Bouncy and Jarring Rear End After MP-HAS

[RElias21]

Update in post below

Back in September 2020, I had my MP-HAS installed. I distinctly recall leaving the shop after install and feeling like that car had gotten MORE comfortable. A few weeks later I had CS-EDC installed, which my understanding would also at least make the ride more compliant. At the time, I didn't notice too much of a difference, one way or the other.

Last November 2020 I traveled for about a week, and upon returning, I felt the car suddenly felt so much more jarring. I was really perplexed, but figured it must be in my head after not driving the car for a week.

Anyhow, the car has felt bouncy and jarring in the rear end for a while now. In fact, I was riding on the 18" 513s for the winter and most of the summer and the car still feels jarring over bumps and bouncy after dips. I went to the Fall Meet & Cruise this past weekend and driving at high speeds, on some twisty roads, and the rear end felt really sloppy with any road surface fluctuations.

My car is a 2017 ZCP with 17k miles on it. I've probably put somewhere between 5-10k on it with the MP-HAS.

Could one or both of my rear shocks have blown? I never thought this could be the case with a car that's not driven hard and has such low miles. I don't think anything is loose in the back.

Thoughts?
If so, where is the best place to buy new OEM ZCP shocks.

Thanks.

[JamesGames]

Why not take it to a shop first to rule out blown shocks vs asking a forum for opinions on if it's blown and subsequently ready to buy new OEM shocks? What if this doesn't solve your issue?

From my past experience with lowering every car I've owned, I have never had a car that was lowered on stock shocks ride as nice as stock springs / shock setup. It's not a setup I would be willing to run long on - I had springs only while waiting for a set of coilovers.

You are running on MP-HAS though so I'd assume those were designed towards the stock shocks. One thing to note though is I never thought the stock springs on 513M rode that nice either. I'm on KW CS with linear rate springs and shocks adjusted towards the stiff end with a much higher spring rate and I still feel it's better than stock and aftermarket springs with stock shocks.

Lowering a car typically reduces travel and you will eventually wear out shocks faster as well. Could be a combination of worn shocks + reduced travel from lowering. Again, take it to a shop to rule out blown shocks would do better than just replacing the shocks. And if you are replacing EDC shocks, those aren't exactly cheap.. consider coilovers? Just my 2 cents

[RElias21]

Originally Posted by JamesGames

Why not take it to a shop first to rule out blown shocks vs asking a forum for opinions on if it's blown and subsequently ready to buy new OEM shocks? What if this doesn't solve your issue?

From my past experience with lowering every car I've owned, I have never had a car that was lowered on stock shocks ride as nice as stock springs / shock setup. It's not a setup I would be willing to run long on - I had springs only while waiting for a set of coilovers.

You are running on MP-HAS though so I'd assume those were designed towards the stock shocks. One thing to note though is I never thought the stock springs on 513M rode that nice either. I'm on KW CS with linear rate springs and shocks adjusted towards the stiff end with a much higher spring rate and I still feel it's better than stock and aftermarket springs with stock shocks.

Lowering a car typically reduces travel and you will eventually wear out shocks faster as well. Could be a combination of worn shocks + reduced travel from lowering. Again, take it to a shop to rule out blown shocks would do better than just replacing the shocks. And if you are replacing EDC shocks, those aren't exactly cheap.. consider coilovers? Just my 2 cents

I am taking it to a shop. Was curious for the forum's opening. A lot of really knowledgeable people here.

Sorry?

[JamesGames]

Originally Posted by RElias21

I am taking it to a shop. Was curious for the forum's opening. A lot of really knowledgeable people here.

Sorry?

I gave you my opinion and tried to offer my experience based on the limited information available and without seeing your shocks or riding in your car - you didn't disclose you were going to take it to the shop. It came off as you were asking for our opinions and if we thought it was blown, where can you buy shocks. In order to save you from doing that move I stated what you responded to.

Don't need to be offended and apologize sarcastically. Interesting that you only respond to my first line, in which I responded to hoping (possibly)to save you from buying new shocks that weren't needed. Hope you figure out your issues.

[TopJimmy]

How many miles on the dampers?
Have they been coded?

I'm thinking if they aren't old maybe have Kubax check your coding settings in the computer.

