[stevehecht]

I took my 328d w/Sportline/DHP/Dinan Shockware/Bridgestone Potenza 245/40/R19 Pole Position out on Saturday for some skid pad, figure eight, emergency braking, and mini-autocross at a local BMWCCA ADSS event.

Overall I was very happy with the car's performance. Dinan Shockware has really transformed the feel of the car on the road, and especially so at ADSS when approaching the limit of traction. The BS tires did very well and were sticky enough for my needs at ADSS. The fact that I kept the car in second gear for all of the exercises meant that I was able to capture a good deal of the car's 280 lb-ft of torque with almost no turbo lag (after initial acceleration). The car was well-composed whether taking tight corners, doing a slalom, or with sudden braking. The main disappointment was with how much understeer I experienced. I found this out early on the skidpad when I found it very difficult to induce oversteer. Even the instructor had a bit of a problem. The car just didn't want to go there. I also encountered a lot of understeer when coming into corners as hard as I'd like.

I realize that understeer is engineered into the F30's DNA but I was surprised at how stubborn it was when the car was pushed to 8-9/10ths. That's one reason why I avoided staggered wheels, since that tends to encourage understeer. I'm considering obtaining a RSB, but it might not be worth it for a few ADSS or autocross sessions per year as it might negatively affect road comfort. Anyway, understeer is not obtrusive on the road now, even with spirited driving.

OTOH, have both fsb and rsb on my E30 and they do not make for a harsh feel on bad roads even with M3 springs and Bilstein HD. I guess the only way to find out for sure is to install the rsb and see how the car feels on the road. I have a feeling that the damping is so good in the F30 that the rsb will not lead to too much harshness and the suspension will feel a good deal tighter than it does now. Plus, if I do more track-type events next year it will be a hell of a lot more satisfying.

Anyone else annoyed by understeer in their F chassis? Are you planning to buy front or rear sway bars? Are there other solutions out there besides anti-roll bars? (Sway bars are not even available for the F30 in NA yet.)

[drob23]

What kind of tire pressures were you running cold and hot? Always measure this for any kind of hard driving, you can deflate the fronts relative to the rears to get some extra front grip. Keep in mind too that any sustained heavy braking will usually inject a lot of heat into the front tires, reducing their grip.

But mod wise I would absolutely get a bigger rear sway bar. I don't think it will negatively affect ride quality at all, maybe make pot holes slightly more jarring, but it's a friggen sports sedan If you upgrade the bars it's nice to upgrade to solid end-links, as long as you can deal with the additional maintenance, they'll will make the car feel more responsive with the reduced roll compliance. If you are still unsatisfied, think about changing your front camber (with plates) or front toe. Coilovers will of course give you tons of flexibility, but maybe too much.

[stevehecht]

Originally Posted by drob23

What kind of tire pressures were you running cold and hot? Always measure this for any kind of hard driving, you can always deflate the fronts a little more relative to the rear to get some extra front grip. Keep in mind too that any sustained heavy braking will usually inject a lot of heat into the front tires, reducing their grip.

But mod wise I would absolutely get a bigger rear sway bar. I don't think it will negatively affect ride quality at all, maybe make pot holes slightly more jarring, but it's a friggen sports sedan If you upgrade the bars it's nice to upgrade to solid end-links, as long as you can deal with the additional maintenance, they'll will make the car feel more responsive with the reduced roll compliance. If you are still unsatisfied, think about changing your front camber (with plates) or front toe. Coilovers will of course give you tons of flexibility, but maybe too much.

What do you mean by additional maintenance related to solid end-links? Good information, thanks.

[drob23]

Originally Posted by stevehecht

What do you mean by additional maintenance related to solid end-links? Good information, thanks.

The solid end-links I have use spherical bearings, they pair fantastically with a larger sway bar. Running them in salty climates or just anywhere will eventually get grime and corrosion inside the Teflon lubricating layer. It's not really worth it to run boots over them, since they are dry lubricated. So they need some maintenance after each winter. When they eventually fail (which they will), they will start to clunk. Just have the bearings rebuilt.

