BMW E36 Blog

BMW E36 Blog hitting the 100 subscribers mark!

30th September 2007

BMW E36 Blog hitting the 100 subscribers mark!

 

Hi Guys, I’m glad to announce that BMW E36 Blog has hit the 100 subscribers mark (well, actually 101 mark) … finally! I’m very excited about this new progress as it indicates that many readers are enjoying this blog. Here’s a screenshot that I’ve taken when I saw the 101 subscribers, although I see 59 :-( now, but I’m sure that’s b/c of the week end and that it will catch up later today or maybe tomorrow.

101 Subscribers Mark

 

And here’s another screenshot of the subscribers change through this year. You can see how it’s building up I LOVE IT!.

Feed Statistics

 

Of course, I want to thank all my faithful readers who are reading this post and also want to welcome my new subscribers and please guys, if you have any notes or suggestions, please do NOT hesitate to drop me a line.

 

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29th September 2007

Why Does BMW M3 Steer So Well? … Part 2

 

This is the second part of the "Why Does BMW M3 Steer So Well?" series. For those of you who’ve missed the first part you can read it here Why Does BMW M3 Steer So Well? … Part 1. BTW, this article was taken from Motor Trend Magazine (November 1998). I hope you enjoy the article.

 

By Kim Reynolds

To check on the M3’s steering linearity, we ventured to the skid-pad where we painted two extra circles, at 160- and 120-ft. diameters, concentric within our standard 200-footer. Circling all three, I progressively built up speed, carefully recording the steering angle all along the way. The resulting curves of lateral-g versus steering angle appear herewith.

They’re not actually linear, are they? They smoothly bend, with more and more steering angle being needed to achieve additional increments of cornering force. Why? The biggest reason is that the BMW is a “front-steer” automobile (no, not as in “front-wheel drive”). The term refers to the steering rack’s location ahead of the front wheels’ centerlines. This placement matters because of the loaded outside front wheel’s tendency to move inward under cornering (due to suspension bushing compression). Assuming you’re holding the steering wheel still (and we know the rack’s bushings don’t flex much), the front-mounted steering rack forces the wheels to reduce their steering angle, turning a little less sharply into the corner. It’s a benign understeer sensation that’s plenty preferable to the spooky-feeling alternative; i.e., having the tie rods behind the wheels’ centers, causing the wheels to twist further into the corner under lateral load as if they have a mind of their own.

Around the skidpad, my hands also noticed that the M3’s steering effort suddenly starts to diminish as the BMW’s tires proceed to squeal. Welcome to the phenomenon called “pneumatic trail.” Dr. Post mentioned it, but for additional illumination I turned to R&T pal Doug Milliken who co-authored (along with his father, Bill) the extraordinary textbook Race Car Vehicle Dynamics (available from the Society of Automotive Engineers, [412] 776-4970).

You’re probably already aware of what common caster does. Like castered wheels on shopping carts, it’s the weathervane effect where a wheel pivots around an axis that’s ahead of the actual contact point with the ground, stabilizing the wheel’s direction. The physical distance between the pivot axis (on cars it’s called the “kingpin axis”) and the contact patch is a “lever-arm” called trail (of course, it’s a distance, not an actual, physical arm). While cornering, this trail causes a goodly torque to arise around the wheel’s kingpin axis. Fed through the steering links, it’s the creature that causes most of what you feel at the steering wheel.

Pneumatic trail adds an extra, and terribly important, wrinkle to the story. While a tire corners, it seems that the lateral forces it creates are not uniformly spread around the tire’s contact patch (as you’d first think); they’re actually concentrated somewhere behind the patch’s center. In other words, the lever arm that gives rise to steering feel actually consists of two ingredients, the geometrically obvious mechanical trail I mentioned – plus this new added element, pneumatic trail.

Now it happens that as the limit of adhesion is approached, the tire’s lateral forces gradually migrate back to the center of its contact patch. If you’re following along, this zeros out the pneumatic-trail factor entirely (leaving only mechanical trail), consequently reducing steering effort. A communicative steering system like the M3’s possesses an ample percentage of pneumatic trail; think of it as the language tires use to speak to us about their limits. And it’s easily drowned out by the background noise of too much steering boost or excessive mechanical trail.

As an aside, remember those video games Paul, Patrick and I were playing? The most sophisticated of them – better called simulators – mathematically employ all of these effects. According to Carey Kriger of Digital Vehicles (maker of Formula One simulators) and Rick Moncrief, whose company, Silicon Entertainment, builds NASCAR simulators, the most convincing steering feel arises from strictly mimicking things like trail. No phony baloney stuff.

