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04-23-2014, 08:40 PM | #1 |
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Need help on next track modification
I just started the 2014 lapping season this evening in Mirabel, Quebec, Canada. Was eager to test my new endurance brake pads (Carbotech XP10), and Quaife LSD. Temperature was cold (8 degrees Celcius/46 degrees Fahrenheit). I am quite happy with the braking performance, with no or very little fade towards the end of my session. After four 20 minute sessions, the front pads already are thinner than the rear pads. Im a bit surprised by that. I now understand why people get a more robust pad in the front than in the rear (XP12f and XP10r).
I have the M3 front control arms, and Camber plates set to max, and my alignment is -3.2. I have RE-11 tires (225/40R18f and 255/35R18r), maintain my hot pressure below 40PSI, but still get outside edge wear and some understeer. My RE-11 front tire outside edge tread is almost gone (looks like slicks). Maybe the sidewalls of this tire is too soft, even with correct pressure in them. I need advice on next modification on my 135i to increase my cornering turn-in speeds. Turn out speed is much better with my LSD, but still overwhelming my rear tires (could use a little more traction). I consider myself an intermediate/advanced driver. To those who track their 135i on stock suspension, how much does the E92/M3 and E93/M3 Front Sway Bar help with reduction of understeer? I wonder what the next logical and affordable modification I should invest in to reduce understeer even more, without sacrificing rear traction. Budget is $1000-$1500. Scenario #1 : Get E93/M3 Front Sway bar. Evaluate results on the track, and move on to the next logical upgrade if required (Swift springs and Koni sport struts). Scenario #2 - On my stock style 261 RIMs, get wider/stickier Extreme Performance tires in the front (235/40R18), or narrower in back (245/35R18, to approach square setup. I would hate to do that because I want best traction possible to have my Quaife LSD (with 3.46 final drive ratio) put the power down. This is already a challenge in second gear with RE-11 tires. Scenario #3 - On my stock style 261 RIMs, get R-compound/streetable tires (front = 225/40R18, and rear=245/35R18, or 255/35R18). I wonder if stickier tires and stiffer sidewalls would help my situation. Scenario #4 - Get a dedicated set of 17" style 68 M RIMS (7.5x17 and 8.5x17) shod with R-compound 225/45R17f and 255/40R17r. Keep my my stock style 261 RIMs for street use, or sell them altogether as I use the car mainly for lapping events (70%) and street (30%). Besides the major advantage of lighter RIMS and reduced unsprung weight, I wonder if this choice would result in better or worse traction than scenario #3. Open to your suggestions. Thanks for your help!
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2011 X3 35i with M pack + 2011 135i w/6SPMT | 255 square tire setup | Quaife 3.46 LSD | Diff lock down bracket | Bilstein B8+Swift SpecR springs+H&R FSB | CDV delete | BMS Oil Tstat bypass | ER FMIC & CP | N54Tuning DP | GC Street Camber Plates | M3 FCA +guide rods+RSFB's+Tranny mounts | Manzo toe arms | Cobb Stg2 agressive tune | Hawk DTC70 brake pads | RB SS brake pistons | Goodridge SS brake lines | Custom brake cooling ducts
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04-23-2014, 08:59 PM | #2 |
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Skip the E9x sway bar and get a Eibach or something similar. I run a 28mm solid sway bar...
You have enough camber to negate any negative effects from the sway bar, although I'm surprised you can only get -3.2* IMO, if you really want to help with increase turn-in you should look at setting your alignment with either 0 toe, or a bit of toe out. Obviously some toe-out would be better...but will increase the tire wear on the inner tire. IMO, in the end you're going to need more tire up front. But IMO some alignment tweaks and a big front bar should help response. |
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04-23-2014, 09:01 PM | #3 |
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Lighter and wider wheels will help you on all fronts. The stock suspension will be able to resist their inertia better in the corners, and you'll get more grip and better acceleration out of them.
