| ewright | 10-06-2005 08:17 PM |
Tire wear on the outside = not enough negative camber?
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Hey everyone,
After a couple of track events and autocrosses I was looking at my tires and it seems as if most of the wear is occuring on the outside of the tires. I was wondering whether this uneven wear is due to the fact that I am not running enough negative camber. I am currently running -2.0 on the front and -.75 on the rear. I really like the way the car handles right now, but do you think there is some more grip to be gained as well as more even wear by going to more negative settings? Thanks for any advice you may be able to offer.
Ernie
After a couple of track events and autocrosses I was looking at my tires and it seems as if most of the wear is occuring on the outside of the tires. I was wondering whether this uneven wear is due to the fact that I am not running enough negative camber. I am currently running -2.0 on the front and -.75 on the rear. I really like the way the car handles right now, but do you think there is some more grip to be gained as well as more even wear by going to more negative settings? Thanks for any advice you may be able to offer.
Ernie
| BlkWRXWag | 10-06-2005 08:37 PM |
What are your front toe settings?
| ewright | 10-06-2005 08:42 PM |
1/8th degree toe out (0 in the rear). I should also note that the uneven wear is on all four tires.
ernie
ernie
| ChrisDP | 10-06-2005 08:52 PM |
Yes, you need more camber to prevent that wear. My car uses the tires pretty evenly with stiff springs and -3.3 camber, but -2.0 won't cut it for track or autocross.
| ewright | 10-09-2005 05:36 PM |
chris,
thanks for your reply. is it common for people to run that much negative camber? -3.3 seems like a lot. do you mind sharing how much camber you are running in the rear? how abrupt is the transition from grip to slide? thanks again.
ernie
thanks for your reply. is it common for people to run that much negative camber? -3.3 seems like a lot. do you mind sharing how much camber you are running in the rear? how abrupt is the transition from grip to slide? thanks again.
ernie
| TexRex2002 | 10-09-2005 07:56 PM |
-3.3 is a tad much for a street car. also keep in mind that the more camber you add the worse the strainght line performance (accel, braking) is.
I run -1.5 camber and get wear on the inside.
you could also try increasing your tire pressure (36 - 50 psi, depending on tire) to reduce "rollover."
I run -1.5 camber and get wear on the inside.
you could also try increasing your tire pressure (36 - 50 psi, depending on tire) to reduce "rollover."
| 00Maddog | 10-09-2005 08:05 PM |
^^ tire pressure, you must be rolling the tires over a little. you shouldn't have any outside wear with negative camber. the 1/8 toe out is good to reduce inside wear from the negative camber.
| ewright | 10-09-2005 08:17 PM |
I dont think it is tire pressures as I typically run between 40 and 42 PSI hot. Moreover, there is no wear on the sidewall, the wear is really only limited to the outside half of the tread pattern.
ernie
ernie
| DrBiggly | 10-09-2005 08:36 PM |
ernie,
You would benefit from more negative camber if you are looking for more even wear and more grip in corners. Sure, braking will be a slight loss (it's not that bad) and acceleration...ha! You're in a Subaru and if you're putting less than say like 350 to the ground then likely you aren't having massive wheelspin issues due to having too much camber.
Loss of braking will be slight at best. Do the distance tests before and after to see if you're really worried and decide from there if the tradeoff is worth it. "Buttdyno" doesn't work here.
-Biggly runs camber more like ChrisDP's :)
You would benefit from more negative camber if you are looking for more even wear and more grip in corners. Sure, braking will be a slight loss (it's not that bad) and acceleration...ha! You're in a Subaru and if you're putting less than say like 350 to the ground then likely you aren't having massive wheelspin issues due to having too much camber.
Loss of braking will be slight at best. Do the distance tests before and after to see if you're really worried and decide from there if the tradeoff is worth it. "Buttdyno" doesn't work here.
-Biggly runs camber more like ChrisDP's :)
| ewright | 10-09-2005 09:42 PM |
DrBiggly,
Thanks for the advice. Can you give me an idea how much camber you are running front and rear?
Ernie:)
Thanks for the advice. Can you give me an idea how much camber you are running front and rear?