But exceptional steering feel like the M3’s also relies upon a soup of other psychologically synergistic ingredients. For example, the BMW’s large windows provide a panoramic view of the road’s texture that your mind can easily, and subconsciously, integrate with what your hands are feeling. Likewise, add in the tires’ whispers, messages that could easily have been masked by too much sound-deadening material. And the little vibrations that jiggle the steering wheel rim over tiny bumps, oscillations on the order of an eighth of an inch – not so large as to annoyingly shake your hands, but enough to be subconsciously noted. Reduce the windshield’s view, quiet the tires, or dampen the steering gear, and I’ll guarantee you’ll be a lot less impressed by the M3’s steering feel.

In other words, there really isn’t a single, simple answer to the title of this story. It resides in a thousand little fragments, from stiff steering bushings to ample pneumatic trail, to subtle steering boost, to even simply letting the driver hear the tires and easily see the road. Add them up as scrupulously as BMW has learned to do, and you have in your hands what feels like steering magic.

 

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posted in E36 M3, Technical Info, Uncategorized | 0 Comments

26th September 2007

Why Does BMW M3 Steer So Well? … Part 1

 

I’m sure that many of you guys will be interested in knowing why BMW M3 cars handle so good. This is an article that Jim has sent me couple weeks ago. I think this article is great and since it’s too long, I decided to make it on 2 parts, this is the first one. If you like this post, I will be posting the second part very soon, so stay tuned and let me know what you think.

This article was published on the Motor Trend Magazine (November 1998)

 

By Kim Reynolds

It’s 11:00 A.M. and Contributing Editor Paul Van Valkenburgh, Road Test Editor Patrick Hong and yours truly are lost in concentration. Video screens are painting our faces with the glow of computer-generated stock cars sliding through the streets of San Francisco, rock-scattering rally cars slithering precariously near mountain-edge precipices, and mighty Indy cars hurtling past blurred super speed way grandstands. Behind us, kids walking past our video game stations at the Park Palace amusement arcade are giving us odd looks, and not just because we’re the oldest gang of truants ever to set foot in the place. The odd looks are because it’s obvious that we’re not really playing these games; we’re just twisting the steering wheels back and forth, holding their rims with the ends of our fingers.

What’s going on here? Shush…this is research.

In fact, we’re in search of one of the automobile’s most elusive and abstract properties – steering feel. Quite frankly, of all the things I want to know about cars, understanding steering feel is very near the top of the list.

It’s such a mysterious, ethereal thing, steering feel. I mean, how does it happen that when I close my eyes for a few seconds while behind the wheel of a great-steering car, the wheel’s torques and tiny kickbacks manage to conjure in my mind such an accurate rendering of the road’s texture and the tire’s dynamics? It’s analogous to how our gray matter can translate the vibrations of a phonograph needle upon a record into a Bach fugue, a Benny Goodman solo, or the Beatles’ White Album.

But enough abstract philosophizing; what the heck is mechanically going on between my hands and the road surface to engender such communication? To get to the bottom of it, we borrowed a BMW M3, arguably the world’s current prime example of proper steering feel.

Hoisted in the air atop our garage lift, the M3’s underbelly yields no obvious clues. There’s a robust structure of welded steel tubes corseting the engine’s belly, no doubt greatly stabilizing the M3’s front suspension geometry. Pokes with an X-Acto knife at the synthetic bushings isolating the ZF steering box from the subframe identify them as unusually stiff. A notably stout structure, but so far we’ve uncovered no big answers.

However, wrap your hands around the M3’s steering wheel while it’s idling and you’ll notice there’s a remarkable amount of engine vibration being transmitted up through the steering column. The wheel’s rim almost hums, a characteristic we’ve come to closely associate with small BMWs. A clue perhaps? Being a suspicious sort, I immediately deduced it to be a deliberate engineering ploy to enhance the M3’s impression of low-speed road feedback by sneakily feeding-in engine vibration. Paul, more clever than I, postulated that the vibration might be a smart way to continuously break up the steering gear’s natural stiction, resulting in an impression of unusual fluidity. These BMW guys are geniuses!

Smug in our penetrating insights, I addressed the question to the Bavarian Motor Works. Answer? It’s just something they can’t get rid of. Great steering feel, they stated, requires a very solid structure with minimal flex anywhere in the steering gear. In other words, that steering rack I noticed so rigidly mounted to the engine’s subframe just can’t avoid also being awash with the inline-6’s tremblings. According to Munich’s engineers, the steering wheel’s buzz is simply part of the deal. Lesson one: Minimal compliance is the first ingredient of sensitive feel.

All right, then how about an element that’s vastly less stiff – the tires? A call to the M3’s tire supplier, Michelin, put me in contact with Dr. Bill Post, whose specialty is just this sort of thing. The good doctor’s most interesting point on the subject, and an entirely unexpected one, is that the most under-appreciated factor in facilitating linear steering behavior is a good rear suspension. Rear suspension?

