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Old 05-27-2018, 07:07 PM   #1
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Optimal negative camber

Track and street. Currently running -1.5 on the front but still wearing that left outside edge quickly (clockwise track). Maybe my hot pressure is too low (36 psi) or Maybe I need to change my driving habits (drive slower, let more people pass, hahahaha. Not gonna happen!). Those of you who are running more neg camber (slotted or whatever), do you find that it affects drivability on the street or highway?
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Old 05-27-2018, 08:02 PM   #2
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Track and street. Currently running -1.5 on the front but still wearing that left outside edge quickly (clockwise track). Maybe my hot pressure is too low (36 psi) or Maybe I need to change my driving habits (drive slower, let more people pass, hahahaha. Not gonna happen!). Those of you who are running more neg camber (slotted or whatever), do you find that it affects drivability on the street or highway?
I'm right around 2.0 neg camber in front, 0 toe.
The only issue and I barely notice it, is "tramming", where you can feel the front of the car moving left/right following grooves in the road. It gets more pronounced with more neg camber.

Question on your setup:

With the H&R lowering springs and the Mantis 2 lt sump, do you ever bottom out/scrape on the underside either on the track or street (i.e. speed bumps etc...)?
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Old 05-28-2018, 12:43 AM   #3
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I have run a shade more than -2 but now run -2 on the front and drive almost exclusively on the road. Tyre wear is even. Handling is fine.
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Old 05-28-2018, 05:24 AM   #4
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I'm up to -3 in front with zero toe, and -2.5 in back with .08 degree toe in per side, I mostly drive on track, and highway driving to/from the track, I'm not wearing the inner edges too much and it doesn't give me any trouble on the street.

I think some tracks just give more wear, for example Roebling really beats up the left tires relative to the right if you are fast. Other tracks seem more even, like Sebring and Road Atlanta, and maybe that's because I am slower there
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Old 05-28-2018, 06:30 AM   #5
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i'm at 2.5F and no problems on the street. still wearing the outside faster than the inside at 34F 36R hot on nt01's at the track (i've got conti extremecontact dw that i run at factory pressure on the street).

i've invested in an inexpensive camber gauge and toe plates and am going to look into changing my alignment between street and track use (combined w softening my suspension when on the street - i've got adjustable coilovers).

first thing to determine is the max i can get out of my setup (ie, if i can only get 3 degrees of camber out of it then i will leave it there) and the other thing to confirm is how significantly toe changes with camber.

hey, camber adjustment is just a few bolts and a $100 gauge, right?
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Old 05-28-2018, 07:04 AM   #6
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One thing to keep in mind when chasing camber to eliminate outside edge tire wear is that if you get enough negative camber for track use, the car will be terrible to drive on the street. AZ986S mentioned the "tramming", or tramlining that you will feel with a lot of camber. My car does that, and if I weren't going to do track days, I'd take some camber out, and my car doesn't have as much front camber as you guys are running.

Outside edge tire wear is just a fact of life with strut suspensions. Strut type suspensions can't have camber gain, as it isn't possible with this type of design.
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Old 05-28-2018, 07:52 AM   #7
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Camber and toe together are the key. Tire temps across the face of the tire should help determine camber as well. Anything over -2 degrees is A lot of camber for the street. Zero toe or slight toe out will create a bit of wandering on the street but is what you want on track. Toe in on the rear. A split of between .5 and .25 degrees of negative camber front to rear seems to be what most are running. I'm currently at -3.25 - 1/16" toe out in the front and my tire temps are within 1 degree across the face. My rears are at 3 degrees with 1/16" toe IN on the rear and I will be reducing it to 2.75 at my next alignment since my face temps were higher on the outside than the inside. It also helps allow you to set tire temps. I run 26 degrees hot front and 28 rear - sometimes though I'll up it t 2 degrees front and rear depending on outside conditions and how quickly my tires heat up during a session.
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Old 05-28-2018, 11:16 AM   #8
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Currently I have -3.7 front and -3.2 rear. Zero toe front, 1/16" toe in at rear.

