The Brake Rotor Controversy

Plain, slotted or cross drilled?
In 1998 BMW M models came with plain rotors.
In 2010 the M3 comes with drilled rotors.

Do slots or holes or both actually help?
After much searching I didn't find anything I'd call authoritative on the subject. I chose to go stock solid rotors. The information from brembo at tirerack.com helped make my decision. (the brembo logo uses a lower case "b"). I ordered stock rotors and ceramic pads - rotor and pad replacement video to follow.

The bottom line is that in their advertising brembo appears to emphasize the appearance aspect of the slots or holes rather than the performance aspect. They indicate that drilled rotors should not be used with racing brake pads at all.

Here is the actual verbiage -

brembo Sport Slotted Rotors
On the "Product Description" tab is the following disclaimer:

"Brembo Sport slotted brake rotors are designed to meet the challenges of high performance street driving while adding an authentic, race-ready look.

NOTE: Brembo Sport slotted brake rotors can be used in conjunction with race compound brake pads on the track for drivers’ schools and lapping days.

IMPORTANT REMINDER: Slotted, drilled or dimpled rotors offered as OEM replacements should not be considered appropriate for high-speed track use.

While grooved, drilled and slotted rotors offer an enhanced appearance and add some resistance to the boundary layer of gasses that can build up between the pad and rotor, they are not designed to withstand the extreme temperatures that are produced on the racetrack. If they are used on the track, it is very important that the rotors be carefully inspected and should not be driven on if even minor signs of deterioration are seen. Note, too, that if any products are used on the track they are not warrantable"

brembo Sport Drilled Rotors 
On the "Product Description" tab is a similar but slightly different disclaimer:

"NOTE: Brembo Sport drilled brake rotors are not recommended by The Tire Rack for track use or intended to be used in conjunction with race compound brake pads on the street. For severe duty brake demands see Brembo Sport slotted brake rotors.

 IMPORTANT REMINDER: Slotted, drilled or dimpled rotors offered as OEM replacements should not be considered appropriate for high-speed track use.

While grooved, drilled and slotted rotors offer an enhanced appearance and add some resistance to the boundary layer of gasses that can build up between the pad and rotor, they are not designed to withstand the extreme temperatures that are produced on the racetrack. If they are used on the track, it is very important that the rotors be carefully inspected and should not be driven on if even minor signs of deterioration are seen. Note, too, that if any products are used on the track they are not warrantable."

brembo Replacement Rotors have no disclaimer. Maybe it's because they don't think people will track plain rotors and so they don't need a warning.

brembo has it's own website. The advertising there indicates benifits in water, to dissipate heat and eliminate brake dust and gases.

Convertible Rear Window Cover

BMW didn't start putting glass windows on the rear of a convertible until the E46 in 2000.
So, if you have a BMW convertible 1999 or older you have a plastic rear window.

The plastic scratches during normal use. Convertible tops wear during normal use.
Having a cover over the window when putting the top down helps reduce wear.

You can buy a cover or make one yourself like I did.

A Short Lesson On Tire Safety

This 52 second video covers two basics of tire safety

1. Tread wear
2. Dry rot

I've had enough experience with worn tires in wet weather to testify as an expert witness on the importance of having enough tread depth to channel water out from under a tire to attain safe traction.

I use to believe that tire dry rot was something invented by the tire sales people. Rubber may crack over time but the tire is held together with steel and fiber strips - right?
My wife experienced the reality of a dry rotted tire flying apart while going down the highway. No one was injured, the vehicle was damaged, and the passenger was freaked out. I take dry rot seriously.

Some articles indicate that dry rot is only a problem if the cords inside the tire are showing. I know this is not true. The tire that flew apart on the highway looked fine except for the tell tale cracked rubber.

Spring is Here

And top down weather has come once again.

I have some plans for this spring.

• replace warped front rotors and brake pads (maybe paint the calipers)
• replace floor mats
• Make a rear window cover using 8 pound pull rare earth magnets

In the meantime it's great just having the top down.

E39 Wipers - BMW 5 Series 1995 - 2003

My 2002 530 needs wipers - bad.
Two ways to fix this problem,

1. Replace just the blade - I was never happy with the performance of the replacement blade.
2. Replace the whole wiper - I have been happy with the performance of the new wipers but they were a hassle to get.

Normal wipers won't work on the E39, they are way too cool for that.

If you want to replace the whole wiper auto parts places around here don't stock the part. I ordered from Bavarian Auto in the past (part number 61 61 9 070 579). The wipers cost $57 plus shipping and take a few days to get here.

I found out that the NAPA part number is 3397001539 and my local O'Reilly can get them in just two days for $55

If I had shopped around a little harder I might have found them in stock somewhere close.

Hitting 100,000k

The M Roadster rolled over 100k miles a few weeks ago. Once upon a time that was an amazingly huge number of miles for a car. I see it as mid-life for most cars made in the last 20 years, especially this one.

Last week I was driving to work, I was on the highway and felt a vibration in the front end. It felt like I had lost a wheel weight and one of the wheels was out of balance. It wasn't terribly bad so I kept driving.
Turned out the vibration was a sticky brake caliper draggin on the rotor.
Normally this is the sort of thing I'd fix but I was no where near home and I felt lazy so I let the shop fix it. Add $288 for parts and labor to my maintenance tally.
I suspect front brake rotors are in my near future. The mechanic said it was obvious that it got pretty hot.

How to Buy a Z3 or M Roadster

It’s important to have a strategy when buying a car. There are lots of good strategies, here is a simple one.

Look the car over carefully in the day light and decide if you want it or not.

If you don’t want it walk away.

If you do want it make a list of the things you don’t like as a discussion point for negotiating price.

Z3 and M Roadster things to look for:

• Sagging glove box – with the glove box closed push up on it from the bottom, it should be firm and not saggy. The glove boxes on these cars are heavy and tend to sag.
• Seat play – the back and forth mechanism on the power seat develops about a quarter inch of back and forth play. Put the seat about in the middle of it’s back and forth adjustment making sure that the seat back is not resting on the inside of the car. With your legs push back and forth and see if the seat will slide back and forth. My car has this problem and it’s very common with Z3s. I’ve had mechanics estimate about two hours work per seat to fix it ($200 per seat)
• Broken seat belt guide – there is a seatbelt guide on both seats, frequently one or both of them are broken. They are very hard to fix so most people just live with it.
• Convertible top wear – a cloth convertible top is a wear item, like tires or brakes. You should expect to have to replace it eventually. A new top will run $3000 to $5000 ( I know that’s a wide range, I’ve never actually replaced the top so I gave a safe range).
• M Roadsters do not have a spare tire. They did come with a can of fix a flat and a 12 volt compressor in the trunk on the right hand side. Frequently the repair kit is missing.
• Z3 check the spare tire, make sure all the tools are there.
• Dash lights – the light bulbs on the three climate control dials are frequently burned out. Check the lights in the other buttons – AC etc. These lights are not too horrible to replace – I’d guess and hour or so for a mechanic. I have replaced some of the ones on my car that are burned out but not others.
• Make sure all the speakers work and sound good – sometimes people play the system too loud and damage speakers.
• The usual car stuff stuff – tire wear, oil puddle on the ground, strange noises, driving straight etc.

If, after making the list you still want the car assign a dollar amount to each item and subtract it from the asking price, then make an offer. When the negotiation starts you can say “Well, the seats slide like a roller coaster and the top is worn so I can’t give you the asking price...”

After you have made your deal and brought your vehicle home here is a link to a site that has links for fixing all of these issues if you feel so inclined.