[uucdigest] Thursday, June 19 2003 Volume 03 : Number 6486
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Send 'em to [EMAIL PROTECTED] |__________________________________________________________________ In this BMW UUC Digest: Re: [uuc] Re: installing gauges in an E30 Re: [uuc] Brake upgrades for E34 525 [uuc] Re: <E30> Wheel questions Re: [uuc] <E30> Wheel questions [uuc] Re: <E30> Wheel questions [uuc] now "black arts of the racers edge" was changing brake bias Re: [uuc] Brake upgrades for E34 525 ---------------------------------------------------------------------- Date: Thu, 19 Jun 2003 12:01:13 -0700 (PDT) From: Andre Yew <[EMAIL PROTECTED]> Subject: Re: [uuc] Re: installing gauges in an E30 On Thu, 19 Jun 2003 [EMAIL PROTECTED] wrote: > Yes Joe, I had my hollow bolt tapped. But just in case, buy an extra one > as a back-up. The temp sender has not leaked. The drain plug is a poor > place for a sender, IMHO. Scott, I'm getting ready to install similar senders on my E46 328Ci. Why is the drain plug is a poor location for the temperature sender? Thanks. - --Andre ------------------------------ Date: Thu, 19 Jun 2003 15:23:29 -0400 From: "Rob Levinson * UUC Motorwerks" <[EMAIL PROTECTED]> Subject: Re: [uuc] Brake upgrades for E34 525 - ----- Original Message ----- From: "Michael McCoy" <[EMAIL PROTECTED]> Subject: Re: [uuc] Brake upgrades for E34 525 > > How crazy do you want to go with the brakes? In about a week or two, UUC > > will have the 355mm 4-piston front and 328mm 4-piston rear available for > the > > E34. They fit under 17" wheels and will be very reasonably priced for > this > > level of braking capability. > > > > you done the math yet on brake balance/bias/dynamics yet? and if so, you > care to share those numbers? Roughly 64% front, 36% rear. > I'm really looking for a system that is truly balanced. as in the limit of > adhesion in braking is attained at all 4 wheels at the same time. At what braking amount? Balance shifts with a variety of factors, most significantly how hard you brake. > also, why such big rotors in the front? seems a bit excessive. 330mm was > more than enough for most LMP cars (granted they are only 1500lbs, but they > do more repetetive stopping from higher speeds than a 5 will ever see.) Race machines like that have completely different needs and hardware, not to mention the weight (which you already mentioned). Rotor size accomplishes two things: brake torque (diameter) and thermal capacity (mass). Assuming good front/rear bias and pad choice appropriate to the temps used, having reserve thermal capacity in a heavy car is a welcomed luxury. > i don't know if bigger is always better. granted the E34 needs better > brakes, but I think sizing the calipers to match the balance and maximum > grip of the car is best. As I wrote above. > i've been trying to work the math backwards, but keep finding things wrong > with my approach. I want the math to be perfect before I figure out what > calipers/rotors match the needs. the trial and error methodology would be an > expensive way to approach this problem. Perhaps you need to clarify exactly what you are trying to achieve, or specifically what problem you are trying to overcome. - - Rob ------------------------------ Date: Thu, 19 Jun 2003 13:09:14 -0700 From: [EMAIL PROTECTED] Subject: [uuc] Re: <E30> Wheel questions Hi John, I find that 15 inch wheels give me plenty of performance without the ride getting rediculously harsh. Tires of smaller diameter are less expensive. The larger the diameter the wheel, the heavier it is. I have the ASA JS1s for autocrossing and occasional track use. They are sturdy, but not particularly light. Then again, they are also not particularly heavy either. Kind of somewhere in between. Specify the aluminum centering rings (they're not hub-centric), otherwise they'll send you the cheap plastic ones. (Ask me how I know. The Tire Rack's John Rastetter says the plastic ones can melt under track or hard autocross use. Despite the fact that I ordered heat-cycled Kumho V700s, they still sent the plastic centering rings. How did they think I was going to use them?) A friend had a set of MMs once, but found that they were not particularly durable. HTH, Scott Miller GGC BMW CCA 1990 325i 225/45-15 Kumho Ecsta V700s on 15x7 ASA JS1s for autocross 205/55-15 S-03s on 15x7 Fittipaldi 500s for street >Date: Thu, 19 Jun 2003 12:37:58 -0400 >From: John Sabatini <[EMAIL PROTECTED]> >Subject: [uuc] <E30> Wheel questions > >Looking to get some new wheels in the near future. I want to get 16" wheels >but am curious if there are any pro and cons between 15" wheels and 16" >wheels. The car is my daily driver as well as track car. I am an >instructor with both BMW CCA and PCA, with my primary tracks being Sebring, >Moroso, and Road Atlanta. > >I like the 5 or 6 spoke wheels and would like any feedback or >recommendations on the following. > >I really like the SSR Competition wheels, but at over $1,200, I wish I could >find something less expensive. > >The only other wheels I have found seem to be too cheap. They are as >follows: > >ASA JS1 (licensed by BBS, but only $100 per wheel) > >Kosei K1 > >Sport Edition Fox 2 > >Mille Miglia MM11-2 > > >Thanks in advance, > >John Sabatini >'90 325is ------------------------------ Date: Thu, 19 Jun 2003 20:12:56 +0000 From: [EMAIL PROTECTED] Subject: Re: [uuc] <E30> Wheel questions On the treet, I use