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CoupeDude
05-18-1999, 07:00 PM
I know that front anti-roll bars join the two joints under the hood, but how would that work for rear anti-roll bars. Wouldn't it go through where the hatch is? Sorry if that's a stupid question. . .<p>What would the noticeable affect on driving be?<p>-Anthony<br><a href = http://www.bluemtn.com/anthony/coupe.html>99 Z3 Coupe 2.8</a>

dp
05-18-1999, 08:50 PM
sounds like you are confusing a strut brace (joining the tops of struts for chassis stiffness) and anti-roll bar, which is usually below the floor and provides limited coupling of left and right suspension movement. <p>the strut brace is a non-moving part and serves to stiffen the body structure. if a rear one is used, yes, it does go through trunk. the effect it has depends on many things (how close the struts are to the firewall, how stiff the brace is, how stiff the body is to begin with, etc). generally the effect is to make car turn in sharper and track better over uneven pavement and under very aggressive cornering. you'd have to be pretty in tune with the car and your driving to notice.<p>anti-roll bars are present in almost all cars at the front, and in some at the rear. the direct effect is to limit body roll in cornering, but it indirectly affects understeer/oversteer when bar size is changed at the front or at the rear. larger bars will make a car corner flatter, but increasing bar size at only one end may result in less traction at that end due to unloading of the inside tire... of course this is grossly oversimplifying things! there are many books on the subject for the interested reader.<p><br><i>: I know that front anti-roll bars join the two joints under the hood, but how would that work for rear anti-roll bars. Wouldn't it go through where the hatch is? Sorry if that's a stupid question. . .<p>: What would the noticeable affect on driving be?<p>: -Anthony<br>: <a href = http://www.bluemtn.com/anthony/coupe.html>99 Z3 Coupe 2.8</a><p></i>

M Sipe
05-19-1999, 06:14 PM
but I know of a few racers that wish there was such a thing as an anti-roll bar after they landed on the roof.

dp
05-19-1999, 11:56 PM
<i>: but I know of a few racers that wish there was such a thing as an anti-roll bar after they landed on the roof.<p></i>

CoupeDude
05-20-1999, 04:11 PM
How would it affect understeer/oversteer? In autocrossing, I beleive that I have too much understeer near the limit.<p>How would just doing the fronts affect things versus haveing nothing now? . . . versus putting one in the front and rear?<p>I like this mod, because it is relatively cheap from what I have seen, and doesn't replace any existing parts, so my warranty should be 100% intact.<p>What brands would be recommended? I eventually want to do more extensive modifications (after warranty has expired, probably not long 11,500 miles in 3.5 months), and I think I'd like to stick with one manufacturer. Dinan, A/C Schnitzer, Racing Dynamics? Who's got the best stuff?<p>-Anthony<br>99 Z3 Coupe 2.8<p><i>: sounds like you are confusing a strut brace (joining the tops of struts for chassis stiffness) and anti-roll bar, which is usually below the floor and provides limited coupling of left and right suspension movement. <p>: the strut brace is a non-moving part and serves to stiffen the body structure. if a rear one is used, yes, it does go through trunk. the effect it has depends on many things (how close the struts are to the firewall, how stiff the brace is, how stiff the body is to begin with, etc). generally the effect is to make car turn in sharper and track better over uneven pavement and under very aggressive cornering. you'd have to be pretty in tune with the car and your driving to notice.<p>: anti-roll bars are present in almost all cars at the front, and in some at the rear. the direct effect is to limit body roll in cornering, but it indirectly affects understeer/oversteer when bar size is changed at the front or at the rear. larger bars will make a car corner flatter, but increasing bar size at only one end may result in less traction at that end due to unloading of the inside tire... of course this is grossly oversimplifying things! there are many books on the subject for the interested reader.<p>: <br>: : I know that front anti-roll bars join the two joints under the hood, but how would that work for rear anti-roll bars. Wouldn't it go through where the hatch is? Sorry if that's a stupid question. . .<p>: : What would the noticeable affect on driving be?<p>: : -Anthony<br>: : <a href = http://www.bluemtn.com/anthony/coupe.html>99 Z3 Coupe 2.8</a><p></i>

