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#1. How does ABS work? - from LoweSeaton@aol.com
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Date: Thu, 24 Jul 2003 15:27:39 EDT From: LoweSeaton@aol.com Subject: How does ABS work? alex.fadeev@verizon.com writes: > AFAIK, once triggered, ABS engages all channels (four wheels) regardless > of which one was detected locked up. > > alex f > Is this true? Perhaps for our simple ABS system E36 M3's. But true ABS should be wheel specific. Just because one wheel loses traction, doesn't mean the other three are unable to brake. I'm pretty sure newer, more sophisticated ABS systems do control each wheel independently. Some cars have this yaw control that can actually "turn" the car. They apply the brakes harder to certain wheels while in a turn to save your butt. I do know for a fact that the rear wheels on the 1995 M3 are coupled because they share the same brake line. The front wheels could (and in my opinion should) be controlled separately. Lowell Seaton '95 M3
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#2. Re: [E36M3] Gunked ABS sensors? Reposting - from Rex Tener
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Date: Thu, 24 Jul 2003 12:46:29 -0700 From: Rex Tener <rex_tener@yahoo.com> Subject: Re: [E36M3] Gunked ABS sensors? Reposting At 02:27 PM 7/24/2003 -0500, LoweSeaton@aol.com wrote: >I am arguing it is the coming OFF the bump that trips up the ABS. Going UP >the bump, you actually increase traction and it would take more braking to >lock >up the wheel. Come DOWN off the bump, you reduce traction momentarily. >Remember there is less weight on the wheel. If you just happen to be >applying >more braking force than the new reduced traction can overcome, the wheel >locks up >and ABS does its thing. And I am not convinced the wheel has to lock to trigger the ABS. It could be that just that one wheel, when it is unloaded and has less traction, has a slower speed than the rest of the wheels, as it is on its way to locking up. The ABS sees this wheel speed differential and decides that a wheel might be on its way to locking up and activates the ABS modulation. -- Rex Tener rex_tener@yahoo.com 1996 BMW M3, SCCA SFR Solo II Street-Mod Light (as in lightly modified) #173
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#3. How ABS works (from a Bosch engineer).... - from Patrick Buthmann
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Date: Thu, 24 Jul 2003 15:52:00 -0400 From: "Patrick Buthmann" <patrick@teutonic.ca> Subject: How ABS works (from a Bosch engineer).... Gang, This is a great article on the E30M3 Performance site, from one of the Bosch ABS engineers. Brings some interesting points to the surface in terms of what ABS really takes into consideration. http://e30m3performance.com/tech_articles/chassis-tech/abs/index.htm In a three channel system (2 front, 1 rear), a rear wheel lock-up will result in ABS affecting BOTH rear wheels. However, a 4 channel system has independent ABS for each wheel. All E36 cars should have 4 channel ABS, so I'm surprised that your 95 M3 would have a 3 channel system. My race car ('94 325is) has a 4 channel system. Realistically, ABS programming has the single biggest impact on how intrusive it is on the race track. Some systems (Subaru's for example) seem to be far more intrusive than that of our BMW's. There is also an article on the Stoptech site which can help to explain why ABS kicks in when driving over bumpy surfaces, particularly given the braking power our cars have. Pat -----Original Message----- From: LoweSeaton@aol.com [mailto:LoweSeaton@aol.com] Sent: Thursday, July 24, 2003 3:37 PM To: E36M3 Subject: [E36M3] How does ABS work? Date: Thu, 24 Jul 2003 15:27:39 EDT From: LoweSeaton@aol.com Subject: How does ABS work? alex.fadeev@verizon.com writes: > AFAIK, once triggered, ABS engages all channels (four wheels) > regardless > of which one was detected locked up. > > alex f > Is this true? Perhaps for our simple ABS system E36 M3's. But true ABS should be wheel specific. Just because one wheel loses traction, doesn't mean the other three are unable to brake. I'm pretty sure newer, more sophisticated ABS systems do control each wheel independently. Some cars have this yaw control that can actually "turn" the car. They apply the brakes harder to certain wheels while in a turn to save your butt. I do know for a fact that the rear wheels on the 1995 M3 are coupled because they share the same brake line. The front wheels could (and in my opinion should) be controlled separately. Lowell Seaton '95 M3 ************************************************* Please help support the E36M3 list by visiting our sponsors: Taylor Autosport http://www.taylorautosport.com Rogue Engineering http://www.rogueengineering.com BMW M3 Specialties http://www.jt-designs.com Bimmerworld http://www.bimmerworld.com Turner Motorsport http://www.turnermotorsport.com DIGEST INFORMATION: http://www.bmw-m.net/resources/digest_info.htm ************************************************* This e-mail and any attachments may contain confidential and privileged information. If you are not the intended recipient, please notify the sender immediately by return e-mail, delete this e-mail and destroy any copies. Any dissemination or use of this information by a person other than the intended recipient is unauthorized and may be illegal.