Ernie:)
| DrBiggly | 10-09-2005 10:03 PM |
On 8k/8k and 24/24 bars and Kooks at about 36psi, I'm running just shy of -4 camber front and (not currently, but want to) run about -1.0 rear. :)
-Biggly
-Biggly
| Butt Dyno | 10-09-2005 10:49 PM |
[QUOTE=DrBiggly]"Buttdyno" doesn't work here. [/quote]
:(
john
(-3.6, IIRC)
:(
john
(-3.6, IIRC)
| MattSTi | 10-09-2005 10:54 PM |
I was running -2.5/-1.5 camber for this season on JIC 7k/5k and I had a lot of extra wear on the outside shoulders. Next year I think I will bump it up to -3.5/-2.5
-matt
-matt
| eyeballs | 10-09-2005 11:01 PM |
hmmmm....i've always gotten excessive outer wear(hardly any inside wear), and have just been re-mounting the tires as they get worn. Maybe its time to get crazy with the camber at my next alignment. I had no idea people were running this much camber on the street.
| DrBiggly | 10-09-2005 11:06 PM |
[QUOTE=ButtDyno]:(
john
(-3.6, IIRC)[/QUOTE]
:lol: :lol:
-Biggly
john
(-3.6, IIRC)[/QUOTE]
:lol: :lol:
-Biggly
| DrBiggly | 10-09-2005 11:07 PM |
[QUOTE=eyeballs]hmmmm....i've always gotten excessive outer wear(hardly any inside wear), and have just been re-mounting the tires as they get worn. Maybe its time to get crazy with the camber at my next alignment. I had no idea people were running this much camber on the street.[/QUOTE]
Most folks don't run more than about -2.5 on the street really. My recommendation for a serious autox, but still daily drive car is to get camber plates and an alignment set for what you need.
For example: Street camber is a little less and perhaps a touch of toe-in (or 0 toe, whichever.) Autox camber is obviously more and will have some toe-out. :)
-Biggly
Most folks don't run more than about -2.5 on the street really. My recommendation for a serious autox, but still daily drive car is to get camber plates and an alignment set for what you need.
For example: Street camber is a little less and perhaps a touch of toe-in (or 0 toe, whichever.) Autox camber is obviously more and will have some toe-out. :)
-Biggly
| WRX_Mundi | 10-09-2005 11:34 PM |
I run a touch over 3 degrees camber and 1/4" toe out on mine and drive it on the street. But the outside shoulder on my street tires wear more from test and tune days than the insides anyway. I also recognize that the car is an autocross vehicle and am willing to live with the compromises -- I'm envious of those that can trailer their cars. :)
The real answer is to use a tire pyrometer after a test and tune type of event where you can do a decent number of runs with a short delay between. Oh, and don't overdrive them or you'll see overdriven results. Well, the Real Answer I suppose is to get Mr Consistent in the car and measure the clock times at different settings, but most of us can't do that. There's a big thread earlier that talked about proper camber settings, and if I recall correctly -2.6 - -3.3 was about the right range for most of the cars. At -4 mine was definitely too hot on the inside, even though the outsides were getting most of the wear.
Anyway, I've run up to -4 front camber and I still get most of my wear on the outside half of the tire. Heavy straight line braking will put some wear on the inside of the fronts, and the pyrometer says the insides are too hot with that much camber, but the outsides still get scrubbed more. I flip my tires on the rim about half-way through, which gives me even wear. I know someone with a similar car to mine who gets much more even tire wear, so maybe it's our surfaces, other car differences, or my driving style. I run about 1/4" toe out in front which may have some effect as well.
The real answer is to use a tire pyrometer after a test and tune type of event where you can do a decent number of runs with a short delay between. Oh, and don't overdrive them or you'll see overdriven results. Well, the Real Answer I suppose is to get Mr Consistent in the car and measure the clock times at different settings, but most of us can't do that. There's a big thread earlier that talked about proper camber settings, and if I recall correctly -2.6 - -3.3 was about the right range for most of the cars. At -4 mine was definitely too hot on the inside, even though the outsides were getting most of the wear.
