DIY adjustable sway bar??

I'm trying to find a budget swaybar upgrade for my E36. I know what I really need is stiffer springs and the appropriate dampers for them, but for reasons of budget, quality of available options and end result suspension characteristics it isn't an option right now. So what I am trying to do is get a stiffer sway bar to reduce roll and hopefully improve my autocross times.

The available sway bars for the car are around $300 each, plus shipping to Canada, plus tax. So a lot. Most of them are adjustable, which is just 3 holes drilled in the end plate. The claim is that the short hole is 167% stiffer (I think they actually mean 67% stiffer, but whatever) than the long hole. Is there any reason why I can't drill a new set of holes in my OEM bar? At least as long as the flat part of the bar extends far enough. I couldn't find anything on google about anyone else trying it, but I figured if anybody would have tried it'd be somebody here.

Also, I do already have the 25.5mm sport package bar, which is the largest available. My struts do not have the mounting tabs or I'd M3 mount the bar there and get a big increase.

Weld on the M3 style mounts to your struts. Not hard at all, if you have a welder of course.

In reply to ross2004: Didn't really think about that. Wasn't sure if it would damage the strut. No welder though.

Drilling more holes should be safe, once they're not packed so close together that they'd create an easy path for a crack to form along.

I once had an idea to make a "sleeve" that goes over the end of a sway bar just before the stock mounting point, that has a tab on it with more holes. It could be clamped & JB-welded on (not traditional welding because the heat would affect the springiness of the bar). I think it would work.

The bars you are looking at are probably correct at 167% comparing a stock m3 bar to a 25.5mm sport bar is 88% stiffer.

a pair of $20 m3 tabs like this company sells: http://store.garagistic.com/ocart/e30%202002%20weld%20on%20tabs

would be a great way to get more roll stiffness on a budget. Are you able to pull the front stuts off and take them to a shop to have the tabs welded in? you could even tackle cleaning up the strut to bare metal to help make less work for a shop, I can't imagine it'd be more than $30-50 to get the pair welded up? You'll just want a shop competent enough to not overheat the strut and ruin them.

I've added an extra hole to a FSB in the manner you are describing. It gave the desired effect and I didn't have any problems with it. As long as there's enough real estate left on the flat part you should have any problems. I would try to get 2x bolt diameter center-center spacing.

In reply to klodkrawler05: Hmm, that's not a bad idea either. Or, I could add those and run 2 bars! Kidding of course. I was going to say I didn't want to buy new endlinks again, but the m3 links are $11 compared to $25 for the 328 ones.
I should try to see what exactly the difference is between M and non M struts are. If the only differences are the tabs and the spring perches I could switch to used M3 struts and springs to get stiffer easier and cheaper.

just to clarify for my own knowledge... drilling a hole closer to the swaybar bushings would make the bar stiffer (i.e. shorter lever arm = less difference in position of the two ends due to the same 'twist' of the bar), right?

or is it the other way around? Why?

I actually heard once that the 325/328 bar itself was stiffer than the m3 bar, but since the m3 bar used different mounting locations relative to the wheel the overall rate was stiffer on the m3. Don't have any real data on that though.

rcutclif wrote: just to clarify for my own knowledge... drilling a hole closer to the swaybar bushings would make the bar stiffer (i.e. shorter lever arm = less difference in position of the two ends due to the same 'twist' of the bar), right? or is it the other way around? Why?

You are correct. Shorter arm = stiffer. If I wanted a softer bar I'd drill the hole further away (right at the end of the flat bit/end of bar). The m3 bar is thinner than the sport bar, but has a higher effective rate because of how it is mounted. A sport bar on the strut would be very stiff. Apparently there is a 318ti bar that is even thicker, but not enough to bother (26mm vs 25.5mm).

Stiffness changes with a^4 of diameter and b^2 of arm. Also, c^1 of center section length, but that's harder to change.

bigev007 wrote:

rcutclif wrote: just to clarify for my own knowledge... drilling a hole closer to the swaybar bushings would make the bar stiffer (i.e. shorter lever arm = less difference in position of the two ends due to the same 'twist' of the bar), right? or is it the other way around? Why?

You are correct. Shorter arm = stiffer. If I wanted a softer bar I'd drill the hole further away (right at the end of the flat bit/end of bar). The m3 bar is thinner than the sport bar, but has a higher effective rate because of how it is mounted. A sport bar on the strut would be very stiff. Apparently there is a 318ti bar that is even thicker, but not enough to bother (26mm vs 25.5mm). Stiffness changes with a^4 of diameter and b^2 of arm. Also, c^1 of center section length, but that's harder to change.

Neat. I see no problem with the DIY solution then, other than to check for bar interference at the limits of suspension travel. I guess changing the position slightly probably isn't an issue, but you might not be able to move the hole very far before the bar moves in a different range. I'm absolutely subscribed to see your results.

I see no issue with heating it up and banging it flat farther back and redrilling.

