[kern417]

Some of you may have seen my post on facebook, and after that discussion I wanted to make a post on here that was more explicit in my goals and findings. Feel free to post your opinions, but my goal is to share facts. Skip to the TL; DR at the bottom if you just want the point.

I originally jumped on a deal for H&R Super Sports that I found and figured, at the price, I'll see if they go low enough for my liking being the lowest option for a spring swap. The ride height was better, but not low enough for me. So I began monitoring the classifieds again, but this time for coilovers. I found some for a great deal but they were listed as only fitting F31 X-drives. I had a hunch that wasn't actually the case so I bought them for my RWD 440i. The worst case scenario is they don't fit and I put them back up for sale.

Admittedly I didn't do much actual research until after buying them (i took the plunge based on a hunch), but what I found made me more confident. KW along with many other suspension companies simply swap springs for different models. All of the coilovers physically fit, but your car may sit slightly differently or ride slightly differently. In my experience, the small differences they choose aren't noticeable or leave anything to be desired. Just slightly optimized in either direction. KW, for example, simply tosses in a 30mm spacer in the rear to give wagons and convertibles an extra 1" to play with.

These are KW's documents that include specs for the front and rear suspension kits. You can see the shocks/struts/front springs/rear helper springs are the same. The only difference is the rear main spring part number (presumably stiffer).
F2x/F3x RWD - 1022000E
F31/f34 AWD - 102200AB

So I installed them over the weekend and, as expected, everything bolted in place without a problem. I set everything to the lowest setting that KW recommended and I didn't install the 30mm spacer in the rear. The fronts were almost to my liking but needed to be raised ~1/4". The rears were lower than the super sports but still not low enough for me, so I removed the adjustment collars for an additional ~3/8" drop. I know it's more aggressive than a lot of folks go for but you can raise it for up to 1" or so more room if you want.

Drove the car and it drives great. Slightly softer than the H&Rs in a weird way. I notice small bumps more but I feel big bumps less, although that may be the placebo of me paying more attention to it. The car stays composed though fast turns and pretty much drives how I'd expect. Despite different (again, presumably stiffer) rear springs, the car doesn't behave weird, feel crashy, or lose any traction in the rear. So looks like I'll be keeping them.

So I post all this to say that I think a lot of the understanding across the board about suspension fitment is incorrect. All of our F2x and F3x cars share the same suspension geometry, and many suspension companies make one suspension kit that fits a bunch of models with varying weights and body types. Not to mention many EDC specific kits simply come with an adapter that can be bought separately.

In general there are a wide range of springs and shocks that work for our cars, so there's not 1 specific combo that works best or for everybody. That's why kits with adjustable dampening don't need different springs with every click of the shock, and that's why companies like Swift and H&R sell springs to be swapped to your liking. So there shouldn't be so much concern about kit fitment when they are all similar. Just look at the whole picture of what you're getting into and make a decision based on the facts. Like if you have an F30 x-drive and want to stick with just springs but H&R Sports aren't low enough, the Super Sports will fit and get you lower despite not showing fitment on H&R's website. I've seen someone go this route and enjoy the results while keeping adaptive suspension.

My only open concern that I haven't seen anyone do is put sedan/coupe suspension on a wagon or convertible. With coilovers the risk would still be pretty minimal since you can raise the height but with springs it might sag more in the rear. But in the opposite direction like i did, or mixing between sedan/coupe variants, you're pretty much good to go.

TL;DR

I bought F31 X-drive coilovers for my F32 S-drive and it fits and drives great. I believe F2x/F3x are interchangeable and if you find a deal on used parts and understand the risks there's nothing to worry about. The main difference will be rear springs, if any. This is not me recommending that you buy new suspension for a different model car, but if you are buying used suspension that's for awd but your car is rwd, or they're for a 328i and you have a 335i, etc....they're pretty much the same thing. If you've experienced the opposite, post the details.


Now for pics

Stock Front Shock + Bump stop vs. KW
You can see how much more suspension travel are in the KWs


Fronts installed
They are side specific due to the brackets for brake lines but they fit fine. They come with brass sleeve adapters since the shocks are skinnier than stock


Stock Rear Shock vs. KW
They look pretty much identical


H&R Rear Spring vs KW
No stock spring to compare with, sorry. But they are all linear and same diameter, they just get shorter and shorter.


Rears Installed
Again, no issues


Final fitment
This is all the way down in the front (within KW's recommended limit, still threads below the adjustment collar if you want to go lower) and the rears all the way down + adjustment collars removed.

[MacklinUSOB]

Nice investigation and drop. Glad you like em. I'm assuming these are V2's?

