[wesmeister]

I'm at the end of my ropes with this front suspension issue on my F31 with KW Street Comfort coilovers. The coil bind is seemingly getting worse over the last 5K miles, and crashes over any road imperfection.
The streets of Los Angeles are not bad, not great either, and they the ride is fine at lower speeds and more gradual road obstacles. But man... any small road transition or tiny pothole and WHAM!

It's the coil travel that binds, same issue as this guy: https://f30.bimmerpost.com/forums/sh....php?t=1830408
We've tried every damper setting and height adjustment under the sun.

KW support will only RMA the springs for the exact replacement.. which has me worried that I would just end up in this same situation again.

So before I go accepting my fate, and purchasing some new shocks with H&R springs... I had a crazy idea:

What if I added a second spring to the front? Create a dual rate setup.
Add a tender/helper spring that does not fully block under load and adds some stroke when engaged.
There is a solid 3-4 inches of adjustment left on the shock body to lower the perch.

What do you think be downside of adding another spring like this one from Eibach? https://eibach.com/product/0200.250.175-550
It's an additional progressive spring, but the block load weight rating is lower than my corner weight... so would I even get any stroke out of them?
Of course, there is always the option of a stiffer static rate spring.

The current KW front progressive springs are rated at 226 lbs/in, so based on the formula:
(upper rate x lower rate) / the sum of the upper and lower = active rate.
If I add a static 3" spring that is 400 lbs/in to the primary spring, I end up with a dual spring rate of about 145 lbs/in. Which doesn't sound right to me.

Thoughts? Prayers? Dumb idea? Thanks.

[_ObiJon]

Have you thought about doing a complete linear spring swap (hyperco)?

[jmanB45]

I had exactly the same issues when I installled the KW Comfort kit last year. Turns out the front springs were too soft. With the stiffer springs (#2041 instead of #2039), it was a night and day difference, I have not bottomed out at all. See details in this thread, my posts are from #18 onwards:

https://f30.bimmerpost.com/forums/sh....php?t=1799518

Another factor may be that you have the spring perch too high. The specified range by KW is quite narrow, 7.3" to 8.5" from the centre of the knuckle bolt. Paradoxically, the car rides better if you are lower, as the spring is in a better working range.

You might also be interested in this clip by FaRKle! about using different springs, in his case #2025 from the M4 convertible

Swift springs seems to be a common upgrade that I have seen on various forums. Here's one on e90post:

https://www.e90post.com/forums/showthread.php?t=487445

Keep in mind if you change the fronts with a drastically different setup, the rears will need to be swapped as well.

[wesmeister]

jmanB45 How did you go about purchasing the #2041 springs? Every email correspondence I have had with KW leads me to a dead end. They say they will ONLY replace the springs under warranty for the exact same springs.

If I go any lower on these.. I won't be able to pull out of my driveway. LOL

[wesmeister]

Originally Posted by _ObiJon

Have you thought about doing a complete linear spring swap (hyperco)?

Definitely an option. The current KW kit uses the stock struts upper mounts, so I am having a bit of trouble finding a coilover top hat that will work and/or is sold independently. I think I found an option on the BCracing website, but then I would have a really bastardized coilover stack

[jmanB45]

Originally Posted by wesmeister

jmanB45 How did you go about purchasing the #2041 springs? Every email correspondence I have had with KW leads me to a dead end. They say they will ONLY replace the springs under warranty for the exact same springs.

If I go any lower on these.. I won't be able to pull out of my driveway. LOL

They will be happy to sell you a pair of springs. Part # is 60210271 for the 2041 springs. Last year, they were priced at US$180 for a pair, plus $45 shipping (to Toronto).

Your wagon looks great btw.

[jmanB45]

Originally Posted by wesmeister

Definitely an option. The current KW kit uses the stock struts upper mounts, so I am having a bit of trouble finding a coilover top hat that will work and/or is sold independently. I think I found an option on the BCracing website, but then I would have a really bastardized coilover stack

Check out the vid above around 1.15, FaRKle! mentions that he uses adapters from Millway to connect standard coilover springs with the OE top hats.

