Robbing the E92 M3 and E46 of suspension components

[nicknaz]

Thanks for sharing the tech and vids!

Any thoughts on modified E89 vs. other similar cars? i.e. Boxster S, SLK AMG, Vette, etc

[wmandra]

Originally Posted by nicknaz

Thanks for sharing the tech and vids!

Any thoughts on modified E89 vs. other similar cars? i.e. Boxster S, SLK AMG, Vette, etc

Not really... Love the E89 Z4, and for serious track driving I'd probably end up modifying the suspension on any of the others you mentioned. Just something about the Z4.

[nicknaz]

Originally Posted by wmandra

Not really... Love the E89 Z4, ..

Just something about the Z4.

That's awesome.

[wmandra]

Spent the past weekend at New Jersey Motorsports Park on the Lightning circuit. This is one of my favorite tracks in the Northeast and the main track I use when testing / comparing any changes to the car. No new changes to the suspension have been done since Thompson, but I have removed the JB4 tune from the car to bring it back to stock HP levels. The reason for removing the tune is that the 10 modification points in NASA TT are better used for Hoosier R6 tires. Although I still ran this weekend on the Bridgestone RE-11's, I wanted to get a baseline here on street tires without the tune. The result.... about 3 seconds a lap faster then when I was at Lightning a few months ago (though a lot of the time difference is driver improvement).

I also finally had the chance to get the Z4 on the scales. Total weight with myself, full safety gear and a full tank of gas was 3,465lbs. Which translates to a total of a 21lb weight reduction from stock with all the modifications done. I do need to corner balance the car though, with the current corner weights the car has a 47/53 front/rear weight distribution (which is the same as factory) and I'd like to bring this closer to 49/51. The weights also show that there is a little reverse wedge in the cross weight at 48% which is actually pretty far off from the 50% it should be at. Left turns currently feel a little less stable than right turns (possibly because most tracks I drive have more right hand turns, but I'd still like to get the cars balance closer to ideal.

Finally, not related to the suspension, I've recently been in contact with the folks over at Hawk Performance. They have a new line of brake pads coming out called "Street/Race" which are based on the DTC-30 race compound but with silica added to help reduce the noise and dust. I will be switching to these pads for testing at Watkins Glen on the Z4 in September. I have also confirmed that Hawk will be making a new pad for those of us who have the Z4 35is rear rotors and calipers installed. The new pad shape number will be HB751 and will become available in October. This will be a big improvement over running the HB669 pad with the larger 35is rear brakes.

[nilfinite]

This is an amazing thread. Thank you trailblazing research on the e89 and for sharing all of your research. This information is invaluable.

[wmandra]

Here's an update on the current state of this build...

I've replaced the AST dampers with JRZ RS-Pro dampers. The JRZ units have both compression and rebound adjustments and remote reservoirs.

I decided to match the new dampers with a new set of Swift springs (784 lb/in front, 560 lb/in rear). I also installed 45lb/in Swift helper springs in the front and 223 lb/in Swift assist springs in the rear. The helpers in the front are merely there to take up the slack between the main spring and the perch. In the rear I opted for a heavier assist spring which will provide a bit of mechanical force to keep the drive wheels in contact with the road when unloaded.

The biggest change with the new setup is that the rears are now a true coilover where the spring is mounted directly on the damper instead of the OE location of the control arm. This changes the motion ratio for the rear spring making it more efficient. In the stock location the effective rear spring rate is roughly half at the wheel vs the coilover setup where the wheel rate is essentially the same as the actual spring rate.

In order to install a coilover setup on the rear of the E89 chassis the damper needs to be inverted. I used the Turner Motorsports E46 upper mounts found here: http://www.turnermotorsport.com/p-31...3-z4-pair.aspx along with the reinforcement kit http://www.turnermotorsport.com/p-34...ement-kit.aspx

The only modification necessary to fit these mounts was to drill a new hole as the E46 mounts are 2-hole vs the 3-hole E89 mounts.

I also replaced the front and rear swaybar endlinks with fully adjustable versions from Turner Motorsports. The fronts are E9x fitment and the rears are E46 fitment.

I did the install myself at the Ratchet Head facility in Newton NH and it took about a day. Once the install was complete, we also did a corner balance and alignment.

