04-19-2024, 12:25 PM | #1 |
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KW Street Un-Comfort(able)... dual rate?
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. Last edited by wesmeister; 04-19-2024 at 12:27 PM.. Reason: grammar |
04-19-2024, 05:39 PM | #3 |
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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. |
04-20-2024, 12:42 PM | #4 |
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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 |
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04-20-2024, 12:46 PM | #5 | |
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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 |
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04-20-2024, 01:11 PM | #6 | |
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Your wagon looks great btw. |
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04-20-2024, 01:21 PM | #7 | |
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I believe this is the item: https://www.millway.se/adapter-for-6...er-plates.html |
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04-20-2024, 01:30 PM | #8 |
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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.
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04-20-2024, 02:35 PM | #9 | |
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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! |
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04-20-2024, 03:33 PM | #10 | |
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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. |
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04-21-2024, 05:15 PM | #11 | |
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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. Last edited by casualDIYer; 04-21-2024 at 06:20 PM.. |
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04-22-2024, 12:49 PM | #12 |
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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.
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04-22-2024, 01:39 PM | #13 |
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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 or 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 or it will clank when the car encounters a depression in the road that causes the suspension to extend to it's maximum. Snug fit 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 greater 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 slam it to any height I like". If a coilover was not low enough, and adjustments would need to go out of spec to get the ride height you want, you need alternative springs but keep in mind, damper and spring are paired. While alternative spring rates are not uncommon, alternative heights are. Shop carefully for the model of coilover you need for your application as making changes kind of defeats the purpose of buying them--all components are carefully matched. 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.
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Last edited by casualDIYer; 07-30-2024 at 08:31 AM.. |
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04-22-2024, 04:00 PM | #14 |
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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. Last edited by wesmeister; 04-22-2024 at 04:00 PM.. Reason: grammar |
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04-22-2024, 04:03 PM | #15 | |
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04-22-2024, 07:36 PM | #16 | |
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My front axle load rating is 1020 kg. |
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04-22-2024, 08:00 PM | #17 |
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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 |
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04-23-2024, 01:10 AM | #18 |
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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.
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04-23-2024, 04:39 PM | #19 |
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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.
EDIT: FYI I ordered mine and shipping came to $35 from Germany, with a 3-4 week lead time. Also, there were cheaper European vendors online (~$72 each), but they didn't offer shipping to the states. Last edited by Dagstar; 05-14-2024 at 09:52 AM.. |
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07-04-2024, 02:31 PM | #20 |
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It took a little over 5 weeks to receive my 2041 springs. After installing I took measurements and everything was in spec. Bumps feel more muted. Not as much of a change as I had imagined, though soon after I rode in my friend's car (stock Ioniq 5) down one of the same roads and they felt similar, so chalk it up to crappy CT roads. I also went through a few spots around town that I used to crash hard over and they were much improved.
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07-05-2024, 12:22 AM | #21 |
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What is the GVWR of your F31 F&R?
I see in the KW v2 TUV data VA (Front Spring) 2039 to 1,000kg 2041 to 1,095kg HA (Rear Spring) 20-60-80/ 110-200* to 1310kg 2039 Wire Size: 11.4mm Outer Dia. Top: 117mm Outer Dia. Middle - Outer Dia. Bottom: 85mm Untensioned Height: 235mm Number of Coils: 6.9 2041 Wire Size: 11.4mm Outer Dia. Top: 118mm Outer Dia. Middle - Outer Dia. Bottom: 84mm Untensioned Height: 235mm Number of Coils: 7.2 I’ve been considering KW v2 or v2 Street Comfort for my 2016 F31 328ix. I’ve been driving on Eibach Pro-Kit E10-20-031-22 and stock EDC struts and shocks for the last 47K miles (car has 88K). The ride is getting pretty bouncy. E10-20-031-15-22 F11-20-031-02-VA 1020kg F11-20-014-14-HA 1300kg My wagon’s GVWR is: F: 980kg R: 1229kg ….so I’m thinking front spring 2041 if I decide to go with KW v2 or v2 Streer Comfort coilovers.
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