But regular rubber ones will crack and then become ineffective...you just won't be able to tell unless you inspect them.

I'm not sure what the offerings are for the F30. There are quite a few BMW examples if you search google, such as this: http://forums.bimmerforums.com/forum...able-end-links

Good luck with the research, the solid end links might not be a necessary direction. This is what I have on my S4 and love them http://www.ecodetuning.com/shop/cart..._detail&p=2048

[DVC]

Until we get sway bars, additional negative front camber is the most effective way to get front end grip. The OEM camber bearings are a good, easy way to get a little (-0.5°); camber plates will get you another couple degrees.

[stevehecht]

Originally Posted by DVC

Until we get sway bars, additional negative front camber is the most effective way to get front end grip. The OEM camber bearings are a good, easy way to get a little (-0.5°); camber plates will get you another couple degrees.

I read through this thread http://f30.bimmerpost.com/forums/sho...=834525&page=3 but wasn't able to find any real feedback on the kind of difference this OEM -0.30' swivel bearing actually makes in terms of handling performance on the street and on the track. Anyone willing to point me to another thread with this kind of feedback, or provide some for this thread?

[drob23]

Originally Posted by stevehecht

I read through this thread http://f30.bimmerpost.com/forums/sho...=834525&page=3 but wasn't able to find any real feedback on the kind of difference this OEM -0.30' swivel bearing actually makes in terms of handling performance on the street and on the track. Anyone willing to point me to another thread with this kind of feedback, or provide some for this thread?

While extremely technical, and mostly aimed at open wheel race cars with tons more chassis setup flexibility, you might want to think about picking up a copy of this book

http://www.amazon.com/Tune-Win-scien.../dp/0879380713

You'll gain a new appreciation for how many factors influence vehicle dynamics.

You never responded to my question about tire pressures. In general, the more pressure a tire has the less grip it will have. Understeer is mathematically a difference between front/rear slip angles (i.e. grip). So setting up your tire pressures appropriately by setting rear higher than front will go a *long* way towards getting a more neutral steering car.

[stevehecht]

Originally Posted by drob23

While extremely technical, and mostly aimed at open wheel race cars with tons more chassis setup flexibility, you might want to think about picking up a copy of this book

http://www.amazon.com/Tune-Win-scien.../dp/0879380713

You'll gain a new appreciation for how many factors influence vehicle dynamics.

You never responded to my question about tire pressures. In general, the more pressure a tire has the less grip it will have. Understeer is mathematically a difference between front/rear slip angles (i.e. grip). So setting up your tire pressures appropriately by setting rear higher than front will go a *long* way towards getting a more neutral steering car.

Thanks for the reference, I'll get the Carroll Smith book from Amazon.

To answer your question: No, I didn't know about how tire pressure differential front/rear can affect grip--nor was this discussed in our classroom session in the ADSS last weekend. I didn't check my pressure before the driving began but I normally keep a few lbs. more pressure in the rear over the front anyway.** Is that the amount of difference you're talking about?

(**I guess I do that because I know in the back of my mind somewhere that it helps handling--but I didn't know why.)

[drob23]

Originally Posted by stevehecht

Thanks for the reference, I'll get the Carroll Smith book from Amazon.

To answer your question: No, I didn't know about how tire pressure differential front/rear can affect grip--nor was this discussed in our classroom session in the ADSS last weekend. I didn't check my pressure before the driving began but I normally keep a few lbs. more pressure in the rear over the front anyway.** Is that the amount of difference you're talking about?

(**I guess I do that because I know in the back of my mind somewhere that it helps handling--but I didn't know why.)

Ah, OK, I understand what you took part of: http://www.boston-bmwcca.org/adss/Default.aspx

The next step is to take part in a HPDE with your BMW club. You'll be amazed at how different track driving is then autox on a skid pad.

My advice would be to speak with your instructor about tire pressure and what he recommends you run. You can also ask other track drivers here what they run. You'll want to get your own pressure gauge so you can measure your tire pressures both before and after your run sessions. Most instructors will keep a log book, noting down F/R pressures along with ambient temps, track and how hard they were driving. A lot of it comes from experience, and the only way to learn what works is to try it.