If you had a sleeve that fit over the bar end you could attach your end to it and then slide it wherever you want and attach the tube to the bar with a bolt through the original hole.

Hmm, took a look and there's less flat area than I remembered. It gets very thick very fast. Maybe try grinding it down? Have to do it slow for heat. I think I can get an extra one for little or no money.

Can you replace the end of the end link with a round clamping sleeve or a metal rod end and some clamping sleeves to provide infinite adjustability? Shouldn't cost too much.

turboswede wrote: Can you replace the end of the end link with a round clamping sleeve or a metal rod end and some clamping sleeves to provide infinite adjustability? Shouldn't cost too much.

Hmmm,.... I'll have to see what I can find. See, you guys are great. Answers I got on BMW forums were "lower it, mine handles great with (random or mismatched springs)"

Edit: something like http://www.jcwhitney.com/mevotech-oe-replacement-tie-rod-adjusting-sleeve/p3058893.jcwx. ? If I get the I.d. right?

Look at the Weltmeister bars for the Porsche 924/944 and you'll see what I'm talking about, but yeah that's close.

In reply to turboswede:

OK, didn't think something that thin would work. That looks barely thicker than conduit clamps. I think I found the right thing from a 1st gen camaro. Just have to verify diameters. Sweet. Maybe. Lol.

The old way of doing this was to use a 2nd sway bar and clamp it to the original bar, using two fixed clamps on the center section, then two outer clamps that can slide in or out on the outer section, thereby adding or subtracting roll resistance.

I did this on my RX3 and it was very effective

Im not positive on this but if you decide to weld tabs on the struts check the length of the non-M and M bar. Memory tells me that the non-M bar is wider... And if you decide to go bigger than an M3 rear bar be aware that the mounting tabs are known to be weak. Reinforcements are available but need to be welded in, this could raise cost. Based on what I have read a larger front bar is the more effective than a rear bar for the E36 so I would look into options there.

It doesn't require much money to make an E36 handle well, but it is rarely done. The front bar obsession is not good.

In reply to Matthew Huizing: I know this isn't the best way to make it handle. I currently have bilstein HD and sport package springs. Even to just change to a different spring I need to change to a different damper. The only spring I'd consider (that I'm aware of) are H&R OE sport. I don't consider the lowering vs stiffness increase of the others to be desirable. The coilover options are better, but expensive. The Canadian autoslalom championship is in August and I'd like to try and pick up a few seconds on the other area STX drivers before then. The budget for this is about $100 at the moment. I have made some other modifications which have helped, now I'm looking for a bit more. If you have any suggestions, I'm all ears (all wrenches?).

I think you're splitting hairs. You might notice (and be able to use effectively) the added stiffness on the track, but it won't be quite so useful (or usable) on the street.

Here is what I have done this year.

Make/find M3 style struts--maybe used Bilstein M3 Sports. Blown stock M3 struts can be gutted and used with various strut inserts. Threaded sleeves for the front struts can be had essentially free, but the stock perches are worth trying before grinding them off.

Caster: Gabriel 1996+ M3 strut mounts $54 for a pair (swap them side-to-side)--might come with the used M3 struts. Febi 1995 M3 offset front control arm bushings ($30 pair).

Best front springs I've found are Landrum 8VB350 ($112 pair). This is a good place to spend money. You will probably need a shorter spring with stock M3 perches. Maybe 7" and slightly stiffer to make up for the reduced of travel. I haven't gone down that route yet.

I am currently running some used 5" O.D. Afcos in back ($60). Lots of other options. Make something to center whatever diameter spring you find. You can also get 2" I.D. or smaller diameter springs that will probably not really need anything. Use the stock rear spring pad(s) to make corner weight adjustments--a little goes a long way. There is no need to use a threaded adjuster in the back. You can use a lot of spring rate in the back.

Any rear shock will fit. I've seen used Koni Sports go for very cheap. Huge pain to adjust, but you can do it.

The 25.5 mm M Sports front bar is plenty stiff for the front. Most likely it will be too stiff. I am running the 25.4 mm Hotchkis rear bar in the back to reduce understeer ($220 used). At least get a 20 mm 1996+ M3 rear bar ($50).

In reply to Woody: You're probably right. It is for autocross and track use though. This is not a daily driver.

This is the road I start down when I can't sleep and my mind starts to wander.

The only clamps I can find that look right are wire clamps. But there's no way they are strong enough. Are they? The brackets on the weltmeister bars look thinner than I expected. Hmm, or something like https://www.acklandsgrainger.com/AGIPortalWeb/WebSource/ProductDisplay/globalProductDetailDisplay.do?item_code=CLKBC2-075A-DP&zone_id=PDPZ2 and grind the end off?

In reply to Matthew Huizing: Ok, thanks! That's some stuff I can work with. I have the swapped m3 mounts and offset bushings now. I'll start looking at some of the other things you mentioned and see what I can find locally.