The sway bars might help your wear a bit, but I lean towards the traditional approach which is to do sway bars last in suspension upgrades to help fine tune the handling balance you want. |
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04-23-2014, 09:24 PM | #4 | |
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Your front tires are wearing their outside edges because your car is rolling too much and even lots of static camber is not enough to keep the outside edges off the pavement. That argues for some combination of stiffer springs or bars. Your understeer indicates too much grip at the back relative to the front. That argues for bigger front tires or smaller rear ones. Realistically you are limited as to how big you can go up front. On 261 wheels that is 225 if you want to stay within the suggested widths for both 7.5" and 8.5" wheel widths. The fact is you can't have it all so you have to decide what is more important - neutral handling or rear grip. Stickier tires for the track are another option that would help all around. Ideally an actual track tire. Good options are painfully limited though. Carl at Perry Performance would suggest Nitto NT01. If you are on OE wheels, this suggests you need a dual duty tire though, so the RE-11 or Direzza ZII or similar are probably better choices. Recalibrate your thinking - a car powerful enough that you need to modulate the throttle at corner exit as opposed to mash it is really part of the fun of having a powerful car. Accept that you are traction limited on corner exit. Really, this is a good thing. Embrace that, and a square tire setup will help you quite a bit. Probably your next step should be coilovers, then bars as required. Of course the big front bar experiment is fairly cheap to try now. Remember though, a bar is meant to be a fine tuning tool and it won't really solve the fundamental problem that you have too much rear grip to actually produce balanced handling. Ever been to Shannonville? For an alternate view and to compare notes, consider dropping by on May 4th, Fabi track. Or if you are interested in signing up for the lapping that day send me a PM and I will provide the details. |
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04-24-2014, 09:08 PM | #5 |
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I agree with fe1x above. Since you are wearing the outside edge of the front tires it seems to indicate part of the problem. I guess your car just has too much body roll in corners and because of the front McPherson strut suspension you don't have enough static front camber to compensate. I think it may be time to address the suspension by getting some firmer springs and dampers. Adding a firmer front sway bar will be a big help in reducing the body roll so it seems a logical mod. Once you do suspension upgrades and wider rubber, then as a final step you can consider upgrading the rear sway bar if you still have an issue with understeer.
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04-24-2014, 09:34 PM | #6 |
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Kyle, James, and John: Thanks for your input! Your arguments make a lot of sense. I learned a lot from them.
Looks like I will be adding a stiffer Front Sway Bar in the near term, and stiffer springs and better dampers in the longer term (2015) due to limited budget. The LSD has made a dent in my 2014 budget, and consumables are not negligible either (tires and brake pads). One more question - do you think that soft sidewalls of the RE-11's might contribute to the rolling and outside edge wear that Im getting? Would the Dunlop Direzza ZII tires be any better on stock style 261 RIMS (7.5x18f & 8.5x18r which weight 26Lbs)? Not ready to buy aftermarket wheels yet, unless I find used ones that are worthwhile (wider, correct offset, and lighter than the 261's). I did come across some old school style 68 (7.5x17f & 8.5x17r 20Lbs) for $350CAD, but would face the same challenge fitting wider rubber.
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2011 X3 35i with M pack + 2011 135i w/6SPMT | 255 square tire setup | Quaife 3.46 LSD | Diff lock down bracket | Bilstein B8+Swift SpecR springs+H&R FSB | CDV delete | BMS Oil Tstat bypass | ER FMIC & CP | N54Tuning DP | GC Street Camber Plates | M3 FCA +guide rods+RSFB's+Tranny mounts | Manzo toe arms | Cobb Stg2 agressive tune | Hawk DTC70 brake pads | RB SS brake pistons | Goodridge SS brake lines | Custom brake cooling ducts
Last edited by dcaron9999; 04-24-2014 at 10:23 PM.. |
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04-24-2014, 09:38 PM | #7 | |
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If I ever get dedicated wheels, reducing unsprung weight is on top of my list. The upgraded springs & dampers will unfortunately have to be postponed until next year due to budget.
