high performance shocks to go with my surgical steel socket set

Cheers...

WOW !!!! Impressive collection considering I have only seen rates quoted a couple of times in forum discussions about standard shocks and springs. Coilover vendors are more forthcoming as they usually have a range of springs on offer. Going to have to take a look at where the springs are located on the back axle to see why the rear rates are so much higher than the fronts

Cheers...

Yeah... and nice to have some reference information to let anyone work out how low his/her car will be with a particular lowering kit. Now if only the companies that sell "lowering springs" could publish the spring rates...

Cheers...

Found the mother lode According to BMW these are the official ride heights. USA cars have different heights but (thankfully) we are not in the US so I have not included them here. 

Cheers...

That may be on the money as I found dimensions posted by someone who actually had a BMW B6 and B8 strut side by side. According to him the body length was exactly the same and the "difference in length" that is often quoted is only how far the spear extends out of the body. His measurements show a difference of 19.3mm in spear extension and that the available stroke is 15.8mm less on the B8. Also shows that the stroke before the spear hits the bumpstop on the B8 is 76.2mm

From what I read it appears that the bumpstops are considered to be a working part of the suspension. They allow at least a further inch of bump stroke and are available in several compression rates (typically between 100lb/inch and 250lb/inch) so tuneable. All of which is fcuking interesting but contains too many variables for further theorising So based on anecdotal evidence I'd say yes you can use the B6 with Msport suspension and yes you can use the B8 with Msport suspension. Either one will be an upgrade over the OEM shocks. Results and ride height may vary.

I'm 95% decided on adding the B4 kit plus the M3 arms as a first step. Just waiting to see how the order for the arms works out before placing an order for the B4 kit. That will pretty much kill my pocket money for this year, so I'd like to get a handle on the total cost before committing.

Cheers...

Maybe so, but last time I decided to upgrade the suspension on my car it took three sets of shocks and three sets of springs to get a result that I was happy with. This time I aim to do it once and get it right I want to go with a factory endorsed combination which leaves me with the B4 Msport version or possibly the Bilstein/Eibach B12 Pro Kit. The fact that B4's are not monotube is no problem... Konis are twin tube and they work OK, and I have no doubt that Bilstein can also build a decent twin tube.

Despite plumbing the depths of the internet I have not been able to find any information on the available working stroke of a correctly installed B6. That is, without cutting down the internal bumpstop. Regardless... the B6 is designed to work with non-Msport springs and if you use them with Msport springs with a (say) 30mm lower ride height, you are 30mm closer to the bumpstops. If the car is more than 30mm down then you are even closer to the bumpstops. So who cares ? Well I do. 

If you have 90mm of available stroke and it was assigned 60mm for bump and 30mm for rebound, with a 30mm drop you now have 30mm for bump and 60mm for rebound. For normal round town driving no problem... works fine. But brake hard into a corner and you are riding on the bumpstop on the outside wheel, and that does not do much for your handling. Sure you can live with it and no doubt thousands of B6 users drive on Msport or lowering springs every day. Luckily, I believe the internal bumpstops are quite soft.

Only if I put down the money for monotubes I'd like to have the shocks sitting in the optimum part of their stroke as Bilstein intended. Just saying...

Cheers...

Below is a pic of the B4 installation kit that FCPeuro offer on their site. You can buy everything separately but easier for me to buy a complete kit rather than select a few parts and then find I need a part I haven't bought ? So is the full kit the recommended deal or is it overkill for a 90,000km refresh ??

Cheers...

PS: Kit is listed for use with non-Msport B4's, but I am assuming that the same kit could be used with Msport B4's.

Yes... I've noticed that it is one of the hotly contested fittings on the internet. Turner Motorsport offer the B8 for the E92 but don't recommend that they be used with Msport springs. Bilstein list B8's for the sedan with Msport which leads me to think that maybe the sedan has stiffer springs or greater mass than the coupe. Turners suggest using H&R or Eibach springs if you want to use B8's on the coupe, and that seems reasonable if the spring rate and ride height maintain adequate bump and rebound stroke.

Interestingly enough, Bilstein do offer the B8's for the 2012-13 E92 with Msport and they are the same shocks as offered for the 2007-11 sedan. Again, there could have been a spring change between the early and later coupes. Too many unknowns for me to want to take a punt on the B8 setup. Even the B6 has a few concerns relating to raising the ride height

All of which helps persuade me that the B4 setup is the way to go with Msport springs. The B4's are reputed to be valved about 10% stiffer than OEM, so that should work well with the extra 0.5 degrees of negative camber that the M3 arms bring to the party.

Cheers...

One of the things I learned when messing around with short stroke suspension on my Corolla was that it is critical to keep the shock in the correct part of its stroke with the weight of the car applied. Rule of thumb for me was 2/3rds of total available stroke for bump and 1/3rd for rebound. That's why I am reluctant to change the OEM ride height without having a lot more information on the springs. .

