Under steer

[Bimmer-Bob]

Something to keep in mind is that both the BMW Performance suspension and Dinan's stage suspensions increase front roll bar diameter while leaving the rear bar alone. True, these aren't hardcore track applications - but by upgrading to the 26,5 mm bar you are following the example of pretty conservative (but respected) tuners. I don't think balance is upset much, if at all.

[The1]

Originally Posted by Eyeman

If sways, etc get too confusing, just get wider front tires and/or add some more camber. At least everyone agrees that helps.

i wish i did this before going the sway bar route.....

I like the stiffness of the M3 bar, but i really only think it's the bushings that i like, they bake the bar react sooner. otherwise, when i turn, the front stays super level, and the back feels sloppier now.

Like i said before, I think the front sway bar is really only working the way it's supposed to when you're in banked on and off ramps to expressways. I have taken some ramps at much higher speeds with the bar. It's limiting the roll nicely on the bank, allowing the car to use whatever negative camber the car barely has.

day to day driving, where i'm not on any banked turns i'm plowing a little bit in ordinary speeds. This is likely because i am since the car isn't leaning into a bank, so the car is still leaning past it's effective camber and responding like it would have with the stock bar, only with less body roll.

I plan to have a bigger rear sway soon as i'm doing lots of suspension work along with an LSD I'm also putting fat and sticky tires on, so in all likelyhood, i will be making the front M3 bar become more effective with an overall better ballance provided by more negative camber, correcting sway bar geometry (by adding rear) and stiffer springs.

(I have non run flat winter tires on right now, and you can definitely tell how softly sprung the car is stock. This anoys me...)

[JB135MDCT]

Based on all the reading here and good old physics, the first mod should be bushings and last mod should be ARB if at all needed. Also, front end dive is shit, must get tighter springs before ARB. For Street Fighting and novice Track Events. Order of my mods will be:

1.) M3 Rear sub frame bushings
2.) 17" wheels with larger front non/RFTs
3.) Camber Plates/CoilOvers
4.) Limited Slip
5.) M3 arms ?
6.) ARBs ?

Stock RFT/18s will be religated to touring only. For refrence, my only performance mods will be muffler, intake, cool carbons and brake ducts. Stock power is plenty for me.

Only reason I am changeing to coil overs are because the shocks are pure junk and springs to soft. I'm not sure whats worse, the rear bushings or the shock/springs. Also, my experience with springs show body roll can be controlled with stiffer springs and stock ARBs

[JimD]

Pulling or drilling the pins out of the top of the strut towers and then getting an alignment to get a little positive camber seems like a cheaper and possibly more definitive way to address camber. The plate modifications would give even more, but cost more too.

The reason our cars understeer was made more obvious to me when I went to a M school recently. I lived the first 40 plus years in snow country and made a habit of playing in the first snow in a parking lot to relearn under and oversteer correction. The first exercise at M school was also under and over steer correction but I learned that it is a bit different on wet pavement. In either case, all you need to do to correct understeer is get off the gas. That is what most people do naturally. Oversteer is significantly more challenging. If the oversteer is throttle induced, you also need to back off the gas even though that throws more traction to the front because your main issue is the rear is way low on traction. The effect of the weight shifting to the front is more subtle. But the hard part for most people was to steer into the slide but then correct that as the rear end comes around. If you fail to correct, you swing wildly to the other side or spin. The same things happen in snow but they are much gentler and slower.

So understeer is much easier for us to avoid making a bad situation worse. Oversteer is more fun but also a lot trickier to control. BMW doesn't think we can and for most of us they are probably right. M3s, M5s, and M6s understeer at the limit too, by the way, the limit is just higher.

Jim

[JB135MDCT]

Originally Posted by JimD

Pulling or drilling the pins out of the top of the strut towers and then getting an alignment to get a little positive camber seems like a cheaper and possibly more definitive way to address camber. The plate modifications would give even more, but cost more too.

So understeer is much easier for us to avoid making a bad situation worse. Oversteer is more fun but also a lot trickier to control. BMW doesn't think we can and for most of us they are probably right. M3s, M5s, and M6s understeer at the limit too, by the way, the limit is just higher.


Jim

Jim, I agree, if you don't upgrade to coilovers, but I can't stand the front end dive.