Anyway, I've run up to -4 front camber and I still get most of my wear on the outside half of the tire. Heavy straight line braking will put some wear on the inside of the fronts, and the pyrometer says the insides are too hot with that much camber, but the outsides still get scrubbed more. I flip my tires on the rim about half-way through, which gives me even wear. I know someone with a similar car to mine who gets much more even tire wear, so maybe it's our surfaces, other car differences, or my driving style. I run about 1/4" toe out in front which may have some effect as well.
| DrBiggly | 10-09-2005 11:55 PM |
WRX_Mundi,
Most of the time when I see a lot of inside tire wear on a car with lots of camber, it's due to usually a combination of toe-out (which gets the inside first) and some wheelspin issues. Having an STi though, you shouldn't have too much of the latter and hopefully not enough of the former to cause that condition. So without being at a test n tune with you, I've run out of advice of what I can recommend for you. :(
-Biggly
Most of the time when I see a lot of inside tire wear on a car with lots of camber, it's due to usually a combination of toe-out (which gets the inside first) and some wheelspin issues. Having an STi though, you shouldn't have too much of the latter and hopefully not enough of the former to cause that condition. So without being at a test n tune with you, I've run out of advice of what I can recommend for you. :(
-Biggly
| ewright | 10-10-2005 12:24 AM |
thanks to everyone who has posted, I think I am going to try -3.0 in the front and -1.5 in the rear.
| Bundyboyz | 10-10-2005 09:36 AM |
I experience this when I roll the tires.... watch your air pressure as well
| dowroa | 10-10-2005 09:58 AM |
Hmmm... normally, I would not reply to posts like this. However, I have some points that are relevant to my situation I will being up:
- I ran -3.0/0 on 325/300 GC setup, and the car rotated AWESOME. Pics of my car under full corner load showed that I was a 0-camber, or for better explaination, I was using all of the tire under full load == full grip. My tire temps were completely even across the section width of the tire as well.If had LOTS of grip until you lifted the throttle which is what I want -- a neutral car. This was a front bar set to 27 and rear set to 23. It was 'loose' on higher speed autoXes, but at lower speed 'tight' courses, the car was AWESOME!
- I am running a 10K/8K setup and I started with the same camber settings -- BAD idea. I have since added camber BACK to the rear, and I am now dealing with understeer going in, and mad looseness at high speed. Why? TOO much front camber and not enough rear with cross camber issues.
I guess my point is that as you eliminate body roll and increase front spring rate, I don't understand why some people are running -4.0 degrees of camber with 12K front springs. To me, under full load, your tire is still retaining LOTS of negative camber. Unless the tire sidewall is folding under itself, I dont see the reason to run UBER camber on something that doesn't roll any longer.
Biggly -- Have you looked at the Challenge photos? Although that surface was a sealed lot which didnt generate as much lateral grip, you still were WAY negative front cambered. Is there any reason why? This is not an attack, as much as I am trying to understand the dynamics of running lots of front static camber when it seems you are just losing LOTS of contact patch as you aren't using the full section width of the tire, and seemingly generating understeer by doing so.
That is, unless you WANT to lose some front grip as you don't have enough rear grip ;)
Alas, let the camber wars begin anew on my car! Time for some rear camber plates ;)
- dow
- I ran -3.0/0 on 325/300 GC setup, and the car rotated AWESOME. Pics of my car under full corner load showed that I was a 0-camber, or for better explaination, I was using all of the tire under full load == full grip. My tire temps were completely even across the section width of the tire as well.If had LOTS of grip until you lifted the throttle which is what I want -- a neutral car. This was a front bar set to 27 and rear set to 23. It was 'loose' on higher speed autoXes, but at lower speed 'tight' courses, the car was AWESOME!
- I am running a 10K/8K setup and I started with the same camber settings -- BAD idea. I have since added camber BACK to the rear, and I am now dealing with understeer going in, and mad looseness at high speed. Why? TOO much front camber and not enough rear with cross camber issues.
I guess my point is that as you eliminate body roll and increase front spring rate, I don't understand why some people are running -4.0 degrees of camber with 12K front springs. To me, under full load, your tire is still retaining LOTS of negative camber. Unless the tire sidewall is folding under itself, I dont see the reason to run UBER camber on something that doesn't roll any longer.
Biggly -- Have you looked at the Challenge photos? Although that surface was a sealed lot which didnt generate as much lateral grip, you still were WAY negative front cambered. Is there any reason why? This is not an attack, as much as I am trying to understand the dynamics of running lots of front static camber when it seems you are just losing LOTS of contact patch as you aren't using the full section width of the tire, and seemingly generating understeer by doing so.