BBS RS Classic 7x15 3-piece gold center wheels with Yokohama AVS ES100 225/50-16 tires. They're beautiful but hard to clean. On the track, I use Kosei K1 7x15 wheels with Michelin Pilot Sport Cup 225/50-15 tires. (No, I'm not made of money, I won the tires in a drawing.) The setup weighs 32 lbs per corner, including lug bolts. They're not that ugly, and the open design makes for good cooling, easy pad inspection and mid-day bleeding, and easy cleaning. They might be somewhat ugly at rest, but their purpose in life is to be light and go fast, and who's looking that close when you're at speed? My car rides a bit lower than stock, on Eibach springs and Koni shocks. I find no evidence of rubbing problems with this set-up. When you get the wheels from Tire Rack, be sure you order a set of their aluminum hubcentric adapter rings. They send plastic centering rings for free with the wheels, but they melt in front. - -- Bob Sutterfield '87 E30 325iS http://bmwe30.net #1129 DAS KAR '88 E28 535iS http://m535i.org #154 IHR FUNF '93 T4 EV Weekender BELUGA BMWCCA #169277 Rocky Mountain Chapter ------------------------------ Date: Thu, 19 Jun 2003 13:14:28 -0700 (PDT) From: John Bolhuis <[EMAIL PROTECTED]> Subject: [uuc] Re: <E30> Wheel questions On Thu, 19 Jun 2003, John Sabatini wrote: > Looking to get some new wheels in the near future. I want to get > 16" wheels but am curious if there are any pro and cons between > 15" wheels and 16" wheels. The car is my daily driver as well as > track car. I am an instructor with both BMW CCA and PCA, with my > primary tracks being Sebring, Moroso, and Road Atlanta. > Mille Miglia MM11-2 I have the 16" MM11-2 wheels on my ragtop. I autocross on them too. They work fine for me, haven't folded over or anything. One of 'em even took a fairly good curb hit and only scratched the edge without bending the wheel like it sounded like. So that leads me to believe they're stronger than my last wheels. I got them because it's easy to clean 5 spoke wheels. The benefit of 16s is that you can reach a rag all the way to the inside of the wheel, clearing all brake parts. The downside is that the stock brakes really look rather pathetic and small now that they're exposed inside a larger wheel. Also, these wheels need the 1cm spacers, which adds complexity to wheel mounting. I woulda got the 15s if they were available. - -- "It is an honor to be Cookie Monster." -Sesame Street spokeswoman Audrey Shapiro ------------------------------ Date: Thu, 19 Jun 2003 13:15:14 -0700 From: "JSN" <[EMAIL PROTECTED]> Subject: [uuc] now "black arts of the racers edge" was changing brake bias Fantastic... clever... hilarious! Anyone else care to share similar anecdotal stories on the "black arts" of gaining the racers edge? These sorts of stories amazing for us plodding low tech non-racer types. Jeff 90 535i - ----- Original Message ----- From: "jkerouac" <[EMAIL PROTECTED]> To: "[uucdigest]" <[EMAIL PROTECTED]> Sent: Thursday, June 19, 2003 11:05 AM Subject: [uuc] re: changing brake bias > re: changing brake bias: > > Here are two low tech ways I've altered brake bias to get more braking > force to the rear or less to the front, when prepping BMWs for stock or > street prepared autocross without violating class rules. If trailing > throttle oversteer to set your tail perfectly into the next gate is your > thing, you may wish to try this: > > 1. Here's one of those 'black arts' that people don't talk about. > Don't bleed the front brakes. Keep fresh fluid in the rears. In fact > you can deliberately introduce air into the front brakes by opening the > bleeder valve with the pedal down, and raising the brake pedal a bit so > some air gets sucked in. > Don't try it if you're tracking the car. In an autocross > setting this method works well because you only need one or two heavy > womps on the brakes, plus some left foot braking during the run. > Therefore heat buildup on the front is not of concern. > > 2. Use smaller diameter rear/larger diameter front tires. Thus the > fronts rotate slower, the rears faster, so the proportion of effective > swept area shifts rearward. Another plus when autocrossing is that > smaller rear tires make the tail more reactive. The car will rake > rearward a bit, causing more caster on the front wheels and shifting the > weight bias rearward. > Enjoy, > > 'jk > > If you want to go as fast as everyone else, first do what everyone else > is doing. If you only do what everyone else is doing, how can you go > any faster? > ---------------------------------------------------------------- > > > ------------------------------ Date: Thu, 19 Jun 2003 16:27:51 -0400 From: "Michael McCoy" <[EMAIL PROTECTED]> Subject: Re: [uuc] Brake upgrades for E34 525 - ----- Original Message ----- From: "Rob Levinson * UUC Motorwerks" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Thursday, June 19, 2003 3:23 PM Subject: Re: [uuc] Brake upgrades for E34 525 > > ----- Original Message ----- > From: "Michael McCoy" <[EMAIL PROTECTED]> > Subject: Re: [uuc] Brake upgrades for E34 525 > > > > > How crazy do you want to go with the brakes? In about a week or two, > UUC > > > will have the 355mm 4-piston front and 328mm 4-piston rear available for > > the > > > E34. They fit under 17" wheels and will be very reasonably priced for > > this > > > level of braking capability. > > > > > > > you done the math yet on brake balance/bias/dynamics yet? and if so, you > > care to share those numbers? > > Roughly 64% front, 36% rear. > <drool> wonderful... that number range I mentioned? 