dp
05-20-1999, 05:00 PM
i have not yet put on a strut brace (none are available for the 99's at this time, maybe another month or so) - so i can't tell you for sure. but from what i understand of chassis dynamics, it should reduce flex under severe cornering, allowing suspension geometry to work as intended - thereby planting the front tires better and (hopefully) reducing understeer. it should also improve turn-in feel and control, since there would be not lag/slop due to chassis flex. notice that i only said front - looking at the coupe body, having the roof structure over the back and the internal bulkhead behind the seats, you are probably not going to improve the rigity in the back too much. the front is another story, the strut towers are pretty far from both the firewall and the forward cross-brace, and so are vulnerable to flex. therefore i would only consider doing a front brace (imho).<p>as for brands (you'll get a lot of opinions here!), dinan has the advantage of being carried by many bmw dealers, and is 'quasi-approved' by the factory. from what i understand, the warranty on unmodified components remains in force, and dinan picks up the warranty on the things modified (sometimes for extra charge, like $2500 on a supercharger installation). dinan should have a brace ready by the end of the month for '99s at $399. generally, dinan parts are pricey. worth is subjective ;) hms is working on a '99 brace, they said sometime mid-june at $265. racing dynamics should have one in the next month or so, too - don't know price.<p>hope this helps. i'll post impressions when i get mine. (check out the strut brace article on mz3.net in the meantime).<p>btw - understeer is not such a bad thing in autocross - keeps you from doing smoky donuts at the end of the slalom ;) you can play with tire pressures (up in front, down in the back) to reduce understeer a bit. and there's always the right foot (ok, easy for me ///M driver to say ;)<p><br><i>: How would it affect understeer/oversteer? In autocrossing, I beleive that I have too much understeer near the limit.<p>: How would just doing the fronts affect things versus haveing nothing now? . . . versus putting one in the front and rear?<p>: I like this mod, because it is relatively cheap from what I have seen, and doesn't replace any existing parts, so my warranty should be 100% intact.<p>: What brands would be recommended? I eventually want to do more extensive modifications (after warranty has expired, probably not long 11,500 miles in 3.5 months), and I think I'd like to stick with one manufacturer. Dinan, A/C Schnitzer, Racing Dynamics? Who's got the best stuff?<p>: -Anthony<br>: 99 Z3 Coupe 2.8<p>: : sounds like you are confusing a strut brace (joining the tops of struts for chassis stiffness) and anti-roll bar, which is usually below the floor and provides limited coupling of left and right suspension movement. <p>: : the strut brace is a non-moving part and serves to stiffen the body structure. if a rear one is used, yes, it does go through trunk. the effect it has depends on many things (how close the struts are to the firewall, how stiff the brace is, how stiff the body is to begin with, etc). generally the effect is to make car turn in sharper and track better over uneven pavement and under very aggressive cornering. you'd have to be pretty in tune with the car and your driving to notice.<p>: : anti-roll bars are present in almost all cars at the front, and in some at the rear. the direct effect is to limit body roll in cornering, but it indirectly affects understeer/oversteer when bar size is changed at the front or at the rear. larger bars will make a car corner flatter, but increasing bar size at only one end may result in less traction at that end due to unloading of the inside tire... of course this is grossly oversimplifying things! there are many books on the subject for the interested reader.<p>: : <br>: : : I know that front anti-roll bars join the two joints under the hood, but how would that work for rear anti-roll bars. Wouldn't it go through where the hatch is? Sorry if that's a stupid question. . .<p>: : : What would the noticeable affect on driving be?<p>: : : -Anthony<br>: : : <a href = http://www.bluemtn.com/anthony/coupe.html>99 Z3 Coupe 2.8</a><p></i>

dp
05-20-1999, 07:10 PM
there are six 'degrees of freedom': three rotations (roll, pitch, yaw) and three translations (longitudinal, lateral, and vertical). an antiroll bar resists the car body's motion in roll - hence the name. 'anti-sway bar' is NOT incorrect - just more 'colloquial' :)<p><br><i>: but I know of a few racers that wish there was such a thing as an anti-roll bar after they landed on the roof.<p></i>

