BSP Z4 M Coupe

[BTM]

Gotta give credit where it's due, Wassup and Illinipo's STR Z4 thread gave me inspiration to start documenting my own proceedings more formally. If you haven't checked their thread out, go do it!

Anyway, last season was my novice season autocrossing, and while my end goal is to end up with a track and Nasa TT car, for now autocrossing is all the budget allows for. Bang for the buck, can't beat it, and the competitive aspect is nice.

INDEX

Trunk Trim Weight
Dynamat Removal
Seat & VAC Mounting kit weight
Race seat installation
Valve Adjustment Prep
Valve Adjustment Measurement, VANOS service
Valve Adjustment Completion
Stud installation
Trunk trim padded clips
Rear shocks
Front struts
Front swaybar, RTAB limiters
RSM reinforcements
Shakedown Autox
Muffler installation
Trunk trim re-installation, shock rebound adjusters
Front tire size fitment (thanks Klin)
FCABs, engine mounts

Backstory:

Bought the car in January of 2011, 2007 with 28k miles on it, completely stock. At the time, I wanted a black car, but now, I don't know I would do it again. Looks good clean though



Plan was to keep it stock. That lasted about 2 days, as a local guy was selling KWV3's from his car which was sold, which I bought, with Rogue Engineering RSMs and Ground Control camber plates.


Next was brake pads. I bought with Axxis Ultimates all the way around. Wassup assured me this was a good street and autox pad, and since I was daily driving the car at the time, I didn't want something too loud or unsuited for DDing. Overall I'm very happy with them. The stock brakes on this car are very good, I see no reason to get a BBK as they already exceed the tire's grip



The KW's external resevoir in the rear makes take the rear slide pins a chore



Some used PS2s for a good price (thanks to Wassup) mounted up for spring and here is how she sat for my first ever event, which was hosted by the Champaign County Sports Car Club



And a bonus shot of Wassup's car in stock class trim and mine driving to Champaign



The car stayed the same for my first BMWCCA event, Windy City chapter held at Maywood Park. Luckily, Gary88 is an excellent photographer and got some nice pictures

Waiting to go, the starter was very talkative, and he liked my gloves





And an embarrassing pose made the Windy City Chapter newsletter (caption added later in some forum dicking around)



The next thing I wanted to focus on was driving position. Not only did I really not care for the stock M-seats (and I know I'm likely one of the few who couldn't get comfortable in them), sliding all over the place and holding onto the wheel made it really distracting and hard to focus on how the car was behaving. I shopped around for nearly a month, sat in as many seats as I could to see what I was comfortable with, and ended up lucking out with this Suzuka S GT (fat American width) I bought locally, mounted using the VAC mounts which are great. Seat fits me perfect, though the standard width would be a little better, for street use the GT is great. I've driven 8hrs + straight in it with no pressure points or complaints at all. When you're buying a seat, make sure you sit in it and it's comfortable!





About now the tires needed to be replaced. As an impulse purchase I bought wheels along with them

SSR Type-F Euro with RE11s. I like the tires a lot, but regret buying the wheels. I think they look great, but were too expensive and I don't want to be buying 18" tires to compete with. I'll be selling them and running a dedicated 17x9 setup this year.







A Gruppe M intake came up for sale on the forums for a good price so I snatched up. I am often too impulsive. It sounds good though





And some pics from one of the last autox's last year. Thanks to Illinipo for lending his garage couch and trig knowledge for a last minute fishing line alignment to get me more front camber which I desperately needed.









Anyway, thanks for reading, and comments / constructive criticism is always welcome.

Since I now have a truck to drive daily, I decided I might shed some weight tonight. My car has a mullet...business up front (cockpit), party in back













The dynamat I put in after installing an aftermarket exhaust which made the cabin louder than I wanted for daily driving. I will be removing it all tomorrow, but ran out of energy tonight.

[BSM_135i]

Awesome build so far!