[RElias21]

Originally Posted by TopJimmy

How many miles on the dampers?
Have they been coded?

I'm thinking if they aren't old maybe have Kubax check your coding settings in the computer.

17k on the dampers.
Yes, they've been coded with CS EDC. I had both Alex@Alpine and KubaX check before and they confirmed the CS coding.
Would I be asking them for anything else in specific?

[TopJimmy]

I was thinking that the coding may be wrong but both those coders are masters, so unlikely.

17K is nothing…not worn out from time.

A damper could have failed if you ran a lower height than suggested…like how lowering springs wear out dampers faster? Not sure. If you have warranty and it's MP then maybe see the dealership.

[spidy512]

Yo!

So a couple quick questions.

How low are you? Can we assume you are within BMW specs?

As others have already said, sounds like possibly your too low in the rear and maybe sitting on the bump stops.

Also, maybe someone smarter than me can chime in, but when the EDC is disconnected, the system defaults to a very stiff setting? Like stiffer than Sport+?

I know aftermarket Bilsteins go full arse hard when disconnected. Is it possible your rear shocks are disconnected? Just thinking outside the box....

Good luck either way!

josh

[RElias21]

Originally Posted by spidy512

Yo!

So a couple quick questions.

How low are you? Can we assume you are within BMW specs?

As others have already said, sounds like possibly your too low in the rear and maybe sitting on the bump stops.

Also, maybe someone smarter than me can chime in, but when the EDC is disconnected, the system defaults to a very stiff setting? Like stiffer than Sport+?

I know aftermarket Bilsteins go full arse hard when disconnected. Is it possible your rear shocks are disconnected? Just thinking outside the box....

Good luck either way!

josh

I don't think I'm THAT low. My rear is NOT tucked in.

And jarring ride aside (which is jarring even on 18s) which was not the case before, what about the bouncy-ness?

[spidy512]

Damn. Now I want 513's. What spacers?

Double damn. I want 763's as well.

The boucy'ness IMO and research has been sitting on the bumps.

I have some recent experience in a bouncy ride. Before the f80, I had a f22 M240ix, and installed B16 co's. I asked for it to be lowered by an inch or so, and the shop had no problem achieving that. The front was tucked for sure, the rears, close to what yours looks like.

I drove the car for about 2 weeks to let the springs settle. I was planning to go for a month, but I found the car to be very bouncy, especially in the rear. The rear end felt like it "skittered" across uneven pavement, etc. B16's, as I found out through a redic amount of research and reading, don't like to be too low. It is the same for the f80 B16's as well (I think this a pretty well documented "feature" of the B16's for many BMW platforms).

So, after the two weeks went by, I decided to raise the car up a bit to see if I could improve the ride. Keep in mind I used the Dinan lowering bumps for this install. As expected, the close I got to stock, the better the car rode and the better the shocks/struts were able to do their magic. It was awesome, but the car was now only lowered about 1/2" all around.

TL: DR = I think that any form of lowering that does not account for maintaining stock levels of travel puts the car too close to or on the bumps and therefore cause the overly stiff, bouncy rear suspension. This also causes the shock to get beat to heck, and possibly limits the shocks ability to provide the proper support for the high-mid-low stroke they were designed for. Adding more compliance to the shock I would think makes it worse.

I am no suspension engineer, so I am sure someone who is can cut holes in that for us...

josh

[1000hp]

Originally Posted by RElias21

Back in September 2020, I had my MP-HAS installed. I distinctly recall leaving the shop after install and feeling like that car had gotten MORE comfortable. A few weeks later I had CS-EDC installed, which my understanding would also at least make the ride more compliant. At the time, I didn't notice too much of a difference, one way or the other.

Last November 2020 I traveled for about a week, and upon returning, I felt the car suddenly felt so much more jarring. I was really perplexed, but figured it must be in my head after not driving the car for a week.

Anyhow, the car has felt bouncy and jarring in the rear end for a while now. In fact, I was riding on the 18" 513s for the winter and most of the summer and the car still feels jarring over bumps and bouncy after dips. I went to the Fall Meet & Cruise this past weekend and driving at high speeds, on some twisty roads, and the rear end felt really sloppy with any road surface fluctuations.

My car is a 2017 ZCP with 17k miles on it. I've probably put somewhere between 5-10k on it with the MP-HAS.

