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#1. Bumpstops are not springs! - from LoweSeaton@aol.com
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Date: Wed, 11 Sep 2002 01:53:30 EDT From: LoweSeaton@aol.com Subject: Bumpstops are not springs! John writes: > I finally solved my latest clunk in the rear end that y'all might > recall from a few weeks ago. As it turns out, the stock rear sway bar > was hitting the muffler. I mistakenly (working too fast, misread the > directions) cut the rear bumpstops when installing new springs and > shocks. New bumpstops solved the problem. One thing that it did > teach me is that the rear bumpstop plays a _huge_ roll in your rear > spring rate. I'm going to get on my soap box. No offense John. I don't know where in the world this idea that bumpstops are "part of the springs, designed to increase the spring rate, tune the springs, etc ..." crap came from or started. I've seen many many guys claim this on our list. Let's think about it logically and from an engineering point of view. You have to support the weight of your car somehow. That's the function of springs. They are fairly important. Take the spring out or if the spring breaks, the car isn't drivable. Agreed? OK, so we have decided that the springs are critical to the functionality of the car. Now lets design the springs. First decision is what material to use to make the springs. Chevy Corvettes use carbon fiber leaf springs. Some old Mercedes Benz used "air springs". Probably plastic bags filled with air. These "springs" had serious maintenance issues [more about this later] and most people converted to conventional steel springs. Then there is this claim that BMW uses foam rubber bumpstops for springs in the M3. Foam rubber, that's the same stuff used in Nerf footballs, right? Let's look at the serviceability requirements of car springs. First is longevity. Your car could last 20+ years. Then you have rain, heat, dryness, temperature. Not to mention the constant motion that springs endure. You really want a wet soggy Nerf football to support you M3 at 1g cornering loads? How long do bumpstops last? I've pulled some off cars that just crumbled in my hands. Remember above we decided that no springs or broken springs will result in loss of drivability. Well, that dried up old crumbling bumpstop isn't going to make it. Yet, you don't hear about M3's breaking down because the bumpstops fail. This is the reason Mercedes Benz air springs didn't last. The materials used didn't last. What is a good material? How about tempered steel? Spring steel has a 100,000 psi tensile strength. 29,000,000 psi modulus of elasticity. 100,000,000 cycle fatigue life. Rain and dryness have little effect, especially if the springs are painted. Unless it is submerged in water for years, it won't rust and corrode to pieces. Steel works well in humanly bearable temperatures ranging from -50 to 140 degrees. Bottom line: steel is strong, durable, and consistent in all the conditions a car will be exposed. If I am designing the springs for a car, I want steel - not Nerf foam rubber crap. I hope this was a long winded way of saying it is silly to expect a foam rubber bumpstop to survive as a "spring". And if this foam rubber bumpstop ever fails, which it will given time, then you have a serious failure. Not a good idea to use a bumpstop as your spring. No engineer with half a brain would use crumbling foam rubber bumpstops for springs. Now let's look at what bumpstops really do. If your car is often bouncing off the bumpstops or riding on the bumpstops, then there is a simple reason why: 1. Your car is overloaded and you need stiffer *steel* springs to support the load. 2. Your *steel* springs are too short. You need longer springs. 3. This would be very very unlikely but it is possible your *steel* springs have fatigue. It is unlikely because it would take a million miles of driving to fatigue the steel. Fix would be new *steel* springs. That's it. Only purpose of bumpstops. Bumpstops make very poor springs. Lowell Seaton '95 M3 - steel springs but no bumpstops
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#2. '95 5-Spoke Rear Wheels - from Greg Gantt
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Date: Wed, 11 Sep 2002 06:54:34 -0400 From: Greg Gantt <ggantt@gantt-consulting.com> Subject: '95 5-Spoke Rear Wheels Anyone have the part number for 1995 silver painted 5-spoke 8.5" rear forged wheels? Also, anyone with a pair of these interested in selling, please contact me via e-mail. Thanks. Greg
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#3. Insurance Coverage for On-track Drivers Ed - from Steve Lilley
