[luckyu]

I'll be checking ride height every few days and noting any changes. I'm also keeping an eye out for any changes in how the shocks feel. Bilsteins are rumored to soften up over the first 2000 miles.

Day 3

LF 14 3/4
RF 14 5/8
LR 14 5/16
RR 14 3/16

[cvc 22349a]

Nice looking hardware
Go flats should help and hopefully the dampers will soften a bit..

[luckyu]

Originally Posted by cvc 22349a

Nice looking hardware
Go flats should help and hopefully the dampers will soften a bit..

Thanks, hope so.

[luckyu]

These are photos of the bump stops that were taken off my car. These bump stops came with the BMW performance shock kit that I had installed some time ago.

Now, the kit I'm talking about is the "Version 1" kit; the kit available today is different and includes springs.

Here are the bump stops together with the ZSP bump stops, so you can compare. From left to right, there's ZSP front, Performance front, ZSP rear, Performance rear.



The performance bump stops are longer than the ZSP ones. This I think is strong evidence that the ver.1 kit was intended to be used with the original springs. BMW is using these bump stops to add a little spring rate to the ZSP springs.

31 33 6 767 333-01 ZSP Front bump stop 2.75", weighs 58 g
31 33 8 036 012-01 Perf (Ver.1) front bump stop 2.94", weighs 63 g

33 53 6 767 335-01 ZSP Rear bump stop 2.88", weighs 51 g
33 53 8 036 000-02 Perf (Ver.1) rear bump stop 3.06", weighs 75 g

Again, the specs on the bump stop I'm using now:

33 53 6 761 903 E85 Z4 2.5i rear bump stop 2.50", weighs 35 g
(The way to order the E85 stop is actually p/n 33 53 6 770 350, which includes bump stop and protection tube)

Here is another shot from an angle.

[cvc 22349a]

Did you use E85 front and rear bumpstops? Which car is that?

[luckyu]

Originally Posted by cvc 22349a

Did you use E85 front and rear bumpstops? Which car is that?

The E85 is the previous generation Z4.

The Bilstein strut has an inverted shock absorber, and uses an internal bump stop of its own. I had Bilstein install a shorter bump stop in there, and it's 2" long.

In fact, I just measured my static extension on the strut. In front, I have:

Bump travel to bump stop contact: 1.2"
Total bump travel: 2.5"
Total droop travel: 3.4"

These lengths are at the wheel. My static extension measurement is not exact, I had to reach in there with a business card to gauge how much the strut is extended. My bump might be as much as 1/8" higher.

I got the necessary specifications on the strut to calculate these numbers from Bilstein Poway.

I think stock ZSP travel to contact is 0.5". So I have an additional 0.7".

The upshot is: I'm running with significantly more bump travel than anyone else. Probably, not every tenth of an inch is absolutely necessary; but this is still not very much travel, and every bit helps. A stiffly damped suspension like this one minimizes suspension movement and therefore makes more out of the inches one has.

[yakev724]

Very informative thread; thanks.

Did you purchase the M3 LCAs from BMW or HPA? HPA modifies them in some way for non-M use (incl. a modified headlight control arm) and I'm now wondering if that's required at all since you're using otherwise M3 components.

Also, are the rear height adjusters required? Are the Hyperco and Swift springs designed tall for use in coilovers?

[luckyu]

Originally Posted by yakev724

Very informative thread; thanks.

Did you purchase the M3 LCAs from BMW or HPA? HPA modifies them in some way for non-M use (incl. a modified headlight control arm) and I'm now wondering if that's required at all since you're using otherwise M3 components.

Also, are the rear height adjusters required?

The 12" race springs are almost a perfect fit without a height adjuster. A 525# 12" spring puts you at 14" on a 328i. Obviously, your ride height will vary depending on your corner weight, and the spring constant.

Eibach makes some 3.0" ID springs that can fit around a factory-style Bilstein strut. All that's needed is enough stroke and an upper spring plate.

We're R&D-ing the auto-levelling bracket. I have a couple different brackets on my desk right now...

[luckyu]

Here are a couple more pictures of the camber arm. In the first ones I took, the spring was obscured a little.

[luckyu]

Here are weights and lengths of various parts in the suspension.

Bilstein claims monotubes are lighter, so I weighed the shocks. The Bilstein strut is actually heavier, which makes sense because there's an insert in the tube. Unfortunately it's difficult to measure the unsprung weight, which is more important and should be lower for the Bilstein inverted design.