Could one or both of my rear shocks have blown? I never thought this could be the case with a car that's not driven hard and has such low miles. I don't think anything is loose in the back.

Thoughts?
If so, where is the best place to buy new OEM ZCP shocks.

Thanks.

Any error messages displayed?

One of my front EDC connectors backed out of the strut the other day, and the car defaulted to some sort of base damping that was really harsh. When I secured the connector and re-started the vehicle, the ride was normal again. But, I got chassis malfunction warnings when that happened.

If you left for a week and came back and it was suddenly harsh, I would suspect something electronic rather than mechanical. Shocks don't blow overnight or over the course of a week of sitting idle. But I can't see having some kind of electronic issue without the car seeing a fault.

[RElias21]

Thanks, all.

I'm taking the car to the shop on Friday for a separate install, and will ask them to take a look and see if they notice anything glaring.

My issue is that the car was riding much better after initial MP-HAS install. So, there is a change in driving characteristics without a change in parts. Also, there appear to be so many members who have this same setup, and sit even lower than me, and I haven't heard this type of complaint. The rear end currently does not inspire much confidence on bumpy roads.

The shocks are not cheap, but I'm almost hoping it's a simple plug and play issue like that that can be easily remedied.

I guess we'll see if the shop notices anything.

[RugbyBro]

If it’s a sudden change it could be either the shocks are toast or they don’t have a charge running thru them for some reason. The latter resorts the shock to a passive state which is even stiffer than Sport+. Don’t take my word as the gospel truth, just spitballing based on the context in this thread

[RElias21]

Originally Posted by RugbyBro

If it’s a sudden change it could be either the shocks are toast or they don’t have a charge running thru them for some reason. The latter resorts the shock to a passive state which is even stiffer than Sport+. Don’t take my word as the gospel truth, just spitballing based on the context in this thread

Update:

My rear driver side shock is indeed blown. This makes sense because that's the side that I felt more of the issues with.

You can see all the oil on the strut in the picture. The other side is perfectly clean.

[knightarmor]

Wow. Curious if you remember hitting any severe bump or something that would have caused this? As stated by other folks lowering does affect the life of the shocks/struts but I would guess BMW kept some compliance in the acceptable range of travel with the MPHAS setup on the factory dampers. I've got well over 40k miles on my MPHAS and have beat on the car pretty good without any issues.

[RElias21]

Originally Posted by knightarmor

Wow. Curious if you remember hitting any severe bump or something that would have caused this? As stated by other folks lowering does affect the life of the shocks/struts but I would guess BMW kept some compliance in the acceptable range of travel with the MPHAS setup on the factory dampers. I've got well over 40k miles on my MPHAS and have beat on the car pretty good without any issues.

I honestly do not. This car spends about 5 out of 7 days parked in the garage.

I don't think this was something recent either. I would guess this has been like this for at least 6 months. I just don't have a lot of weight in the rear often, nor do I get a chance to drive very spirited that often. I did this weekend, and it just did not feel right.

I honestly think this is just a freak occurrence.

Anyhow, I'm kind of relieved because if nothing was wrong, I was going to have to either raise the car or start looking into a different setup, neither of which I wanted to do.

[RElias21]

Originally Posted by spidy512

Damn. Now I want 513's. What spacers?

Double damn. I want 763's as well.

josh

Sorry I didn't answer your question from before.

I went with 18F/15R for the 513s and 15F/12R for the 763s (and previously the 666s).

I currently have BMS spacers and previously had MS.

They all caused my steering wheel to vibrate and I needed to modify my install to reduce it to almost no vibration.

[spidy512]

Thanks bro!

I am running 15/15 on the stock 19's. No vibes for me thankfully.

I love the look of the 513, but another 19" wheel really makes the most sense as I have 2 sets of tires (summer/winter) that are 19". But dang, your set up looked good with the 18'son there.

FWIW, I like the new wheels better... haha

cheers!
josh

[RElias21]

Finally had my shock replaced today.
To say that the shock was gone, would be a vast understatement.

When we pulled the shock off the car, the rod just slid right down on its own into a fully compressed state.

It was def spewing for several months. Luckily, the shop looked over the rest of the components in the rear and everything looked fine.

Car feels much better now.