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Date: Wed, 11 Sep 2002 08:00:24 -0400 From: Steve Lilley <m3steve@earthlink.net> Subject: Insurance Coverage for On-track Drivers Ed American Collector Insurance (http://www.americancollectorsins.com) writes policies for on-track driver education events -- their application is available at the web site (though the drop-down boxes don't work with Netscape 4.x browsers). Currently it's available in CA, CT, FL, IL, and PA. Pricing looks reasonable: annual premium is 1.5% of the value of the car. So a driver with a car worth $20K would pay a $300 annual premium for coverage. The deductible is 20% -- so the owner of the $20K would be responsible for the first $4K in damages. Is anyone familar with them? Are there any other companies offering similar policies/coverage? Regards, Steve
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#4. Re: [E36M3] RE: USAA Insurance - from matthew c. mead
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Date: Wed, 11 Sep 2002 08:11:01 -0400 From: "matthew c. mead" <mmead-bmw@goof.com> Subject: Re: [E36M3] RE: USAA Insurance On Tue, Sep 10, 2002 at 10:23:14PM -0500, BOOM,BILL (HP-Roseville,ex1) wrote: > I smell a bruised, dead horse here, but couldn't resist: :) *THWACK* > > From: "matthew c. mead" <mmead-bmw@goof.com> > > > > On Tue, Sep 10, 2002 at 01:43:13PM -0500, m3ltw@msn.com wrote: > > > ... > > > The insurance industry is getting wise! Darn. > > > > I don't understand why people can't take responsibility for their > > accidents... > Making a claim, without any misrepresentation of what happened, for > something that is legitimately covered by my insurance carrier, and > expecting that claim to be paid is not a failure to take responsibility for > my actions. I pay good money to be covered for what I am covered for. The > insurance companies are doing just fine, and I have no reservations about > making a legitimate claim. The fact that they might be able to make more > money by *not* covering track days is not my concern. I don't either. If it's covered, you should claim it. I guess my big point is that from my experience, there is often some component to a driver's school that is racing. Yes, you wait for a point, but what driver's school doesn't drill you to be observant and poitn faster drivers? How many tales do we hear about red misting at track schools? If that's the case, you're not covered in a situation where your carrier excludes competitive or racing events. Many people make the claim anyway. > That's not necessarily true. Insurance companies have known of the > existence of driving schools on road courses for some time without feeling > the need to explicitly exclude them like they have recently been doing. > When I asked mine if I was covered for it, they said yes. Being at the > track makes me a better driver in emergency situations (not *despite* the > fact that I'm going faster than I would be in public, but *because* of it.) > So for all we know, the actuaries have figured out that for every $30,000 > loss they incur from covering someone who totals their car at the track, > they may have saved themselves a $300,000 hospital bill for injuries that > were avoided as a result of an accident *not* happening because another > person they insure benefited in an emergency situation from skills they > learned at the track. Yeah, we're both making guesses, here. I've never spoken with an actuarial person about this. > > The fact that the wording is > > currently so broad for carriers that have awoken to this risk is > > probably due to a fraudulent claims history connected with > > driver's events/racing/autocross. > Agreed. I think the reason we are seeing the new wording in some policies > has a lot to do with fraudulent claims. Hopefully it doesn't go so far as to prevent us from even having driver's events/club racing. Insurance costs for club liability alone are getting HUGE. -matt -- matthew c. mead 97 Dakar M3/4 - sharked, xbraced 97 White GS-R/4 - stock (wife's) 92 Black Miata - dropped, dampened, headed towards SM http://www.goof.com/~mmead/
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#5. Cross drilled rotors? - from Mo Karamat
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Date: Wed, 11 Sep 2002 08:24:18 -0400 From: Mo Karamat <karamatm@optonline.net> Subject: Cross drilled rotors? Dear All, I will be going to the glen at the end of the month for a 2 days school, so I ordered some PF97's pads. Well I also wanted to buy a set of rotors for the track as well. I was going to purchase stock type Balo rotors, when a friend suggested Zimmerman cross drilled rotors. Does anyone have any experience with crossed drilled rotors? Will they help with braking at all? I have heard stories about them cracking, and eating up pads?? Thanks for any help! Mo Is anyone else going to the glen on Sept 28 & 29th?
