What part should I get to improve the handling?

[JWC]

Forgive my laziness... Just want to start a new thread here to ask some comment. I am going to build my car for track, and just ordered KW CS. wondering what other part should I get to improve the handling. I just read the other thread saying E93 front sway is not necessary. So what part should I get, and what shouldn't? Thanks for all your words!

[chachacha28]

rear subframe bushings

[int2str]

Camber plates

A 135i with just lowering springs and camber plates came in 4th out of 59 participants at our last autocross.

Camber plates make for the biggest handling increase. Rear subframe bushings make the car feel much better, but not necessarily go any faster around a bend...

We had a recent discussion here on the E93 front sway bar. It may be a bit stiff and introduce some unwanted understeer. Some like it, others don't. Maybe compromise and get the E92 M3 front bar instead? Or hold off alltogether and wait until you've driven your car with camber plates to see if you still need the sway bar.

[GaryS]

You didn't say what your budget is. If you did, I would probably not answer because I was unhappy with my car until I upgraded everything. So my opinion is that you should do the entire M3 conversion including E92 M3 front swaybar (not E93). Also camber plates, rear toe arms and LSD.

[Dackelone]

tires - good ones.

[fourtailpipes]

KW clubsports come with camber plates already, so he's covered there. they're also pretty stiff, so i'd say upgraded bushings all around and sticky tires. if using square tires, go with the front swaybar too.

[pixelblue]

lets not forget losing weight anywhere you can. start with light weight wheels and tires, battery and seats to name a few. of course replace all fluids, filters and pads with the highest grade stuff

[JWC]

yeah. KW Clubsports came with camber plate already. And I think subframe bushing all around and LSD, maybe Sway in the front?
I am still looking for wheel though. Went to track last weekend with my 19 Advan RZ, feel like the wheel is too big. I don't know what else to get expect of Apex.
I have Ferodo 2500 pads with Endless 600 brake fluid. Will run AD08 or RS3 most of the time.

[JWC]

Originally Posted by GaryS

You didn't say what your budget is. If you did, I would probably not answer because I was unhappy with my car until I upgraded everything. So my opinion is that you should do the entire M3 conversion including E92 M3 front swaybar (not E93). Also camber plates, rear toe arms and LSD.

What is included for the M3 conversion? Do I still need it if I have KW CS? And why not E93 sway instead of E92? Definitely need LSD.

[yandy]

If this will be a serious track car get an LSD

[GaryS]

Originally Posted by SFN55

What is included for the M3 conversion? Do I still need it if I have KW CS? And why not E93 sway instead of E92? Definitely need LSD.

Yes, you still need M3 conversion with KW CS. Complete M3 conversion kit is at this link.

http://www.hpashop.com/BMW-E8X-E9X-t...conversion.htm

There are a lot of options listed. I personally recommend the E92 M3 front swaybar and keep your stock 135i rear swaybar because Dinan recommended them to me and said stiffer swaybars than those would hurt more than they help. Other people have different opinions, so you'll have to decide.

Otherwise, I recommend every option listed at the link.

[fourtailpipes]

if you do get a mechanical LSD, get the rear swaybar too. those two travel together, like salt and pepper. some of the m3 suspension links are more justified than others. really what you need is the stiffer bushings they come with. the front control arms and tension rods will also increase track and thus improve front camber, so that's useful, but the M3 rear camber arm, for example, would be a bad idea. it won't work with your clubsports (assuming you ordered the e82 non-M clubsports). the M3 rear camber arm is only compatible with coilovers made for the M3 and 1M.

[int2str]

Originally Posted by fourtailpipes

if you do get a mechanical LSD, get the rear swaybar too. those two travel together, like salt and pepper.

Can you expand on this a bit please?
Any references?

[fourtailpipes]

Originally Posted by int2str

Can you expand on this a bit please?
Any references?

rear swaybar will "stiffen" the rear end by moving more weight to the outside tire, and less weight to the inside tire than if you were using a softer (oem) rear swaybar. without a limited slip differential, the stock "e-diff" will send power via the path of least resistance (meaning the inside rear tire, which has less grip). the result will be slipping of the inside rear tire, which will then be (poorly) corrected by the "e-diff" applying the brake to the inside rear tire to move more power back to the loaded (outside) rear tire. with a limited slip differential, the power moves via the path of MOST resistance, so the increased proportional load to the outside tire can be effectively managed by the differential. put simply, a stiffer rear swaybar in a car with a stock differential will decrease understeer (or increase oversteer), HOWEVER, will cost you in your ability to put power down on track out. when paired with a mechanical limited slip, a stiffer rear swaybar will have this same effect of reducing understeer without the cost of corner exit speeds. you dont necessarily have to do them together, but the labor for the swaybar will be just about free if you're already in there getting the diff replaced, so it's a pretty good time to do the two together.

[GaryS]

Originally Posted by int2str

Can you expand on this a bit please?
Any references?

