[leftcoastman]

Originally Posted by fast_lap28

good thought and point here....

I def don't want to wait to get back on the thorttle during hard cornering! all I want is to reduce the body roll with stock since I haven't had time to go w/ coilovers yet. the car is DD but I'm hoping to hit some driving schools later this year. I also don't want to upset the balance by throwing in the bar and it upsetting the rest of the suspension....that's why I wasn't sure if this is even worth doing figuring you still have to drop the sub frame to get it installed?

Installing it isn't cheap. It's far more than the cost of the bar.

Instructors who rode in the car with me all agreed that, with stock open diff and stock springs, the bar had to be removed. I was giving up far too much exit speed.

When I played around with stock suspension, Quaife and HR rear bar, it would power oversteer way too easily for my tastes.

Considering it's $150 for the bar and $300-500 for install, I'd save up and get the coilover setup and stick with the stock bars.

[stressdoc]

This is useful stuff -- keep up the conversation guys. If I can't get my M3 slot for a March 26 ED I'm sticking my Quaife, coilovers, and some sway bar option in.

[just4kickz]

im on stock suspension and H&R front/rear sways. makes a big difference...but i think id rather get coilovers... maybe later on down the line when i have more time.

[Orb]

Originally Posted by leftcoastman

No worries. The biggest issue I had with the fat rear sway was that the limit became so much sharper.

In decreasing radius turns, with the upgraded sway, I had to be extremely careful with throttle steering. If I lifted too hard, I'd be facing the front end of the guy behind me.

For my driving style, that doesn't make for confidence, which for me doesn't make for speed.

For the short period of time that I drove with the Quaife and the thicker rear sway, I didn't get to take it on track. In my hooligan moments, I did find that getting the rear out was much easier than it is now (with Quaife, stock sway and coilovers). Granted, the coilovers have a bunch of toe-in dialed in the back, so power oversteer isn't as prevalent.

I’m assuming your had stock sport shock and springs. If you only upgrade the rear bar you going to have a bit over steer not matter what. The increase lateral stiffness needs to compensated with relative good dampeners and the stock shock are not up to the task when pushed this hard. I read through my notes on sway bar upgrade only in the summer and made note the rear rebound dampening was very weak and front compression dampening was too soft. The low speed to high compression knee was to low. I upgraded to a Quaife and FSD a few weeks later.

The condition you described for throttle lift is the worst possible case (you can do this with the stock car to). It will pitch the car more in roll and forward with an open diff. This transition is usually smooth with a balanced car like ours but certainly magnified in unbalanced car. If this condition is at mid/exit corner then the shocks and spring with play a dominant roll in the transition. Too much motion will upset the car and make it very lose which results in uneasy feeling but mostly the car will regain and not loop. I suspect this happen more at medium to high speed corners knowing the weakness of the shocks.

We should also realize the stiffer spring will also cause more inside wheel spin just like sway bars.

Most cars with longer travel with softer spring and good dampening will do well with a front and rear sway bar upgrade. It allows the better roll resistance while than suspensions still stay compliant. This setup usually excels in for street applications (weekend autocrosser) were the bumps are much bigger. In the case, with a full race setup the sway bar are less important and plays a minor roll for fine tuning.

I’ve done quite a few autocrosses in the last year 60% if this were in the rain. I have not come across any trait that causes the car to snap due to stiffer sway bars. I spent a fair amount of testing in open area and it really is not that easy to get the ass end around without an effortless recovery. I also found that it is hard to loop the car with any traction controls on. I have purposely looped this car at least 100 times in practice session in an open area. It is the only way to learn the limits fast and what recovery methods work. I just can't see how this car can over steer in most cases but don't get me wrong you can do it just as as you can plow the front end as well.

I think the wheel spin was a killer for you not the worst possible oversteer case you mentioned. The wheel spin is not oversteer.

Orb

[leftcoastman]

Yes, I had stock shock and springs, which as you mentioned, is likely part of the problem.

The lift issue is on a decreasing radius 70-80mph turn. With stock suspension (stock sways), I could come in pretty hot and then lift at the end to make the nose tuck in. To me, that was perfect throttle steering.

Once I stuck the rear sway on, I could do the same. BUT the margin for error is much lower. I have video where you can see the front end dive the same amount, indicative of the throttle lift. If I got it perfect, the nose tucked in just fine - otherwise if I'm outside of the now-thinner margin for error (with respect to rate of throttle lift), the scenery would start rotating on me.

Now, this is not theory based, but just my experience, video analysis and lap times. Maybe I'm falsely attributing the problems to the swaybar. But on slower turns, my track buddies told me that I was riding on three wheels. The stiff rear sway was preventing proper articulation in the rear and giving me the classic dog-pissing stance. Again, not based on theory, but this loss of one tire contact patch causes BOTH wheelspin and massive oversteer. Introducing a bit of theory (dangerous b/c I'm not an engineer), my understanding is that a swaybar transfers traction to the other, opposing end of the car.

