[uucdigest] Friday, February 7 2003 Volume 03 : Number 6095
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Send 'em to [EMAIL PROTECTED] |__________________________________________________________________ In this BMW UUC Digest: [uuc] Doubling up on Swaybars Re: [uuc] E36 Sways Re: [uuc] E36 sways Re: [uuc] E36 Sways [uuc] E34 525iA post balance shimmy Re: [uuc] E34 525iA post balance shimmy RE: [uuc] E34 525iA post balance shimmy Re: [uuc] E34 525iA post balance shimmy Re: [uuc] E36 sways, WTB M3 rear ---------------------------------------------------------------------- Date: Thu, 6 Feb 2003 20:40:56 -0500 From: "BMWBITS" <[EMAIL PROTECTED]> Subject: [uuc] Doubling up on Swaybars All this talk about increasing the stiffness of swaybars brings up a thought ... A few yrs ago in a British auto mag I read about a couple of upgraded Jaguars that had been 'gone over' by a tuner -I think it was Lister but I wouldn�t swear to it . What they did was build some 'double brackets' onto the frame into which they mounted TWO stock dia swaybars one above the other both front and rear. When the car was used for road ,only one bar was hooked up ,the second bar was just tied up to the fixed chassis . When tracked , two bars were connected -all connection being at the ends of course and supposedly very quick and easy to do. Anyone thought of trying that with BMWs? There are lots of cheap stock bars for sale ..............might be an easy way to double your stiffness (shades of Viagra ??..paint the second bar light blue ?) . Think of the fun you'd have at the track when the rulebook says 'only stock dia swaybars may be used in this class" ..but it doesn�t say how many !! Bill & Shirley Proud, Tennessee..winters, Seattle..summers Long commute in between . ------------------------------ Date: Thu, 6 Feb 2003 22:32:57 EST From: [EMAIL PROTECTED] Subject: Re: [uuc] E36 Sways Chris, I have been thinking about this over the last year and spent yesterday researching it. I have a '92 325is on H&Rs with stock bars that I track a lot. The rear end is very stable until pushed over the edge. When it goes it can go quite quickly and without a lot of warning. My guess is this is probably due to toe changes of the rear tires due to the stock rear trailing arm and control arm bushings. My concern was a stiffer sway in back exacerbating this or hindering recovery. My thought was to tighten the rear with urethane bushings to make it more predictable when approaching the limit and then if needed playing with sways and/or M3 upper strut bearings to increase the front camber for more balance. If any body has more input I would love to hear. Neil's car is a totally different animal and handles great after what he did, but the street comfort is gone. Gordon Date: Thu, 6 Feb 2003 16:43:23 -0500 From: "Chris Baker" <[EMAIL PROTECTED]> Subject: [uuc] E36 sways Just doing a little thinking before the summer... I currently have a '94 325i with Bilstein Sports and H&R Sports. The sway bars are stock. The springs and shocks/struts got rid of a lot of the understeer, and I'd like to get rid of some more. Like all of it. I'm not necessarily interested in getting the flattest cornering possible, since this is my daily driver and I drive in Michigan so the ride quality is of some (minor) concern. Spending as little as possible is also a household priority. By household I mean my wife. Anyway, can anyone tell me what size the stock bars are in my car (sport package) so I can make some comparisons? I'm hoping I can do something like just put in a rear M3 bar, assuming it is bigger, and see what I think of that. Or just buy a rear bar from some other set that may kick things in the right directions. Feel free to offer suggestions for my particular setup. Or offer to sell me appropriate parts. Thanks Chris Baker '94 325i ------------------------------ Date: Thu, 6 Feb 2003 23:02:00 -0500 From: "Matt Tremmel" <[EMAIL PROTECTED]> Subject: Re: [uuc] E36 sways Gary, The stiffnesses are based on anti-roll bar diameter and arm lengths. I don't have anything in for the linkages. Spring stiffnesses are based on number of coils, wire diameter, etc. They match what information I found on the web (Ben Liaw?) with measured spring stiffness' somewhere (~90 lbf/in front and 300 lbf/in rear). The rear's should adjusted for their effective rate since they are slightly inboard of the unsprung weight. The roll centers, COG, track width, etc. are used with the total F/R stiffness to determine roll couples and thus weight transfer. The important thing to remember is the RATIO of front to rear stiffness is what matters. The weight transfers regardless, it just gets split to the rear and the front by the ratio of the front to rear stiffness. For example, on my car, 3240 pounds with me int it, a 0.8g turn (steady state, like a skid pad) results