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The BMW Shock Cheat Sheet

10/11/2024

Seems like there are so many choices of shocks (and struts) for your BMW?
Well, here is your cheat sheet!

1. Koni Special Active (1st shock on left above) is Koni's newest technology. It automatically adjusts to your driving style - comfortable when cruising and firm when cornering, accelerating from a stop, or otherwise compressing the dampers. It is best for those who like fun Sunday drives, but spend most of their time commuting on poor roads! It gives you the best of both worlds - firm control when you need it and comfort the rest of the time.

BMW x5 Special Active kit

2. Koni Sport (2nd shock) - otherwise known as the "Koni Yellow" - is one of the most popular and well-known performance shock for BMWs. It is manually adjustable, meaning you can set the firmness to what you want - with a dial on the front; and by compressing the shock in the rear (off the car). This is the best shock for enthusiasts who want to choose their firmness (or aren't quite sure how firm they want their suspension). Also great for those who track their car because they can firm up their suspension for the track, and soften it for the ride home!

BMW 3-series Koni Sport kit

3. Koni STR.T (3rd shock) - also known as "Koni Orange". This is a great replacement shock for your BMW factory units. It is slightly firmer than a stock BMW shock, but otherwise keeps the same ride feel. It works great with stock springs and lowering springs. This is great option for owners who want to refresh their suspension without spending a lot of money.

BMW Koni STRT kit

4. Bilstein B4 (4th shock) - This is by far the most popular shock for those who want to simply replace their factory suspension with new, but want to avoid the high BMW shock prices. It also comes in many specific versions, e.g. non-sport, msport, xdrive, to best match your exact vehicle. A great quality OEM shock with lifetime warranty from Bilstein. Great with mild lowering springs too!

2012-18 BMW 3-series Bilstein B4 kit

5. Bilstein B8 (5th shock) - The B8 is a high-performance shock upgrade. It transforms your car into a handling beast - it turns a base 3-series in into an M3! It is a lot firmer, so you will feel the bumps in the road more, but shines on the curves at high speeds. You can see that the shock is 3/4" shorter than the others, so it is perfect for factory msport springs and pretty much any lowering springs. If you do not plan to lower your car, then get the Bilstein B6 model. It is the same as the B8, but slightly taller for factory springs.

BMW 5-series Bilstein B8 kit

6. Sachs (not shown) - Sachs is the OEM supplier for BMW's factory shocks on most of their models. It is very popular for those who want to simply refresh their current suspension with the shock that most closely resembles their current BMW shocks. It is a great option especially if you are only refreshing the front or rear of your vehicle, because it will closely match the BMW components on the other axle. It is a close cousin to the Bilstein B4 shocks and most would not be able to tell the difference between the two. We can't! It comes with a 2-year warranty from the manufacturer.

Sachs BMW x5 front struts

New Suspension Kits for the BMW F3x!

8/12/2023

Here are three popular BMW F3x series shocks (actually front struts!). The one on the left is the stock BMW msport version; the middle one is the BMW MPeformance version, and the one on the right is the very popular Bilstein B8. They all have their place in BMW F30 suspension world.

The stock msport strut - and its Bilstein and Sachs OEM style aftermarket equivalents - is the recommended replacement for customers who simply want to refresh their suspension back to factory new. They also work great with a mild lowering spring, like Eibach or Dinan. In fact, Eibach and Dinan tests their springs with factory dampers, so you know that they match up is fine.

The Bilstein B8 is the go-to strut for most high-performance applications. Quality is extremely high and their technology - without going into details - sets them apart. We strongly recommend them for most applications where a customer wants to lower their vehicle. They are a firm shock - maybe even firmer than a stock M3. There is obviously some trade off between performance/handling and comfort, but that is always the case when you want superior handling. Most people will find them perfectly acceptable for daily driving unless perhaps you like comfort and live where the roads are horrible. We've used B8s on most of our personal cars and love them. Well, sometimes the wife doesn't :-)

Now look at the one in the middle. It is the BMW MPerformance strut. No, it is not the same as the msport. There are big differences. First, the MPerformance strut is significantly firmer than the msport. It is closer to the B8 in dampening, and has all of the same great performance/handling benefits of a firmer strut. But look closer... you can see that it is shorter than the msport strut and B8. It is exactly 1/2" shorter than both, which is because BMW made it to match their MPerformance springs, which are also 1/2" shorter than stock. Talk about attention to detail! Because of this precision, we used the MPerformance strut and springs on our shop car and LOVE them! This set up fits perfectly in between the msport and B8 for comfort, performance, and handling.