This is something that we've been arguing about for four years and are never going to stop arguing about.

[fourtailpipes]

Originally Posted by GaryS

This is something that we've been arguing about for four years and are never going to stop arguing about.

i wasn't aware that there was ever an argument... this is a philosophy that has been pretty universally applied across most modern bmw track applications (and other makers too of course). is there a vaild train of thought that challenges this relationship between rear swaybar and differential?

[int2str]

Originally Posted by fourtailpipes

with a limited slip differential, the power moves via the path of MOST resistance, so the increased proportional load to the outside tire can be effectively managed by the differential.

This is an often cited misconception around here. A mechanical differential (clutch based or otherwise) limits the maximum amount that wheel speeds can differ between the inside and outside tires. In other words, even with a mechanical differential, most power will still go to the path of LEAST resistance. It's just that a limited slip guarantees that SOME power will also go to the wheel that has more traction.

Still would like to understand the rear-swaybar/LSD interaction better.

[pixelblue]

Originally Posted by fourtailpipes

rear swaybar will "stiffen" the rear end by moving more weight to the outside tire, and less weight to the inside tire than if you were using a softer (oem) rear swaybar. without a limited slip differential, the stock "e-diff" will send power via the path of least resistance (meaning the inside rear tire, which has less grip). the result will be slipping of the inside rear tire, which will then be (poorly) corrected by the "e-diff" applying the brake to the inside rear tire to move more power back to the loaded (outside) rear tire. with a limited slip differential, the power moves via the path of MOST resistance, so the increased proportional load to the outside tire can be effectively managed by the differential. put simply, a stiffer rear swaybar in a car with a stock differential will decrease understeer (or increase oversteer), HOWEVER, will cost you in your ability to put power down on track out. when paired with a mechanical limited slip, a stiffer rear swaybar will have this same effect of reducing understeer without the cost of corner exit speeds. you dont necessarily have to do them together, but the labor for the swaybar will be just about free if you're already in there getting the diff replaced, so it's a pretty good time to do the two together.

+1

[fourtailpipes]

Originally Posted by int2str

This is an often cited misconception around here. A mechanical differential (clutch based or otherwise) limits the maximum amount that wheel speeds can differ between the inside and outside tires. In other words, even with a mechanical differential, most power will still go to the path of LEAST resistance. It's just that a limited slip guarantees that SOME power will also go to the wheel that has more traction.

Still would like to understand the rear-swaybar/LSD interaction better.

this is true (in shades of grey). the least resistance/most resistance is just for illustration purposes. there are many different kinds of mechanical differentials collectively referred to as "limited slip", each having tendancies if its own, but one thing they have in common is that they are able to send far more power to the loaded tire than an open differential, and in much shorter order than the roundabout method taken by the e-diff. regardless of which type of limited slip differential you're referring to, the dynamic relationship between the swaybar's proportionate loading of the rear tires to the differential's ability to cope with this greater "differential" in proportionate loading remains. a stiffer rear swaybar will reduce the droop travel of the unloaded tire. this droop travel is something built in by BMW to aid the e-diff. reducing this droop travel will make the shortcomings of the e-diff far more apparent.

[GaryS]

Originally Posted by fourtailpipes

i wasn't aware that there was ever an argument... this is a philosophy that has been pretty universally applied across most modern bmw track applications (and other makers too of course). is there a vaild train of thought that challenges this relationship between rear swaybar and differential?

Sorry, I wasn't clear. There is no argument about the relationship between swaybar and diff. The argument is whether a stiffer rear swaybar is better on 135i's. Some people say yes, some people say it's only better on 135i's that have LSDs, others say the stock swaybar is the right size with or without LSD. There are lots of very interesting and entertaining threads, also at e90post.

[fourtailpipes]

Originally Posted by GaryS

Sorry, I wasn't clear. There is no argument about the relationship between swaybar and diff. The argument is whether a stiffer rear swaybar is better on 135i's. Some people say yes, some people say it's only better on 135i's that have LSDs, others say the stock swaybar is the right size with or without LSD. There are lots of very interesting and entertaining threads, also at e90post.

i see what you mean. very true. even with an LSD, an upgraded rear swaybar is not always necessary. my e46 m3 (with standard M LSD) was best set up with no rear swaybar whatsoever. roll reduction was handled by way of a massive front bar, and the handling was made neutral by way of springrates, damper settings, alignment specs, and huge square tires. this is actually quite a common setup among e46 m3 track cars, but the e46 m3 is a car that can easily be adjusted to reduce understeer (negative camber is very easily attainable, and the widebody accommodates very wide front tires). the e82 tends to be a little tricky in the front camber department and as we all know doesnt have much room for front tires, so understeer may need to be dialed out wherever possible, like with a stiffer rear bar.

[pixelblue]

it all depends on what you prefer and how you drive. a stiffer rear end with an lsd would be loads of drifting fun. personally I prefer a small amount of movement in the car.