This also highlights the one worthwhile advantage of decent coilovers (as far as I am concerned) in that ride height and damping can be adjusted without changing the spring preload. Still not enough to talk me into using them on a road car.

Cheers...

OK... ordered that Looking at the pieces it seems that the kit can be installed without disturbing the struts or installing new shocks. But I already have a set of discs and pads waiting to be installed, so I figured I might as well collect up all the new bits (shocks, bushes, spring pads, mounts etc) and get the whole lot installed at one time. My current goal is to get get the car riding like it did when it left the showroom (except without the run flats)  Maybe better if these arms are as good as you say. Then I can drive it for a while and see if I think it needs Eibachs and B8's. That would be phase two

Cheers...

This kit ? That's all I need ? https://www.fcpeuro.com/products/bmw-control-arm-kit-5-piece-m-upgrade-bmwmcakit

Nothing wrong with 475 You got a beautiful flat torque curve with level 5 smoothing... but that takes away a bit from the peaks if there are any humps in your power delivery. Try the same run with level 1 smoothing and you might pick up a few hp

Cheers...

Yes... generalisation for sure... most of my opinions are pretty general unless talking about specific items. I was trying to draw the line between people who buy a poly bushing kit that replaces every rubber bush on the car, and those who select poly bushes for certain places that can benefit from them without generating excessive NVH. On my Corolla I bought a TRD hard rubber bush set and replaced every bush on the car But the only place I used poly was for rollbar drop links. Of course the BM suspension is a totally different to an old live axle Corolla, so different rules may apply.

Or to put it another way; if I found that the best way to solve a handling problem with the BM was to use poly bushes, I would use them... providing they did not generate an objectionable (to me) increase in noise inside the car. NVH is the reason I have never used coilovers with camber plates. Once again, if I was building a race car I would be prepared to overlook the down side to gain the benefits.

Cheers...

Interesting... and basically you are describing the dilemma that faces anyone looking for that "ideal" setup Having spent many hours now poring over hundreds of old  posts on many different forums,  the one factor that becomes clear is that there is no one setup that will make all owners happy. What I might describe as firm and supple, someone else will call harsh and uncomfortable. This makes it virtually impossible to draw any conclusion from reading reviews. Poor selections, mismatched components, run flats vs non-run flats, too much drop, not enough drop, insufficient bump travel, worn bushes, wrong bump stops... there are a hell of a lot more ways to get it wrong than there are to get it right.

If I was starting from scratch with a non-Msport car, I would also likely go with the Eibach/Bilstein B8 combo based on the some of the more favourable reviews and the reputation of these two companies. Plus, once they are in they are there to stay with no fiddling possible. However, having looked at all the options and bearing in mind that all I want is to do is refresh the shocks and related mountings/bushings etc without changing the spring rates or ride height, I'll probably settle on the B4's. Bonus being that I don't have to explain what those coloured things are behind the wheels.

One of the hallmarks of a quality vehicle is the absence of intrusive NVH, and this a key part of my approach to modifications. The builders of up market vehicles put a lot of effort into tuning the suspension to minimise NVH while still providing a smooth and well controlled ride. Rubber bushings and mounts play a big part, and while they are popular modifications, I would not replace rubber with poly bushes or pillowballs in my cars. Oui for race cars no problem, but non for road cars. I am not prepared to downgrade the pleasure of driving my car every day just for some minor performance gains that only come into play at the limit of adhesion, but annoy me every time I hit a manhole cover. But that's just me

Cheers...

Yes... I have no argument with progressively improving a car based on the careful evaluation of each modification and ensuring that it will work in harmony with previous or future modifications. I also recognise that we are all different and each owner will have their personal preferences and goals when modifying their car... wouldn't have it any other way It is possible that further down the road I will look at adding selected M-car components if I feel that there will be worthwhile benefits for the use I am making of the car.

Presently I am focusing on shocks and while I like Koni yellows there is no chance I will ever change the setting on the rears once they are installed !!! Even when I had top adjustables front and rear in my Corolla, once I found a sweet spot I never changed them again. I understand that the factory sets the rears at the midpoint of the adjustment... what did you end up with on yours ?

As a matter of interest, the first set of bottom adjustable Konis I bought for a Corolla were model specific and factory tuned for the AE86 (came with a set of Koni springs). The instructions that came with them indicated that the adjustment was to compensate for wear. Seemed reasonable, as I don't think tearing a strut apart to tweak damping is much of a sales feature !!!

Graph looks good to me Accuracy is reputed to be close to machine dynos. However given that there is considerable variation between the different brands of machines, the main use for VD is checking to see if your mods are working. Looks like you are riding on 17's and your car weight is a bit higher than I estimated mine to be. All of these factors need to be realistic because they directly affect the VD calculations. I need to get my car down to the local landfill to get an accurate weight of car with driver and spare wheel in the boot.