[BTM]

Thanks a lot man. On the to do list are:

Valve Adjustment
Install new shocks



Rates are 580 and 630. Though I bought some 650s for the rear



And get new wheels. Probably Dforce LT5s.

[illinipo]

Gotta give credit where it's due, Wassup and Illinipo's STR Z4 thread gave me inspiration to start documenting my own proceedings more formally. If you haven't checked their thread out, go do it!

The stock brakes on this car are very good, I see no reason to get a BBK as they already exceed the tire's grip

Once you start doing 120-40 3 times a lap for 20 laps, you might want some more rotor mass or aluminum hats. For autocross, the stock stuff is more than adequate, save the silly holes in the metal parts.

The KW's external resevoir in the rear makes take the rear slide pins a chore

Cant you just pull the shock down? The Rogue RSM makes it too easy. 2 nuts and a bolt.

And a bonus shot of Wassup's car in stock class trim and mine driving to Champaign

IT'S SO TALL!

I'll be selling them and running a dedicated 17x9 setup this year.

I hope you know as couch tax we will be borrowing these for an event or at least some hooning. (fitment check)

And some pics from one of the last autox's last year. Thanks to Illinipo for lending his garage couch and trig knowledge (he's not even asian!) for a last minute fishing line alignment to get me more front camber which I desperately needed.

Anything to help out the community It was painful to watch you struggle with 2 degrees on plates that can do over 4. And when we found out what the "Professionals" did to the right side camber I think that was your ah-ha moment for doing your own work

Might want to double-check the SP rules on removing all that interior trim. I don't keep up with SP but last I checked, trim removal is a hot ticket to SSM.

[JETninja]

A proper Harness would keep you from moving around. I don't know if the stock Z4M seats can take a harness without modding, but I added on to my M3 and it locks you in place making you one with the car. Adding one to my Z06 ASAP! I know your race seat can take one. Leave the street belts for the street...

You'll need a Harness bar and a quality harness. You'll wonder why you didn't do it earlier....

[BTM]

Thanks for the heads up, just read (skimmed) them twice, and it's not specifically addressed (not looking good for removal). There are specific things that can be removed, the radio and related components can be removed

The OE radio may be removed. The OE sound system components,
except wiring, may be removed.

Also, the addition of cages is permitted (which invariably results in modification/removal of interior trim, especially when putting in nascar bars)

Installation of roll cages in Street Prepared cars must follow the
same standards for interior modifications to accommodate the
cage installation as those which are applicable to Showroom
Stock or Touring cars in Club Racing.

So I will need to read up on those rules. If worse comes to worse, I have everything out to weigh of what I would've lost. I wish jeff told me this was a possibility when I told him I was going to take my interior out and he said "do it"

A proper Harness would keep you from moving around. I don't know if the stock Z4M seats can take a harness without modding, but I added on to my M3 and it locks you in place making you one with the car. Adding one to my Z06 ASAP! I know your race seat can take one. Leave the street belts for the street...

You'll need a Harness bar and a quality harness. You'll wonder why you didn't do it earlier....

Thanks - the stock seats are not suited for a harness per the Scroth harness installation guidelines. And like I said, I really didn't like them too much to begin with. But I am definitely going that route sooner than later. I kept the stock 3 point as it was a DD, and didn't want to go too far with the drivers side without addressing the passenger side with respect to equivalency. Thanks for the comments

Cant you just pull the shock down? The Rogue RSM makes it too easy. 2 nuts and a bolt.

I guess we never thought of that?

I hope you know as couch tax we will be borrowing these for an event or at least some hooning. (fitment check)

hmm I'll allow it

[gary88]

Looks good, needs JB4 and eurofog switch though

[BTM]

I bought a jb50 but use it in the bathroom since I'm so constipated lately. My euro fog switch is backordered

Anyway, thanks for that heads up Pete. The trim will be going back in. I guess I should make those rules my bathroom reading until I have them memorized

But, all is not lost. Much was needed to come out to remove the dynamat, I can weigh how much the trunk area is capable of giving, and I'm not positive but believe the RSM bushings necessitate removing the RSM? Which will get done when the new shocks go in. Also, I'm all for introducing new and interesting rattles

[illinipo]

Yeah, have to take the RSM off the shock to do bushings. Are you doing the Rogue race bushings? they are only a 15A durometer increase. The rubber is 60A and the "track" is 75A. Not really worth it, save your pennies and go for spherical.