in about 850 lb of weight transfer, 336 on the front, 514 on the rear (with my bars, 22.5/18). Put in the stock 325 bars (24/15), it goes to 450 front , 400 rear. More load on the front, thus understeer sooner, but the total weight transfer stays the same. You could also play around with the weight transfer by adjusting CG, track width, and roll center heights, and wheelbase (affects the weight transfer due roll center height changes), but that is pretty hard to do unless you are building the car from scratch! Matt 1994 325is >Matt, are your stiffness calcs only based on anti-roll bar diameter or do >you have all the factors included, linkage, roll center heights, etc. >Gary Derian >> >> Based on stock springs, you get this (F/R distribution of >> total stiffness) >> >> M3 (22.5/19) Stock (24/18) >> Front stiffness 44% 55% >> Rear Stiffness 56% 45% ------------------------------ Date: Thu, 6 Feb 2003 20:26:28 -0800 (PST) From: "Neil N." <[EMAIL PROTECTED]> Subject: Re: [uuc] E36 Sways - --0-1688845347-1044591988=:39672 Content-Type: text/plain; charset=us-ascii Regarding the comfort comment - very true... :-) I would highly recommend these TYPES of mods, but down a notch for street driving, like perhaps the Dinan fixed camber plates, or as Gordon mentioned, the M3's, although I don't personally know the camber specs those would yield. Anything urethane instead of aluminum bushed would be a big comfort improvement. Be aware, though, that any adjustable camber plates may be subject to misalignment at the hands of a big Michigan pothole. Urethane rear bushings are absolutely an aid to stiffening up the rear end. When I did mine, I also did the weld in rear swaybar reinforcements - probably not a bad thing to consider. It also made my car less wandery in the rear at speed. HTH, Neil [EMAIL PROTECTED] wrote:Neil's car is a totally different animal and handles great after what he did, but the street comfort is gone. - --------------------------------- Do you Yahoo!? Yahoo! Mail Plus - Powerful. Affordable. Sign up now - --0-1688845347-1044591988=:39672 Content-Type: text/html; charset=us-ascii <P>Regarding the comfort comment - very true... :-) <P>I would highly recommend these TYPES of mods, but down a notch for street driving, like perhaps the Dinan fixed camber plates, or as Gordon mentioned, the M3's, although I don't personally know the camber specs those would yield. Anything urethane instead of aluminum bushed would be a big comfort improvement. Be aware, though, that any adjustable camber plates may be subject to misalignment at the hands of a big Michigan pothole. <P>Urethane rear bushings are absolutely an aid to stiffening up the rear end. When I did mine, I also did the weld in rear swaybar reinforcements - probably not a bad thing to consider. It also made my car less wandery in the rear at speed. <P>HTH, <P>Neil <P> <B><I>[EMAIL PROTECTED]</I></B> wrote: <BLOCKQUOTE style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #1010ff 2px solid">Neil's car is a totally different animal and handles great after what he did, but the street comfort is gone.<BR></BLOCKQUOTE><p><br><hr size=1>Do you Yahoo!?<br> <a href="http://rd.yahoo.com/mail/mailsig/*http://mailplus.yahoo.com";>Yahoo! Mail Plus</a> - Powerful. Affordable. <a href="http://rd.yahoo.com/mail/mailsig/*http://mailplus.yahoo.com";>Sign up now</a> - --0-1688845347-1044591988=:39672-- ------------------------------ Date: Fri, 7 Feb 2003 10:15:03 -0500 From: "Beaudette, Roland" <[EMAIL PROTECTED]> Subject: [uuc] E34 525iA post balance shimmy The car has had an imbalance present since I picked it up last December, primarily felt during braking. It was quite disconcerting to brake at highway speeds. Replacing the thrust arms using 750 bushings really helped as the vibration was reduced to minor pulsating during braking. The next step was to have the wheels balanced. I used a local Goodyear place that had treated my alloy wheels fairly well in the past. Now, following the balance, the car vibrates heavily under breaking again (like when I first picked it up). Have it rebalanced? Suggestions are appreciated. The next item to replace would be the lower arms (unless someone has a better idea). Cheers, Roland ------------------------------ Date: Fri, 07 Feb 2003 10:31:22 -0500 From: Ed MacVaugh <[EMAIL PROTECTED]> Subject: Re: [uuc] E34 525iA post balance shimmy I would bet on bent rims. You can perfectly balance a rim even though it is bent. The weight shift during braking exacerbates the effect of the front rims being bent as more weight is transferred to them. If possible, shift rims front to rear. This might have happened at the tire shop leading to your new found reoccurrence of the problem. Ed Beaudette, Roland wrote: >The car has had an imbalance present since I picked it up last December, >primarily felt