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#1. re: Stiff suspension + Sway bars (Ron K) - from albert jenab
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Date: Tue, 09 Jan 2001 02:47:21 -0500 From: albert jenab <jenab@his.com> Subject: re: Stiff suspension + Sway bars (Ron K) Got to agree with Ron on this one. Some random thoughts here. The bigger the bars, the more wheel control you sacrifice over one-wheel bumps (like just about all bumps) and more forces get transferred to the chassis. The trade-off is bigger bars mean less body roll under similar cornering conditions on perfectly flat surfaces than smaller bars. The compromise I have settled on is stock bars, Bilsteins + H&R sports. I may go to the later, slightly larger stock rear bar this spring to dial in a little less oversteer. One thing many people don't realize is that when you go to stiffer springs, you are increasing roll stiffness as well. Add big bars and the car to me at least is too harsh for any kind of street driving. I've made this mistake on other cars before (stiff spring plus big bars) and always regretted it. The other point (for roll) is that the shocks need to match the bars/springs in the low speed region of the force velocity curve (say up to 5 inches/sec in rebound), then get a lot firmer in the high speed region to control wheel motion and the stiffer springs. With the larger bars and stiffer springs, you have quite a lot of force resisting unloading of the inside wheel in a turn already. If you have a shock valved for smaller bars and softer springs, it will be more firm in this region to slow down the inside to outside wheel weight transfer. I.e.; the shocks are controlling the rate at which weight transfers, and the springs/bars control total amount of weight transfer for a given lateral g. So the inner shock in rebound determines how fast that roll angle is achieved. With larger bars, the body roll amount is much lower for the same lateral g. So if you have shocks which have high rebound forces in this low-speed region, it will slow down the rate of weight transfer and make side-to-side transitions sluggish. This will also amplify the harshness on one wheel bumps, making the car feel like it has no suspension at all as every little surface imperfection gets transmitted to the body. And you lose that razor sharp transition feel you should have with a properly set up track suspension. You want the car to take its set in a corner quickly, get that outer tire loaded up ASAP, which it will not do with large low speed rebound forces. With smaller bars & softer springs you want to slow the rate of weight transfer down, otherwise the car will be flopping side to side too much and too quickly, to a comparatively greater total roll angle and associated bad things wrt contact patch on the outer tire. Take a look at the front strut Bilstein damping curves at http://www.his.com/~jenab/ This compares the M3, E36 HD, and E36 Sport struts. At 5 inches per second, the (true) E36 Sport is putting out approx 1/3 the rebound force that the HD or M3 units are. That is because it is a real Sport and intended for cars with big bars and stiff springs which will not have much total body roll. The forces go up quickly at higher piston speeds as they should for stiffer springs. The M3 and the E36 HD have a lot more low speed rebound damping to control body roll since the car is assumed to have smaller bars and softer springs, therefore a lot of roll. This fact, plus the similarity between the E36 HD and M3 curves leads me to believe the M3 units are not true sports, no matter what Bilstein says. Also they only differ marginally from the HD's at high piston speeds, and not by much. I think a lot of the bad rap the M3 Bilsteins get for being "too harsh" is from folks who have bigger bars and stiffer springs. The set up I have now is very comfortable on the street, but much firmer than stock, and does well on track the few times I've run it. A little too much understeer though, and maybe a bit too little high speed rebound damping, and a little bit too firm in low-speed rebound. But a decent compromise. Big bars would push this into the unusable or uncomfortable handling region. This is all very subtle, the H&R's with stock bars provide just enough extra roll stiffness without being too over-roll damped by the Bilsteins, at least for my taste. I have not looked at curves for Konis or other adjustable shocks. -Al 95 M3 At 06:13 PM 1/8/01 -0600, Ron Katona <rkatona@bellatlantic.net> wrote: >> Ron ,can you please give a few more details on why you like softer bars. >> It seems to me that until recently most German tuner favored stiff >> springs/shock and stock bars. Now I see many of them marketing stiffer bars >> but I wonder if its only because the market is asking for them and not >> because they are really worthwhile? > >I think there's some "bigger