E8X Would using the M-sport rear springs help?

[rhodesman]

Background:

I have the MFactory YCW coils all around which I upgraded from the OEM M-sport suspension on my E88. I felt the M-sport suspension had good ride height and ride however when going through tight, technical roads with multiple switchbacks and alternating road grades, the m-sports made the chassis feel "floaty" and "soft" (put in quotes because of personal observation while driving vs. actual technical data).
At the time I started to look for upgraded spring/shock combos and ran across a group buy for the MFactory YCW coils. After they answered a bunch of my questions, I pulled the plug and have had them on for just over a year now. I do love them, and they have resolved 95% of my issues with the M-sport setup I mentioned.
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Problem:

I find the Front coils & springs handle the road just fine and I have the stiffness and ride height tuned to my liking. The rear is a little less than I was hoping. The rear spring rate I feel is a little too stiff causing the car to have a "bumpy" ride when driving over bridges or sections of road that have a sort of "~~~~" surface. I have tried different adjustments of the shocks but softer shocks turns the bounce into like sitting on a water bed and stiffer makes the bounce more harsh and teeth breaking.
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Question:

My question is could I combine the rear M-sport springs with the MFactory YCW shocks for a lesser spring rate spring with a stiffer shock to help balance that "bump" I get when cruising? If so, what effects can I expect to see on those tight technical back-roads with the YCW full setup front and a Hybrid YCW/M-Sport rear?
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Obviously I will gain some ride height in the rear which I'm okay with. Currently my rear YCW setup is as close to OEM height as they allow plus I like a more "raked" stance look anyways and don't even consider "slamming" my car in the least. But also knowing the M-sport springs are meant to hold the car from the unibody to control arm, can I use the MFactory Spring Hat adjusted to the highest point or would I have to go back to the OEM Spring Hats? (not a big deal ether way, but I'm 99% sure I threw out my OEM spring hats and thus would need to buy new ones first if I can't use the YCWs.)

Thanks for any help you can offer and sorry for the book-long read, here's a TL; DR; for you:

TL;DR:

I have YCW Coils all around. Ride quality on highways are more "bouncy" than I would like. Wondering if using the M-sport springs in the rear WITH the YCW shocks could possibly fix the problem without loosing the "crisp" ride/feel on the backroads.​

 

[zero2sixtyZ]

What are the spring rates you bought with the YCW coils?

 

[rhodesman]

if I remember correctly it’s 12k for the rear.

 

[zero2sixtyZ]

Fronts?

 

[rhodesman]

Ooh sorry 4K

 

[zero2sixtyZ]

Any reason you wouldn't want to buy a pair of YCW or Swift rear springs to swap in? You could try an 11k? I bought a pair of swift rears in 14k for about $150-160 shipped, and then sold the other 12ks I had. Any lower in rate and you might need a revalve of the struts, if they were valved to match the original 12ks.

Also, are you on RFTs? Tire size? Replaced strut mounts during install? Struts haven't deteriorated, have they? There's a bunch of reasons why it could be giving a rough ride.

 

[rhodesman]

Since you ask a bunch of questions here, Let me break them up and answer then individually:

Any reason you wouldn't want to buy a pair of YCW or Swift rear springs to swap in?

A: Fair Point. My reasoning here is only that I have the M-sport springs sitting in my garage. So why not test out something that's free vs. spending money.

You could try an 11k?

A: When I had originally spoke with MFactory about it I was suggesting a 4K/10K setup but they swayed me to the 4K/12K as it was the M-Sport OEM spring rates. I guess the firmness isn't my problem, just the fact that the spring is so much shorter so it's a 12K rate in half the space as the M-Sport spring (M-Sport going from control arm to chassis while MFactory goes from control arm to adjustible spring perch currently set 2.5" lower than the chassis so the rear ride height is closer to OEM height).

I bought a pair of swift rears in 14k for about $150-160 shipped, and then sold the other 12ks I had. Any lower in rate and you might need a revalve of the struts, if they were valved to match the original 12ks.

A: Good to know!

Also, are you on RFTs? Tire size?

A: Michelin Pilot SS XL, F:225/40R-18 R:255/35R-18

Replaced strut mounts during install?

A: You know, I meant to do these but were backordered when I got the YCWs and totally forgot about it. This could be a very likely culprit.

Struts haven't deteriorated, have they?