[BTM]

That was the idea but didn't look into it very closely. I doubt they need a rebuild already after only ~12k ish miles on them, but I guess worth inspecting. I would like the spherical AST mounts, but we'll see how the budget goes.

[jakermac]

You should give the rules a read. I guess your local club might have a different ruleset than SCCA Solo2, but you need that interior back in the rear of the car to be fully Street Prepared legal.

[BTM]

Thanks for the input - you're right, the trim will be going back in for competition (see a few posts above). Luckily, there are things to do that requires much of it out anyway. Exactly why I posted this here...many eyes are better than just my own. I just printed out the SP pages and they are sitting on the toilet now...now to keep pounding coffee so I can become more intimate with them

[illinipo]

That was the idea but didn't look into it very closely. I doubt they need a rebuild already after only ~12k ish miles on them, but I guess worth inspecting. I would like the spherical AST mounts, but we'll see how the budget goes.

Once we get the car together I will take a high speed video of the Rogue RSM with the rubber bushings and see just how much it moves. That will make the decision of whether to get the 75A or go spherical.

[JETninja]

You don't (and should not!) have to dump the stock 3 point. Unless you have Roll Bar you should should never run a Harness on the street anyways, it prevents your upper body (and HEAD) from rotating to the side in a roll over. Not as much a concern on the track cause you have a helmet on.

And "some" stock seats can be modified, Sparco sells the plastic pass harness pass throughs..and upholstery shop cuts and inserts them. Its what I'll probably do to my Z06 as I've seen it done.

I'm 6'1" and skinny at 142lbs...so any seat I'm moving around unless I have a Harness. Then I'm locked into it, its a night and day difference.

[BTM]

A quick mini-update. More just for information.

Since I cannot remove the trim, the opportunity to use the AST adjuster extenders presents itself. I cut adjusting holes in the carpet with plugs to better access the KW's rebound, which will give a route for the extensions; having the adjustment outside of the carpets will make it that much easier.





Available in 6" 8" and 10" lengths, I decided to measure. Though whether or not I will be using the RE mounts is uncertain, and there is currently a different shock in there, anything over 6" appears it will interfere with the hatch when closed. Maybe even trim those down some for a cleaner appearance of the adjuster knob.

My thumb is at the 6" mark on the ruler:







Also, got the weight of the trunk trim:

9lbs 9 oz





12lbs 1.5oz





6lbs 7.5oz





Total: a tick over 28lbs. We'll call it even to account for the boxes. Not an insignificant amount, wish I could leave it out. Time to continue tackling the dynamat, though since I put it myself it of course doesn't count toward any weight reduction.

[modernbeat]

A quick mini-update. More just for information.

Since I cannot remove the trim, the opportunity to use the AST adjuster extenders presents itself. I cut adjusting holes in the carpet with plugs to better access the KW's rebound, which will give a route for the extensions; having the adjustment outside of the carpets will make it that much easier.

Available in 6" 8" and 10" lengths, I decided to measure. Though whether or not I will be using the RE mounts is uncertain, and there is currently a different shock in there, anything over 6" appears it will interfere with the hatch when closed. Maybe even trim those down some for a cleaner appearance of the adjuster knob...

BTM, the rigid adjusters can be cut down to any size you need. I'd trim the rod down to just get past the interior panels. We also have flexible extenders, but for your use I'd get the short, rigid extensions and trim them down to the right size. OR, if you call Vorshlag and tell them the length you need we can cut them down for you.

[BTM]

BTM, the rigid adjusters can be cut down to any size you need. I'd trim the rod down to just get past the interior panels. We also have flexible extenders, but for your use I'd get the short, rigid extensions and trim them down to the right size. OR, if you call Vorshlag and tell them the length you need we can cut them down for you.