Because the MPerformance struts fits so well between the msport and B8, it is a fantastic choice for customers who want a performance suspension set up using lowering springs that is significantly higher performing than the stock struts, but with a bit more daily comfort than B8s. (Of course, another great choice is Koni Sport shocks, which allow you to adjust the firmness).

This is why we are announcing that we now have a new option for our RWD F3x customers: Our SM70X series kits will use BMW MPerformance struts and shocks with any lowering spring that you choose - Eibach, H&R, Dinan, or MPerformance!

Like all of our kits, our SM700X kits will come fully-assembled and 100% complete. No spring compressors or special BMW tools needed. Just open box and install.

Give us a shout!

The "bloody" truth about compressing coil springs.

9/28/2022

Everyone has heard about the dangers of compressing coil springs yourself when trying to do a suspension refresh or upgrade. Fact is that injuries occur and the risk is real. This is true for even professionals as seen in a bunch of Youtube videos, like this one:

And it happened to me! I have done hundreds of assemblies on BMW and MINI. I have all the best equipment, including a commerical-grade spring compressor and accessories. I am always careful, but the truth of the matter is that all springs are slightly different and one piece of machinery cannot work perfectly with all of them. Well, a while back I was building a kit and a spring perch under extreme pressure gave way right when I was grabbing the strut. The perch "bit" off the parts of my thumb and palm that were touching it. The above is the result! Extremely painful when it occurred... and again when doctor cleaned it out... and again when the dressing stuck to the wound and had to be pulled off.

LESSON: For all of you thinking of installing a new suspension, the risk is even greater because you may be doing it for the first time and using a cheap auto store rental. Seriously, this why Strutmonkey only sells fully-assembled kits. We do the hard, and sometimes painful, work so you can do what you want: Open the box, install your suspension, and find your favorite road!

Bumpstop Confusion?

6/15/2018

Almost everyone knows the importance of the bumpstops in our BMW and MINI suspensions. It is not just a failsafe to protect your struts and shocks, but an integral part of your suspension. Your bumpstops are engaged whenever you hit a bump, turn sharply, or even hit a dip in the road. That is why it is important to make sure your bumpstops are in good condition. Not like this:

The above shows why it is almost never a good idea to reuse your old bumpstops when refreshing or upgrading your suspension. We recommend they be replaced at 50K mile mark, perhaps sooner if you drive in snow, salt, or other harsh conditions. Why would you pay to have springs and shocks installed, and then pay again to have bumpstops replaced? Do it right, do it once!

Lots of chatter about which bumpstops to use when you lower your car with lowering springs. Hopefully nobody is still replacing their bumpstops with the same ones or not using any at all. Like reusing old ones, these are both wrong. The key is to get a bumpstop that is shorter than your stock ones to better match the amount of lowering from your spring, so you are not "riding on your bumpstops". This is what BMW itself does, if you compare the non-sport and sport bumpstops for the same car:

That is why we custom match the new bumpstops to every suspension kit we sell. Like these:

But even these are not to be used on every BMW model. Heavier cars need different bumpstops than light cars. Wagons and convertibles need different ones than sedans and coupes. We even have to consider the diameter of the strut shaft and the size of the bumpstop hole!

This is one of the many benefits of getting a Strutmonkey assembled suspension kit... you leave the bumpstops to us!

Welcome to the B(MW)log

The BMW Shock Cheat Sheet

New Suspension Kits for the BMW F3x!

The "bloody" truth about compressing coil springs.

Bumpstop Confusion?

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