A: I hope not! I don't think so because there is not any more travel than normal and none of my wheels "bounce" when hitting a bump. Also none of the struts show signs of leaking or any visual indication of damage or deterioration.

There's a bunch of reasons why it could be giving a rough ride.

Right, and that's why I figured opening a post about it would be helpful for me figuring out WTF I can do as well as help anyone in the future. Honestly, suspension settings elude my understanding. I understand every other aspect of my car including the software running every part of it but I have never understood proper suspension setups.

I guess when you boil it down, my issue isn't with the spring rate per-say but really the initial bound-rebound has a little bit of play in it which may very well be the rear strut mounts as those are now what, 7-8 years old!? I'll place an order for some new ones and see if that helps fix anything before changing anything else.

Another Consideration:

My other thought about going back to the M-Sport rear springs had to do with wheel travel. Currently my fronts have a lot more travel on both bound and rebound which tends to make the rear feel stiffer because it's not moving as much. I was wondering if having the longer M-sport Spring back in there would help with that as obviously I would still be limited by the total travel of the strut but curious if the longer spring would remove some of that aggressive rebound force as it wouldn't get AS compressed as the shorter YCW Spring. Thoughts?​

 

[zero2sixtyZ]

Since you ask a bunch of questions here, Let me break them up and answer then individually:

A: When I had originally spoke with MFactory about it I was suggesting a 4K/10K setup but they swayed me to the 4K/12K as it was the M-Sport OEM spring rates. I guess the firmness isn't my problem, just the fact that the spring is so much shorter so it's a 12K rate in half the space as the M-Sport spring (M-Sport going from control arm to chassis while MFactory goes from control arm to adjustible spring perch currently set 2.5" lower than the chassis so the rear ride height is closer to OEM height).

I guess when you boil it down, my issue isn't with the spring rate per-say but really the initial bound-rebound has a little bit of play in it which may very well be the rear strut mounts as those are now what, 7-8 years old!? I'll place an order for some new ones and see if that helps fix anything before changing anything else.

Another Consideration:

My other thought about going back to the M-Sport rear springs had to do with wheel travel. Currently my fronts have a lot more travel on both bound and rebound which tends to make the rear feel stiffer because it's not moving as much. I was wondering if having the longer M-sport Spring back in there would help with that as obviously I would still be limited by the total travel of the strut but curious if the longer spring would remove some of that aggressive rebound force as it wouldn't get AS compressed as the shorter YCW Spring. Thoughts?​

YCW rear struts are body length adjustable, right? Doesn't make sense for a short travel coilover to have more travel in the front, with the rear suspension design we have. I'd be interested to see what spring length they used, and what the strut looks like at rest, up in the air, with no wheel on. For reference, I went from a 9" 12k spring to a 9" 14k with my Fortune Autos, stock like ride height.

Maybe YCW meant the spring frequency would match the M-Sport spring rates? The M3 stock rear spring is right under a 10k, so I can't imagine the M-Sport being that high.

 

[Rob09msport]

You must have gotten the first set they sent out if you follow their launch post you will see they learned 4k 12k was actually a mismatch and upped it to 6k 12k their whole 1 to 3 ratio keep stock rates sounded good but they didn't understand that they were measuring springs by themselves when our cars use bump stops as secondary springs that add to spring rate I think you should deff change mounts but also should up the front rate. Just my opinion

 

[rhodesman]

You must have gotten the first set they sent out if you follow their launch post you will see they learned 4k 12k was actually a mismatch and upped it to 6k 12k ...

Is that post on here? I connected with them from a post they made on another forum before I found this one. I've had the suspension since 2016 so I would definitely say I was in the first batch.

With your suggestion I should thus change the fronts to 6k?

EDIT: I messaged MFactory Directly to see if they offer any kind of discount or Refundable deposit to exchange. If not, I'll look for another option to replace the front springs. Does anyone have any suggestions as to a spring/company I should look into (if MFactory doesn't help out)?

 

[zero2sixtyZ]

I'd suggest a Swift or Hyperco coil spring, but you would want the struts revalved to match the new spring rates.

 

[Rob09msport]

Is that post on here? I connected with them from a post they made on another forum before I found this one. I've had the suspension since 2016 so I would definitely say I was in the first batch.

With your suggestion I should thus change the fronts to 6k?