I saw the flexible ones as well, but like you said the rigid ones are all I need. I'll just cut them to size like you said so the knobs are just slightly above the carpet and not sticking way up.

Dynamat is out, went surprisingly smoothly



This blue tool is part of the Harbor Freight trim removal kit. Though I've actually only ever used it for scraping, never for it's intended purpose. Special service tool





All out, only took an hour or so. Less time if I could find an extension cord without looking everywhere. And my sister will probably wonder why there are spots of a rubbery tar substance on her hurr drier





Though it doesn't count toward weight reduction, I figured I'd weight how much was in there anyway. A little under 4lbs.

[BTM]

Another "informational log" type post...

I was able to weigh the Cobra seat and associated mounting brackets. Regarding the seat, rules stipulate:

15.2.F The driver and front passenger seats may be replaced, with the following restrictions: Seats must be securely mounted per 3.3.3.B.2.
The seating surface must be fully upholstered. Any replacement
seat must be a full back, bucket-type automobile seat incorporating
a functional headrest. Kart seats, low-back dune buggy seats, and
other similar types of seat are expressly prohibited. Cars may have
no fewer than the standard number of seats. The seat tracks are
considered part of the seat and may be substituted. Alternate seat
tracks may serve no other purpose. The standard seat belts may be
removed to facilitate the installation of alternate restraints complying
with safety requirements. An alternate seat which replaces an
airbag-equipped seat is not required to have an airbag.

There is nothing mandating a minimum weight, like there is in STR

14.2.B The driver and front passenger seats may be replaced, with the following restrictions: The seating surface must be fully upholstered.
The top of the seat, or an attached headrest, may not be below the
center of the driver’s head. The seat, including mounting hardware,
must weigh at least 25 pounds and must be attached using the OE
body mounting holes/studs. Additional mounting points may be added.

Even if there was, I would be easily over the minimum weight with the GT width Suzuka. Maybe helpful for anyone who would run this seat and VAC mounts in STR or other classes that might have minimum weight requirements

The stock seat, which is powered and heated, weights a tick under 63lbs (sorry, no picture)

The Suzuka S GT weighs 19lbs 13.5oz





The VAC floor mounts weigh 6lbs 0.5oz



The side brackets weigh 2lbs 5oz



And the hardware weighs 5oz



For a total of 28lbs 10oz, or savings around 34lbs per seat. Of course I only have the drivers replaced as of now.

[jakermac]

That's right. There is no seat minimum weight rule in Street Prepared.

[BTM]

That's right. There is no seat minimum weight rule in Street Prepared.

Yup - have the rules in all of my "main" bathrooms now

Have you seen the proposed rule changes for engine and trans mounts in SP? What do you think?

[illinipo]

Prototype shock adjuster extenders, used cheap too-hard proof of concept material for $2, should have just bought 1/2" aluminum key stock in the first place for $5, but anyway here are some fab pics. Good work, BTM.

[BTM]

thanks, I think it will go much better with the aluminum and a drill press. I'll pick up some new raw this week sometime. Still need reset my seat...take my coilovers off, do valve adjustment...lots to do

But I was out there when I got home today and first things first is a cleaning session.

[5mall5nail5]

Since it looks like your tool collection is a little short of what's needed, just go on mcmaster carr and order aluminum tube of whatever dimension you require. Then you just need to cut it.

[BTM]

Yup been sourcing from mcmaster. They offer tubing but its expensive and the id is too large. Contrary to our original thought, the $45 ast adjusters aren't as overpriced as we thought, but all said and done, $10 in materials, a drill press, tap set, (both of which I have) and some time should yield more than enough for both cars

No hate on the ast or vorshlag parts, and if I wasn't on a budget I'd shell out the money and be done with it.

[illinipo]

Hand drill is more than adequate if we had just used aluminum in the first place... This isn't some .001 tolerance part, its a damn shock adjuster. Weight and cost are primary design constraints.