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#6. Re: [E36M3] Bumpstops are not springs! - from Jeff A
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Date: Wed, 11 Sep 2002 07:39:24 -0500 From: "Jeff A" <aabel@austin.rr.com> Subject: Re: [E36M3] Bumpstops are not springs! Whoa there Lowell. You said: > I'm going to get on my soap box. No offense John. > > I don't know where in the world this idea that bumpstops are "part of the > springs, designed to increase the spring rate, tune the springs, etc ..." > crap came from or started. I've seen many many guys claim this on our list. > snippage, huge snippage< I admire your passion, but you ask where this ludicrous idea of bumpstops being an active component of a suspension system. Well, how about directly form the H&R website! Here's the full text: ---------------- Attention - calling all bumpstops. Well, we call them bumpstops because we always have. It is what we are used to calling them. But in the age of specialized tech-talk they are "bumpstops" no more; now they are micro-cellular progressive jounce bumpers. - What? ... That was a double decafe Mocha, skinny, no whip! Most people think of a bumpstop as a black rubber snubber hanging down from the frame above the axle to protect against metal-to-metal contact. Just like my dad's 1974 Chevrolet Caprice station wagon. You know, the one with the big block 454 and the hide - away tailgate. The Caprice was the cruising wagon of choice when highway 5 between L.A. and San Francisco first opened and gas stations were few and far between. The song, "Head out on the Highway, look'in for adventure" keeps ringing in my head. Where was I, oh yeah, trying to avoid the dreaded bumpstop (dumpstop). The thing was, no matter where you went in that wagon; you rarely came into contact with the bumpstop. The micro-cellular progressive jounce bumper, or simply put, the foamy bumpstop, is actually a supplemental spring. It works to make the suspension progressive, allowing a smooth transition to full compression. What most people don't realize is that the foamy bumpstop is an active part of the suspension. Let's say you're sitting in your M3, 996, Accord, Golf, S4, or Civic. (Hmm I can't decide). They all use the foamy. Ok, you're in your brand new Integra, just drove it off the showroom floor and are sitting at the stoplight waiting for the green. The foamy is actively engaged even while waiting at the stoplight. Car manufacturers use this brilliant piece of high-tech engineering for many reasons. By using an almost zero-weight supplemental spring, you can build the main (steel) spring with a reduced spring rate for a comfy ride. The softer spring uses less weight, and, saving weight is a number one priority of new car manufacturers. Cars have thousands of parts. A little weight saved here and there really adds up. When the manufactures save weight they also save costs, less material=less cost. So we now know why these foamy gems are used. But how do they really work? As mentioned earlier, the foamy bumpstops are an active working part of the suspension. They work in harmony with the springs and the rest of the suspension components allowing the ride to be comfortable while cruising. When the car is in a handling situation, such as in a turn, they make the car feel firmer for better handling. Think of the foamy as a little progressive spring over the shock rod. All car manufacturer bumpstops have a specifically calculated spring rate and compressed height. (block height). When a spring is designed the spring rate must be calculated with the rate of the progressive bumpstop in mind. Otherwise the spring will not work in harmony with the bumpstop and the frequency of the suspension will be out sync. The human body interprets a certain range of suspension frequency as comfortable or uncomfortable. Frequency in an automotive chassis is like chords in music. If two or more notes are combined in a pleasing combination you have harmony, otherwise you have uncomfortable dissonance. The same thing happens in suspension tuning. A balanced suspension is important for correct function. This is why it so critical to understand the true effect of the pro-active foamy and the spring. Everything must work together in harmony! The compressed height is what limits the wheel travel and controls how far the wheel and tire move up into the fender well. Aftermarket suspension designers must consider that enthusiasts will be upgrading the tires and wheels. Therefore, it is vital that these designers take into consideration the needs of tire and wheel fitment. By trimming the bumpstop you allow the tire and wheel to move further into the fender. This can cause the tire to rub where it did not before. If your application does not require bumpstop trimming and you are concerned about tires rubbing, just load up your car with your buddies and drive over some dips and speed bumps. If your tires do not rub with a full load in the car, they should not rub with lowering springs installed. So, what has little Johnny learned today? There is no such thing as a bumpstop in a modern suspension. The bumpstop has been replaced by a supplemental, active foam rubber spring, which is one of the essential components in the suspension.