during braking. It was quite disconcerting to brake at >highway speeds. Replacing the thrust arms using 750 bushings really helped >as the vibration was reduced to minor pulsating during braking. The next >step was to have the wheels balanced. I used a local Goodyear place that >had treated my alloy wheels fairly well in the past. Now, following the >balance, the car vibrates heavily under breaking again (like when I first >picked it up). > >Have it rebalanced? Suggestions are appreciated. The next item to replace >would be the lower arms (unless someone has a better idea). > >Cheers, > >Roland > > > ------------------------------ Date: Fri, 7 Feb 2003 07:40:29 -0800 From: "Marco Romani" <[EMAIL PROTECTED]> Subject: RE: [uuc] E34 525iA post balance shimmy In no particular order Are you sure the rotors aren't warped? Swap wheels front to back. Possible one on the front is out of round. You can guess which one it is if there are a lot of wheel weights on a particular wheel. Make sure they actually torqued down the lug bolts. I can't count how many times I've found mine loose after visits to "professional". Marco - -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Beaudette, Roland Sent: Friday, February 07, 2003 7:15 AM To: Uuc (E-mail) Subject: [uuc] E34 525iA post balance shimmy The car has had an imbalance present since I picked it up last December, primarily felt during braking. It was quite disconcerting to brake at highway speeds. Replacing the thrust arms using 750 bushings really helped as the vibration was reduced to minor pulsating during braking. The next step was to have the wheels balanced. I used a local Goodyear place that had treated my alloy wheels fairly well in the past. Now, following the balance, the car vibrates heavily under breaking again (like when I first picked it up). Have it rebalanced? Suggestions are appreciated. The next item to replace would be the lower arms (unless someone has a better idea). Cheers, Roland ------------------------------ Date: Fri, 7 Feb 2003 07:41:02 -0800 From: "JS Nord" <[EMAIL PROTECTED]> Subject: Re: [uuc] E34 525iA post balance shimmy Couple thoughts... If you have aftermarket rims it's possible they forgot to replace the hubcentric rings (if you had them). Bad tire? Maybe start by having them rebalance the tires...maybe they made a mistake? Jeff 90 535i - ----- Original Message ----- From: "Beaudette, Roland" <[EMAIL PROTECTED]> To: "Uuc (E-mail)" <[EMAIL PROTECTED]> Sent: Friday, February 07, 2003 7:15 AM Subject: [uuc] E34 525iA post balance shimmy > The car has had an imbalance present since I picked it up last December, > primarily felt during braking. It was quite disconcerting to brake at > highway speeds. Replacing the thrust arms using 750 bushings really helped > as the vibration was reduced to minor pulsating during braking. The next > step was to have the wheels balanced. I used a local Goodyear place that > had treated my alloy wheels fairly well in the past. Now, following the > balance, the car vibrates heavily under breaking again (like when I first > picked it up). > > Have it rebalanced? Suggestions are appreciated. The next item to replace > would be the lower arms (unless someone has a better idea). > > Cheers, > > Roland > ------------------------------ Date: Fri, 7 Feb 2003 10:38:22 -0500 From: "Chris Baker" <[EMAIL PROTECTED]> Subject: Re: [uuc] E36 sways, WTB M3 rear Just to better my own understanding, is this correct? What I've been told, by what I thought were reputable sources, was that increasing the stiffness of the rear bar actually transferred more weight to the front inside tire, increasing grip there and reducing understeer. I know I've seen Gary comment on this before and thought his comments were along the same lines - is that right Gary? Regardless of the theory, It sounds like there is something to be gained from an M3 bar. I definitely can't get away with $350-$400 for a new aftermarket bar set, so is there any reason I shouldn't just try an M3 rear bar? Anybody got a used 96+ M3 rear bar they want to sell? Thanks, Chris B. > Date: Thu, 6 Feb 2003 18:43:57 -0500 > From: "Matt Tremmel" <[EMAIL PROTECTED]> > Subject: Re: [uuc] E36 sways > > Chris > > 95 M3 sway (22.5) in the front and 95 M3 sway in the > rear (19) will probably get you all the oversteer you want > the cheapest. > > Based on stock springs, you get this (F/R distribution of > total stiffness) > > M3 (22.5/19) Stock (24/18) > Front stiffness 44% 55% > Rear Stiffness 56% 45% > > More rear stiffness means more weight transfer to the > rear, thus exceeding the grip of the rear tires sooner > for a given lateral load. > ------------------------------ End of [uucdigest] V3 #6095 *************************** | | 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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