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      08-02-2016, 02:03 PM   #1
E90Dave
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Sway bars

Have searched and searched... there doesn't seem to be a good consensus here -

I just put some TCK DA coilovers on my E92 M3 and the car still has a little problem with transitioning and ultimate neutrality.

The car will see 1-2 track days a season.

Are a sway bar set like H and R or Eibach worth it for our cars handling wise?

*I know a sway bar is meant to help your car under or oversteer more" but I've also noticed decreased pitch and sharper turn in and exit with sways.

But for the E92 M3 are they worth it??
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      08-02-2016, 02:13 PM   #2
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Dinan front bar is what I recommend to people. This chassis needs a bigger front bar IMO. I see no reason at all to change the rear
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      08-02-2016, 02:28 PM   #3
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Quote:
Originally Posted by Richbot View Post
Dinan front bar is what I recommend to people. This chassis needs a bigger front bar IMO. I see no reason at all to change the rear

Well I feel like the car has a bit of understeer as it sits so with the wider rear tire I'm running I feel as if I may be working the rear bar too hard.
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      08-02-2016, 08:55 PM   #4
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Rear sway bar is a pain in the arsh and honestly you won't see any difference. Front is a must if you plan to get rid of the understeer but also some negative camber will help that aswell
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      08-03-2016, 10:02 PM   #5
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A front bar will not help with understeer.

OP:
What tire configuration are you running, and how much front camber?
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      08-04-2016, 12:31 AM   #6
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Quote:
Originally Posted by WhatsADSM View Post
A front bar will not help with understeer.

OP:
What tire configuration are you running, and how much front camber?
Exactly. How would someone think that a thicker front bar beats under steer lol!?

255/35/19 and 285/35/19 Potenza RE-11

-2* camber!
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      08-04-2016, 12:48 AM   #7
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Talk to TC Kline...he doesn't run a front sway although he sells it. Reason: he's not faster with it. Also as others mentioned, it induces mid-corner understeer. Might make more sense for auto crossing where rapid transitions are more prevalent. Give him a call, his advice is quite good/unbiased and may have some advice for your particular situation, especially as you're running his suspension kit.
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      08-04-2016, 12:55 AM   #8
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Would dial negative camber to -2.5-3.0, which is what is recommended. I don't know who installed, but this suspension has to be set up exactly right. PM me for any more recommended settings from TCK.

Quote:
Originally Posted by E90Dave View Post
Exactly. How would someone think that a thicker front bar beats under steer lol!?

255/35/19 and 285/35/19 Potenza RE-11

-2* camber!
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      08-04-2016, 09:42 AM   #9
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There's room for a lot more tire up front, use it. OP, that 27" tall 285/35-19 in the rear is doing you no favors, unless you're supercharged if I were you I'd do a bunch of burnouts/donuts and kill those 285/35's and go to a 285/30 or 295/30, you get back a gearing advantage and you're not adding so much rake, and get a 9.5-10" wide wheel with a 265 or 275/30 on the front and you'll have a lot better balance without changing anything in the suspension IMO

From what I can tell after fooling with this chassis for 6 years is there are three ways to make this car quicker on a track without spending a bunch of money:

Widest front tire and wheel you can fit
Appropriate camber
More roll stiffness, especially up front.

Most coilover kits multiply the stock spring front rate in the neighborhood of 3x (stock is ~160lb/in, many c/o kits go to 500+), and typically from what I've seen only increase rear rates about 40% (750-800 if the spring is left in the stock location, with stock rate is ~550, assuming they increase the rates at all, some don't). Why? Because this car, like most cars, needs more front roll stiffness to go quickly around a racetrack. You can get that from two places, springs and the bar. If it's a street car, I definitely recommend swaybar. It keeps the suspension in its happy geometry place, livens up the turnin without much of a ride penalty at all, and still keeps you off the bumpstops for longer as you turn down to the apex.

why I recommend a front bar for track: Because you can add a bunch of front grip very easily with camber and a wider, stickier front tire, but you will start to unload the inside rear to the point our diff is semi-helpless; anyone who knows these cars well knows the diff likes to lock hard after a bit of wheelspin and throw the car sideways if you aren't careful with the throttle on corner exit. The force generated by the front bar's resistance to roll transfers in part to the inside rear. Corner exit is where the magic happens. You can be fast through the brake zone and dive into the corner hard because you have a neutral chassis in steady state but if you can't get to WOT faster than the other guy, you lose. Understeer is easy to tune out and unless you're running on a staggered wheel/tire setup with stock-ish alignment, usually a driver issue. One of the things a bar does that stiffer front springs cannot is help keep the inside rear on the ground on corner exit, and he who gets to the throttle first, wins. And critically, a front bar is tuneably between 6-8 different positions. You can quickly and easily adjust balance, a thing that is not so easy to do via spring change. Same concept behind adjustable swaybars in racecars; it's a brute-force tuning tool when conditions change and damper settings and air pressure can only help so much

I agree the bar is more critical for autocross. For 3rd gear where you spend most of your track time, not so much, and I agree getting the front rates, camber, and most critically, wide tire and wide wheel on the front are what gets this car to boogie

All of that is to say; don't knock it till you try it, the only thing that doesn't lie to you is the clock, yada
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      08-04-2016, 07:55 PM   #10
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Richbot, which sway bar do you recommend?
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      08-04-2016, 10:43 PM   #11
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Quote:
Originally Posted by E90Dave View Post
Exactly. How would someone think that a thicker front bar beats under steer lol!?