is better" marketing out there. I like >Dinan's direction with the M3 which includes a smaller front bar. Having >said that I think big bars are an excellent choice for cars with near >stock spring rates who's owners want to retain most of the stock ride >compliance but add some roll resistance and adjustability - great idea. > >What I believe from purely a performance perspective is that you select >spring rates to keep the car off the bumpstops (or pavement) at the >limits of cornering, at the ride height you want, while giving the car >the basic balance you want, under the conditions that you most often >will drive the car. You then use sway bars merely to tune the balance of >the car using the smallest (lightest and least intrusive in single wheel >bumps) sway bars that will do the job. If you do it the other way, going >with softer springs and heavier bars to increase the total roll >stiffness, you tend to start to lift wheels in the corners because of >the action of the heavy sways. This causes either understeer or >difficulty putting power to the ground depending on which end of the car >is stiffer. > >And as I said before: YMMV... there are racers who use big bars quite >successfully. If there's anything I've learned from people like Bob >Tunnell though, it's that you can't be better than everyone else by >copying exactly what they all do. And although my setup just happens to >be a lot like Bob's <g>, I'm starting to understand how the E36 works >and take a few baby steps in trying things my own way. We'll see whether >I'm genius or maroon next autocross season. :-) >-- >Ron Katona
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#2. Re: [E36M3] RE: Brakes, ABS, rear brakes etc. - from Jeff Thompson
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Date: Tue, 09 Jan 2001 07:57:19 -0500 From: Jeff Thompson <jthompson@telco.com> Subject: Re: [E36M3] RE: Brakes, ABS, rear brakes etc. Lowell, This particular tidbit of information has no real value tho... It is entirely possible (and likely) that Mercades just didn't bother to tune the brake bias in the car under the assumption that ABS would take care of that. If they had done it with the same tires on multiple cars, then it might have been somewhat valid. All this says is that an S600 stops faster with ABS than without. ABS can come in so many flavors and tunings that it is impossible to make a judgement on the system in a blanket statement like "ABS sucks". The rear-ending phenomenon probably comed from the fact that it is all ABS cars, not just ABS equipped S600s. ABS in a Toyota Camry is nothing like ABS in the M3. Personally I don't like ABS because it removes a measure of driver control (try to go both-feet-in and let me know what happens), but it has to be there from a cover-your-ass legal perspective. Imagine if BMW was neglignet enough to make people responsible for their own driving actions and didn't jump on the perceived "safety bandwagon". *gasp* Just my $0.02, -jeff > Motor Trend used a Mercedes Benz S600 and about 40 sets of high performance > tires. They tested the S600 on about 8 different surfaces - dry, wet, sand, > gravel, deep fresh snow, hard packed snow, scarified snow, and glare ice. > They tried 3 different braking techniques - ABS, threshold, and full lock. > The drivers were Motor Trend test drivers. Extremely experienced drivers. > > In every single case, ABS beat both threshold and full lock except for two > and one tie. The only time ABS lost by a slight margin was in gravel and on > the glare ice. And I think the deep fresh snow was a tie with full lock. > Threshold braking never stopped the shortest. I wish I could find the > article so I could quote exact figures.
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#3. Suspension Terms and Theory - from Richard Sperry
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Date: Tue, 9 Jan 2001 09:33:57 -0500 From: "Richard Sperry" <richardsperry@home.com> Subject: Suspension Terms and Theory Nice site, and good explanations, But why no Ackerman? Rich 95///M3 Date: Mon, 8 Jan 2001 10:40:59 -0600 From: "DiVincenti, A.J." <ADiVin@lsuhsc.edu> Subject: Suspension Terms and Theory Hey guys here is a nice page I stumbled upon for those of you trying to learn about suspension geometry. It is a good explanation of terms and theories. You might find it helpful. http://www.ingallseng.com/terms.htm A.J. DiVincenti
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#4. RE: [E36M3] RE: Brakes, ABS, rear brakes etc. - from Davis, Jake A