Looks like you got a good log to work with. So long as the torque curve is not dropping off and the revs are going up you are going to make more power. I'm hoping to squeeze a few more killerwasps out of mine if I ever get a chance to make a log that goes past 5000rpm  

Cheers...

The biggest problem with selecting which suspension components are needed to meet ones own requirements is that virtually all recommendations or opinions found on the internet are entirely subjective. Put the same components on two identical cars for two different drivers and inevitably the impressions and opinions of the drivers will be different... sometimes radically different. If we consider that "comfort" and "performance" lie at opposite ends of the suspension spectrum, then it is not too difficult to identify the dominant components of shock and springs. But when it comes to trying to hit the middle ground of blending a firm but comfortable ride with decent performance, this is where driver opinions tend to diverge wildly.

And since we are dealing with opinions, I'll state mine From my somewhat limited experience with my E92, I consider that both the performance and handling are pretty damn good. BM have done a great job of hitting a middle ground that is well suited to the potential of the car without losing sight of the fact that it is a "luxury sport coupe" if I might use that phrase. In my view the ride height and spring rate are acceptable, but I feel that the shocks could stand an upgrade.

I'm not interested in in entering the wormhole and going down the path of upgrading every suspension component to achieve M-car handling in a non-M-car. That does not make sense to me when if you want that level of performance/handling you can buy an M-car. So I just started looking for some replacement shocks that would do a better job of keeping the wheels in contact with the road surface. In the past I have used Koni yellows and Koni Sports adjustables and found them to be a decent compromise for a road car. But legend has it that Koni has an edge in the comfort stakes while Bilstein does better on performance.

Hence my search for Bilstein shocks that will work with the existing springs without altering the ride height. Despite conflicting evidence to the contrary, I believe that B8's can work with Msport springs as they are classified as "lowering springs" when compared with non-Msport springs. In the end I think that my choice will be between Koni and Bilstein so I am keen to hear about anyone's experience with either when used with stock Msport springs

Cheers...

Dayum boy.... researching suspension throws up some interesting stuff !!! Seems that the Bilstein B4 is a twin tube design and not the famous mono tube design that everyone knows and loves. So now I am looking at Bilstein B8's which definitely are mono tube. Haven't been able to find a definitive review of them when paired with the stock Msport springs, but from what I can glean from reading in many forums, is that (a) they are far too stiff and give a rough ride, or (b) they give a great compliant ride with much improved road feel and handling...  a little firmer than stock but quire acceptable for a "sports" sedan.

Anyone run the B8's with Msport springs (or similar mild lowering springs) and if you did, how did you like them ??

Cheers...

If the front shocks are are Bilsteins high pressure gas type and they lose their gas the ride height will drop... maybe and inch or more.  Yes, I know that BM's are metric but if I said they might drop by 25.4mm you would think that I know what I am talking about ?

cheers...

Discovered that BM have a range of factory springs for the 3-series and fit specific springs to each model. The springs are tagged and the correct front spring for a Msport E92 N54 335i is a D6. Armed with this information I went and peered under the fenders and yusss... my springs are tagged D6. So, seeing as I am happy with the present ride height, there does not seem to be much point in going to lower, stiffer springs. b

Revised plan now is to get a set of Bilstein B4 OEM-Replacement Msport shocks and all the associated hardware that is recommended for replacement when the shocks are changed out. I'll see if I can squeeze M3 arms into the shipment and keep the total landed cost under NZ$1000. NZ Post have added a seafreight option to their North American forwarding service. That should work out quite well if I can get free shipping to Oregon from the vendor.

Cheers...

You just reminded me that I have a Passport GTimer sitting on the shelf above my desk It's another one of those speed / distance / power gadgets except this one works off a 3-axis accelerometer for making its calculations. I bought it years ago and stopped using it when I got hold of an Apexi RSM. I'll have to recommission the GTimer to get a few performance figures as it is a lot quicker and easier to use the GTimer than to make logs and extract the data for Virtual Dyno. From memory, I don't think that it is fussy whether you use second or third which should make it easier to find somewhere to do some testing.

Cheers...

Dunno... I don't think BM would have designed it that way Could be that there is a bit more weight in that corner from the steering and turbos etc. If I replace the suspension it will be with something along the lines of the Bilstein/Eibach kit or the Koni/H&R equivalent. If/when that happens (depending on how the exchange rate looks next year) I shall also replace all the associated wearing parts to try and get a nice tight "as new" ride with a decent balance of comfort and performance. When I find a place that can install all that for me, I shall be asking for corner weights and an alignment to see what kind of numbers you get with a non-adjustable factory style setup.

I want something that is set and forget... does everything reasonably well without having to fiddle with with ride heights, damper settings and multiple sets of tyres. As it sits at the moment the ride height is about right for clearing driveways and speed bumps, but I have the feeling that a decent set of shocks and springs would help sharpen up the handling. In the end, short of being able to scrounge a ride in a car with the exact setup, it comes down to doing your research and then taking a punt that whatever you buy will meet your expectations

Cheers...