[ashmostro]

As do I- was mere curiosity only, seeing as I have ASTs on the way.

Thanks regardless.

[Alpha_Onion]

Anybody have an answer to my question?

[Sparkee]

Originally Posted by Alpha_Onion

Anybody have an answer to my question?

I'll give you what I believe to be the tuner's answer. If you have understeer, you want to make the front suspension relatively more compliant than the rear so you get more front end grip. One way to do this is to install new sway bars with a a bigger ratio of stiffness in the rear bar to that of the front. Another way is stiffer springs on the rear and/or softer in the front. And you can play with air pressures in your tires.

And, obviously the opposite would be true for oversteer.

Also note that if the rear sway bar is (or rear springs are) too stiff, you can induce more tire spin coming off corners because the rear is not compliant enough, at least with non-LSD RWD cars (like mine). I was a bit worried about that with the H&R sway bar.

So, I don't think there is really any absolute answer to your question. It depends on what you are trying to achieve. If you don't really want to change the handling performance of your car other than to eliminate body roll, then a balanced upgrade might be the best.

One of the reasons I went with a whole system was to ensure that I had a matched set up that had been tuned by the suspension engineers. One would hope they did this through a bit of a trial and error process playing with different front and rear sway bar spring rates to see what worked best on the vehicle. I don't know if Eibach did that, but the sport system plus kit seems to be really good in my car - except the car is still is a little bit tight on the track.

[Alpha_Onion]

Originally Posted by Sparkee

I'll give you what I believe to be the tuner's answer...

That actually explains it pretty well. I guess what I'm trying to achieve are two things; performance and comfort, properly balanced. That means:

- Eliminating almost all body roll

- Decreasing understeer while also allowing enough traction to the rear wheels (best front/rear bias)

- Maintaining some ride comfort (not excessively thick bars)

I will already have adjustable coilovers by the time I get sway bars. They'll be more of a finishing touch to the suspension.

[Javi335]

Hi gentlemans. What size of antiroll bar do you think is best than oem but without goes to stiff so you need to install a LSD?

[Javi335]

Originally Posted by Javi335

Hi gentlemans. What size of antiroll bar do you think is best than oem but without goes to stiff so you need to install a LSD?

Maybe its my bad english fault. I try again.

I find stock bars are too soft.

but M3 are too stiff, need a LSD.

Logic must be "well, pick a number in the middle" ... but in practice it works like that? its a lineal formula?

Thx

[Bbox]

If you are installing stiffer springs or coilovers, then there's less of a need for stiffer swaybars. You're already going to get flatter cornering from the stiffer springs. So you're better off leaving the stock bars on. Don't let a business trick you into thinking you need to upgrade everything. Thicker bars usually destroy the ride quality, because they make the suspension less independent. On bumpy roads it's like driving a pickup truck with a solid axle.

[ashmostro]

Normally I'd agree but in practice my m3 bars feel a bit soft for my tastes, despite my ast coilovers.

[cwbiii]

Originally Posted by Marc Fitz

Need some advice, I have a E90 320d M Sport and looking at installing the BMW performance Chassis Kit does anyone know how much this will lower the car.

Mine dropped a bit over an inch and was a bit too low... I pushed it back up 3/8 of an inch and it is just right.

[cwbiii]

I upgraded to the "BMW performance suspension kit" quite a while ago to the tune of about $1400 plus labor (me and my son). It is a bit harsh of a ride but gives incredible feedback. Its my daily driver to the tune of about 22k miles per year. Its about twice as stiff as the sports suspension option. It rides about an inch+ lower. I brought that back up to about 3/4 of an inch and it is perfect. I seldom rub on anything. I try to avoid all the divet's in the road I can. The biggest problem with my car is rear traction.
I've upgraded to the sport wheels but it still is not enough... I'm going to try a sticky compound set of tires on my next tire change to see how much improvement that will give.

With the 335d I have so much torque that spinning the wheels is just about how hard I push the pedal down... if the electronics don't intervene. Tuning it up higher is a simple and inexpensive ECU reprogramming. A significant increase is advertised... though I should probably make a couple other changes if I plan on using it often. Larger intercooler, radiator and transmission cooling to keep up with the increased heat load.

The diesel reacts to controls slower than gasoline so auto crossing offers some new challenges in operator timing... especially braking into a tight turn and then powering out of it. It doesn't help that this car is a bit heavier than an e46. The ECU reprogramming is supposed to fix some of this sluggishness in the throttle control. When my warranty expires I may try to find out if any of this is going to add to my driving fun. Until then all I'm willing to do is dream and do research. Speaking of which I'm interested in any other 335d/x5d owners with mods and what they think of theirs.