Bilstein e9x front strut weight, Left 3.469 kg, Right 3.466 kg

E90 Performance strut 31 31 8 036 553 weight, 3.223 kg

The Bilstein rear shock is lighter by a small amount:

Bilstein M3 rear shock weight 2.203 kg (shaft is sprung)

E90 Performance shock plus saddle weight 2.225 kg

Here's the weight of the front spring:

335d front spring 31 33 6 767 379 weight 1725 g (approximate)
length 13" or 13 1/4" (approximate)

Here are weights for the stock perch and the SP lowering perch:

E90 stock upper spring plate weight 237 g
Supersport SUFT015 upper spring perch 783 g

Measured at the spring's highest point, the SUFT015 lowering perch gives 0.343" more offset than the stock perch. Removing the upper rubber isolator that's normally used with the stock perch -- which is recommended by SupremePower -- gives you an additional 0.1" of lowering. That's 0.44" total.

Here are weights and heights for the two front strut mounts that are used on E90s. 098 is used on E90 and E92 sport suspension cars. 943 is used on the base model 328i sedan, all E82, all E46, and some other models. The 943 part is made of aluminum, which is why it's half the weight.

Guide support 31 30 6 775 098 2.19" +- 0.03" 805 g

Guide support 31 33 6 760 943 2.37" +- 0.03" 419 g

Here's the rear camber arm weight:

M3 right camber arm, weight 1.837 kg
E90 left camber arm, weight 2.349 kg

[luckyu]

Here is a summary of spring rates and frequencies I'm using. I'm using my best current guess for the front, since I don't know exactly what it is.

Springs

Front main spring rate 150# (1.35 Hz)
Rear main spring rate 525# (1.56 Hz)

(The flat ride is "optimized" for 62 mph. The ride is actually perfectly flat at 80, but that's partly because at higher speeds there's less pitch to correct for anyway, because the front and rear hit the bump closer together in time. The "flat ride" at 60 is very good.)

M3 sway bars front and rear.

BMW's wet weight for the 328i is 3362 lbs.

Shocks

Bilstein M3 "HD" valving on struts and shocks.

Note: one thing I don't have is the correct roll centers for my ride height.

Note: another thing the spreadsheet doesn't take into account is the extra springrate that is added by bump stops. However, I've shortened the bump stops so much, they are not as large a factor in my setup.

[luckyu]

A while ago I was complaining about a perceived 3 Hz oscillation after every medium bump. Like an afterbump. This was occurring during low speed driving, like 30 mph, over roads that caused the car to move up and down.

I think a significant part of this is the seats! The seat cushion has a lot of give, and bounces me at 3 Hz -- but only over particular bumps that excite that frequency. The car itself is not oscillating.

Is anyone else bothered by this bounce in the seats? I will say that it has all but gone with the new suspension. But it still happens on particular bumps.

[Fraggy]

Luckyu, what do you do for work, you sound like an engineer.

[luckyu]

Originally Posted by Fraggy

Luckyu, what do you do for work, you sound like an engineer.

Yeah, maybe it's a little too much information. I think it'll be helpful to someone, though.

[jah29]

Good work!

I think new tires will solve your last problem.

When I changed to the M3 front arms on my 135i the ride was very choppy/loud over big bumps like you describe. This was with the OEM run flats. I thought it so bad that I ordered new tires and wheels the next day. I bought Breyton gts-r's and bridgestone Re-01s. I thought the new tires and rims changed the ride back to the way it was with the mushy original control arms and runflats, but kept the improved steering precision and cornering.

The rims were about 8# less than stock, but I think the majority of the ride improvement came from more supple tire sidewalls.

justin

[luckyu]

Originally Posted by jah29

Good work!

I think new tires will solve your last problem.

When I changed to the M3 front arms on my 135i the ride was very choppy/loud over big bumps like you describe. This was with the OEM run flats. I thought it so bad that I ordered new tires and wheels the next day. I bought Breyton gts-r's and bridgestone Re-01s. I thought the new tires and rims changed the ride back to the way it was with the mushy original control arms and runflats, but kept the improved steering precision and cornering.