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Date: Tue, 9 Jan 2001 08:36:50 -0600 From: "Davis, Jake A" <Jake.Davis@SW.Boeing.com> Subject: RE: [E36M3] RE: Brakes, ABS, rear brakes etc. from Lowell<<I hate to disagree but argh! I like ABS. :-) I think it is one of the best automotive inventions in the last 30 years. I'll argue that ABS can stop a car quicker than any human every time on any surface. Pretty bold statement I know ;-) >> We're not disagreeing here. I failed to make clear that I believe for 90% or more of us (including myself) ABS is (as Martha Stewart would say) a good thing. There has also been great progress in ABS over the last few years. <<Motor Trend Magazine did a test of ABS vs. threshold braking... In every single case, ABS beat both threshold and full lock except for two and one tie. The only time ABS lost by a slight margin was in gravel and on the glare ice. And I think the deep fresh snow was a tie with full lock. Threshold braking neverstopped the shortest. I wish I could find the article so I could quote exact figures.>> Very good counterpoint! I've got that one somewhere, I'll have to see if I can find it. <<I certainly agree that ABS allows you to steer and brake without losing control. That is a huge benefit. However, did you know cars with ABS rear end more vehicles than cars without ABS?? It is almost unbelievable but true. I don't know if anybody has figured out why yet. Maybe people driving ABS equipped cars think they can stop much shorter and get overconfidentOr another theory is people get scared in panic stops when the ABS starts pulsing the brake pedal and they LET OFF the brakes! Bam!>> BINGO!! That reinforces my point. ABS may allow somewhat shorter stopping distances, but lots of misinformation on that subject has convinced the general public that ABS somehow suspends the laws of physics. The real benefit to the average driver is not stopping distance, it's retention of control. And I agree with the other theory also...average drivers don't ever find out what ABS feels like until they feel that 'BRPRPRPR' in their first panic stop. Add to that many drivers don't have the situational awareness to consider steering around the obstacle, or never consider that possibility at all...but I'm getting off on a different rant here. Just another point...in a 'performance' driving mode, we're more often concerned about 90 to 40 braking rather than 60 to 0, as well as turning the car rather than just stopping in a straight line. Here again, control is as important as the absolute shortest braking distance. I think a lot of what we're saying here just points out the differences in track driving (or precision street driving) and dealing with everyday traffic situations.
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#5. Re: Brakes, ABS, rear brakes etc. - from Neil Maller
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Date: Tue, 09 Jan 2001 09:39:27 -0500 From: Neil Maller <neil.maller@gte.net> Subject: Re: Brakes, ABS, rear brakes etc. on 1/9/01 2:03, LoweSeaton@aol.com wrote: > > However, did you know cars with ABS rear end more vehicles than cars without > ABS?? It is almost unbelievable but true. I don't know if anybody has > figured out why yet. Maybe people driving ABS equipped cars think they can > stop much shorter and get overconfident? An explanation I've read - correct or not - is that most people don't understand what to do when ABS begins to operate. Instead of keeping their foot hard on the pedal, letting the system do its thing and steering out of trouble if possible, they either let off the brake or start pumping it. Pretty hard to establish the truth, since I doubt people either remember or report accurately what happened just before a crash. My further suspicion is that that the reason they don't know what to do is because they've never been taught, and most have never practiced intentionally locking up the brakes/engaging ABS. I hope that as car enthusiasts we're a little better educated and practiced in this respect than the populace at large. Anyone with teenaged kids know what Drivers' Ed in their area teaches these days? I drive at Mid-Ohio a couple of times each year, and there's usually a Honda Safety School for teenage drivers being held on the skid pad while we're there. Strikes me as an excellent way to give your driving age kids a better chance out there. Neil 96 M3
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#6. Re: WTB - 3.38 Rear End - from BobTunnell@aol.com
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Date: Tue, 9 Jan 2001 11:36:43 EST From: BobTunnell@aol.com Subject: Re: WTB - 3.38 Rear End In a message dated 1/9/01 12:04:26 AM, Chris Gant (cgant@home.com) writes: >I am looking to swap my 3.15 for a 3.38 and have not seen too many around. >Does anyone know where I might find one...Would prefer a T.C. Kline or >Turner built one, but a stock one will work too. Rob Hatrack (destined to hate his car <g>) had one a month ago. Try him at Hatrak@ix.netcom.com. Otherwise, try Jason Lile at Zionsville Autosport (jason@zionsvilleautosport.com). That's where I got mine (OEM unit) and I'm *very* happy with it. --BT
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#7. Re: [E36M3] Re: Badass Brakes - from Sean Hester