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#7. Re: [E36M3] More bumpstops functionality [was Klunk Found] - from Jeff A
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Date: Wed, 11 Sep 2002 07:51:02 -0500 From: "Jeff A" <aabel@austin.rr.com> Subject: Re: [E36M3] More bumpstops functionality [was Klunk Found] > > > Hmm, that's interesting. What shocks/springs? I'm trying to remember whether > > I trimmed my rear bump stops or not when I put the H&R/Konis on, but it was > > so long ago I forget. Think I'll go and look... > > > > Neil > > 96 M3 > > Neil - You can be assured he is NOT using Bilsteins :-) I guarantee you > won't get enough suspension travel with my Bilsteins to come close to > bottoming out. Bilstein designed their shocks to support a cement truck. > > Seriously, you really don't have to trim the bumpstops on the rear. I know > you don't need to with Bilstein and I'd bet the same for Koni. Why? Because > the rear shock does not need that much range of travel. I'll bet the rear > wheel can't move up and down as much as the front wheels and the rear shock > is mounted in board of the rear wheel. Then consider the way the rear shock > is mounted. It attaches to the shock mounts way up in the truck making it > quite long to start. > > Bottom line: The rear shocks don't come close to bottoming out regardless > who makes the shock. The rear bumpstops are just there to hold up the dust > boots. > > I completely removed my Bilstein bumpstops (front and rear!) 2 years/20,000 > miles ago. I got so mad with the front Bilstein struts that I totally > removed the internal bumpstops and for good measure took the rear bumpstops > and dust boots off too. Removing the front bumpstops was a noticeable > improvement. Removing the rear's had no affect. > > Lowell Seaton > '95 M3 - we don't need no stinking bumpstops! Huh, well I can tell you with absolute certainty that bumpstops are NOT present as window dressing in my car, and rear shock travel fairly closely approximates rear wheel travel. I've spent many hours under the rear suspension of my car doing fine tuning with my Ground Control setup (Koni based). I've put bumpstops in place to get *just* the right amount of compression. Without bumpstops (I experimented a great deal with this) I can get to full block (bottoming out) quite easily, and this is with 525 lb rear springs. FWIW, I get exactly 2 7/8" of rear shock travel until spring goes to full block. I have enough bumpstop now that the last 3/4" of travel is into the bumpstops, and this amount of crush is effective to prevent Big Bottoming Sounds. When I was running H&R coilovers, before the GC setup, I was certain that I was into the bumpstops quite a bit. Lowell, I'm not sure of the reason why your car is immune to bumpstop setup, but my H&R setup and my current GC setup are senstive enough to bumpstop length that dramatic difference in ride quality and handling can effected with proper length bumpstops. Jeff
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#8. RE: High(er) Octane Fuel Source - from Bob Stommel
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Date: Wed, 11 Sep 2002 08:25:19 -0500 From: Bob Stommel <rstommel@iquest.net> Subject: RE: High(er) Octane Fuel Source Just make sure the racing fuel is unleaded. Oxygen sensors are effective for only about 20-30 hours on leaded fuel. Most 110 octane racing fuel is leaded. Sunoco makes a 104 octane unleaded racing fuel ("GT Plus"). More info at www.racegas.com. Union 76 makes a 100 octane unleaded racing fuel ("Competition 100"). More info at www.76.com. All the higher octane race fuels from Sunoco and Union 76 are leaded. Don't know anything about Marathon. HTH, Bob Stommel >Date: Tue, 10 Sep 2002 20:05:14 -0500 >From: Paul Smith <pauls@ontario.com> >Subject: High(er) Octane Fuel Source >I asked at a local parts store. I was able to find a station (marathon) that >had 110 octane racing fuel. Mix it with 93+ (or what ever) and you have a >great mixture. A bit more than the additive, but much higher octane. >Paul Smith
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#9. Re: [E36M3] Cross drilled rotors? - from Gerald Low