[jts1981]

Bill,
Can't wait to see the new set up in person at Mpact!

I wonder if any other E89's will be there this year...

[ttuner]

Originally Posted by wmandra

nicknaz/janissa,
I'll try and address both of your questions the best I can. First, in regards to this setup vs an aftermarket setup for an E89, there is no complete aftermarket suspension setup for the E89 platform currently available. If you are talking about a coilover setup, which I'll address below, that still leaves a lot of other suspension components stock.

A suspension is very complex with a number of components that each individually play a part in how the car handles and feels. Springs and shocks control the vertical movement of the wheel when cornering or driving over any kind of bump. Other components, like the control arms and bushings, are also important. If the bushings used are too soft (which the stock hydraulic isolators are) they can deflect under load. This deflection can change the geometry of the suspension, even if just slightly. In a full blown race car many of the bushings are eliminated and solid joints used instead but the ride would be so harsh on the street that you'd never want to drive it. So everything is a compromise, trying to find the right balance of stiffness and comfort.

Here's a quick summary of the various components, stock weaknesses and possible solutions. Every single one of these items will have some impact on the overall suspension and handling:

Front tension struts:
Stock - soft bushings which will deflect under load
Upgrade - replace with ones from E9x M3 which have stiffer rubber bushings.
Effect - less deflection in front toe with a little more vibration transferred into the steering wheel. Will help reduce under steer.

Front wishbones:
Stock - soft bushings that will deflect
Upgrade - none currently as the headlight leveling rod is on the opposite side on the E89 and E9x. Still working on some possible solutions here

Front upper spring perch / guide plate:
Stock - no real "issue" other than stack height and lack of adjustment.
Upgrade - replace with ground control or Vorshlag camber plates.
Effect - camber and caster adjustment. lower stack height on the camber plate will give more travel in the strut when lowered

Front springs / struts:
Stock - no ride height adjustment. minimal adjustment to rebound possible (comfort vs sport mode)
Upgrade - fully adjustable coilovers or lowering springs
Effect - lower/adjustable ride height (also allows for corner weighting). adjustable compression and rebound can be made stiffer at the sacrifice of ride quality.

Front sway bar end links:
Stock - no real "issue" at stock ride height. Incorrect length when car is lowered causes geometry to be off.
Upgrade - adjustable sway bar end links
Effect - sway bar geometry restored so that frame mount and end of bar on same horizontal plane increasing effectiveness

Front sway bar:
Stock - a little on the soft side which can lead to under steer and limited roll control
Upgrade - replace with H&R 27mm sway bar
Effect - reduction in under steer, better roll control and turn in response

Rear lower wishbone:
Stock - no adjustment for camber, soft rubber inner bushing which can deflect under load
Upgrade - E46 adjustable rear camber arms with inner bushing replaced with rod end (solid mount)
Effect - large adjustment range for rear camber. slightly rougher ride with rod-end, but no deflection under load.

Rear trailing arm bushing:
Stock - lots of deflection under load will cause rear toe to change during hard corners
Upgrade - E46 rear trailing arm bushing limiters. These are just shims that are installed on both sides of the bushing greatly reducing deflection
Effect - rear toe maintained under hard cornering, no impact on ride quality

Rear trailing arm upper ball joint:
Stock - no issues, part used in E89 is the same as E46 M3 which is already fairly stiff
Upgrade - none

Rear trailing arm lower ball joint:
Stock - rubber bushing that will deflect under load
Upgrade - none. unfortunately BMW used a different size lower bushing in the E89, in the E85 and E46 this could be replaced with the better upper ball joint.

Rear upper wishbone inner ball joint:
Stock - rubber bushing that will deflect under load
Upgrade - Turner E46 monoball or Group N E46 bushing
Effect - Group N bushing uses stiffer rubber than stock will reduce deflection; Turner monoball replaces rubber bushing with a bearing that will not deflect.

Rear springs / shocks:
Stock - no ride height adjustment. minimal adjustment to rebound possible (comfort vs sport mode)
Upgrade - fully adjustable coilovers or lowering springs
Effect - lower/adjustable ride height (also allows for corner weighting). adjustable compression and rebound can be made stiffer at the sacrifice of ride quality.