CoupeDude
05-20-1999, 07:40 PM
Cool, please do post when you get a strut brace. I probably won't do HMS because they don't have a whole line of upgrades, do they?<p>I do like the fact that Dinan is somewhat approved. I read somewhere that you can even order a brand new Dinan BMW from select dealers.<p>But on the other hand I'd like to perhaps go with a German tuner for purity's sake. I don't really know too much about mods right now, so I really don't know.<p>Thanks,<p>Anthony<p><i>: i have not yet put on a strut brace (none are available for the 99's at this time, maybe another month or so) - so i can't tell you for sure. but from what i understand of chassis dynamics, it should reduce flex under severe cornering, allowing suspension geometry to work as intended - thereby planting the front tires better and (hopefully) reducing understeer. it should also improve turn-in feel and control, since there would be not lag/slop due to chassis flex. notice that i only said front - looking at the coupe body, having the roof structure over the back and the internal bulkhead behind the seats, you are probably not going to improve the rigity in the back too much. the front is another story, the strut towers are pretty far from both the firewall and the forward cross-brace, and so are vulnerable to flex. therefore i would only consider doing a front brace (imho).<p>: as for brands (you'll get a lot of opinions here!), dinan has the advantage of being carried by many bmw dealers, and is 'quasi-approved' by the factory. from what i understand, the warranty on unmodified components remains in force, and dinan picks up the warranty on the things modified (sometimes for extra charge, like $2500 on a supercharger installation). dinan should have a brace ready by the end of the month for '99s at $399. generally, dinan parts are pricey. worth is subjective ;) hms is working on a '99 brace, they said sometime mid-june at $265. racing dynamics should have one in the next month or so, too - don't know price.<p>: hope this helps. i'll post impressions when i get mine. (check out the strut brace article on mz3.net in the meantime).<p>: btw - understeer is not such a bad thing in autocross - keeps you from doing smoky donuts at the end of the slalom ;) you can play with tire pressures (up in front, down in the back) to reduce understeer a bit. and there's always the right foot (ok, easy for me ///M driver to say ;)<p>: <br>: : How would it affect understeer/oversteer? In autocrossing, I beleive that I have too much understeer near the limit.<p>: : How would just doing the fronts affect things versus haveing nothing now? . . . versus putting one in the front and rear?<p>: : I like this mod, because it is relatively cheap from what I have seen, and doesn't replace any existing parts, so my warranty should be 100% intact.<p>: : What brands would be recommended? I eventually want to do more extensive modifications (after warranty has expired, probably not long 11,500 miles in 3.5 months), and I think I'd like to stick with one manufacturer. Dinan, A/C Schnitzer, Racing Dynamics? Who's got the best stuff?<p>: : -Anthony<br>: : 99 Z3 Coupe 2.8<p>: : : sounds like you are confusing a strut brace (joining the tops of struts for chassis stiffness) and anti-roll bar, which is usually below the floor and provides limited coupling of left and right suspension movement. <p>: : : the strut brace is a non-moving part and serves to stiffen the body structure. if a rear one is used, yes, it does go through trunk. the effect it has depends on many things (how close the struts are to the firewall, how stiff the brace is, how stiff the body is to begin with, etc). generally the effect is to make car turn in sharper and track better over uneven pavement and under very aggressive cornering. you'd have to be pretty in tune with the car and your driving to notice.<p>: : : anti-roll bars are present in almost all cars at the front, and in some at the rear. the direct effect is to limit body roll in cornering, but it indirectly affects understeer/oversteer when bar size is changed at the front or at the rear. larger bars will make a car corner flatter, but increasing bar size at only one end may result in less traction at that end due to unloading of the inside tire... of course this is grossly oversimplifying things! there are many books on the subject for the interested reader.<p>: : : <br>: : : : I know that front anti-roll bars join the two joints under the hood, but how would that work for rear anti-roll bars. Wouldn't it go through where the hatch is? Sorry if that's a stupid question. . .<p>: : : : What would the noticeable affect on driving be?<p>: : : : -Anthony<br>: : : : <a href = http://www.bluemtn.com/anthony/coupe.html>99 Z3 Coupe 2.8</a><p></i>

M Sipe
05-21-1999, 04:04 PM
<i>: : but I know of a few racers that wish there was such a thing as an anti-roll bar after they landed on the roof.<p></i>

M Sipe
05-21-1999, 04:11 PM
ou can buy either strut tower braces and/or anti-sway/roll bars from <A HREF="http://www.hms-motorsport.com">HMS Motorsport</A>.<p>

M Sipe
05-21-1999, 04:18 PM
everything isn't necessarily listed on the website. Give them a call.<p><A HREF="http://www.hms-motorsport.com">HMS Motorsport</A>

CoupeDude
05-21-1999, 08:25 PM
<i>: everything isn't necessarily listed on the website. Give them a call.<p>: <A HREF="http://www.hms-motorsport.com">HMS Motorsport</A><p></i>

dp
05-22-1999, 11:06 AM
a few years back my 2002 had antiroll bars front and rear, and still ended up on its roof! i wasn't even racing :)<p><i>: : : but I know of a few racers that wish there was such a thing as an anti-roll bar after they landed on the roof.<p></i>


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