Dorachagi
08-14-2008, 10:42 AM
I wanted to make this post after purchasing and installing a DC5-R rear swaybar (showstoppers) and CorSport V2 endlinks. I research everything I do pretty thoroughly, but somehow I never really found anything that explained preload and how to properly setup the bar. Mine was installed with the car on jack stands and the suspension uncompressed (wheels just hanging). Installing it like this gives it no preload. After driving for awhile (and autocrossing) with the bar rattling and loose I finally figured it out (after finding some good info on BMW sites), and after a 20 minutes job I was able to feel a huge difference (and eliminate most of the rattles from the rear). Hopefully this might explain things a little clearer for anyone else who already has or is going to install a sway bar/endlinks. Oh, and fair warning, I'm not a mechanic or any kind of authority on suspension, so if I'm wrong about anything please post a reply and let us all know, I'd appreciate it.....
Here's the deal....The bar needs to have some preload on it while the driver is in the car, otherwise it's just loose until you are already in a turn and the weight of the car starts to act on it. It will still help then, but if it's already preloaded you will feel the stiffness all the time, in a straight line and, most importantly, the moment you start a turn. Plus it gets rid of almost all the rattles, which are often from people installing the bar incorrectly. If you install it while the car is on jack stands without compressing the suspension first, you have no preload and aren't getting the full effect of the bar. Likewise, if you install it without jacking up the car (my EP3 is not lowered, so I can get to the endlinks fine with it on the ground) you must have at least the weight of the driver in the car. Otherwise, as soon as you get in the bar is again unloaded from the extra 150lbs you just added (or more if you're bigger of course), and you're right back to a loose bar again.
The two methods I've found to install the bar with some preload depend on whether or not your EP is lowered. If, like me, you have a stock suspension and don't need to put it on jack stands to get to the endlinks, then here's what ya do. While the bar is bolted into the bushings on the crossmember and the endlinks are attached to the brackets on the arms but NOT to the bar, have someone or something sit in your car that weighs more than you. I'm about 145lbs, so I put about 200-220lbs into the car (2 girls sitting in the front seats). THEN rotate the bar until it's where you want it, roughly adjust one endlink and attach it to the bar, then carefully adjust the other endlink to fit and attach it to the bar. Of course, make sure everything is tight and flush. This way when I'm driving alone the bar has 50-70lbs of preload on it already. This method of install is great because if you want more preload for sharper response, or if you usually have passengers or some other kind of extra weight that's unloading the bar and you're still getting annoying rattles, just unbolt the endlinks from the bar but not the arms and add more weight than the first time you put it on, then reinstall and retighten. I think you might be able to just undo one endlink when adjusting like this and still be fine.
The other method, if you must use jack stands to get under you car, is to use two jacks under each control arm to compress the suspension while the car is up. I would think this is the most common method of install, but I don't know if everyone realizes how useless it is to put a swaybar on without compressing the suspension first. If you install a sway bar with your suspension uncompressed entirely (wheels just hanging loose in the air)it means the bar will be massively unloaded, will rattle horribly all the time, and is doing nothing for your handling at all. You'd be better off without the rear sway in this case, since taking it off would at least get rid of the rattle. I fear there could be an awful lot of people driving around with the rattle after jacking up their car and sticking the bar on with the suspension fully UNcompressed.
When you compress the suspension, look at the arms from behind the car and make sure they are both compressed the same amount by looking at the angle of the arms to the ground or chassis. Word of caution though.....it's difficult to judge how much preload you're adding because you can't tell where the suspension is compressed to when the car is on the ground, and it's very difficult to adjust the preload accurately like you can by changing the amount of weight in the car when it's on the ground.
The first time I did this I compressed the suspension as far as I could by using jacks under the arms with the car on stands. It felt very nice and stiff, and didn't rattle at all, but it took all of a day for it to rip the nut off one of the corsport endlinks. The endlinks were fine, just had to get a new nut, and this may not be a problem with different endlinks or setups, or even an aftermarket suspension that doesn't roll as much and put as much strain on the bar, but on my car I prefer the "on the ground" method so I don't overload the bar unnecessarily.
Anyways, hope this helps someone, and apologies for anything I got wrong....
Here's the deal....The bar needs to have some preload on it while the driver is in the car, otherwise it's just loose until you are already in a turn and the weight of the car starts to act on it. It will still help then, but if it's already preloaded you will feel the stiffness all the time, in a straight line and, most importantly, the moment you start a turn. Plus it gets rid of almost all the rattles, which are often from people installing the bar incorrectly. If you install it while the car is on jack stands without compressing the suspension first, you have no preload and aren't getting the full effect of the bar. Likewise, if you install it without jacking up the car (my EP3 is not lowered, so I can get to the endlinks fine with it on the ground) you must have at least the weight of the driver in the car. Otherwise, as soon as you get in the bar is again unloaded from the extra 150lbs you just added (or more if you're bigger of course), and you're right back to a loose bar again.
The two methods I've found to install the bar with some preload depend on whether or not your EP is lowered. If, like me, you have a stock suspension and don't need to put it on jack stands to get to the endlinks, then here's what ya do. While the bar is bolted into the bushings on the crossmember and the endlinks are attached to the brackets on the arms but NOT to the bar, have someone or something sit in your car that weighs more than you. I'm about 145lbs, so I put about 200-220lbs into the car (2 girls sitting in the front seats). THEN rotate the bar until it's where you want it, roughly adjust one endlink and attach it to the bar, then carefully adjust the other endlink to fit and attach it to the bar. Of course, make sure everything is tight and flush. This way when I'm driving alone the bar has 50-70lbs of preload on it already. This method of install is great because if you want more preload for sharper response, or if you usually have passengers or some other kind of extra weight that's unloading the bar and you're still getting annoying rattles, just unbolt the endlinks from the bar but not the arms and add more weight than the first time you put it on, then reinstall and retighten. I think you might be able to just undo one endlink when adjusting like this and still be fine.
The other method, if you must use jack stands to get under you car, is to use two jacks under each control arm to compress the suspension while the car is up. I would think this is the most common method of install, but I don't know if everyone realizes how useless it is to put a swaybar on without compressing the suspension first. If you install a sway bar with your suspension uncompressed entirely (wheels just hanging loose in the air)it means the bar will be massively unloaded, will rattle horribly all the time, and is doing nothing for your handling at all. You'd be better off without the rear sway in this case, since taking it off would at least get rid of the rattle. I fear there could be an awful lot of people driving around with the rattle after jacking up their car and sticking the bar on with the suspension fully UNcompressed.
When you compress the suspension, look at the arms from behind the car and make sure they are both compressed the same amount by looking at the angle of the arms to the ground or chassis. Word of caution though.....it's difficult to judge how much preload you're adding because you can't tell where the suspension is compressed to when the car is on the ground, and it's very difficult to adjust the preload accurately like you can by changing the amount of weight in the car when it's on the ground.
The first time I did this I compressed the suspension as far as I could by using jacks under the arms with the car on stands. It felt very nice and stiff, and didn't rattle at all, but it took all of a day for it to rip the nut off one of the corsport endlinks. The endlinks were fine, just had to get a new nut, and this may not be a problem with different endlinks or setups, or even an aftermarket suspension that doesn't roll as much and put as much strain on the bar, but on my car I prefer the "on the ground" method so I don't overload the bar unnecessarily.
Anyways, hope this helps someone, and apologies for anything I got wrong....