Dr. Post explained that when you turn into a curve, steering linearity relies enormously on the rear tires loading up with cornering forces in a nicely progressive manner. If there’s anything unpredictable about the car’s rear end, it’ll destroy the car’s steering quality. Makes sense.

 

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posted in E36 M3, Technical Info | 4 Comments

24th September 2007

Get Expert Help for your BMW

 

In case you didn’t notice, I’ve added a new service to BMW E36 Blog. Take a look here:

Expert Help

This service is being provided by JustAnswer.com. By using this service you can get help to fix a problem with your car from one of their great experts. The service costs you 15$ normally. You have two other options in which you can pay 9$ if you have a tight budget or 30$ for a really urgent question. I know that some of you will say that I can ask on the forums or here on the BMW E36 Blog, but I really don’t recommend the forums, because you don’t always know who’s the guy that’s answering. you don’t know if he even has a good experience in what he’s talking about.

I contacted Ron from JustAnswer.com and asked him if they have experts in BMW E36 cars and he sent me information about two of their experts in that car:

William B is BMW Master Certified, Auto Service Technician. 100% Positive Feedback on 297 Car Accepts. Associate Degree Automotive Technology, Master ASE, Master BMW, Master Mazda, 30+ years experience

here’s a sample of his answers:
http://car.justanswer.com/bmw/p4ao-1992-bmw-318i-serious-gas-leak

Doctor D Specializing in BMW cars. But also has extensive experience with all other Lines. He has ASE Master Tech, Rotary Club, AAA FL State Finalist, All data information specialist, IATN Member

here’s a sample of his answers:
http://car.justanswer.com/questions/uuq5-1994-bmw-325-water-pump-radiator

 

I hope you like this new service. I recommend you to try it, if you have a problem with your car that needs expert help. I’m sure you’ll find it great.

 

BMW E36 Blog: The ultimate BMW E36 information source.

 

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posted in Technical Info, Tips & Tricks, Uncategorized | 5 Comments

23rd September 2007

Footwell light for your BMW E36 . . . DIY!

 

First of all, I want to start this post by welcoming our new friend Sean C who filled his information recently in the Welcome BMW E36 blog readers! post. For those of you who didn’t read that post yet, please do and let us hear from you. Simply, just fill your information in the comments box at the bottom of that post and you’re done. Very easy isn’t it?

I think everyone of you guys will love today’s post as it will show you how easy it’s to install foot well lights inside your BMW. I know that many of you will try to do it because it looks great on your car. If you’re anxious to see the end result of this procedure, simply skip to the end of this post to see a photo of the car at night while the foot well lights are on. I hope you like this DIY and thanks for Jarozila who created the original write-up.

For those of you who like to fix their BMW car(s) by themselves, I recommend you to get the Bentley BMW 3 series service manual which is one of the best books I’ve ever read. I got it and recommend you to get one for yourself as it will save you too much time and money while fixing your car.

 

 

Disclaimer: Use this info at your own risk!! I’m not responsible if this didn’t work for you :-).

The BMW parts I used were:

63 31 8 360 588 Lamp (2x)
61 13 8 377 072 Socket Housing (3-pin connector) (2x)
61 13 0 005 197 Bushing Contact (4x)

If you take out your dome light and take a look at the wires you will see a Brown/Red wire (power) and a Brown wire (ground). These are the wires to use if you want the new foot well lights to work with the dome light switch settings.

Using these wires the foot well lights can be set to come on with the dome light when you open the door and they fade out, or you can turn them on with the dome light.

I did not want to run wires from the dome light down the side pillar, so I thought I have to be able to find the wires when I remove the glove box. I found a Brown/Red and a Brown wire and I exposed the core to see if these would work – THEY DID.

It was then just a matter of connecting a few wires into these two cables, making holes in the panel under the glove box and steering wheel, and connecting the lights.

I really like how it looks and it will make it so much easier to find things if they drop on the floor. Was also easier to vacuum with the lights on.

This is where I found the red/brown and brown wires that looked like they went up the back and into the side pillar going up to the dome light.

This is a picture from underneath to show the new wires I connected. I also put in two wires to run over to the driver’s side. The two black wires go the the foot well light, the red & brown wires go over to the driver’s side.

This is the light inserted in the hole I cut on the passenger side.

Foot well lights off during the day with my car in an open car port.

Foot well lights on also during the day in the car port.

Here’s a picture of how it looks at night

 

Are you looking for more do it yourself procedures (DIY) ? I recommend the Bentley BMW 3 series service manual for you. I got it and I think it’s a gold mine for us -BMW E36 Owners-. If you didn’t grab your copy yet, get it right now! I’m sure you’ll find this book worth every penny you’ve paid for. Get the Bentley BMW 3 series service manual

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posted in Do It Yourself, Electrical, Interior, Technical Info, Tips & Tricks | 12 Comments