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2011 X3 35i with M pack + 2011 135i w/6SPMT | 255 square tire setup | Quaife 3.46 LSD | Diff lock down bracket | Bilstein B8+Swift SpecR springs+H&R FSB | CDV delete | BMS Oil Tstat bypass | ER FMIC & CP | N54Tuning DP | GC Street Camber Plates | M3 FCA +guide rods+RSFB's+Tranny mounts | Manzo toe arms | Cobb Stg2 agressive tune | Hawk DTC70 brake pads | RB SS brake pistons | Goodridge SS brake lines | Custom brake cooling ducts
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04-24-2014, 09:42 PM | #8 | |
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Wider tires up front means aftermarket rims, which is not in my budget this year. Will keep your advice in mind during my next alignment. Will probably go for a stiffer FSB as well.
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2011 X3 35i with M pack + 2011 135i w/6SPMT | 255 square tire setup | Quaife 3.46 LSD | Diff lock down bracket | Bilstein B8+Swift SpecR springs+H&R FSB | CDV delete | BMS Oil Tstat bypass | ER FMIC & CP | N54Tuning DP | GC Street Camber Plates | M3 FCA +guide rods+RSFB's+Tranny mounts | Manzo toe arms | Cobb Stg2 agressive tune | Hawk DTC70 brake pads | RB SS brake pistons | Goodridge SS brake lines | Custom brake cooling ducts
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04-24-2014, 10:51 PM | #9 |
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Another (free) solution to think about is driving inputs. Shocking, I know!
I have almost always tracked cars with street suspensions (including the 1er). Stiff suspensions let you get away with sharper inputs because they don't allow as much weight transfer. But if you do the same with softer suspension, the extra body roll will create the positive camber that hinders your grip and overworks your outside tread. So yes, you could try stiffer suspension and improve tire wear that way (not cheap). Or, you could try modifying your driving inputs to be extremely smooth to minimize the weight transfer and improve your tire wear that way (free). Remember: "He who turns the least, wins." And none of the above means you aren't already smooth (impossible to say without riding with you), but we all can almost always be smoother. If there's anyone at your track days driving fast on a street suspension, I'd highly recommend chatting with them, following them for a few laps, or riding with them if they'll let you tag along for a session. |
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04-25-2014, 11:02 AM | #10 |
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So, you spent $1,400 on a diff before having dedicated wheels and rubber???
That seems backwards some. But I say that as I prepared to take my 135 on track first time. I have taken my 1M on track and have taken may others on track (e30,e36,e46,etc).
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04-25-2014, 11:57 AM | #11 |
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Take a look at me driving the Z4M.
Basically no camber, big front bar, and 235/265 Hankook RS3s. Listen to my throttle inputs. IMO - Just gotta learn how to drive your certain car |
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04-25-2014, 02:18 PM | #13 | |
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I think this video is a good example: Despite being a full on race car with perfect camber and suspension settings, watch his steering inputs entering every corner. He never once jerks the wheel in any direction on entry or mid-corner, they are all progressive roll on, roll off (same with the throttle) inputs. The only sharp inputs he gives the entire lap are at corner exit as he's countering throttle oversteer. |
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04-25-2014, 02:32 PM | #14 | |
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I'll be tracking the 128i very shortly. Here is of my Z4M though...(This was pre-exhaust, so the sound isn't so great) |
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04-25-2014, 02:45 PM | #15 | |
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Would Koni sport shocks be OK on stock springs (linear)? I find the M sport linear springs (2011+ 135i) already pretty firm for our rotten roads here, and height is OK. I assume the idea is to get firmer springs like Swift or other if I want to reduce body roll ...