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Date: Tue, 09 Jan 2001 08:50:59 -0800 From: "Sean Hester" <seanh_race@hotmail.com> Subject: Re: [E36M3] Re: Badass Brakes >Easy. It wasn't FWD. It was an AWD car that hooked up amazingly well with >it's back tires. oh yeah. duh. those can be 4wd. of course, since they're not M3s, i tend to forget the specifics... _________________________________________________________________ Get your FREE download of MSN Explorer at http://explorer.msn.com
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#8. Re: [E36M3] ride quality - from Sean Hester
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Date: Tue, 09 Jan 2001 09:13:21 -0800 From: "Sean Hester" <seanh_race@hotmail.com> Subject: Re: [E36M3] ride quality >none of the mods > > i ever did fit that category. i'd say they all worsened the ride more >then > > they improved the handling. > >whhhhaaattt?!?! Dude, that's some fatty weed you're smoking. :) > >Admittedly, I came from a much better handling car than the stock M3. >(A Miata and an S2000.) With the mods I've done to the car (STBs front >and rear, stock sway bars, h&r coilovers, k-mac camber plates, gc rear >shock mounts and tc kline trailing arm bushings, the M3 still rides >better than either the Miata or the S2000 over most roads (except for >really big drop offs) and handles better than either as well, both on >the street and on the track. i'm not saying that those mods make the car have "bad" street ride. just worse then stock. (street ride to me means soft, absorbs bumps, doesn't spill my drink when i go over a bump, doesn't require me to hold the wheel with both hands because with all the negative camber it wants to follow every hill/valey in the road) and i'm not saying i didn't like it. i did it didn't i? but i at least admitted to myself that i had chosen to forego a nice comfortable ride for my extra handling. i had similar mods to you. (not too many really...) and my car was still a "better street ride" then a stock miata. but a stock M3 has an almost luxury quality street ride. closer to a caddy to a miata. i missed it. i like 1-10 scales. i'd say a stock M3 gets an 8 for street ride. mine was about 5 when i was done. still good, but not as good. >Remember, my M3 isn't my race car... it's what I drive to work >everyday... I prefer the ride of the H&Rs to the floaty (admittedly 53K >old) stock suspension. maybe your suspension WAS shot? maybe it's the roads where you are? (the constant rain makes the roads here in seattle CRAPPY. cracks, bumps, potholes, soft roads with HUGE crowns, etc...) or... maybe the h&rs are magic? when i test drove an S4 a year ago i didn't like it because of the floaty suspension. but... i just bought an S4 used with h&rs already installed. i love the ride. it's alot less floaty, and handles alot better, but the coilovers only BARELY affected the ride quality. my S4 with coilovers has a better "street ride" then my M3 (with stock springs) did. the only "problems" are with sharp dropoffs, like potholes. (just like you mention) hmmm... maybe everyone should stop all this talk of "what springs, and shocks go together?" and just go buy h&r coilovers? _________________________________________________________________ Get your FREE download of MSN Explorer at http://explorer.msn.com
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#9. Re: [E36M3] RE: Brakes, ABS, rear brakes etc. - from Sean Hester
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Date: Tue, 09 Jan 2001 09:21:31 -0800 From: "Sean Hester" <seanh_race@hotmail.com> Subject: Re: [E36M3] RE: Brakes, ABS, rear brakes etc. >Hi Jake! I hate to disagree but argh! I like ABS. :-) I think it is one >of the best automotive inventions in the last 30 years. me too. >I'll argue that ABS can stop a car quicker than any human every time on any >surface. Pretty bold statement I know ;-) usually but not always. i can (sometimes) stop a car faster then the ABS. at PIR they have skid cars for instruction. part of the advanced skid car class is threshold braking. they'll have you panic stopthe car with ABS. and measure the distance. then they'll have you try it without ABS. (they have a switch to turn it off) at first you are much worse. after 15-20 minutes you can stop better then the ABS. of course... in the real world... when you haven't been thinking about it for hours in a row... and practicing over and over and over... and you're ont he highway with a latee in your hand and need to panic stop... the ABS is probably gonna beat you. ;-) it might depend on the car and ABS system too. the skid cars are toyota camrys. they probably don't have the best ABS sytem in the world. the $10000 ABS system on the PTG M3 race cars is probablyharder to beat. ;-) >Sean? Didn't we debate ABS a couple of years ago? :) You still have your >old >posts? last time we debated ABS i thought it was in regard to why it warped rotors. i maintain that if you use the ABS on your M3 all day at the track, you're going to warp alot more rotors then if you stay out of the ABS. i don't know why... maybe the ABS pulsing is bad for the rotors? maybe the ABS system generates some heat? maybe ABS stops the car better, which makes more heat? i dunno... _________________________________________________________________ Get your FREE download of MSN Explorer at http://explorer.msn.com