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#4. Re: [E36M3] Gunked ABS sensors? Reposting - from alex.fadeev@verizon.com
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Date: Thu, 24 Jul 2003 14:56:17 -0500 From: alex.fadeev@verizon.com Subject: Re: [E36M3] Gunked ABS sensors? Reposting LoweSeaton@aol.com wrote: > > alex.fadeev@verizon.com writes: > > Even if road imperfections cause momentary decrease of traction, those > > should not result in lock up. > > > Why not? This is under braking right? I assume your ABS is not kicking in > when you are driving down the road. ;-) Right, but in our cars, ABS comes out blazing even under the lightest of brake applications over bumpy roads. > You are braking, the brakes are resisting the rotation of the wheel. What > is making the wheel rotate? Well.... the ground passing underneath. What > happens if there is no more ground, that is, the tire is airborne? The tire hardly ever becomes airborne. That is if your cars has half-ass functional shocks. > I am arguing it is the coming OFF the bump that trips up the ABS. I can gladly postulate that come off the bump the tire momentarily looses some of the traction. But not all. And under light braking, that should not engage the ABS. Unless it is either miscalibrated or purposely coded to engage every time the driver sneezes. alex f
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#5. E36 Coolant leak - from Robert S. Hatrak II
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Date: Thu, 24 Jul 2003 12:57:44 -0700 From: "Robert S. Hatrak II" <rshatrakii@earthlink.net> Subject: E36 Coolant leak With all of the talk of over-heating and radiators failing and being replaced, you all have cursed me! I just drove the car home for lunch and parked it in the garage today. After lunch, I come out to the car and find it doing a great impression of an island...surrounded by coolant. The radiator is relatively new, and I could see no signs of a failure or a leak at the top side. Does anyone have any "been there, done that" advice they could share with me? I'm thinking a hose is possibly failing/letting go somewhere, or there is a failure at the bottom of the radiator. Or....it could be the other obvious failures (water pump, thermostat failing, etc...) Any diagnosis tricks that I should be aware of? I felt my radiator hose and it was hot as heck. The car is a 95 M3 with a 6yr old metal (the good one) water pump. Roughly 20k mile old radiator. Original hoses, thermostat, and housing. Thanks in advance! Rob
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#6. Re: [E36M3] How does ABS work? - from Michael Lawrence
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Date: Thu, 24 Jul 2003 16:04:41 -0400 From: "Michael Lawrence" <95m3ltw@comcast.net> Subject: Re: [E36M3] How does ABS work? ----- Original Message ----- > alex.fadeev@verizon.com writes: > > > AFAIK, once triggered, ABS engages all channels (four wheels) regardless > > of which one was detected locked up. > > > > alex f here is another link to explain ABS. When using ABS, it does NOT engage all 4 wheels if only 1 is sliding, locked etc. I can attest to this many times from experiences on track. It only modulates the sliding wheel. http://auto.howstuffworks.com/anti-lock-brake5.htm But it does affect braking pressures to the other wheels but that is another discussion itself. Mike
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#7. RE: [E36M3] garage floor coating - from Steve Stoner