It is quite remarkable how tire pressure can make such a difference. You want to shoot for a pressure balance that helps translate to the chassis balance you desire (oversteer/understeer). There can be other negatives/positives to, as far as how much sidewall you'll roll onto and how stiff your sidewall is.

The other thing you will want to consider when driving at the track are your brake pads and fluid. Make sure you have fresh fluid for the event. Definitely preferable to speak with people who run similar cars to yours at the same track. But for the first time you should be extremely cautious of any fade and then take some cool off laps to bring your fluid temp back down.

[S4NoMore]

Originally Posted by stevehecht

Are there other solutions out there besides anti-roll bars?

Yes, take your E30 to the track and leave the diesel for commuting

But seriously, I'm curious why you wouldn't.

[tuned2ride]

Stiffer rear shocks. Lower the suspension.

If not enough change the sway bar.

[stevehecht]

Originally Posted by S4NoMore

Yes, take your E30 to the track and leave the diesel for commuting

But seriously, I'm curious why you wouldn't.

I've done that in the past and it was a ton of fun. This time I wanted to see how the F30 did with the sport suspension and Shockware upgrade and BS S-04 PP tires. I was happy with how it performed overall. I'm not convinced that that OEM swivel bearing (-0.30') is worth the money, so I might just wait for a RSB to become available.

[DVC]

Originally Posted by stevehecht

I've done that in the past and it was a ton of fun. This time I wanted to see how the F30 did with the sport suspension and Shockware upgrade and BS S-04 PP tires. I was happy with how it performed overall. I'm not convinced that that OEM swivel bearing (-0.30') is worth the money, so I might just wait for a RSB to become available.

"Worth the money" is hard to quantify... I got some right after I bought the car back in October, knowing that it would be a little while before camber plates were available. I definitely felt an improvement in front end grip with an extra -0.5°; I still like more on the track though, so camber plates are still necessary.

[therealm3]

Originally Posted by stevehecht

I'm not convinced that that OEM swivel bearing (-0.30') is worth the money, so I might just wait for a RSB to become available.

one could argue that the camber up front is more "worth it" than a rear sway bar. Just cause the car "feels" flatter with a sway bar doesn't necessarily mean its faster or handling "better".

Its too bad F30's don't have slotted strut towers like the E9X cars and can add a bit of camber for free with about 30 min of work. That made a big difference on my past two cars.

[stevehecht]

Originally Posted by DVC

"Worth the money" is hard to quantify... I got some right after I bought the car back in October, knowing that it would be a little while before camber plates were available. I definitely felt an improvement in front end grip with an extra -0.5°; I still like more on the track though, so camber plates are still necessary.

Any improvement with turn-in response time?

[drob23]

Originally Posted by DVC

"Worth the money" is hard to quantify... I got some right after I bought the car back in October, knowing that it would be a little while before camber plates were available. I definitely felt an improvement in front end grip with an extra -0.5°; I still like more on the track though, so camber plates are still necessary.

Do you guys have a track thread or place where most of this experience is being logged? I'm curious how the F30 is faring. I've seen quite a few e9x's at track events, but only a couple F30's.

[DVC]

Originally Posted by stevehecht

Any improvement with turn-in response time?

Yes, more negative camber also improves the turn-in responsiveness somewhat. -0.5° is a pretty modest change, but enough to be noticed.

Originally Posted by drob23

Do you guys have a track thread or place where most of this experience is being logged? I'm curious how the F30 is faring. I've seen quite a few e9x's at track events, but only a couple F30's.

There is a track sub-forum where some experiences have been shared...
Some of us also have been trading e-mails on the side

[drob23]

Originally Posted by DVC

Yes, more negative camber also improves the turn-in responsiveness somewhat. -0.5° is a pretty modest change, but enough to be noticed.




There is a track sub-forum where some experiences have been shared...
Some of us also have been trading e-mails on the side

haha oops, thanks for pointing me in the right direction