[wantm135i]

[wantm135i]

got it all done

[ashmostro]

Looks great! How does it feel?

[GreekboyD]

Originally Posted by cwbiii

I upgraded to the "BMW performance suspension kit" quite a while ago to the tune of about $1400 plus labor (me and my son). It is a bit harsh of a ride but gives incredible feedback. Its my daily driver to the tune of about 22k miles per year. Its about twice as stiff as the sports suspension option. It rides about an inch+ lower. I brought that back up to about 3/4 of an inch and it is perfect. I seldom rub on anything. I try to avoid all the divet's in the road I can. The biggest problem with my car is rear traction.
I've upgraded to the sport wheels but it still is not enough... I'm going to try a sticky compound set of tires on my next tire change to see how much improvement that will give.

With the 335d I have so much torque that spinning the wheels is just about how hard I push the pedal down... if the electronics don't intervene. Tuning it up higher is a simple and inexpensive ECU reprogramming. A significant increase is advertised... though I should probably make a couple other changes if I plan on using it often. Larger intercooler, radiator and transmission cooling to keep up with the increased heat load.

The diesel reacts to controls slower than gasoline so auto crossing offers some new challenges in operator timing... especially braking into a tight turn and then powering out of it. It doesn't help that this car is a bit heavier than an e46. The ECU reprogramming is supposed to fix some of this sluggishness in the throttle control. When my warranty expires I may try to find out if any of this is going to add to my driving fun. Until then all I'm willing to do is dream and do research. Speaking of which I'm interested in any other 335d/x5d owners with mods and what they think of theirs.

I also own a 335d as well. Click on it in "my garage" to see the suspension mods on it.

[JPflip509]

Springs are my choice to go. I think ill do H&R

[mir-ali604]

Not sure if this question has already been answered, but couldnt find the answer on forums so here we go

I found a set of used KWv1 coilovers with about 40,000 kms on them. I was wondering how long do the KW v1 usually last in terms of mileage. The seller has it posted for $700. is this a reasonable price??

[jme93]

I've read through the whole thread, some great comments- thank you!

I have an '07 e93 335i sport with 24k miles on it as a DD. So far, I have put in a JB4 and PSS10's and replaced the bushings, dropped by about 1".

I would like to improve turn in and holding a line without stiffening it up too far- wondering what your suggestions would be for that as to sway bars or strut braces.

Also noticed at about 75mph/120kph I feel the steering is way too loose, especially under hard acceleration. My first thought was downforce but my e36&39 were stable at over 100mph.

Appreciate the advice.

[ashmostro]

Originally Posted by jme93

I've read through the whole thread, some great comments- thank you!

I have an '07 e93 335i sport with 24k miles on it as a DD. So far, I have put in a JB4 and PSS10's and replaced the bushings, dropped by about 1".

I would like to improve turn in and holding a line without stiffening it up too far- wondering what your suggestions would be for that as to sway bars or strut braces.

Also noticed at about 75mph/120kph I feel the steering is way too loose, especially under hard acceleration. My first thought was downforce but my e36&39 were stable at over 100mph.

Appreciate the advice.

Alignment / camber I bet. Get your toe back in spec to help with the stability, and set up more negative camber up front relative to rear. Whatever you set your rear to, try to get one more negative degree up front relative to that- that will help with turn in and balance.

[Alpha_Onion]

If I were to get the Eibach Pro-Kit, would I be able to keep my factory non-sport shocks?

[jjellyneck]

Originally Posted by ashmostro

Alignment / camber I bet. Get your toe back in spec to help with the stability, and set up more negative camber up front relative to rear. Whatever you set your rear to, try to get one more negative degree up front relative to that- that will help with turn in and balance.

I agree. Another set of components you might want to add are the M3 control arms and tension arms for the front suspension. It helps make the front end and steering more precise. Handling and response is better overall for me...but now I notice the mushiness of the rear suspension bushings more than before! The tighter front brought out the weaknesses of the back...or just made them more noticeable because I can drive faster inn all turns now. Ah well.

[Alpha_Onion]

Ok, disregard my above post. I've decided that I want to keep my non-sport suspension for now, but replace the front springs with ZSP springs, just to lower the front of the car a little. Will this work or do I need to get an entire ZSP kit?

[ashmostro]

Get the full set, regardless of what you get.

But I think the zsp springs aren't a big enough improvement to justify the cost and effort.