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Date: Thu, 24 Jul 2003 16:01:06 -0400 From: Steve Stoner <sstoner@treev.com> Subject: RE: [E36M3] garage floor coating I checked out this site. www.ucoatit.com . Looks like good stuff. Anybody on list actually used the product? They have a project calculator where you can select your stuff and it tells you what to get and prices it. For my 30x45 garage, the cost is $1126, for Gloss A/F with fleck. How bout everyone on the list chip in and I'll be the guinea pig and try it and provide a complete report. Even better, everyone contribute some money and time, and we can knock the whole project right out! Steve Stoner
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#8. RE: [E36M3] How ABS works (from a Bosch engineer).... - from Patrick Buthmann
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Date: Thu, 24 Jul 2003 16:10:29 -0400 From: "Patrick Buthmann" <patrick@teutonic.ca> Subject: RE: [E36M3] How ABS works (from a Bosch engineer).... Hmmm, In doing some further research, it appears as though BMW changed ABS systems from 95-96, so I'll have to climb under my car and check my brake lines again. Last time I looked, I was sure I saw 4 output lines from the ABS pump; perhaps my eyesight or math is getting worse in old age! BMW's ABS system from '91 onward was TEVES, from '96 on it became a BOSCH setup. This would probably suggest that both systems have completely different programming specs, though obviously ultimately controlled by BMW engineers. Pat PS. My apologies for not deleting all the footers from my previous e-mail.
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#9. Re: [E36M3] How ABS works (from a Bosch engineer).... - from Michael Lawrence
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Date: Thu, 24 Jul 2003 17:15:49 -0400 From: "Michael Lawrence" <95m3ltw@comcast.net> Subject: Re: [E36M3] How ABS works (from a Bosch engineer).... ----- Original Message ----- From: "Patrick Buthmann" <patrick@teutonic.ca> > This would probably suggest that both systems > have completely different programming specs, though obviously ultimately > controlled by BMW engineers. Also, M3's have a different ABS brain than the 325i's do. From driving both, it does seem that it is much easier to threshold brake in a M3 vs 325. Mike
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#10. Re: [E36M3] E36 Coolant leak - from alex.fadeev@verizon.com
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Date: Thu, 24 Jul 2003 15:58:03 -0500 From: alex.fadeev@verizon.com Subject: Re: [E36M3] E36 Coolant leak "Robert S. Hatrak II" <rshatrakii@earthlink.net> wrote: > > I just drove the car home for lunch and parked it in the garage today. > After lunch, I come out to the car and find it doing a great impression > of an island...surrounded by coolant. The radiator is relatively new, > and I could see no signs of a failure or a leak at the top side. Does > anyone have any "been there, done that" advice they could share with me? Rob, You mean other than: "find the leak and fix it"? How new is the radiator? If you had worked on it recently, check/tighten all the hose clamps. They tend to shrink a bit after the first few heat cycles. Did you use new screw-type hose clamps? Even on the little return hose hidden under the shroud? > I'm thinking a hose is possibly failing/letting go somewhere, or there > is a failure at the bottom of the radiator. Or....it could be the other > obvious failures (water pump, thermostat failing, etc...) Any diagnosis > tricks that I should be aware of? I felt my radiator hose and it was hot > as heck. Hot upper hose == open thermostat. Is your thermostat housing plastic or aluminum? Did you replace the thermostat the last time your worked on the cooling system? Used new gaskets? Torqued everything back to spec? You may want to get under the nose of the car to find the source of the leak. > The car is a 95 M3 with a 6yr old metal (the good one) water pump. > Roughly 20k mile old radiator. Original hoses, thermostat, and housing. Take a look at the upper radiator neck. Just to rule it out. good luck, alex f