I'll take oversteer any day of the week, even in Upstate New York snow. I drove my e30 more than a my 4x4 in blizzards (up to certain depth of course).

[timhatimay]

I don't understand how people are experiencing plow and understeer regularly on the street? I've only felt this at the limit of the car, and while the balance is noticeable on the street actually plowing through a turn seems unreasonable to feel often on public roads. For those that felt the front sway made your times slower, is it possible that due to the lack of body roll you felt confident in taking the corners too fast and thus overwhelming the front tires (=understeer)? I've noticed its very easy to misjudge and come in hot (I'm a novice mind you), but I think a lot of these understeer problems could be solved with driving a little different. At least that is true with me, and with minor changes to the way I drive the car and approach turns, the 135i can behave quite neutrally. I have the e93 sway and I liked the improvement it made. On turn-in and during the turns the positive camber change is not as significant (judging by pictures), and I feel this is helping with grip up front (along with my other modifications as well). I'm not an expert driver or with suspension, but it seems to me the car certainly does understeer, however its totally blown out of proportion. I think much of it can be mitigated by adapting the driving style.

Tim

[GaryS]

Originally Posted by timhatimay

I don't understand how people are experiencing plow and understeer regularly on the street?

Sometimes it's better not to ask.

[bluesunit]

Originally Posted by timhatimay

I don't understand how people are experiencing plow and understeer regularly on the street?

100% agreement on that. I can't say that I've seen an understeer situation on the street . . . oversteer and some half ass drift, maybe a bit

Autocross, on the other hand, she plows like a pig if overdriven . . . but that's the main point here. If I set up nice and early, the car responds very well.

My oversteer solution package as it stands now:

Hotchkiss Front Sway
Pin removal and negative camber addition.
245 Hoosiers on all four corners (stock rims )

[HP Autosport]

Originally Posted by timhatimay

I'm not an expert driver or with suspension, but it seems to me the car certainly does understeer, however its totally blown out of proportion. I think much of it can be mitigated by adapting the driving style.

Tim

Sure, I agree. However, I think most of us want to faster both on the street and track, and for those purposes neither understeer nor oversteer is desirable.

[timhatimay]

Originally Posted by HP Autowerks

Sure, I agree. However, I think most of us want to faster both on the street and track, and for those purposes neither understeer nor oversteer is desirable.

Yes, that's true, a neutral car can be fast and fun in both places! Do you have any suggestions for front/rear sway size ratio? Just curious if you've found that front only hurts the cars balance as mentioned by some? Do you think that a front/rear combo (m3 for example) is the best combo, or front only/rear only can make this car behave more desirably?

I seem to remember someone saying they experienced some snap oversteer after installing a rear sway bar, but also some really love the bar. I know these are not a totalitarian solution to the 135i suspension/balance, but seem to be a common modification to try and tune the understeer/oversteer tendencies of the car.

Tim

[vwrefugee]

Nick135i, thanks for the detailed reply to my post about the whole swaybar thing being frustrating. Your take on things makes some sense and explains how a front sway upgrade on the 135 may make things feel better.

Regarding the posts wondering how understeer can be felt on the street, I guess it comes down to how you define understeer. At even moderate speeds around sharp bends the steering wheel feels like it's fighting your effort to turn (this is subtle mind you, but it's there) whereas other cars I've been in that I would say do not understeer seem to feel more like they're following a track around the bend and not trying to straighten the wheel out on you. Some may characterize this as "turn-in" but I think lack of turn-in response and understeer are related phenomena, perhaps separated mostly by the speed at which you are traveling.

[The1]

i can feel the understeer pulling into a parking space in the rain.

[HP Autosport]

Originally Posted by timhatimay

Yes, that's true, a neutral car can be fast and fun in both places! Do you have any suggestions for front/rear sway size ratio? Just curious if you've found that front only hurts the cars balance as mentioned by some? Do you think that a front/rear combo (m3 for example) is the best combo, or front only/rear only can make this car behave more desirably?

I seem to remember someone saying they experienced some snap oversteer after installing a rear sway bar, but also some really love the bar. I know these are not a totalitarian solution to the 135i suspension/balance, but seem to be a common modification to try and tune the understeer/oversteer tendencies of the car.

Tim

Tim,

I am not a big fan of anti roll bar tuning. I always address the spring rates first, then move on to anti roll bars for fine tuning.