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Date: Wed, 11 Sep 2002 09:30:23 -0400 From: "Gerald Low" <gerry@parallel-mkt.com> Subject: Re: [E36M3] Cross drilled rotors? Mo, I will be at the Glen at the end of the month too. Any interest in a meeting of Listers sometime on Saturday to put a face to the names? Regarding the cross-drilled rotors, no personal experience but I use the floating rotors for track and street use. They provide maximum surface area, minimize heat transfer to the hub, and resist warping if properly cooled at the end of a hot session. Go with what works instead of what looks good. Gerry ----- Original Message ----- From: "Mo Karamat" <karamatm@optonline.net> To: "E36M3" <e36m3@bmw-m.net> Sent: Wednesday, September 11, 2002 8:33 AM Subject: [E36M3] Cross drilled rotors? > Date: Wed, 11 Sep 2002 08:24:18 -0400 > From: Mo Karamat <karamatm@optonline.net> > Subject: Cross drilled rotors? > > Dear All, > > > I will be going to the glen at the end of the month for a 2 days school, so > I ordered some PF97's pads. Well I also wanted to buy a set of rotors for > the track as well. I was going to purchase stock type Balo rotors, when a > friend suggested Zimmerman cross drilled rotors. Does anyone have any > experience with crossed drilled rotors? Will they help with braking at all? > I have heard stories about them cracking, and eating up pads?? > > Thanks for any help! > Mo > > Is anyone else going to the glen on Sept 28 & 29th? > > > > ************************************************************* > List Commands > UNSUBSCRIBE - (in subject line) unsubscribes you from the mailing list. > DIR - sends a listing of files available in the list's GET directory. > GET filename1.ext,filename2.ext - sends the requested file(s). > > To issue a command/request to the server: > Send a message with the command you wish executed as the > subject of the message to the email address e36m3@bmw-m.net. > ************************************************************* > >
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#10. RE: [E36M3] Cross drilled rotors? - from Carey Probst
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Date: Wed, 11 Sep 2002 10:07:34 -0400 From: "Carey Probst" <hcprobst@alum.mit.edu> Subject: RE: [E36M3] Cross drilled rotors? Hi Mo, I don't claim to be a Glen or track expert but have done a fair amount of research on the subject I've done 12 days at the Glen and 1 at NHIS on the OEM rotors and pads and still have about 50% of the pad left. (And no, none of my instructors have accused me of being too slow or nursing the brakes). On a good day I'll hit just about 130 before braking at the bus stop but it's usually in the 120 range and I tend to brake hard. I do get occasional pad material build up by the end of the 2nd day that feels like a warped rotor BUT it goes away after 2-3 weeks of normal driving with a little extra riding the brakes to smooth it out. From one earlier lister's comment, (paraphrased since I don't have the mail) "Warped brakes aren't warped". Usually it's pad material. My feeling is that the extra mass of the solid rotors offsets the advantage if any of slotting or drilling, esp. drilling which can weaken the rotors. Porsche 'drilled' brakes are really cast with the holes to prevent weakening. My personal opinion is that drilled or slotted rotors are fine if you want the look but aren't necessary for DE events. Carey Probst, '99 M3/2, BMW CCA Patroon and Genesee Valley Chapters Sharked, Stressed, Schrothed, Gauged, Hitched, X-Braced A well regulated militia being necessary to the security of a free State, the right of the people to keep and bear arms shall not be infringed. -----Original Message----- From: Mo Karamat [mailto:karamatm@optonline.net] Sent: Wednesday, September 11, 2002 8:33 AM To: E36M3 Subject: [E36M3] Cross drilled rotors? Date: Wed, 11 Sep 2002 08:24:18 -0400 From: Mo Karamat <karamatm@optonline.net> Subject: Cross drilled rotors? Dear All, I will be going to the glen at the end of the month for a 2 days school, so I ordered some PF97's pads. Well I also wanted to buy a set of rotors for the track as well. I was going to purchase stock type Balo rotors, when a friend suggested Zimmerman cross drilled rotors. Does anyone have any experience with crossed drilled rotors? Will they help with braking at all? I have heard stories about them cracking, and eating up pads?? Thanks for any help! Mo Is anyone else going to the glen on Sept 28 & 29th? ************************************************************* List Commands UNSUBSCRIBE - (in subject line) unsubscribes you from the mailing list. DIR - sends a listing of files available in the list's GET directory. GET filename1.ext,filename2.ext - sends the requested file(s). To issue a command/request to the server: Send a message with the command you wish executed as the subject of the message to the email address e36m3@bmw-m.net. *************************************************************