The rims were about 8# less than stock, but I think the majority of the ride improvement came from more supple tire sidewalls.

justin

Thanks that's really encouraging! I too encountered rattling and choppiness when installing front arms. I had installed the performance shock kit at the same time, and I attributed it to the shocks at the time. And that was... just after I had changed from 17" goflats to 16" runflats!

I'd be interested in hearing more about your current setup, Justin. I know you've done lots of research and experimenting in the past, and your results have been helpful to me.

[jah29]

Originally Posted by luckyu

I'd be interested in hearing more about your current setup, Justin. I know you've done lots of research and experimenting in the past, and your results have been helpful to me.

Car has been traded in for an audi Q5 since the twins have been born. (btw, Horrible SUV!!! Can't do anything without the electronics getting in the way. I have to go through an assortment of to urn of the radio after my wife drives it, otherwise it turns the radio back on every time I start the car.)

Anyway, I don't think I have any more info to provide you with other than change the tires. The bushings in the standard 3-series arms are super soft to cancel out the ultra stiffness of the RFT. The M3 arms with any ultra high performance tire, or reg tire, has the same ride quality because the sidewalls will now flex as much as the original bushings did -and handling will be much better.

I'll be back in a BMW when/if they come out with the next 4-door M3.

Justin

[luckyu]

Originally Posted by jah29

Car has been traded in for an audi Q5 since the twins have been born. (btw, Horrible SUV!!! Can't do anything without the electronics getting in the way. I have to go through an assortment of to urn of the radio after my wife drives it, otherwise it turns the radio back on every time I start the car.)

Anyway, I don't think I have any more info to provide you with other than change the tires. The bushings in the standard 3-series arms are super soft to cancel out the ultra stiffness of the RFT. The M3 arms with any ultra high performance tire, or reg tire, has the same ride quality because the sidewalls will now flex as much as the original bushings did -and handling will be much better.

I'll be back in a BMW when/if they come out with the next 4-door M3.

Justin

Apparently the impact of twins is far-reaching... New tires are on their way, I will update when they are installed.

[luckyu]

As I mentioned before I'm keeping an eye on ride height. I'm interested to see if the front OE springs I'm using take a set. They are brand new springs from a 335d.

FRONT
Day 2: 14.75 14.63
Day 3: 14.75 14.63
Day 10: 14.63 14.63 (26.31 26.25)

REAR
Day 2: 14.25 14.19
Day 3: 14.31 14.19
Day 10: 14.34 14.25 (25.94 25.81)

I'm going to measure from the ground from now on, that's what those numbers in parentheses are. I think measuring from the ground is more accurate.

The front left may have dropped 1/32". It's hard to tell because it's too small a change to measure reliably.

[EDIT: I don't know why I said 1/32", it's more like 1/10". After waiting a while and finding the right front go down too, I now think this change is real. Both fronts dropped about 1/8".]

[hdrewh]

luckyu, the E36 bump stops that you use for the front, would that be p/n 31332225377 as shown HERE?

Just want to be sure.

Thanks.

[luckyu]

Originally Posted by hdrewh

luckyu, the E36 bump stops that you use for the front, would that be p/n 31332225377 as shown HERE?

Just want to be sure.

Thanks.

Yes, those are the ones. Actually, I do not use them on my car. I have Bilstein struts, which are inverted and have an internal bump stop. I had Bilstein install a shorter bump stop for me when the struts were being revalved. I do use the Z4 bump stop in the rear.

For others who may be reading this: the E36 M3 front bump stop is the one used by Dinan in their M3 lowering kit. Steve D. wrote a "white paper" about it, where he talks about what he's trying to accomplish and why they chose that part. It's slightly shorter than the stock ZSP bump stop, which is why I keep mentioning it.

[luckyu]

Well the front OE springs may have sagged just a little. Not much, just an eighth of an inch. The rear Hypercos seem to have stayed the same; the measurements are oscillating up and down. I'm just giving the raw data here, I'm obviously not able to measure very accurately.

FRONT

Day 2: 14.75" 14.625" eye level with fender lip
Day 3: 14.75 14.63
Day 10: 14.63 14.63
Day 17: 14.63 14.5
Day 19: 14.63 14.53

REAR

Day 2: 14.25" 14.19"
Day 3: 14.31 14.19
Day 10: 14.34 14.25
Day 17: 14.25 14.12
Day 19: 14.25 14.19

I changed tires on day 17, so my "from the ground" measurements were all different. I'm showing "from the centercap" measurements here.