How to make my car less bouncy? and a couple other questions.

[chachacha28]

i have an 08 135, all stock save H&R Sport Springs and an aftermarket muffler. The car seems very bouncy when driving at speed. I live in germany, so i spend a lot of time over 150km/h (~90mph), and it seems like every bump i hit just tosses the car around in my lane. Is there anything i can do to fix this? aero, tires, shocks? or is this just the nature of the beast?

also, everywhere i read that has an article about this car raves about the amazing brakes, but i dont think they are all that great. I may or may not have OEM pads (20k miles on the car, not sure how long the OE's last, but they guy i bought it from didnt seem like the type to change them out early, but i forgot to ask.) But it seems like i can only do 50% braking effort before the car starts to get really light in the booty, and i feel like if i push anymore, i will do an impromptu u-turn. Is this normal? can i fix it?

Other than that, i love all 5 days ive had this car. I just get annoyed sometimes because the engine begs me to push it, but i really dont feel safe. I havent been over 220 km/h (~135mph) in the car because thats all my winter tires are rated for. Im planning on getting new wheels and tires (18x8.5 front, 9.5 rear, with 235 or 245 front, 255 rear, hoping the more square setup will help the understeer and breaking)

Hopefully some of you track guru's can give me a little insight. I really want to take this car around the 'ring before i head back to the land of 24/7 (haha, america) but i want to make sure both Simona and I are ready to tackle it.

*Disclaimer* I have 1 autocross under my belt as far as racing experience goes (and that was in a 89 honda crx 4 years ago). This is the newest, fastest, everythingest car ive owned, so im definatly not used to it. It is quite possible, no, probable that i have no idea what i am talking about, so please forgive me.

Thanks!

[Augenbrauezug]

Originally Posted by ezeedee

i have an 08 135, all stock save H&R Sport Springs and an aftermarket muffler. The car seems very bouncy when driving at speed. I live in germany, so i spend a lot of time over 150km/h (~90mph), and it seems like every bump i hit just tosses the car around in my lane. Is there anything i can do to fix this? aero, tires, shocks? or is this just the nature of the beast?

also, everywhere i read that has an article about this car raves about the amazing brakes, but i dont think they are all that great. I may or may not have OEM pads (20k miles on the car, not sure how long the OE's last, but they guy i bought it from didnt seem like the type to change them out early, but i forgot to ask.) But it seems like i can only do 50% braking effort before the car starts to get really light in the booty, and i feel like if i push anymore, i will do an impromptu u-turn. Is this normal? can i fix it?

Other than that, i love all 5 days ive had this car. I just get annoyed sometimes because the engine begs me to push it, but i really dont feel safe. I havent been over 220 km/h (~135mph) in the car because thats all my winter tires are rated for. Im planning on getting new wheels and tires (18x8.5 front, 9.5 rear, with 235 or 245 front, 255 rear, hoping the more square setup will help the understeer and breaking)

Hopefully some of you track guru's can give me a little insight. I really want to take this car around the 'ring before i head back to the land of 24/7 (haha, america) but i want to make sure both Simona and I are ready to tackle it.

*Disclaimer* I have 1 autocross under my belt as far as racing experience goes (and that was in a 89 honda crx 4 years ago). This is the newest, fastest, everythingest car ive owned, so im definatly not used to it. It is quite possible, no, probable that i have no idea what i am talking about, so please forgive me.

Thanks!

i have an 08 135, all stock save H&R Sport Springs and an aftermarket muffler. The car seems very bouncy when driving at speed. I live in germany, so i spend a lot of time over 150km/h (~90mph), and it seems like every bump i hit just tosses the car around in my lane. Is there anything i can do to fix this? aero, tires, shocks? or is this just the nature of the beast?

I am no 'track guru' but I'll help where I can. This is not the nature of the beast, but my car is bone stock. From my Japanese car days I remember it being a problem when people would replace the springs without doing any other suspension work, providing a bouncy ride that you speak of. Coilovers should solve this problem, but if you don't mind stock ride height it'd be cheaper to replace to OEMS.