So the net result is that the swaybar caused both wheelspin AND reduced my control over the throttle steering.

Once I got rid of the sway and put on the coilovers with thicker rear springs, the problem went away. I could tuck the front end quite predictably by lifting throttle. The margin for oversteer error was back where I wanted it.

I disagree that stiffer springs cause inside wheelspin as bad as a swaybar. The swaybar effectively links the two rear wheels, so you lose independent articulation. On a right hander, the compression on the left side causes compression on the right side too, lifting the right side wheel and causing light-up city.

A stiffer spring retains the independent rear suspension action. On the same turn, compression of the left side DOES NOT cause compression (and accompanying tire lift) on the right side.

Trust me man, I'm not happy about spending nearly $1,000 to purchase, install and remove the H&R rear swaybar.

As I said many times before - for street use the thicker rear sway is fine. Without a Quaife, autocross use is worthless too. My videos show nothing but wheelspin city.

Originally Posted by Orb

I’m assuming your had stock sport shock and springs. If you only upgrade the rear bar you going to have a bit over steer not matter what. The increase lateral stiffness needs to compensated with relative good dampeners and the stock shock are not up to the task when pushed this hard. I read through my notes on sway bar upgrade only in the summer and made note the rear rebound dampening was very weak and front compression dampening was too soft. The low speed to high compression knee was to low. I upgraded to a Quaife and FSD a few weeks later.

The condition you described for throttle lift is the worst possible case (you can do this with the stock car to). It will pitch the car more in roll and forward with an open diff. This transition is usually smooth with a balanced car like ours but certainly magnified in unbalanced car. If this condition is at mid/exit corner then the shocks and spring with play a dominant roll in the transition. Too much motion will upset the car and make it very lose which results in uneasy feeling but mostly the car will regain and not loop. I suspect this happen more at medium to high speed corners knowing the weakness of the shocks.

We should also realize the stiffer spring will also cause more inside wheel spin just like sway bars.

Most cars with longer travel with softer spring and good dampening will do well with a front and rear sway bar upgrade. It allows the better roll resistance while than suspensions still stay compliant. This setup usually excels in for street applications (weekend autocrosser) were the bumps are much bigger. In the case, with a full race setup the sway bar are less important and plays a minor roll for fine tuning.

I’ve done quite a few autocrosses in the last year 60% if this were in the rain. I have not come across any trait that causes the car to snap due to stiffer sway bars. I spent a fair amount of testing in open area and it really is not that easy to get the ass end around without an effortless recovery. I also found that it is hard to loop the car with any traction controls on. I have purposely looped this car at least 100 times in practice session in an open area. It is the only way to learn the limits fast and what recovery methods work. I just can't see how this car can over steer in most cases but don't get me wrong you can do it just as as you can plow the front end as well.

I think the wheel spin was a killer for you not the worst possible oversteer case you mentioned. The wheel spin is not oversteer.

Orb

[stressdoc]

So my recipe of OEM ZSP, Quaife, M-sport rear sway, and Bilstein PSS10s (ride control) sounds OK to you all? I like to retain as much suspension travel as possible because I still get off road now and again.

[sdiver68]

Originally Posted by stressdoc

So my recipe of Quaife, M-sport rear sway, and Bilstein PSS10s (ride control) sounds OK to you all? I like to retain as much suspension travel as possible.

Only if you bring it to the June 6-8 DE at Gateway so I can try it and decide on the same or go with the TCKlines (If I haven't gotten a new car by then lol)

[Orb]

Originally Posted by leftcoastman

Yes, I had stock shock and springs, which as you mentioned, is likely part of the problem.

The lift issue is on a decreasing radius 70-80mph turn. With stock suspension (stock sways), I could come in pretty hot and then lift at the end to make the nose tuck in. To me, that was perfect throttle steering.

Once I stuck the rear sway on, I could do the same. BUT the margin for error is much lower. I have video where you can see the front end dive the same amount, indicative of the throttle lift. If I got it perfect, the nose tucked in just fine - otherwise if I'm outside of the now-thinner margin for error (with respect to rate of throttle lift), the scenery would start rotating on me.

Now, this is not theory based, but just my experience, video analysis and lap times. Maybe I'm falsely attributing the problems to the swaybar. But on slower turns, my track buddies told me that I was riding on three wheels. The stiff rear sway was preventing proper articulation in the rear and giving me the classic dog-pissing stance. Again, not based on theory, but this loss of one tire contact patch causes BOTH wheelspin and massive oversteer. Introducing a bit of theory (dangerous b/c I'm not an engineer), my understanding is that a swaybar transfers traction to the other, opposing end of the car.

So the net result is that the swaybar caused both wheelspin AND reduced my control over the throttle steering.