That is, unless you WANT to lose some front grip as you don't have enough rear grip ;)
Alas, let the camber wars begin anew on my car! Time for some rear camber plates ;)
- dow
| T-Man | 10-10-2005 01:13 PM |
[QUOTE=ewright]I dont think it is tire pressures as I typically run between 40 and 42 PSI hot. Moreover, there is no wear on the sidewall, the wear is really only limited to the outside half of the tread pattern.
ernie[/QUOTE]
You may want to consider dropping tire pressure a bit. I have had great success with around 34 psi hot.
ernie[/QUOTE]
You may want to consider dropping tire pressure a bit. I have had great success with around 34 psi hot.
| ewright | 10-10-2005 01:33 PM |
T-man,
what tires are you running?
ernie
what tires are you running?
ernie
| zzyzx | 10-10-2005 03:07 PM |
[QUOTE=dowroa]I guess my point is that as you eliminate body roll and increase front spring rate, I don't understand why some people are running -4.0 degrees of camber with 12K front springs. To me, under full load, your tire is still retaining LOTS of negative camber. Unless the tire sidewall is folding under itself, I dont see the reason to run UBER camber on something that doesn't roll any longer.[/QUOTE]
Spring rates alone do not eliminate body roll. The picture below was with 700F/900R rate springs:
[img]http://zzyzxmotorsports.com//images/intro/flsh2.jpg[/img]
Camber around -3.0F/-2.5R.
Always keep in mind that though higher spring rates reduce body roll, they do not eliminate it.
Optimal camber is also very tire specific - different tires like different amount of camber. Typical R compunds like a good deal and for street tires it depends. If anything over -3 deg. seems absurd, keep in mind that some World Challenge cars will run up to -6 or more deg. in the front.
Spring rates alone do not eliminate body roll. The picture below was with 700F/900R rate springs:
[img]http://zzyzxmotorsports.com//images/intro/flsh2.jpg[/img]
Camber around -3.0F/-2.5R.
Always keep in mind that though higher spring rates reduce body roll, they do not eliminate it.
Optimal camber is also very tire specific - different tires like different amount of camber. Typical R compunds like a good deal and for street tires it depends. If anything over -3 deg. seems absurd, keep in mind that some World Challenge cars will run up to -6 or more deg. in the front.
| ratt_finkel | 10-10-2005 05:25 PM |
I'm suprised no one has mentioned this yet. Are you over-driving the car? Pushing the car too hard, even with the worlds best suspension is going to wear the outside of the tires.
| ewright | 10-10-2005 06:16 PM |
ratt_finkel,
I dont tihnk so. When people talk about over driving a car I always picture someone who goes way too hot in the corners and is continually sliding. I am more like the slow in, fast out type
ernie:)
I dont tihnk so. When people talk about over driving a car I always picture someone who goes way too hot in the corners and is continually sliding. I am more like the slow in, fast out type
ernie:)
| DrBiggly | 10-10-2005 08:46 PM |
[QUOTE=dowroa]Biggly -- Have you looked at the Challenge photos? Although that surface was a sealed lot which didnt generate as much lateral grip, you still were WAY negative front cambered. Is there any reason why? This is not an attack, as much as I am trying to understand the dynamics of running lots of front static camber when it seems you are just losing LOTS of contact patch as you aren't using the full section width of the tire, and seemingly generating understeer by doing so.
That is, unless you WANT to lose some front grip as you don't have enough rear grip ;)
Alas, let the camber wars begin anew on my car! Time for some rear camber plates ;)
- dow[/QUOTE]
The answer to this is simpler than you think: I haven't set the car up. Different coilovers and they haven't had an alignment. I had the choice of too much negative camber up front or not enough, and I had tried the "not enough" about 3 times. I was going for the other extreme. If I can get an actual alignment sometime soon then that will be quite remedied with a reasonably measured value of camber. :)
-Biggly
That is, unless you WANT to lose some front grip as you don't have enough rear grip ;)
Alas, let the camber wars begin anew on my car! Time for some rear camber plates ;)
- dow[/QUOTE]
The answer to this is simpler than you think: I haven't set the car up. Different coilovers and they haven't had an alignment. I had the choice of too much negative camber up front or not enough, and I had tried the "not enough" about 3 times. I was going for the other extreme. If I can get an actual alignment sometime soon then that will be quite remedied with a reasonably measured value of camber. :)
-Biggly
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