Drove LA to Vegas last month on my Toyo RR tires (UTQG = 40) and had no handling issues on the 4 hour drive (each way) to/from the race track.
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Old 05-28-2018, 02:29 PM   #9
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Quote:
Originally Posted by thstone View Post
Currently I have -3.7 front and -3.2 rear. Zero toe front, 1/16" toe in at rear.

Drove LA to Vegas last month on my Toyo RR tires (UTQG = 40) and had no handling issues on the 4 hour drive (each way) to/from the race track.
Just curious why so much camber up front? What is it based upon? Just curious because I'll be able to go more camber up front when I install my new adjustable control arms. My tire temps are nice and even and I've pretty much nailed hot pressure. So not sure why I'd go more.
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Old 05-28-2018, 03:14 PM   #10
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To determine optimal camber you use a tire pyrometer after a run, or even better by running the tire at maximum load on a skid pad for a while. If the outer side of the tread is warmer than the inner side you need more camber for optimal tire contact. After you have the camber right you check the pressure by comparing the temperature at the middle of the tread with the edges. If the center is warmest you need to reduce tire pressure and if its the other way round you need to increase it.

Optimal camber will vary from one tire brand to another and at its extreme between street tires and slicks.
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Old 05-28-2018, 04:55 PM   #11
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Originally Posted by rastta View Post
Just curious why so much camber up front? What is it based upon? Just curious because I'll be able to go more camber up front when I install my new adjustable control arms. My tire temps are nice and even and I've pretty much nailed hot pressure. So not sure why I'd go more.
Alignment isn't static. In my driving career, I have often changed the alignment as I have become faster and to work better with my particular driving technique/style.

My front camber settings are based on tire wear and temps. I drove with -3.3 in the front for quite awhile, but as I gained speed I found that the outside of the tires were once again wearing substantially faster and the tire temps were uneven. So I had the car aligned with a little bit more camber and now (at -3.7) the tire wear/temps are fairly even. This happened over about a two year period.

I want to emphasize that individual driving technique starts to play a role as a driver learns to drive better. That is why there is no single "best" or "optimum" setting that will work for everyone. Each of us turns in at a slightly different rate, adds throttle differently, etc. Also, some drivers like a loose car (tending to oversteer) while others like me, like a very neutral car. And some drivers want a little bit of understeer to give them confidence. Thus, the alignment settings that works well for you may not work well for me at all.

For example, one thing technique that I often use is to push the car into a corner at too fast of a speed and then let the car scrub speed mid-corner rather than lifting or tapping the brakes before corner entry. This takes confidence in your car handling skills because the car can feel pretty sketchy (loose) as its scrubbing speed. This technique really loads the front tires and puts then under a more severe loading as compared to another driver who slows to the proper corner speed before corner entry. There are a myriad of cornering techniques that you may or may not use as compared to other drivers and thus, the "best" alignment will vary depending on the driver and the techniques used.

With that being said, I am not saying that the technique that I use is the best or the fastest. If fact, the results suggest the opposite - if it was the best or fastest, I'd be winning a lot of races! I am just saying what works best for me right now. Later this year, I might realize that this technique is actually slower than something else and then I'll change it whatever is faster. I am continually trying new techniques to see which is fastest and over time that might mean making alignment changes to get the suspension to work best with whatever driving style I am using.

With that being said, I know some of the fastest drivers in Boxster Spec are around -4. I don't know if I'll ever need to go that high but I continually review the alignment settings to determine if a change is needed. The key is to make sure that the alignment settings maintain good tire wear/temps and provides confidence in the handling so I can push harder.
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Old 05-29-2018, 04:17 AM   #12
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I have GT3 LCAs and a race alignment on my CSS. Settings are:

Frt: -2.5 camber, -.05 toe
Rear: -2.1 camber, .2 toe

My initial thought was to use this alignment during race season, then go back to a std alignment in the fall since I use my CSS as my winter beater. That plan changed 2 yrs ago when I lost my job, so I've left the race alignment on full time. I don't drive as many miles in the winter as I used to, but my snows have not shown any excessive wear on the inside edges. I've also driven from OMA to COTA and Indy for DEs and my summer tires have not shown extra wear either. For me, the race alignment hasn't been detrimental to normal driving.
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Old 05-29-2018, 04:25 AM   #13
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Wow! Fascinating perspectives on this topic. Brings up even more questions in my mind. Since I drive my car often on the street/highway between monthly 2-day track sessions, my concern was tramlining and/or other squirrelly behavior on a trip. To increase my neg camber, I guess we’re looking at camber plates an adjustable toe links to start? I guess if I am cheap, I can slot the towers but would still need the toe links?
For heat, what type of pyrometer would be sufficient? I have a cheapo infrared gun but I question its accuracy.
Note to AZ986: Lowering has occasionally caused some mid-car belly scratching but never touches the deep sump. 911s have more of a problem with this due to the motor position.
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Old 05-29-2018, 04:52 AM   #14
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I run -2 up front, -1.9 in the back, toe is basically zip. drives fine on the street. I still wear the outside of my NT01s, so I plan to add some camber plates to try to get to 2.5 or even 3 if possible.
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Old 05-29-2018, 06:19 AM   #15
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Originally Posted by thstone View Post
Alignment isn't static. In my driving career, I have often changed the alignment as I have become faster and to work better with my particular driving technique/style.

My front camber settings are based on tire wear and temps. I drove with -3.3 in the front for quite awhile, but as I gained speed I found that the outside of the tires were once again wearing substantially faster and the tire temps were uneven. So I had the car aligned with a little bit more camber and now (at -3.7) the tire wear/temps are fairly even. This happened over about a two year period.

I want to emphasize that individual driving technique starts to play a role as a driver learns to drive better. That is why there is no single "best" or "optimum" setting that will work for everyone. Each of us turns in at a slightly different rate, adds throttle differently, etc. Also, some drivers like a loose car (tending to oversteer) while others like me, like a very neutral car. And some drivers want a little bit of understeer to give them confidence. Thus, the alignment settings that works well for you may not work well for me at all.

For example, one thing technique that I often use is to push the car into a corner at too fast of a speed and then let the car scrub speed mid-corner rather than lifting or tapping the brakes before corner entry. This takes confidence in your car handling skills because the car can feel pretty sketchy (loose) as its scrubbing speed. This technique really loads the front tires and puts then under a more severe loading as compared to another driver who slows to the proper corner speed before corner entry. There are a myriad of cornering techniques that you may or may not use as compared to other drivers and thus, the "best" alignment will vary depending on the driver and the techniques used.

With that being said, I am not saying that the technique that I use is the best or the fastest. If fact, the results suggest the opposite - if it was the best or fastest, I'd be winning a lot of races! I am just saying what works best for me right now. Later this year, I might realize that this technique is actually slower than something else and then I'll change it whatever is faster. I am continually trying new techniques to see which is fastest and over time that might mean making alignment changes to get the suspension to work best with whatever driving style I am using.

With that being said, I know some of the fastest drivers in Boxster Spec are around -4. I don't know if I'll ever need to go that high but I continually review the alignment settings to determine if a change is needed. The key is to make sure that the alignment settings maintain good tire wear/temps and provides confidence in the handling so I can push harder.
Thanks for the insight. Just like hearing from people on what they are using and how they arrived there. Now I guess I just need to drive a bit harder :-)
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Old 05-29-2018, 06:21 AM   #16
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Originally Posted by NewArt View Post
Wow! Fascinating perspectives on this topic. Brings up even more questions in my mind. Since I drive my car often on the street/highway between monthly 2-day track sessions, my concern was tramlining and/or other squirrelly behavior on a trip. To increase my neg camber, I guess we’re looking at camber plates an adjustable toe links to start? I guess if I am cheap, I can slot the towers but would still need the toe links?
For heat, what type of pyrometer would be sufficient? I have a cheapo infrared gun but I question its accuracy.
Note to AZ986: Lowering has occasionally caused some mid-car belly scratching but never touches the deep sump. 911s have more of a problem with this due to the motor position.
I've gone without adjustable LCA's but finally dropped the coin on a set of Elephant Racing LCA's for the front and adjustable toe links for the rear. I'm slotted up front with -1 degree camber plates up top. I want to have more adjustability as currently I can get the numbers I want but it's a PITA, especially in the rear.
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