Once I got rid of the sway and put on the coilovers with thicker rear springs, the problem went away. I could tuck the front end quite predictably by lifting throttle. The margin for oversteer error was back where I wanted it.

I disagree that stiffer springs cause inside wheelspin as bad as a swaybar. The swaybar effectively links the two rear wheels, so you lose independent articulation. On a right hander, the compression on the left side causes compression on the right side too, lifting the right side wheel and causing light-up city.

A stiffer spring retains the independent rear suspension action. On the same turn, compression of the left side DOES NOT cause compression (and accompanying tire lift) on the right side.

Trust me man, I'm not happy about spending nearly $1,000 to purchase, install and remove the H&R rear swaybar.

As I said many times before - for street use the thicker rear sway is fine. Without a Quaife, autocross use is worthless too. My videos show nothing but wheelspin city.

I appreciate your comments as it gives me a better idea how the car behaves under different circumstances. My theory was based on two things way the car is behaving like it did. One the rear sway bar only increase you roll resistance about 22% more than the 20 mm bar rating. The second is the stock shock and under dampened (especial rear rebound) to handle this big of a bar change. The effects of the under dampen shock make the throttle lift transition a bit scary and the effect would be like having unbalanced car. Basically, you lift the throttle the car pitch and rolls and take a long time to settle but overshoots so you get a really lose rear end while having under steer feeling at the wheel but the back end wants come out(depends how weak the front compression dampening is). I suspect the car behaved/felt a lot better under the throttle lift off you mentioned at speed below 50 MPH.

I pretty sure with good shock, front sway bar and alignment tweaks would have helped balanced the car more but it wouldn’t have helped a lot with wheel spin (You have a PROcede…right). The stock sport spring are fairly stiff once matched with better shocks.

I should have been clearer about stiffer spring. If try to take to much roll out with stiffer spring you simply lose mechanical grip at some point; hence, more wheel spin and rough transitions. The sway bars really just reduce roll but at the expense of the lift to the inside wheel. The softer the suspension you have the less noticeable it should be in theory but obviously not in practice and not with a driver that pushes as hard as you do.

There a few tweaks that give my car a bit advantage in keeping stable with a stiffer rear bar just so other know:

• One size up tire but are effectively 15 mm wider than stock on 19”
• Alignment: -1.0 degree front camber, rear toe-in at 80% of maximum, rear camber 30% of maximum.
• Quaife LSD, FSD shock, front & rear H&R sway bars.

Give everything that could be done I think you made a very wise choice. BTW, I woild love to see a clip of smoke show.

Orb

Edit: Attached is a good tuning flow chart. It is the best one i have seen and the guy created this documnet knows his stuff well. It should be useful tuning your coilovers.

[Orb]

Originally Posted by stressdoc

So my recipe of OEM ZSP, Quaife, M-sport rear sway, and Bilstein PSS10s (ride control) sounds OK to you all? I like to retain as much suspension travel as possible because I still get off road now and again.

FYI:

Hotchkis Performance:

Here's the specs on our kit 22834 BMW E92

Front Bar
Ø32mm hollow
95% Stiffer than Stock

Rear Bar
Ø16mm hollow
105% Stiffer than Stock

Thanks,

Aaron Ogawa
Chief Engineer

Orb

[stressdoc]

Ooooh yea, Hotchkis was my other option. I like the idea of more weight loss and I'm thinking the Hotchkis sways are likely set up to match coilovers & LSD. That is a lot of increase at the front though.

[Orb]

Originally Posted by stressdoc

Ooooh yea, Hotchkis was my other option. I like the idea of more weight loss and I'm thinking the Hotchkis sways are likely set up to match coilovers & LSD. That is a lot of increase at the front though.

Yup, it’s a big jump but thought you want some info. The front is pretty good and wouldn't want anymore.

Let see what BMW come out with shortly...it not he same as M sport bars. The shocks are also dampening adjustable but I think people missed that.

I still don't see the M-sport doing much once you consider changing the tires and shocks. The H&R is overkill for you but I love them. The safe beat is UUC as the rear can be tuned down to 17.0 mm effective. The next is the Dinan 15 mm bar as well.

We need more choices.

Orb

[1WickedE90]

Originally Posted by Orb

Yup, it’s a big jump but thought you want some info. The front is pretty good and wouldn't want anymore.

Let see what BMW come out with shortly...it not he same as M sport bars. The shocks are also dampening adjustable but I think people missed that.

I still don't see the M-sport doing much once you consider changing the tires and shocks. The H&R is overkill for you but I love them. The safe beat is UUC as the rear can be tuned down to 17.0 mm effective. The next is the Dinan 15 mm bar as well.

We need more choices.