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2011 X3 35i with M pack + 2011 135i w/6SPMT | 255 square tire setup | Quaife 3.46 LSD | Diff lock down bracket | Bilstein B8+Swift SpecR springs+H&R FSB | CDV delete | BMS Oil Tstat bypass | ER FMIC & CP | N54Tuning DP | GC Street Camber Plates | M3 FCA +guide rods+RSFB's+Tranny mounts | Manzo toe arms | Cobb Stg2 agressive tune | Hawk DTC70 brake pads | RB SS brake pistons | Goodridge SS brake lines | Custom brake cooling ducts
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04-25-2014, 02:52 PM | #16 | |
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I have M Sport Springs off my 128i that have 18k miles on them. I don't know if they are any different than the 135i M Sport, but I can sell them to you cheap |
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04-25-2014, 02:55 PM | #17 |
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Garage List E86 Z4 M [10.00]
F15 X5 xDrive35i [9.17] F10 550i (Retired) [9.17] F25 X3 xDrive35i (R ... [9.43] E82 135is (Retired) [9.53] E85 Z4 M (Retired) [9.41] E90 328i xDrive (Re ... [9.25] E86 Z4 3.0si (Retired) [8.93] |
I didn't think RE-11's had soft sidewalls, or anything noticeably softer than Star Specs. Me personally, I would just drive car as is and wait till I can afford suspension/springs and do sways last. Toe out up front will help but will lead to increased tire wear and not sure if that's something you want to deal with for tires that are dual duty. Have you taken your temps after a few hot laps?
Yes Koni shocks would be OK on stock springs. If you think M-sport springs are pretty firm, stay away from Swift. I know people on forums say Swift springs are so great but I've spent time in a car with Swift springs and I thought they were WAY too firm for daily driving. |
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04-25-2014, 03:02 PM | #18 | |
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I will touch base with him on best options to match shock and springs, as I know the Swift Springs will drop the ride height some, but I prefer stock height ... http://hpashop.com/Koni-Sport-Strut-...ut-e82-e9x.htm
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2011 X3 35i with M pack + 2011 135i w/6SPMT | 255 square tire setup | Quaife 3.46 LSD | Diff lock down bracket | Bilstein B8+Swift SpecR springs+H&R FSB | CDV delete | BMS Oil Tstat bypass | ER FMIC & CP | N54Tuning DP | GC Street Camber Plates | M3 FCA +guide rods+RSFB's+Tranny mounts | Manzo toe arms | Cobb Stg2 agressive tune | Hawk DTC70 brake pads | RB SS brake pistons | Goodridge SS brake lines | Custom brake cooling ducts
Last edited by dcaron9999; 04-28-2014 at 09:48 PM.. |
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04-25-2014, 03:04 PM | #19 | |
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My last event at Thunderhill I rode with one of our race group members who has a turbo charged Miata and I couldn't believe the steering inputs he could get away with. But that's what you get with a 2,000 lbs. car on track suspension and r-comps. 3,400 lbs. 1er on stock suspension and RFTs (in my case)...not so much. Working on a mounting point for my GoPro that will let me catch my steering wheel in the frame too. So far I've had it too far forward mounted from the sunroof so all I see is dash. Used to be perfect in my RSX because you could see the track well, the steering wheel, and even my rear view mirror and what was coming up in it. Speaking of the RSX (also totally stock suspension), I can definitely say that typical of a FWD car, it seemed like it wanted to understeer on entry, but if you just smoothly rolled in, it would set its weight and you could drive it on rails all the way to corner exit after that. In the beemer, I get that weight set and then the RFTs run out of grip and my DSC kicks on and...my lap times weep for Star Specs. Last edited by 02rsxpilot; 04-25-2014 at 03:12 PM.. |
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04-25-2014, 03:05 PM | #20 | |
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Would shocks alone address the problem Im trying to solve though (reduce plowing and outside tire wear)?
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04-25-2014, 03:59 PM | #21 | |
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04-25-2014, 04:04 PM | #22 | |
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