Rear sway bar:
Stock - a little on the soft side which can lead to under steer and limited roll control
Upgrade - replace with H&R 21mm adjustable sway bar
Effect - increase in over steer, better roll control

Rear sub frame bushings:
Stock - rubber bushings that will deflect
Upgrade - none currently. still investigating


All of the above can be broken down into various "stages" (these are just mine, but feel free to define your own):

Stage 1:
- Stock struts/shocks (with adaptive suspension)
- Eibach or H&R lowering springs
- Front M3 tension struts
- Front adjustable sway bar end links
- Rear adjustable camber arms

Stage 2:
- Everything in Stage 1
- H&R front and rear sway bars
- rear trailing arm bushing limiter
- rear upper wishbone inner ball joint replacement (Group N or Turner)

Stage 3:
- Everything in Stage 1 & 2
- Vorshlag or Ground Control front camber plates
- Fully adjustable coilovers
- rear subframe bushings (if available)


Hope this helps....


Bill

Thanks for this post. I was just searching around for some suspension mods for after i get my turbos upgraded. This helps alot.

[wmandra]

Originally Posted by jts1981

Bill,
Can't wait to see the new set up in person at Mpact!

I wonder if any other E89's will be there this year...

Unfortunately I won't be at Mpact this year. Other racing commitments have me at Sebring this weekend. I am going to try and make it to Bimmerfest East this year though.

-b

[jts1981]

Originally Posted by wmandra

Unfortunately I won't be at Mpact this year. Other racing commitments have me at Sebring this weekend. I am going to try and make it to Bimmerfest East this year though.

-b

Pm sent

[jts1981]

Originally Posted by wmandra

For the M3 wishbones, the guys at Rogue had to make up a mount for the headlight adjuster which is on the opposite side vs the M3. The headlight leveling regulator rod also had to be slightly modified to get everything to mount up correctly.

I'm starting to source the parts now. I saw Turner and ECS have complete kit for the front, including regulating rod. Can you explain what needed to be done to the stock one to make it fit correctly? Will the OEM E9X rod work?

***Edit*** I saw this was pointed out on post #38. Thanks.

[jts1981]

I just had my parts installed and initial impression is just "WOW." The feedback on steering, handling, and grip are just awesome. I can wait to get some more seat time!

Bill, thanks again for sharing the info, and being so helpful.

I didn't go as extreme because I don't track as often as you. But the key components definitely made a huge difference.

Shout out to Sean from Turner Motorsport for helping get 95% of all the parts.

For any one else interested I went with the following:
- E9X M3 OEM upper/ lower control arms package from Turner
- KW V3 w/ EDC
- Turner E46 rear adjustable camber arms, rod end style
- Rear control arm upper inner bushings, group N- hard rubber
- Rogue Engineering Front tension arm bushing

Another side note, we managed to utilize the E89 headlight sensor and arm, no need for unique mount, or modifying the leveling rod.

I'll post up good pics soon..

[Asbjorn]

Originally Posted by jts1981

I just had my parts installed and initial impression is just "WOW." The feedback on steering, handling, and grip are just awesome. I can wait to get some more seat time!

Bill, thanks again for sharing the info, and being so helpful.

I didn't go as extreme because I don't track as often as you. But the key components definitely made a huge difference.

Shout out to Sean from Turner Motorsport for helping get 95% of all the parts.

For any one else interested I went with the following:
- E9X M3 OEM upper/ lower control arms package from Turner
- KW V3 w/ EDC
- Turner E46 rear adjustable camber arms, rod end style
- Rear control arm upper inner bushings, group N- hard rubber
- Rogue Engineering Front tension arm bushing

Another side note, we managed to utilize the E89 headlight sensor and arm, no need for unique mount, or modifying the leveling rod.

I'll post up good pics soon..

This is awesome! I really wish I could try how this setup feels in-person.

BTW If someone was to do this, but without lowering the car, and aiming for E9X M3 suspension comfort/sport levels (ie a sporty road-worthy suspension matched to nonRFTs and 400ish hp), what would you add/remove from your list of mods?

[jts1981]

Hi Guys,

More pics of the install, and of the headlight sensor. It works like a charm.

