The BMW UUC Digest Volume 3 : Issue 530 : "text" Format Messages in this Issue: Re: Offset CAB's Re: Offset CAB's E36 M3 Mystery Noise Re: E36 M3 Mystery Noise Re: E36 M3 Mystery Noise Re: E36 M3 Mystery Noise Re: E36 M3 Mystery Noise Re: E36 M3 Mystery Noise
---------------------------------------------------------------------- Date: Fri, 27 Jul 2007 00:11:14 -0400 From: "Stan Jackson Jr." <[EMAIL PROTECTED]> To: "Chet Dawes" <[EMAIL PROTECTED]>, <[email protected]>, "Gary Derian" <[EMAIL PROTECTED]> Subject: Re: Offset CAB's Message-ID: <[EMAIL PROTECTED]> Thanks, Chet & Gary. The first use (I think -- racing E30 M3) clearly must have been for the dynamic camber gain. The E30 325iX starts with very little positive caster -- yet the turn-in is not amazing. Other suspension settings as well as the AWD, I suppose. Stan ================= Sent: Tuesday, July 24, 2007 4:50 PM Subject: Re: [UUC] Offset CAB's > More caster means better stability at some expense in initial turn-in. Also > improves camber gain in sharp turns and lenghtens the wheelbase a smidge. > Gary Derian > ================== > Stan, > Offset control arm bushings change caster (positive direction) giving the car more straight line stability and dynamic camber at the expense of turn in response. > Think sport bike vs. chopper. The chopper won't corner sharply......making straight line stability great as you're very unlikely to produce a 'tank slapper' unstable condition on a chopper. The sport bike (on the flip side) is very agile and therefore less stable. Another extreme is negative caster like a shopping cart - go too fast and the front wheels reach an unstable condition.......but it turns on a dime. :) > > Another benefit of increased caster is dynamic camber gain, as you turn the wheel, camber increases (negative direction) which can help mid corner performance. Increased caster will allow you to set slightly less static negative camber which helps your contact patch under braking stay as large as possible while maintaining the desired mid-corner camber. But your initial turn-in response may suffer from more positive caster. > > If you change to offset CAB, you'll need to check alignment. I'm not sure how much the geometry changes will affect toe and camber on the car in question with caster increases. > > BMW went back to a centered and solid CAB on 96+ M3's as they changed the control arm (and perhaps the knuckle as the part numbers are different) geometry instead of the bushing offset. This is the preferred approach as the bushing maintains it's designed functionality better in a centered location than offset location. Also worth noting is BMW changed the strut mounts, control arms and bushing location at the same time to get the desired alignment in 96+ M3's. They did a 'temporary measure' on the 95 M3's with increased caster in the strut mount and offset bushing with a common control arm to non-M cars. > > Hope that helps. > > Cheers, > Chet Dawes > > -----Original Message----- > >From: "Stan Jackson Jr." <[EMAIL PROTECTED]> > >Sent: Jul 24, 2007 3:25 PM > >To: [email protected] > >Subject: [UUC] Offset CAB's > > > >I've seen advertising descriptions, I've been involved in discussions, but > >I've never felt I had a conclusive answer regarding offset control arm > >bushings. When installed, offset CAB's give you more caster? And this > >improves turn-in at the expense of striaght line stability? Other effects? > > > >Thanks, > > > >Stan > > > >Search the ARCHIVES:http://www.mail-archive.com/[email protected] > > > > > >__________________________________________________________________________ > >In memory of Michel Potheau - friend, enthusiast, founder of the BMW CCA. > > > >UUC Motorwerks - BMW Performance Fine-tuning and home of the Ultimate > >Short Shifter - accept no substitutes! > >908-874-9092 . http://www.uucmotorwerks.com > ------------------------------ Date: Fri, 27 Jul 2007 09:07:03 -0400 From: "Gary Derian" <[EMAIL PROTECTED]> To: "Stan Jackson Jr." <[EMAIL PROTECTED]>, <[email protected]> Subject: Re: Offset CAB's Message-ID: <[EMAIL PROTECTED]> The turn-in effect is small but present. I would not reduce caster in order to improve turn-in. That is better served with camber and stiff tires. Gary Derian > Thanks, Chet & Gary. > > The first use (I think -- racing E30 M3) clearly must have been for the > dynamic camber gain. > > The E30 325iX starts with very little positive caster -- yet the turn-in > is > not amazing. Other suspension settings as well as the