Other than that, i love all 5 days ive had this car. I just get annoyed sometimes because the engine begs me to push it, but i really dont feel safe. I havent been over 220 km/h (~135mph) in the car because thats all my winter tires are rated for. Im planning on getting new wheels and tires (18x8.5 front, 9.5 rear, with 235 or 245 front, 255 rear, hoping the more square setup will help the understeer and breaking)

I'm not surprised, this little car is easy to fall in love with! It's smart that you don't push the car beyond the recommended speed of the tires, swap them out when you can and you should feel more comfortable. Here in the states it's difficult to get a car to such speeds while still being safe. That said I've pushed those speeds once or twice when conditions allowed and I never felt unsafe, this was on summer tires though. I'm pretty sure 245s up front will be difficult, if not impossible to fit, 235s might be doable.

also, everywhere i read that has an article about this car raves about the amazing brakes, but i dont think they are all that great. I may or may not have OEM pads (20k miles on the car, not sure how long the OE's last, but they guy i bought it from didnt seem like the type to change them out early, but i forgot to ask.) But it seems like i can only do 50% braking effort before the car starts to get really light in the booty, and i feel like if i push anymore, i will do an impromptu u-turn. Is this normal? can i fix it?

Oops, I got your post out of order, no big deal. The brakes are not great, but they do have really good initial bite. If your breaks don't have good initial bite they are probably not OEM. Does the braking feel adequate? You should never feel as though the brakes are 'weak', and it certainly isn't normal for the car to feel as though it will spin from stabbing the brakes. The car should definitely feel planted. Sounds like this might also be related to your bouncy suspension.

Good luck. Hopefully someone can help you a bit more with the suspension.

[chachacha28]

Originally Posted by Augenbrauezug

I am no 'track guru' but I'll help where I can. This is not the nature of the beast, but my car is bone stock. From my Japanese car days I remember it being a problem when people would replace the springs without doing any other suspension work, providing a bouncy ride that you speak of. Coilovers should solve this problem, but if you don't mind stock ride height it'd be cheaper to replace to OEMS.

Thanks, I guess coilovers are in my future, if they have a chance at fixing the problem. I had a couple suspension mods planned anyway (camber plates, m3 CA's/sway bar), so i guess coilovers are the natural evolution of things.

Originally Posted by Augenbrauezug

I'm not surprised, this little car is easy to fall in love with! It's smart that you don't push the car beyond the recommended speed of the tires, swap them out when you can and you should feel more comfortable. Here in the states it's difficult to get a car to such speeds while still being safe. That said I've pushed those speeds once or twice when conditions allowed and I never felt unsafe, this was on summer tires though. I'm pretty sure 245s up front will be difficult, if not impossible to fit, 235s might be doable.

I think i have to keep my winters until march, but im not sure. It still drops below freezing every once in a while, so i will leave them on a bit longer. My summer tires are y-rated... so once those go on As for the wheel fitment, I shot Apex an email yesterday to see if they had any suggestions on wheel/tire fitment, and what if any modifications i would have to do to make them fit (see above).

Originally Posted by Augenbrauezug

Oops, I got your post out of order, no big deal. The brakes are not great, but they do have really good initial bite. If your breaks don't have good initial bite they are probably not OEM. Does the braking feel adequate? You should never feel as though the brakes are 'weak', and it certainly isn't normal for the car to feel as though it will spin from stabbing the brakes. The car should definitely feel planted. Sounds like this might also be related to your bouncy suspension.

Good luck. Hopefully someone can help you a bit more with the suspension.

There was really just one time they bugged me out, I was driving down the road (no speed limit road, in between towns) and i passed a tractor going like 50kmh, and got bit by the bug and decided to run it through the gears, i was going probably 120kmh, and realized that my turn was coming up a bit sooner than i realized, so i got on the brakes and started slowly increasing pressure. I dont know if it was just a rough spot in the road or what, but i felt like my front bumper was two hairs off the road, and my rear tires were hardly touching, then it just got loose for a second, so i let off the brakes a tiny bit. I got about 50m away and really didnt think i could safely make the turn, so i just went straight and did a u-turn when i had a chance. It really wasnt that big of a deal this time, but if for some reason i would have had to make that turn (pedestrian, inop vehicle, whatever) it definatly could have been very nasty.

Now that I think about it, im no suspension expert, but if i got coilovers with seperate rebound/compression, would i be able to tune the dive out and make the rears feel more planted?

Thanks for your help.

[Augenbrauezug]

Originally Posted by ezeedee

Now that I think about it, im no suspension expert, but if i got coilovers with seperate rebound/compression, would i be able to tune the dive out and make the rears feel more planted?

Thanks for your help.