Without knowing what you have on your car, I can not recommend anything for you.

The only way I see snap oversteer can happen is the rear start to lose traction, instead of using steering inputs to correct the minor oversteer, the inexperience driver lifts, the rear unloads, snap!

Harold

[timhatimay]

Originally Posted by HP Autowerks

Tim,

I am not a big fan of anti roll bar tuning. I always address the spring rates first, then move on to anti roll bars for fine tuning.

Without knowing what you have on your car, I can not recommend anything for you.

The only way I see snap oversteer can happen is the rear start to lose traction, instead of using steering inputs to correct the minor oversteer, the inexperience driver lifts, the rear unloads, snap!

Harold

Thanks for the input Harold. That's consistent with what I've read from others experienced with tuning suspensions, so surely as you mention the ARB is not a one ticket fix. I have the M3 front sway (from HPA of course along with other modifications) and haven't experienced the increased understeer that other's have mentioned, so I was just curious if you've found a replacing front/rear/both/neither created a major unbalance in the car causing it to greatly reduce/increase the understeer or oversteer.

Regarding the snap, I've certainly done that (and don't have an enlarged rear sway bar), and I would call it 'Oh Shit' oversteer not snap! Suffice to say I've learned my lesson! I still feel the understeer comments about the 1er are exaggerated, and while not really ideal, isn't as bad as its made out to be.

[HP Autosport]

Originally Posted by timhatimay

Thanks for the input Harold. That's consistent with what I've read from others experienced with tuning suspensions, so surely as you mention the ARB is not a one ticket fix. I have the M3 front sway (from HPA of course along with other modifications) and haven't experienced the increased understeer that other's have mentioned, so I was just curious if you've found a replacing front/rear/both/neither created a major unbalance in the car causing it to greatly reduce/increase the understeer or oversteer.

Regarding the snap, I've certainly done that (and don't have an enlarged rear sway bar), and I would call it 'Oh Shit' oversteer not snap! Suffice to say I've learned my lesson! I still feel the understeer comments about the 1er are exaggerated, and while not really ideal, isn't as bad as its made out to be.

In most cases understeer is reduced with the replacement of the oem front bar with either the M3 or slightly larger unit by reducing roll induced camber changes(positive camber), thus giving you more traction at that end of the vehicle. I can see if you install a larger than ideal bar, you can actually induce even more understeer, but there is so many variables here....springs, shocks, wheel and tire sizes, inflation pressures, alignment settings and last but not least the driver behind the wheel.

Most people are too hyped up on adding anti roll bars to reduce understeer, sure, it works, but adding more negative front camber will do more(you give up some tire life beyond a certain point). And you want to keep the negative camber you just added under cornering loads? You will need the M3 front wishbones, the deflection is much less with the bearing than with the 135/335 rubber bushing wishbones. I have never measured it, but a significant amount of camber is lost in bushing deflection. This applies in the upper portion of the strut as well, the oem upper mounts deflects a lot!

[GaryS]

Originally Posted by HP Autowerks

adding more negative front camber will do more(you give up some tire life beyond a certain point).

IIRC Tim and I have similar setups. Performance springs, a lot of M3 parts, front camber around -1.1.

How much camber do you recommend for a daily driver plus 8-12 track days a year?

[JimD]

vwrefugee,

I would call what you describe as steering feedback. Understeer is when you turn the wheel and the car's angle does not change. On dry to damp pavement, it is often accompanied by shuddering - pretty unmistakable. The shuddering is the tires gripping and then loosing grip. If you still have full directional control of the vehicle, you are not in understeer. It sounds like you are used to lighter steering than our 1s have. The wheels wanting to be pointed straight ahead is also the way the front end is aligned.

With oversteer you have lost directional control from the steering wheel too but many people do not notice it as quickly - which is another reason it is more dangerous for the average driver. You have lost adhesion at the rear and the back of your car is starting to do it's own thing. You have to point the front where the back is headed and reduce throttle so the rear can hook up. It is especially important to not make violent changes in anything, throttle, brakes, steering when in oversteer. Mild oversteer may be corrected through a little less throttle and steering into it. Hard oversteer requires steering into it, significantly less throttle, and then recovery of the steering angle back where you really want to go when the rear end hooks up. The steering input in the middle of this has to be pretty quick. If you wait a little too long to point the front you will spin. But that is only when you have really lost the rear and it is trying to come around on you. You really should never get to this - absent ice or something. On dry or even damp pavement, oversteer correction should be a small steering movement and a little less throttle.