AWD, I suppose. > > Stan > >> More caster means better stability at some expense in initial turn-in. > Also >> improves camber gain in sharp turns and lenghtens the wheelbase a smidge. >> Gary Derian ------------------------------ Date: Fri, 27 Jul 2007 07:53:01 -0500 From: "Chris Harper" <[EMAIL PROTECTED]> To: [email protected] Subject: E36 M3 Mystery Noise Message-ID: <[EMAIL PROTECTED]> All, I own a 95 M3 that has a strange clunking/rattling noise coming from the passenger rear side of the car. It occurs when driving over uneven surfaces or bumps, but typically not at highway speed (assuming the highway is a little smoother) so in Jackson, MS with our roads it happens a lot. It is driving me crazy and if anyone can help me out I would appreciate it. I first thought it was the RSM, changed it, no difference. Then I thought it was the rear shock, changed it, although it was shot, no difference. I have taken everything out of the trunk, spare, CD player, tail light plastic covers, plastic panels, anything that could possibly make the noise from inside. The only thing I could possibly link it to would be that I changed my brake rotors and pads on all four corners sometime close to when the noise started. Like I said it has me pulling my hair out, any help would be appreciated. Thanks Chris 95 M3 ------------------------------ Date: Fri, 27 Jul 2007 06:29:30 -0700 (PDT) From: Tammer Farid <[EMAIL PROTECTED]> To: [email protected] Subject: Re: E36 M3 Mystery Noise Message-ID: <[EMAIL PROTECTED]> --- Chris Harper <[EMAIL PROTECTED]> wrote: > I own a 95 M3 that has a strange clunking/rattling noise > coming from the passenger rear side of the car. It occurs when > driving over uneven surfaces or bumps, but typically not at highway > speed (assuming the highway is a little smoother) so in Jackson, MS with > our roads it happens a lot. I'm going to predict the noise does NOT occur when the brakes are applied. Correct? > It is driving me crazy and if anyone can help me out I > would appreciate it. I first thought it was the RSM, changed it, no > difference. Then I thought it was the rear shock, changed it, > although it was shot, no difference. I hope you replaced these parts in pairs. snip > The only thing I could possibly link it to would be that I > changed my brake rotors and pads on all four corners sometime close > to when the noise started. The spring clip on the inboard pad on the right rear, that holds the pad into the caliper piston, is probably not holding. My bet says the noise is the brake pad rattling around. -tammer some cars ____________________________________________________________________________________ Be a better Heartthrob. Get better relationship answers from someone who knows. Yahoo! Answers - Check it out. http://answers.yahoo.com/dir/?link=list&sid=396545433 ------------------------------ Date: Fri, 27 Jul 2007 09:41:26 -0400 From: "Steve Nash" <[EMAIL PROTECTED]> To: [email protected] Subject: Re: E36 M3 Mystery Noise Message-ID: <[EMAIL PROTECTED]> What Tammer said. I had the same issue on my M3 and it drove me nuts. Turns out the spring clip was broken. -Steve On 7/27/07, Tammer Farid <[EMAIL PROTECTED]> wrote: > > --- Chris Harper <[EMAIL PROTECTED]> wrote: > > > I own a 95 M3 that has a strange clunking/rattling noise > > coming from the passenger rear side of the car. It > occurs when > > driving over uneven surfaces or bumps, but typically not > at highway > > speed (assuming the highway is a little smoother) so in > Jackson, MS with > > our roads it happens a lot. > > I'm going to predict the noise does NOT occur when the > brakes are applied. Correct? > > > It is driving me crazy and if anyone can help me out I > > would appreciate it. I first thought it was the RSM, > changed it, no > > difference. Then I thought it was the rear shock, > changed it, > > although it was shot, no difference. > > I hope you replaced these parts in pairs. > > snip > > > The only thing I could possibly link it to would be that > I > > changed my brake rotors and pads on all four corners > sometime close > > to when the noise started. > > The spring clip on the inboard pad on the right rear, that > holds the pad into the caliper piston, is probably not > holding. My bet says the noise is the brake pad rattling > around. > > -tammer > some cars ------------------------------ Date: Fri, 27 Jul 2007 10:32:05 -0400 From: "Matt Bader" <[EMAIL PROTECTED]> To: "'Tammer Farid'" <[EMAIL PROTECTED]>, <[email protected]> Subject: Re: E36 M3 Mystery