I believe this is the item:
https://www.millway.se/adapter-for-6...er-plates.html

[jmanB45]

wesmeister just noticed you mentioned your current KW front progressive springs are rated at 226 lbs/in... this is the rating for the #2041 springs, so you might have them already.

[_ObiJon]

Originally Posted by wesmeister

Definitely an option. The current KW kit uses the stock struts upper mounts, so I am having a bit of trouble finding a coilover top hat that will work and/or is sold independently. I think I found an option on the BCracing website, but then I would have a really bastardized coilover stack

I would honestly go this route. Adding a secondary non-helper spring may introduce unwanted noises. Plus, you'd have to get a torington bearing between the two (imo), which don't last the longest on a daily driver.

As mentioned, millway sells an adapter and you can get hyperco springs pretty cheap in various weights. And you can get a taller spring, which would further minimize spring bind, to an extent.

Following, because I'm curious how this turns out, regardless of which way you go!

[wesmeister]

Originally Posted by jmanB45

Check out the vid above around 1.15, FaRKle! mentions that he uses adapters from Millway to connect standard coilover springs with the OE top hats.

I believe this is the item:
https://www.millway.se/adapter-for-6...er-plates.html

Oh man! this product changes everything LOL! You are helping me out so much jmanB45 I really appreciate it.

I just checked the physical spring, and I do already have the 2041 spec springs for this KW kit 180200AB. I'm going to sit here and watch Farkle's vid... then head to Hyperco and Swift to see what i can find.

Definitely thinking longer spring for more stroke. Any thoughts on going 6K or 7K? This is a daily driver for sure... which is why I went progressive in the first place With the cost savings, I'll replace all of the springs together.

[casualDIYer]

Originally Posted by jmanB45

Another factor may be that you have the spring perch too high. The specified range by KW is quite narrow, 7.3" to 8.5" from the centre of the knuckle bolt. Paradoxically, the car rides better if you are lower, as the spring is in a better working range.

jmanB45 has a really good point. That perch is way too high. If you did the work yourself it looks like a newbie mistake. Congratulate yourself as you rip apart the work and redo it. You’re learning car mechanics is back breaking work. You won’t make the mistake twice.

If a shop did it, get your a$$ kicking boots on. That’s sloppy for a pro. The manual isn’t for beginners but even a diyer can figure it out.

[Dagstar]

I'm having the same issue as well with Street Comforts on my 2014 wagon. The front crashes over all but the smallest road imperfections. The coating on my springs at the bottom has cracked off just like yours. I had one replaced under their 1 year finish warranty but still haven't installed it. I just checked it and it's part number 60210257, which is a 2039 (and the old one shows it in the pic). My perch is set a bit lower than yours.

[casualDIYer]

The problem described may indeed be due to a spring insufficient for the weight of the car but I would check the install. If you can

a) Remove (and re-install, intact) the front wheels from your car
b) Use a tape measure of other straight edge measuring device

Try this

1) Jack up car and take off the front wheel (pick a side, either side)
2) Using your measuring tape (a flashlight will be helpful here), look behind the the wheel hub and notice where the strut goes into the wheel hub. You'll see a bolt. As shown in the following diagram, measure from the centre of where the bolt goes into the bolthole to the TOP of the BOTTOM spring perch (shown as A in the image)



That distance has to be between 185 and 215 mm (7.3 inches - 8.5 inches). If out of spec, that will need to be fixed.

3) With wheel back on, and car on a ramp, the bottom perch is moved up and down to adjust the ride height of the car. But a) it cannot move outside of the 185 and 215 mm range mentioned and b) ideally the spring should not be overly pre-compressed. This is why the range is stated. In fact, when the strut is off the car, the spring should snuggly fit between the top hat and bottom perch. This should be the starting point of the bottom perch but once the adjusting starts, watch the limits outlined by KW.