Regardless of under or over steer, you do not want to hit your brakes. That makes a bad situation worse. Your car is nearly out of control and will get out of control if you do one more bad thing - like hit your brakes. The stability control may save you but it won't fix everything - including bad driver error. The safest thing to do if you are in doubt is to ease off the gas. If the rpm is reasonably low or you drive a torque converter automatic, you can probably get off the gas entirely. If you have the engine up near redline with a manual (including a auto shifting manual like a DTC), you should think of easing off rather than taking your foot off the gas because the engine braking will have a similar effect on the back end as hitting the parking brake - it can make you oversteer worse.

When we were practicing over steer correction at the BMW Peformance Center, the way the instructors put us in oversteer was to quickly apply the parking brake (very briefly) while we were going fairly quick around the skid pad. We had the rear tires pretty well loaded and then they got the additional challenge of the brake. That put the car in hard and immediate oversteer. You should not see this on a track, maybe on a road in icy conditions. But recovery is not that hard if you just steer into it, get off the gas some, and then steer where you want to go when the back end hooks up. Forget that last part and you spin. Failing to steer into it also results in an immediate spin. It's fun to practice under controlled circumstances like this. All we did to get understeer was go a little too fast around the skid pad. All we did to correct it was lift off a little. We did the understeer first, then the oversteer and if you could recover from oversteer correctly several times in a row, you got to try drifting. I did not do as well at the drifting as I expected based upon prior experience in snow. I found it harder on a wet skidpad with more and quicker throttle modulation required. But it was all a lot of fun.

Jim

[HP Autosport]

Originally Posted by GaryS

IIRC Tim and I have similar setups. Performance springs, a lot of M3 parts, front camber around -1.1.

How much camber do you recommend for a daily driver plus 8-12 track days a year?

-1 is the minimum you will need for street use.

-1.5 is what we do on most of street/HPDE/Track day cars for street use. You may need camber plates to get there. At the track camber is adjuted to max. negative or around -3 with camber plates.

You also want to set your toe to 1/16" total toe in for street use.

The above static alignment settings are good as long as there is no deflection in your control arm bushings. With the oem 135/335 front control arms, you will see some drastic alignment changes under conering/braking loads.

[timhatimay]

Yes my setup is similar to Gary, but I have dinan camber plates as well. I run -2* with very little toe on the street and autox all the time. I actually have completely even wear across the entire tread so far. Also have the hpa front m3 control arms. Possibly the reason I experience much less understeering than those with just a arb change.

Tim

[GaryS]

Thanks! Very helpful. My car feels balanced on track and skidpad, but I will add the Dinan camber plates and see how maximum camber works out. I'm also wondering whether enough front camber for Apex Arc-8 wheels with 245/35 would be too much, but Tim's even wear sounds promising.

[vitig]

Harold I would like to know your opinion on this configuration.

Bisltein sport b8 shocks
oem springs
front swaybar 28mm-rear swaybar 20mm

Now i had this combo but whit eibach springs(several lower around 3,9cm) and worked bad,too low and short path.I could mount the performance springs(lower 1,2cm) but i don´t want to spend a lot of money on then and not solve anything. So I thought of returning to oem springs and see how it goes.

[HP Autosport]

Originally Posted by vitig

Harold I would like to know your opinion on this configuration.

Bisltein sport b8 shocks
oem springs
front swaybar 28mm-rear swaybar 20mm

Now i had this combo but whit eibach springs(several lower around 3,9cm) and worked bad,too low and short path.I could mount the performance springs(lower 1,2cm) but i don´t want to spend a lot of money on then and not solve anything. So I thought of returning to oem springs and see how it goes.

The problem I see with some aftermarket sport spring is that if there is significant drop, the spring rate isn't increase enough to compensate for the drop to prevent the suspension from bottoming out. The BMW Performance springs is a better choice for min. drop and to gain back some of the lost compression travel. I have never liked the Bilstein line of products because of the very firm ride they offer, at times harsh depends on the application. Koni has always been the damper choice when going with a shock and spring combo for me and recommended to all my customers.