65% to 63% front? 64% seems like a *lovely* compromise between the two. :o) > > > I'm really looking for a system that is truly balanced. as in the limit of > > adhesion in braking is attained at all 4 wheels at the same time. > > At what braking amount? Balance shifts with a variety of factors, most > significantly how hard you brake. > well, if you're braking hard enough to reach the limit of adhesion... rather hard. in fact, that would be the hardest you could brake. (or rather the fastest you could stop. you could brake harder, but that would just result in locked tires... not stopping too well that way.) I was saying that I would want there to be a braking force that, when applied, reached the limit of adhesion of the fronts at the same time it reached the limit of adhesion at the rears. this of course would be speed dependent as to what the force would be, but the balance front to rear would be relatively consistent. the car doesn't generate any downforce (not a horrible amount of lift either thankfully) so the max attainable decelerative G's is within a relatively narrow region. so weight transfer is within a relatively confined region as well. balanced at the limit is ideal. anything less than that and the balance won't really be noticed anyway. > > also, why such big rotors in the front? seems a bit excessive. 330mm was > > more than enough for most LMP cars (granted they are only 1500lbs, but > they > > do more repetetive stopping from higher speeds than a 5 will ever see.) > > Race machines like that have completely different needs and hardware, not to > mention the weight (which you already mentioned). > needs are more excessive than what a street car would see. the weight contributes less to the equation than the speed squared part. a 3400 lb car (E34 525?) going 100 mph has the same energy as a 1500 lb LMP car going 150 mph. so both coming to a stop will generate the same amount of heat in the brakes. that same LMP car (LMP-675) also makes 550+ hp. so it gets to that 150+ mph much faster (as well as much more frequently) than the 3400 lb street car would (unless said street car is making well over 1000 hp). so the LMP car makes the same or more heat, in less time, with less time to dissapate that heat, and the 330 mm rotors work for it. thats why I was questioning the use of something larger. > Rotor size accomplishes two things: brake torque (diameter) and thermal > capacity (mass). Assuming good front/rear bias and pad choice appropriate > to the temps used, having reserve thermal capacity in a heavy car is a > welcomed luxury. > extra thermal capacity is a good thing. what i don't understand is when there is a disproportionately large amount of thermal capacity in the front. or just bigger brakes up front in general. most tend to ignore whats in the rear of the car as far as brakes are concerned. > > i don't know if bigger is always better. granted the E34 needs better > > brakes, but I think sizing the calipers to match the balance and maximum > > grip of the car is best. > > As I wrote above. > > > i've been trying to work the math backwards, but keep finding things wrong > > with my approach. I want the math to be perfect before I figure out what > > calipers/rotors match the needs. the trial and error methodology would be > an > > expensive way to approach this problem. > > Perhaps you need to clarify exactly what you are trying to achieve, or > specifically what problem you are trying to overcome. > > - Rob > problem that i am trying to overcome is mostly the balance issue. i want to stop faster. stopping faster will require using all 4 tires to their limit. not just the fronts to their limit with the rears kinda just *along for the ride*. next aspect will be brake cooling. but as I probably mentioned before, thats best addressed with better cooling. granted larger rotors can give more surface area. but generally people look at rotors just as a heat sink. thermal capacity is one thing, but if you're going to be hitting the brakes again soon, you need to look at how fast you can get rid of the heat you just absorbed. surface area is good for this, but you can make lots of internal surface area in a vented rotor without lots of external surface area. a good example of this is thicker rotors... say the thicker rotor has more mass, but no more surface area (inside or out). it will have the ability to absorb more thermal energy before its "full", but it won't be able to dissapate the heat any faster than its thinner lighter brother. so it might have an advantage the first time you hit the brakes, but that advantage is gone after that. - -Michael McCoy *I guess in general I'm more of a "small brakes with big ducts" kind of guy. that probably complements the "small motor with big turbo" thing well. ------------------------------ End of [uucdigest] V3 #6486 *************************** | | In memory of Michel Potheau - friend, enthusiast, founder of the BMW CCA. |________________________________________ | Please visit these UUC-approved BMW parts vendors/service providers: | (listed alphabetically) | | Autoscope-Motorsports - http://www.autoscope-motorsports.com | |==================================================== | | Koala MotorSport . 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