Some coilovers will allow you to adjust dampening rate, while others will not. I am far from a suspension expert, and I would post that specific question in the suspension forum. In fact you may try re-posting your entire thread in teh suspension sub-forum for the mere fact that it is frequented more often and you will get more responses.

I understand now what you are saying about the brakes making you do an unexpected u-turn, and your reasoning for continuing strait. It still does not seem normal to me. While I've never had to do the same thing in my 1er, I have made a 'emergency' maneuver like this in my 335 and it had no issue, the 1er should be the same.

The coilovers will be a huge change! The spring rates will match the dampening rates of the coilovers and your ride will feel very firm, and depending on which coilovers you opt for you will be able to adjust them in a slue of different ways. I am sorry I cannot really advice as to a brand to buy, I've never modified any of my Bimmers. The KX v2s seem to be popular around here though.

Good luck!

[GaryS]

You need better shocks. Try Koni Sports. They are adjustable, but I don't know the right setting to match H&R Sport Springs. Call HPA Shop and ask. http://www.hpashop.com/product.sc?pr...categoryId=170

If body roll is also a problem, try an M3 front swaybar.

...adding: After you add better shocks or coilovers, your car's rear will probably still bounce over bigger bumps. To cure that, you need M3 rear subframe bushings. It is a difficult install, but adds a ton of stability and very sporty feel.

[RimasRS]

Leave your stock wheel sizes (just lighter ones would be upgrade, eg Breytons), get non run flats. And look for Performance suspension. You will be happy. Wider wheels will not help wider tires is good.

[chachacha28]

Originally Posted by RimasRS

Leave your stock wheel sizes (just lighter ones would be upgrade, eg Breytons), get non run flats. And look for Performance suspension. You will be happy. Wider wheels will not help wider tires is good.

wouldn't wider wheels allow for better fitment of wider tires? i dont want to run 235+ tires on stock front wheels.

[Bimmer-Bob]

You don't need coilovers but you need better dampers.

If you replace stock springs but not dampers, you're gonna get bounce. Essentially the stiffer springs are more than the stock dampers can handle. A lot of people here actually think that the car is underdamped in stock form, so stiffer springs will only exacerbate the problem.

Coils are nice because it's one-stop shopping and you end up with matched springs and dampers. But if you already have the springs and you're happy with the ride height, I would save your money and just get new shocks and struts. Konis are a pretty safe bet.

[Augenbrauezug]

Originally Posted by Bimmer-Bob

You don't need coilovers but you need better dampers.

If you replace stock springs but not dampers, you're gonna get bounce. Essentially the stiffer springs are more than the stock dampers can handle. A lot of people here actually think that the car is underdamped in stock form, so stiffer springs will only exacerbate the problem.

Coils are nice because it's one-stop shopping and you end up with matched springs and dampers. But if you already have the springs and you're happy with the ride height, I would save your money and just get new shocks and struts. Konis are a pretty safe bet.

+1

Was just trying to save him the hassle of matching spring rates to dampers. This is best way to go.

[chachacha28]

i might buy the yellows for now, but i think down the road, i will upgrade to coils, probably the KW V3's. If nothing else, just for the ability to adjust ride height to fine-tune wheel fitment.

[RimasRS]

Originally Posted by ezeedee

wouldn't wider wheels allow for better fitment of wider tires? i dont want to run 235+ tires on stock front wheels.

Well 7.5 inch rim in the front for sure will work good with 235/35 tire and 8.5 rear with 265/30 if you want 9.5 for them you have to mount at least 275 I think our suspension components is to weak for that, and wide wheels will drag your car to sides you will have to hold your steering wheel tough.

For BMW performance suspension you will pay +- same price like for KW3 or less. And you will get OEM calibrated suspension with sway bar.

[1-2MANY]

I had the exact same concerns as you about the car being too bouncy. Recently I installed: m3 front control arms, m3 front sways, kw v1 coilovers, and got rid of the run flats for better tires. Made a huge difference! I guess if you're going to be tracking it, maybe kw v2 or 3? Good luck!

[chachacha28]

Just thought id update, I have kw V3's and vorshlag camber plates in the mail!

[TJ bmw135i]

Will the 235/35 and 265/30 fit without rubbing on the 264 18" rims? or do you need to increase the camber?

[RimasRS]

There was post that even 235/40 265/35 fits without rubbing on stock wheels, butt I would go with 35 30 to be on the safe side and tyres will look better, will be closer to oem tyre sidewall