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#10. RE: Brakes, ABS, rear brakes etc. - from Chris Casey
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Date: Tue, 9 Jan 2001 10:34:28 -0800 (PST) From: Chris Casey <ccasey1@yahoo.com> Subject: RE: Brakes, ABS, rear brakes etc. Lowell, I test drove one of the C class MB's in 99, which had the panic stop addition - I think they call it Brake Assist. I didn't notice it continuing to brake after I released the pedal. It did have the effect of braking much quicker than I intended with what I considered normal pressure. I believe the system just adds pressure when the speed with which you depress the brake pedal crosses some threshold. Here's what MB's site says: "Upon sensing emergency braking via the speed at which the driver presses the brake pedal, Brake Assist immediately applies maximum available power boost, potentially reducing the overall stopping distance by eliminating the delay caused by a common human tendency not to brake hard enough, soon enough. Letting up on the brake pedal releases Brake Assist. Braking effectiveness also depends on proper brake system maintenance, and tire and road conditions." Whether it's the best stopping procedure or not, I test out my ABS everytime the weather gets worse. If nothing else, it keeps me aware of how quickly the M can stop, and it's worth the ~$2 of tires and brakes that I use up to do the test. -Chris > Date: Tue, 9 Jan 2001 01:39:00 EST > From: LoweSeaton@aol.com > Subject: Re: [E36M3] RE: Brakes, ABS, rear brakes > etc. > > Hi Jake! I hate to disagree but argh! I like ABS. > :-) I think it is one > of the best automotive inventions in the last 30 > years. > > I'll argue that ABS can stop a car quicker than any > human every time on any > surface. Pretty bold statement I know ;-) > > Motor Trend Magazine did a test of ABS vs. threshold > braking. I wish I could > find the issue now! I have it somewhere if you give > me time to dig it up. > It is the famous one with the 3 Dinan M3's. > > Motor Trend used a Mercedes Benz S600 and about 40 > sets of high performance > tires. They tested the S600 on about 8 different > surfaces - dry, wet, sand, > gravel, deep fresh snow, hard packed snow, scarified > snow, and glare ice. > They tried 3 different braking techniques - ABS, > threshold, and full lock. > The drivers were Motor Trend test drivers. > Extremely experienced drivers. > > In every single case, ABS beat both threshold and > full lock except for two > and one tie. The only time ABS lost by a slight > margin was in gravel and on > the glare ice. And I think the deep fresh snow was > a tie with full lock. > Threshold braking never stopped the shortest. I > wish I could find the > article so I could quote exact figures. > > I certainly agree that ABS allows you to steer and > brake without losing > control. That is a huge benefit. However, did you > know cars with ABS rear > end more vehicles than cars without ABS?? It is > almost unbelievable but > true. I don't know if anybody has figured out why > yet. Maybe people driving > ABS equipped cars think they can stop much shorter > and get overconfident? > > Or another theory is people get scared in panic > stops when the ABS starts > pulsing the brake pedal and they LET OFF the brakes! > Bam! > > Mercedes Benz invented a panic stop feature to ABS. > It has a sensor that > detects how fast you initially depress the brake > pedal. Say in a panic stop, > you react and slam on the brakes. That is human > nature. But this is where > people go wrong and either lift off the brakes when > the ABS kicks in or don't > continue to press further down on the brakes. The > MB feature takes over and > continues to apply the brakes harder whether you > want to or not. MB assumes > you started the panic stop for a reason and had > better stop immediately using > full ABS. > > Has anybody driven a late model MB? How does it > feel when the brake pedal > goes clear to the floor without any effort? I can > imagine it must freak you > out. > > OK, enough for now. Anybody have that Motor Trend > article handy? Sean? > Didn't we debate ABS a couple of years ago? :) You > still have your old > posts? > > Lowell Seaton > '95 M3 > Dallas, Texas __________________________________________________ Do You Yahoo!? Yahoo! Photos - Share your holiday photos online! http://photos.yahoo.com/