Sway bar delete setups for auto-x and canyon runs?

[Bullwings]

^^ I don't know much about Fn rates and how all of that works, but I do have OEM spring rates for the S2K. The springs are identical front and rear, both length and diameter and can be interchanged freely. Here are the design specs on "rates". It looks like you're right about that, most of those have higher rear rates, although in later years it looks like they go pretty even, and almost non-staggered with rates.


Model Year | Spring(f) Spring(r) | Sway Bar(f) Sway Bar (r)
--------------+------------------+--------------------
2000-2001 | 219f / 291r | 393f / 427r
2002-2003 | 246f / 309r | 300f / 396r
2004-2005 | 262f / 278r | 300f / 311r
2006-2007 | 262f / 269r | 300f / 311r
2008-2009 | 280f / 294r | 354f / 311r
2008-2009 CR | 384f / 343r | 392f / 362r

Note 1: All figures are in lb/in. Divide by 56 to get kg/mm.
Note 2: Edited 17Nov2010 with slight updates to spring rates per rev1 of paper.

crazy as link for the "study" that was done on the s2k suspension.

http://www.s2ki.com/s2000/topic/8188...nsion-springs/


Anyway, back to e30s. I need to get some tabs welded on.

[robgoesvroom]

don't ever compare an E30 to an S2000! Not fair at all lol. I've yet to see a video of an E30 (non M3) vs S2000 on track, I've been searching for a while

What times do you run at BW in your S?

[Bullwings]

BW CW13?

Completely stock OEM setup, OEM shocks/springs , OEM wheels (17x7F/17x8.5R), OEM sways, on 225F/255R tires (RS3s), I can consistently run 2:10.xxx to 2:11.xxx's in 85F+ weather. I've seen better drivers run 2:06s and 2:08s on the same stock setups (part of our Time Trial series - Stock Class). Other tracks
-ACS - 2:05s
-SOWS CCW - 1:31s
-SOWS CW - 1:30s
-WSIR - 1:44s
-CVR CW - 2:13s


My current setup is still OEM suspension and power, but now with 17x9s F/R with 255 Direzza ZII's square and a GTC-200 wing. On that setup i'm running consistent 2:06s in the same weather. I'm pretty sure the setup is capable of 2:02 with a more capable driver. other tracks:
-CVR CW - 2:06s
-SOWS CCW - 1:27s

And no, you won't see or find those videos because the versus part doesn't happen. It's usually the S2K flying by the E30 with probably only 3 seconds of either car being in each others' videos.

NA miatas are a much better and fairer comparison. I think Spec Miatas run 2:10s at BW CW13. NB miatas will likely out class an e30 on a track with lots of turns and technical sections.

On a side note, I was considering JB welding the tabs. That lasted about a whole 2 minutes before I decided that was really a mickey mouse solution and bound to cause future problems... LOL

[mike156]

While I don't have an E30,I do have an E36 318ti that weighs ~2400 pounds. I would guess it handles roughly like an E30.

I recently attempted a no sway bar setup. I am running 680/950 lb/in spring rates. This comes out to roughly 580/390 wheel rates and a natural frequency balance of 2.9/2.6 Hz.

I thought the wheel rate balance would be sufficiently front biased that the car was going to tend to understeer. On the street, at 7/10ths it felt pretty decent so I thought it was going to be great. I could not have been further from the truth though as the car was crazy loose at the first auto cross event. So much that I'm almost certain I was faster on the 18 year old stock suspension.

Front grip was great and turn in was phenomenal. The back just wanted to keep going straight though and I really had to back off on how hard I was pushing it just to avoid spinning it.

I've since put the stock front bar back on. I haven't been to an auto cross since but it mellowed the car out considerably on the street. It still tends towards over steer 100% of the time though. My biggest complaint though is the front bar KILLED the turn in response. Without the bar, it felt like a scalpel now it's all numb and boring.

Maybe you could balance the car out without any sway bars but I really doubt it considering I still haven't got it balanced with a 25mm front bar. That is a decent amount of roll stiffness to make up for. The back would have to come way down on spring rate as the front is already at the limit for a street tire.

[Bullwings]

Thanks for the feedback.

I've since ordered the Ireland Eng 22mm front bar with hardware. It should go in this weekend. I'm also going to reconnect my OEM rear bar when I do.

I've found people have said the optimal track setup is a 22mm Front bar with the OEM rear. Spec e30 guys have complained about not being able to run OEM rear bars (I think they mandate 22mm non-adjustable front and 19mm rear - adjustable ok). They do have the option to delete the rear and not run anything, but most have said it's too understeery

anyway, updates in a week or two on my impressions. I'm also planning to auto-x it in a month or so - time and budget permitting.

[Fusion]

The IE bar is a good choice. I'm really happy with mine and adjustibility is a great feature.
If you're looking for even crisper steering, I would recommend getting rid of the rubber OEM upper shock mounts in exchange for something solid. Also, PU front arm bushings (lollipops) make a huge difference. You will be compromising comfort though, depending on how comfortable you expect it to be.
Don't get frustrated because of some experimenting. It may take you a couple track/autox days before you feel the setup is the way you like it. We can recommend all we want, but that doesn't mean you'll be happy wit the setup right away.