EDIT: I messaged MFactory Directly to see if they offer any kind of discount or Refundable deposit to exchange. If not, I'll look for another option to replace the front springs. Does anyone have any suggestions as to a spring/company I should look into (if MFactory doesn't help out)?

it's their beta thread they did group buy ill look for it

 

[Rob09msport]

http://www.n54tech.com/forums/showthread.php?t=38578&page=3

 

[Rob09msport]

At end of page

 

[ShocknAwe]

Probably already covered as was TLDR of a thread for me, but your problem is most likely that the rate and length of the spring and other suspension modifications you've made to your car have unbalanced the F/R rate, making the rear end oscillate at a higher frequency than the front. Especially if you're sitting on 4/12 with M3 front arms, thats a lot of front rate loss.

Sort of going through this myself (not the same issue) and trying to fine tune my suspension. It's fun!

I THINK what you want to do to fix this is to increase front spring rate vs rear for what you have. Not an expert though so do your homework. Best results I've seen are folks running either ~40% front vs rear, or 50% front vs rear depending on how much front bar they use.

Lastly, you have an E82, which has a short wheelbase. We are going to feel every bit of oscillation more so. I have a bridge near me that definitely seems to have its bumps perfectly synced up to my wheelbase. That said, current setup oscillates a lot less than previous attempts did.

 

[rhodesman]

Probably already covered as was TLDR of a thread for me, but your problem is most likely that the rate and length of the spring and other suspension modifications you've made to your car have unbalanced the F/R rate, making the rear end oscillate at a higher frequency than the front. Especially if you're sitting on 4/12 with M3 front arms, thats a lot of front rate loss.

Sort of going through this myself (not the same issue) and trying to fine tune my suspension. It's fun!

I THINK what you want to do to fix this is to increase front spring rate vs rear for what you have. Not an expert though so do your homework. Best results I've seen are folks running either ~40% front vs rear, or 50% front vs rear depending on how much front bar they use.

Lastly, you have an E82, which has a short wheelbase. We are going to feel every bit of oscillation more so. I have a bridge near me that definitely seems to have its bumps perfectly synced up to my wheelbase. That said, current setup oscillates a lot less than previous attempts did.

Thanks @ShocknAwe ! Great info! I appreciate the help! I connected with MFactory and they are honoring their beta testing offer so I will talk to them about going up to a stiffer front swift spring. They also said they would be happy to re-valve the shocks per my liking/setup for the cost to ship them back, which is insanely awesome!

IF there is anything this beta process has showed me is that MFactory is one of those companies that stands 100% behind their product and making sure their customers are happy!

 

[Rob09msport]

Is that post on here? I connected with them from a post they made on another forum before I found this one. I've had the suspension since 2016 so I would definitely say I was in the first batch.

With your suggestion I should thus change the fronts to 6k?

EDIT: I messaged MFactory Directly to see if they offer any kind of discount or Refundable deposit to exchange. If not, I'll look for another option to replace the front springs. Does anyone have any suggestions as to a spring/company I should look into (if MFactory doesn't help out)?

That's awesome and swift are the best which I think is what they will be sending you even if you don't specifically ask for that I am currently installing 8k 12.5k on e92 but I have a heavy ade intercooler and you have shorter wheelbase if I was e90 I would prob up my rear spring but I would do 6 or 7k front even maybe 8k if you added rake with decent drop which I think rake affects necessary spring rate.

 

[rhodesman]

So funny enough, I got my suspension dialed in without any further hardware or swaps! MFactory had me set the front shocks to 3/6 and the rear shocks 6/6 and that balanced the front/rear ride with the springs. Now I'll admit, that's a very hard teeth shattering setting, so I dialed the front down to 1/6 and the rear 4/6 and that seems to be a nice sweet spot! The ride is firm but not bouncy, hard but not teeth shattering, and when the top is down and I'm planning a more spirited drive, I bump the rear shocks up 1-2 clicks to help offset the weight shift. Very happy now!!

 

[doublespaces]

Glad to see you got this sorted out. I ended up selling these coilovers and remain stock suspension.

 

[rhodesman]

Glad to see you got this sorted out. I ended up selling these coilovers and remain stock suspension.

The ride is still too stiff up front when the top is up, but once the top is down the ride evens out perfectly! I just need to find a way to adjust the front shocks up or down 1-2 clicks when i open/close the roof!! ;P