I get what you mean about it feeling more soft in a weird way. I didn't come from aftermarket springs, but from my worn out front shocks and rear B6's the ride quality improved. It's quiet the balance; soft, but very taught and composed. Best part is that if it is too soft for some, they can be adjusted.

One note to swapping kits around. I myself had to contact KW because, long story short, the install shop put that helper spring on the front (all fixed now). In that warranty claim form they make you collect all of the part numbers for every part and your VIN to check if it is the correct kit for the vehicle. I would see them raising this issue if making a claim. In your case, it obviously doesn't matter because you bought it private party, but to anyone buying new, I would keep this in mind.

[kern417]

Originally Posted by MacklinUSOB

Nice investigation and drop. Glad you like em. I'm assuming these are V2's?

I get what you mean about it feeling more soft in a weird way. I didn't come from aftermarket springs, but from my worn out front shocks and rear B6's the ride quality improved. It's quiet the balance; soft, but very taught and composed. Best part is that if it is too soft for some, they can be adjusted.

One note to swapping kits around. I myself had to contact KW because, long story short, the install shop put that helper spring on the front (all fixed now). In that warranty claim form they make you collect all of the part numbers for every part and your VIN to check if it is the correct kit for the vehicle. I would see them raising this issue if making a claim. In your case, it obviously doesn't matter because you bought it private party, but to anyone buying new, I would keep this in mind.

The downside is my kit is just V1 so no dampening adjustment. But I really don't need it.

And I agree with buying new. They're all priced the same so no reason to buy something not for your car unless your kit is out of stock or something and you need it now. But this is mostly related to FS posts in the classifieds .

This was the pic I posted for friends when I first got the kit. You can see I made the same wrong assumption at first I've never seen a coilover kit with helpers in the rear before this car, and if it wasn't for KWs installation guide I would have installed them the same way. You can see how many threads are left on the fronts in my picture above, and that's with the collars raised just enough so that the spring is compressed with the strut bearing. Any lower and the spring would be loose. If they're going to provide all those additional threads to make it look like it could go lower, they really should include helper springs to compensate.

[MacklinUSOB]

Originally Posted by kern417

The downside is my kit is just V1 so no dampening adjustment. But I really don't need it.

And I agree with buying new. They're all priced the same so no reason to buy something not for your car unless your kit is out of stock or something and you need it now. But this is mostly related to FS posts in the classifieds .

This was the pic I posted for friends when I first got the kit. You can see I made the same wrong assumption at first I've never seen a coilover kit with helpers in the rear before this car, and if it wasn't for KWs installation guide I would have installed them the same way. You can see how many threads are left on the fronts in my picture above, and that's with the collars raised just enough so that the spring is compressed with the strut bearing. Any lower and the spring would be loose. If they're going to provide all those additional threads to make it look like it could go lower, they really should include helper springs to compensate.

Yeah as far as V1 vs V2 goes, I don't think most will ever adjust them and all F's all get INOX/Stainless kits afaik, anyway. I was close to buying V1's from Turner, but I was looking on the site one day and saw the V2 kit for my car for about 50 bucks less than the V1, so I snatched them immediately suspecting some sort of pricing error. Day after I order, price shot back to regular $1,8XX.

Man, that is really funny you say that. I literally did the same thing when I took a photo for my buddies! It wasn't until I had been sent the instructions from KW that I also realized they belonged in the rear. Thankfully my shop was more than accomodating in fixing it. Agreed on the strut body threading as well, it looks way longer than the included spring could hope to fill.

[kern417]

Another user's post lead me to check my sway bar end links, and I found that the one on the right side snapped at the bushing. I'm not sure when it happened, but I dug deeper and found that EDC cars have a different endlink for the front right. The part number 31306792212. I'm about to order it and see if it works better.
https://www.realoem.com/bmw/enUS/sho...diagId=31_0951

[kern417]

Update

Everything installed fine. The main difference between the two is that they have different orientation. You can see where mine broke, basically the bearing popped out of the end of the endlink. But It stayed sitting straight up and between that and still seeing something attached to the arm on the strut, it just never registered that it was broken for all the times i've had the wheels off for other things. Whatever it was that broke it, it definitely got torqued in their hard though. I went through one of my T30s before hitting it with an impact wrench to at least loosen it up.

The new endlink is Delphi brand, hence the different look. No plastic on the ends, the nut is slightly bigger (17mm vs 16mm) and counter hold in the endlink tip is different (5mm allen vs T30). It was $15 vs $50+ for OEM from the dealership or other websites. Purchased from RockAuto.

Link:
https://www.rockauto.com/en/partsear...um=31306792212
https://www.rockauto.com/en/moreinfo...1928&jsn=10407

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