[Jaxx_]

This - most people talk about E30s like they're all M3s. Even the "sport" trims ride on very soft suspensions.I know it's becoming a cliche, but a lot of people seem to forget these cars were just sporty yuppie-wagons.

I use these pictures a lot to demonstrate how soft a stock e30 really is...

yep, stock suspension is soft.



I'll mention that in my 318 using a stock rear 325i bar, the car is super neutral. I'm running H&R Race all around. Stock sway in the front. As mentioned, if you go without a front sway you will need a ridiculously strong coil in order to not have crazy body movement. Keep in mind that the spring design had a swaybar in mind so without it you are effectively cutting a significant amount of spring rate... up to double the original spring rate at one side of the car.

edit: Also concerning turn in... there are other factors that can help. I run 1 deg of toe out on each side of the car in order to add twitchiness. This is probably infeasible for a daily driver.

[Bullwings]

^ Wow, that's some crazy body roll there.

Anyway, I finally got my sway bars on - IE 22mm front on middle adjustment, and OEM rear. The car feels awesome now. it's a blast to drive. I can't wait to take it to an auto-x and some canyon runs after that.

No plans to track it right now - i'm not sure how well it would handle that abuse. It's my DD, so I'd like to keep it mostly operational and keep the repairs/maintenance to a minimum.

[henryki]

You must have something set up wrong if it doesn't drive like god's chariot

lol'd pretty hard. but yes e30 is the best car in the world. period. Thank the germans for coming up with such a great machine. :hitler:

[robgoesvroom]

get ready for some understeer if you add a huge bar up front and no camber plates, you'll definitely have to adjust your driving style!

[knuklehead92]

yep, stock suspension is soft.



I'll mention that in my 318 using a stock rear 325i bar, the car is super neutral. I'm running H&R Race all around. Stock sway in the front. As mentioned, if you go without a front sway you will need a ridiculously strong coil in order to not have crazy body movement. Keep in mind that the spring design had a swaybar in mind so without it you are effectively cutting a significant amount of spring rate... up to double the original spring rate at one side of the car.

edit: Also concerning turn in... there are other factors that can help. I run 1 deg of toe out on each side of the car in order to add twitchiness. This is probably infeasible for a daily driver.

omg.....

[GillesBigCowboy]

Also concerning turn in... there are other factors that can help. I run 1 deg of toe out on each side of the car in order to add twitchiness. This is probably infeasible for a daily driver.

Last few months I have been running some significant toe out on my vert dd (don't know the degrees), and I would not recommend it to anyone, but the twitchy feel keeps you on your toes, and it does like to turn in hard. I am hoping the experience is subconsciously embedding smoothness in my driving.

[Jaxx_]

get ready for some understeer if you add a huge bar up front and no camber plates, you'll definitely have to adjust your driving style!

trail braking king lol

Last few months I have been running some significant toe out on my vert dd (don't know the degrees), and I would not recommend it to anyone, but the twitchy feel keeps you on your toes, and it does like to turn in hard. I am hoping the experience is subconsciously embedding smoothness in my driving.

Yes, even with 0 degrees you have to "drive" the car 100% of the time--hence the -0.1 degrees that you usually see on most front alignments. However, toe out really starts to make up for the slow racks on these cars.

[603Racing]

I've since put the stock front bar back on. I haven't been to an auto cross since but it mellowed the car out considerably on the street. It still tends towards over steer 100% of the time though. My biggest complaint though is the front bar KILLED the turn in response. Without the bar, it felt like a scalpel now it's all numb and boring.

I'm sure you know this, but I will comment for the sake of those that do not. Your 'bar balance' was way off by having a front and no rear. Add a rear bar to your setup and your turn in will improve.

I tend to disagree with a lot of the sway bar talk. For me it comes down to driving style. I like a large front bar AND a large rear bar. I also prefer that my car be slightly on the loose side, slightly. But stricly talking bars is pointless because you have to consider everything... tires, tire pressure, toe, camber, caster, bushings, spring rates, bound/rebound, corner balance, AND driver style. Rear toe/camber is important too.

Throw huge bars on a stock e30 and the track times may not necessarily be better. Could say the same for any single part.

Bottom line, suspension/tire upgrades should be done wholey. Now that I've jacked the thread a bit.... I personally would never run an event (drifting excluded) on pavement with either bar disconnected.

[mike156]

Difference in mind set I suppose.

You ditch the rear bar simply in an effort to try and keep the rear inside tire from lifting. Compared to the 950 lb rear springs, the stock bar is doing very little for roll stiffness but will help pick the inside wheel up. How much it matters though, I'm not sure as the car will roll more without the bar
While it might keep the tire on the ground with slightly more body roll, if it's rolling more to start with, is probably 6s.

I've since added the BMW Motorsports X brace and urethane sway bar mount bushings. The car is finally getting some mild understeer on the street if you over cook the entrance. Seems like the chassis was starting to dominate and the added chassis stiffness of finally letting the heavy front spring bias do it's thing?