Orb

Orb, on a '08 E90 328i w/ ZSP, would you recommend M-sport or UUC to dial-out some of understeer? Will be running 19" wheels and not changing the shocks/springs any time in the near future.

[Lane]

Having HR-stiff rear bar cannot be cured by LSD. Lifting up the inner rear wheel is the problem. It doesn't matter if the wheel in the air spins or not. Adjustable coilovers - enhanced dampening is needed, especially rear rebound. Personally, I would go with somewhat smaller diameter rear bar upgrade, but that's just my preference.

[stressdoc]

M-sport rear -- cost about $150. Install $, but not too bad if done with LSD install. I'm thinking that the 25% increase at rear might be enough to be close to neutral. Plus resale not affected negatively. No hassle with warranty or bushing maintenance.

Hotchkis more expensive, need matched set and install on f & r. Resale negative. My guess is about $500+ more cost all told. Benefit = lighter weight (20+ lbs), more roll resistance. Need coilovers.

[Orb]

Originally Posted by Lane

Having HR-stiff rear bar cannot be cured by LSD. Lifting up the inner rear wheel is the problem. It doesn't matter if the wheel in the air spins or not. Adjustable coilovers - enhanced dampening is needed, especially rear rebound. Personally, I would go with somewhat smaller diameter rear bar upgrade, but that's just my preference.

You assuming the rear the H&R sway bar set is to stiff in the rear. This is not the case and we have different opinions. The setup is natural and biased slightly towards under steer. The one user more or less added a rear sway bar and by not doing the front he might as well have the left the stock bar in as well plus a bit more.

Orb

[Orb]

Originally Posted by stressdoc

M-sport rear -- cost about $150. Install $, but not too bad if done with LSD install. I'm thinking that the 25% increase at rear might be enough to be close to neutral. Plus resale not affected negatively. No hassle with warranty or bushing maintenance.

Hotchkis more expensive, need matched set and install on f & r. Resale negative. My guess is about $500+ more cost all told. Benefit = lighter weight (20+ lbs), more roll resistance. Need coilovers.

I suggest you just try 1-2 PSI more in the front tire than the rear. If you keeps going with changing the tire pressure change up to 10 PSI more in the front like I did you know that 15 mm rear will not get rid of the terminal under steer.

If you think 1-2 PSI test is enough then do the M-sport which will do nothing for roll at all. Not one person has posted installing a 14 or 15 mm rear bar yet. I’m not sure we anyone could recommend them stating it will change anything that one can notice.

Orb

[stressdoc]

I think that the best information on the M-sport comes from the Euro folks that have extensive experience comparing it to SE or regular sport set-ups. I've only had a couple short rides in a 330 M-sport. But it felt more neutral than my ZSP 335. Part of that might be the weight difference. It would be useful if we had a detailed list of specifications on the springs and dampers for all the different suspensions.

[e46e92love]

Originally Posted by stressdoc

I think that the best information on the M-sport comes from the Euro folks that have extensive experience comparing it to SE or regular sport set-ups. I've only had a couple short rides in a 330 M-sport. But it felt more neutral than my ZSP 335. Part of that might be the weight difference. It would be useful if we had a detailed list of specifications on the springs and dampers for all the different suspensions.

+1000000, I really want to know whether going from my e92 335i ZSP suspension to M-sport is going to be much of a difference. This car just doesn't feel planted all the time, a little to floaty/too much body roll in turns. But I don't want to go crazy with coilovers and stuff cause I want to have a well-balanced and well tuned suspension.

Found this description of the performance suspension offered for the e90 335i on the bmwusa web site:

"With a tighter, sportier feeling and lower suspension setting of 15mm in comparison with series-production vehicles, the inclusion of a BMW Performance control arm with stiffer bushings gives your 3 Series an almost instinctual feel for the road. With adjusted spring rates and bushings, roll is drastically reduced, creating cat-like quickness, increased responsiveness, and stunning agility. Flexing with the motion of your vehicle around even the tightest curves, a BMW Performance control arm means athletic handling, faster turn-ins, and a totally immediate and much more intense reaction to the tarmac. It delivers a perfect compromise between racing car performance and driving comfort."

I currently have the ZSP on my 335i and was wondering if anyone knew how this compares to the stock ZSP---PLEASE SOMEONE CHIME IN!!!

[uberschnell]

Through a timing slip up I had the rear HR sway bar installed first and drove around for a few days with just the rear upgraded. I had the front HR installed and wow - World of difference!

[Orb]

Originally Posted by Magna3

Through a timing slip up I had the rear HR sway bar installed first and drove around for a few days with just the rear upgraded. I had the front HR installed and wow - World of difference!

Glad it is working out for you. It should spice up your day to day drive. Let us know how it works out on the track when you go for another run…I’m very interested in any comments good or bad.

Orb

[Josephkao]

Anyone have the BMW Performance control arm with stiffer bushings on their E90?
Please comment.