4) There is another restriction you are advised to obey. As height is adjusted, for the 1802000S model I've used as an example here, the bottom of the fender lip to the centre cap of the wheel, cannot be less than 340mm, which would be considered too low for this model of coilover. It can be greater (i.e. higher) for correct KW install but this too has limits as moving the perch upward has the effect of pre-tensioning the spring to a great degree. Check this number while the car is on the ground or ramp (i.e. the car's weight is on the spring). If less than 340mm by a couple of millimetres, not that big of a deal. Get up to 5, 6, 7, 10, 15, etc. Yeah, that's out of spec and needs to be fixed by moving the perch up. Keep in mind, springs do settle. Today's 340mm might be 338mm or less in a week. Re-check.

Coilovers should be thought of as "The minimum height is X" not "I can do whatever I like", which some people try. Aren't coilovers lovely?



Note: Over-compressing the spring (accomplished by setting the ride height closer to the max, and beyond) is a little like cutting it. Excessive pre-tensioning causes some of the 'springiness' to be used up. Ideally you want the car, not the perch, using as much spring as possible. It was mentioned by another poster that higher isn't better. I'd agree.

[wesmeister]

Thanks for this input casualDIYer. I'll take these measurements tomorrow or the next day to confirm.

The reality is that the current spring perch location creates a 1.75" drop from stock. I can certainly lower it more, which I have already done in the past, but that will definitely throw the advertised 10-40mm drop completely out the window.

As for you previous comment. These were installed by AutoTalent about two years ago.

[wesmeister]

Originally Posted by Dagstar

I'm having the same issue as well with Street Comforts on my 2014 wagon. The front crashes over all but the smallest road imperfections. The coating on my springs at the bottom has cracked off just like yours. I had one replaced under their 1 year finish warranty but still haven't installed it. I just checked it and it's part number 60210257, which is a 2039 (and the old one shows it in the pic). My perch is set a bit lower than yours.

Oh man, I feel your pain. Based on both of our pictures, you would almost think that the two lower coils are waaaaaay too soft.

[jmanB45]

Originally Posted by Dagstar

I'm having the same issue as well with Street Comforts on my 2014 wagon. The front crashes over all but the smallest road imperfections. The coating on my springs at the bottom has cracked off just like yours. I had one replaced under their 1 year finish warranty but still haven't installed it. I just checked it and it's part number 60210257, which is a 2039 (and the old one shows it in the pic). My perch is set a bit lower than yours.

Yup, that does not look like a happy spring. For reference, here is how mine looks with the wheels on the ground, 2041 springs, perch set to 8" from the knuckle bolt centre and ride height just over 26" from ground to top of fender lip.

My front axle load rating is 1020 kg.

[wesmeister]

Alright, after taking some "you don't know how modified cars work..." type feedback, I got the car up off the ground after work (to do more work) and came out feeling worse.

I learned two things:

1. I do, in fact, have the 2039 springs in the front. Had to spin those bad-boys around but that is the number. Based on this thread, and other threads posted in the past, it seems obvious that KW made a miscalculation during a volksfest.

2. Everything is within spec from KW.
https://www.kwsuspensions.com/extras...-h180200AB.pdf
My measurements:
A= 8.45 in (within spec)
B= 13.55 in (within spec)

Interesting note: My settings are at the top of the spec sheet parameters BUT If I went any lower on measurement A specs, I would be out of the minimum height required by measurement B specs. Good stuff.

Another interesting note: Am i reading the manual wrong here, or does the technical specs sheet linked above state that these springs are rated at 3K? wtf

[FaRKle!]

KW 2039 springs shouldn't be used on xDrive 4cyl or heavier vehicles (despite them being configured from KW). As you've seen, there's lots of cases of spring/coil bind with it. As the spring perch is moved higher, you're more likely to bind before engaging the bump stops too.

Easiest solution is to go to the stiffer 2041 spring. If you wanted to go to the 2025 spring I'd recommend boosting the rear spring rate to something higher too.

[Dagstar]

Thanks everyone for the info. Looks like changing the springs is my next step. I contacted KW and the 2041s are still priced at $90 each, as jmanB45 previously stated.