255/35/19 and 285/35/19 Potenza RE-11

-2* camber!
I would go up in width on the front as well as add a bit more camber if possible. Especially given that you have considerably more tire in the back than stock.

For reference I run stock bars, 275mm square setup, along with KW CS (which IIRC are rated at 500/800 rates). The car is very neutral with that setup. When I occasionally take it out on my regular staggered (stock spec) street tires I do feel it understeers too much for my liking.
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      08-05-2016, 08:42 AM   #12
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Quote:
Originally Posted by FogCityM3 View Post
Richbot, which sway bar do you recommend?
I echo everything Richbot has stated, and the front bar is mandatory for autox where transient response is greatly improved plus in stock class once you go to square tires (still have to run staggered stock wheel widths) and pins-out-max-negative camber up front, the car is very well balanced for a stock class car without too much understeer at all. Hence the reason one won the SCCA F-street National title last year. It is significantly faster than running a stock front bar and much better balanced in transitions. It absolutely helps plant the inside rear tire coming off elements too -- that's one of the biggest benefits as Rich mentioned.

The bar to get now is the adjustable Dinan front bar. At all costs stay away from the current RD Sport bars given all the bar failures they have experienced (fractures) recently. The Dinan bar is tubular, adjustable and well designed.
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      08-05-2016, 09:55 AM   #13
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I have an RD Sport bar that has not broken yet, but I got it in 2012ish and it's been on the car for 60k+ miles, so I don't think there's anything wrong with the older RD Sport bars, they just had some recent QC issues and these are low volume parts so one bad production run can kill the rep of a part. I wouldn't get one again and don't recommend because of lack of support compared to Dinan and QC issues. Dinan is the one I'd look at. The RD Sport bar is same diameter as Dinan but has much beefier blade at the endlink attachment which from I can tell serves absolutely no purpose. They also claim it's hollow, but if it is it's very thick wall, it was a pound or two heavier than stock

But like I said, nothing really beats putting a wide wheel and tire with good camber on the front of this car that's where the low hanging fruit is
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      08-05-2016, 10:37 AM   #14
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Great info guys, thank you!!!

I am supercharged, hence why I have the 285/35/19 out back.

I'm going to be buying some Apex ARC-8 in 19x10 squared and I'll throw some 275/30/19 all the way around.

I don't want to increase neg camber up front as it's a 90% street car. If I go up to -2.5 or -3 then I am going to get much more increased wear.

Should I do a front bar for a street car?
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      08-05-2016, 10:44 AM   #15
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Quote:
Originally Posted by E90Dave View Post
Great info guys, thank you!!!

I am supercharged, hence why I have the 285/35/19 out back.

I'm going to be buying some Apex ARC-8 in 19x10 squared and I'll throw some 275/30/19 all the way around.

I don't want to increase neg camber up front as it's a 90% street car. If I go up to -2.5 or -3 then I am going to get much more increased wear.

Should I do a front bar for a street car?
Yes you should, I recently swapped my OEM front bar to the ECS tuning front sway bar and I have been really happy. I have noticed a big difference for autocross and a noticeable difference in street driving. I run 275/35-18 NT-05s for autocross with -2.2 front camber.
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      08-05-2016, 10:52 AM   #16
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Well now I don't know which front bar to go for lol!
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      08-05-2016, 11:07 AM   #17
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Quote:
Originally Posted by E90Dave View Post
I don't want to increase neg camber up front as it's a 90% street car. If I go up to -2.5 or -3 then I am going to get much more increased wear.
That's the beauty of adjustable camber plates. Mine are set so I have -2 with slight toe in for street and -2.5 with 0 toe for the track. It's a 5 minute adjustment either when I get to the track, or I do when I swap my front pads out prior to heading to the track.
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      08-05-2016, 11:17 AM   #18
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Quote:
Originally Posted by macdude357 View Post
That's the beauty of adjustable camber plates. Mine are set so I have -2 with slight toe in for street and -2.5 with 0 toe for the track. It's a 5 minute adjustment either when I get to the track, or I do when I swap my front pads out prior to heading to the track.
Don't I need an alignment rack to get that right?

Nonetheless, I was gonna go for a square RE-11 275/30/19 setup, but theyre on backorder!

Only PSS available in that size and I don't wanna go down in grip... maybe AD08r...
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      08-05-2016, 11:18 AM   #19
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Pfft, the faster you wear out tires the faster you get to buy new ones! Win/win!
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      08-05-2016, 11:31 AM   #20
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Quote:
Originally Posted by Richbot View Post
Pfft, the faster you wear out tires the faster you get to buy new ones! Win/win!
I think I may sell these current wheels and tires and buy a set of Apex ARC-8 19x10 squared with AD08R 275/30/19 squared... hoping I wont rub in front!
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      08-05-2016, 11:36 AM   #21
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Quote:
Originally Posted by E90Dave View Post
Don't I need an alignment rack to get that right?
A good shop can set this up for you and mark the plates. I have two markings on my plates, one for track and one for street. You can also look at it this way. If you don't put camber plates on and you track often enough, you'll wear out the outsides of your tires. So getting plates can actually increase your tire life.
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      08-05-2016, 11:43 AM   #22
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Quote:
Originally Posted by macdude357 View Post
A good shop can set this up for you and mark the plates. I have two markings on my plates, one for track and one for street. You can also look at it this way. If you don't put camber plates on and you track often enough, you'll wear out the outsides of your tires. So getting plates can actually increase your tire life.
I have camber plates on the car with my TCK DA coils!
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