Noise Message-ID: <[EMAIL PROTECTED]> The other possibility is the parking brake shoe. I have the same problem on my car but haven't had time to fix it. Try driving slowly over rough surfaces and gently pull on the parking break. If the noise goes away, I believe that is your problem. And it is very annoying.... Matt Bader 98 M3 -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Tammer Farid Sent: Friday, July 27, 2007 9:30 AM To: [email protected] Subject: Re: [UUC] E36 M3 Mystery Noise --- Chris Harper <[EMAIL PROTECTED]> wrote: > I own a 95 M3 that has a strange clunking/rattling noise > coming from the passenger rear side of the car. It occurs when > driving over uneven surfaces or bumps, but typically not at highway > speed (assuming the highway is a little smoother) so in Jackson, MS with > our roads it happens a lot. I'm going to predict the noise does NOT occur when the brakes are applied. Correct? > It is driving me crazy and if anyone can help me out I > would appreciate it. I first thought it was the RSM, changed it, no > difference. Then I thought it was the rear shock, changed it, > although it was shot, no difference. I hope you replaced these parts in pairs. snip > The only thing I could possibly link it to would be that I > changed my brake rotors and pads on all four corners sometime close > to when the noise started. The spring clip on the inboard pad on the right rear, that holds the pad into the caliper piston, is probably not holding. My bet says the noise is the brake pad rattling around. -tammer some cars ____________________________________________________________________________ ________ Be a better Heartthrob. Get better relationship answers from someone who knows. Yahoo! Answers - Check it out. http://answers.yahoo.com/dir/?link=list&sid=396545433 Search the ARCHIVES:http://www.mail-archive.com/[email protected] __________________________________________________________________________ In memory of Michel Potheau - friend, enthusiast, founder of the BMW CCA. UUC Motorwerks - BMW Performance Fine-tuning and home of the Ultimate Short Shifter - accept no substitutes! 908-874-9092 . http://www.uucmotorwerks.com ------------------------------ Date: Fri, 27 Jul 2007 07:39:05 -0700 From: bbarry <[EMAIL PROTECTED]> To: Chris Harper <[EMAIL PROTECTED]> Cc: [email protected] Subject: Re: E36 M3 Mystery Noise Message-ID: <[EMAIL PROTECTED]> Check for a slight bent lower control arm. I had one a few years ago. The sound was a mystery clunk/twang/doink sound. Teh small slow bump is what triggered it. Drove me nuts til I figured it out. Barry Chris Harper wrote: > All, > > I own a 95 M3 that has a strange clunking/rattling noise coming from > the passenger rear side of the car. It occurs when driving over > uneven surfaces or bumps, but typically not at highway speed (assuming > the highway is a little smoother) so in Jackson, MS with our roads it > happens a lot. It is driving me crazy and if anyone can help me out I > would appreciate it. I first thought it was the RSM, changed it, no > difference. Then I thought it was the rear shock, changed it, > although it was shot, no difference. I have taken everything out of > the trunk, spare, CD player, tail light plastic covers, plastic > panels, anything that could possibly make the noise from inside. The > only thing I could possibly link it to would be that I changed my > brake rotors and pads on all four corners sometime close to when the > noise started. Like I said it has me pulling my hair out, any help > would be appreciated. > > Thanks > > Chris > 95 M3 > Search the > ------------------------------ Date: Fri, 27 Jul 2007 14:17:49 +0000 (UTC) From: "[EMAIL PROTECTED]" <[EMAIL PROTECTED]> To: <[email protected]> Subject: Re: E36 M3 Mystery Noise Message-ID: <[EMAIL PROTECTED]> Another thing to try if you have a friend is to lie under the back of the car with it on the ground while someone with the trunk open grabs the sides of the trunk and shoves it from side to side. You might be better able to isolate the problem. There's another alignment adjustment arm (?!) back there that came loose on my 325. This diagnostic trick helped find it. Any other mods on the car? Aftermarket exhausts can collide with suspension components, though that's more of a baseball bat kind of klunking. The pitch of the sound will give you a hint of the size of the components impacted. Marc Plante E36 M3/4 80k Vienna, VA ------------------------------ End of [bmwuucdigest] digest(8 messages) **********