One comment is I asked to lift the rear by 1/2 inch from where my car sat with H&R springs, but keep front as is. Then we noticed the front coilover collar was slightly rubbing against the tire so we raised it slightly as well. I noticed that a few guys on E90 mentioned they needed spaces for this set up. Maybe I'll throw them in when I do stud conversion as well.

Asbjorn,

I think you can run the same set up as mine w/o change. The KW can get pretty close to stock height, I think. I would definitely do the E9x M3
front package from turner, rear trailing arms, and f/r bushings as called out in original post.

- Jake

[BIGBOYQ]

Hi,

Great thread - but want some help and advise on what is the best route to do down.

I only do 2 -4 track days an year - and the issues en-counted have been:-

• feeling unsettled at 90 Mph
• Overs steer mid corner

My z4 is my daily driver, so don't want to aggressive drive. Retain my stock Msport struts.

1) Replace Run Flats with Michelin-pilot-super-sport
2) H&R Springs
3) Change front and rear camber

Adding the below items - would an novice track drive notice the difference?

Since the suspension is effected with many components - without changeling all the recommended items - what would be the next item to replace?

Trying to keep the car stock as possible?

Here are some videos of my exploits

From 19 Secs to 45 Secs - were the car did not feel settled -and i was loosing an lot of time

I did find this track a lot easier to drive

[ttuner]

is it true the E89 shares the rear axle with the E46 M3?

[jts1981]

Originally Posted by ttuner

is it true the E89 shares the rear axle with the E46 M3?

I'm using some E46 bits for my rear suspension, so I think the geometry and basic setup is similar, if not same.

Looking at real oem.Com the drawings between look close, but parts are slightly different. Not sure about the actual axels, etc.

If you need I can email you my invoice for my suspension with everything you'll need, minus 1 bushing you'll need to get from Rogue.

[ttuner]

Originally Posted by jts1981

I'm using some E46 bits for my rear suspension, so I think the geometry and basic setup is similar, if not same.

Looking at real oem.Com the drawings between look close, but parts are slightly different. Not sure about the actual axels, etc.

If you need I can email you my invoice for my suspension with everything you'll need, minus 1 bushing you'll need to get from Rogue.

that would be awesome. ill PM you my email.

[jts1981]

Just wanted to bump this thread so new comers have easy access...

Also wmandra ...any updates to report?

[Vetracr]

I have a 2010 E89 3.0si 6 speed with 10K on the odometer. Several people on this thread have noted there is no replacement for the E89 rear lower control arm bushing at the hub. The E89 upper control arm has the same bearing as the E46 M3. The E46 M3 uses this same bearing at the lower control arm. I did some home work. First off, Super Pro offer a polyurethane bushing kit for this application P/N SPF3806K. I ordered the kit and its a nice piece. I still preferred the M3 bearing so I ordered a stock E89 bushing and a pair of M3 bearings. The M3 bearing is .16mm (.0063") smaller in diameter than the E89 bushing. The bearing and bushing is a press fit into the hub. To make up the slight difference in diameter between the two parts I applied a small amount of Loctite 641 bearing retainer on the M3 bearings when I pressed them in. Loctite 641 can accomodate up to .008" diametral clearence. It also allows the bearing to be pressed out if required. As the bearing only sees radial load this should not be a problem. See attached photos. I now have a complete M3 suspension on my E89. E90 M3 tension struts and control arms at the front and E46 M3 RTAB's with Vorschlag limiters and E46 upper and lower M3 hub control arm bearings at the rear. I also added H&R sway bars with rod end links at the rear and Koni FSD shocks all around. I'm running TSW rotary forged 18x8.5 Fr and 18x9.5 Rr rims shod with 235/40 Fr and 265/35 Rr Firestone Indy 500 tires (rebadged Bridgestone R003's). I kept the stock springs and ride height. I installed Ground Control camber plates and a Turner strut bar up front. I also added 330 Front brakes, slotted rotors all around and Cool Carbon pads. I now have a car that handles great at the track or autocross but is still comfortable to drive on the street.

[Vetracr]

I thought I'd add picture of car at Sebring. Check ride with instructor at Chin event. Notice how little roll I'm getting in high speed corner.

[BIGBOYQ]

Latest attempt at Donnington