What are my tires telling me?
08-07-2006, 12:29 PM
#1
Rennlist Member
Thread Starter
What are my tires telling me?
I am trying to figure out why my front tires are wearing unevenly.
History: I used to use MPSCs, my last set I only got 5 days out of them because the insides wore down quickly. I had ANOTHER alignment which showed the toe was still at zero, my camber at -2.8, caster (I think) was at 3.5. I'm running with 575 pound springs on Leda coilovers, all solid bushings. There is no rubber in the front suspension at all. All we could think to do was knock the camber out to -2.1 and see what happened.
My car was also understeering in the first 1/3 of certain turns, which we attributed to too much camber (based on tire wear) and not utilizing the full tread width. After adjusting camber out to -2.1, the understeer tendencies disappeared. However, tire wear is still uneven.
Handling is great now, but these are pics of my front 1 day old (three hours on track, 40 psi hot, 225/50/16 on 7" wheels) RA1s: What's up? Any suggestions on what may be causing this tire wear? LF on left, RF on right.
History: I used to use MPSCs, my last set I only got 5 days out of them because the insides wore down quickly. I had ANOTHER alignment which showed the toe was still at zero, my camber at -2.8, caster (I think) was at 3.5. I'm running with 575 pound springs on Leda coilovers, all solid bushings. There is no rubber in the front suspension at all. All we could think to do was knock the camber out to -2.1 and see what happened.
My car was also understeering in the first 1/3 of certain turns, which we attributed to too much camber (based on tire wear) and not utilizing the full tread width. After adjusting camber out to -2.1, the understeer tendencies disappeared. However, tire wear is still uneven.
Handling is great now, but these are pics of my front 1 day old (three hours on track, 40 psi hot, 225/50/16 on 7" wheels) RA1s: What's up? Any suggestions on what may be causing this tire wear? LF on left, RF on right.
08-07-2006, 01:10 PM
#3
Race Director
Looks like toe out on the RF or way too much camber.
If the static numbers look good then check bushing for play. Something could be shifting or flexing causing a problem. Look at both the left and right front as a problem on the left could be causing the right to suffer.
If the static numbers look good then check bushing for play. Something could be shifting or flexing causing a problem. Look at both the left and right front as a problem on the left could be causing the right to suffer.
Probably time to think of getting one, huh?
08-07-2006, 01:15 PM
#5
Race Director
Well I don't belive the pyrometer will help at this point. It will just tell you the inside is too hot. Why? It won't tell that. So it will confirm the same informatin you have now.
Something is screwed up and casing excessive tire wear on that tire. Given that you have checked the camber & toe I would really look at all the attachments to ensure their is no play. Check tie-rods (both inner and outer joints) as maybe the tie rod is pulling out and causing toe out when driving.
BTW.... 3hr is alot of time on the tires. One thing you can do is to rotate the tires (sway left to right on the fronts) to even up the wear some. Won't fix the issue you have, but will cause the tire to last a bit longer. The directional arrows on the RA-1's are not needed unless you are running tread in the wet. The carcass is the same and can be run in either direction.
Something is screwed up and casing excessive tire wear on that tire. Given that you have checked the camber & toe I would really look at all the attachments to ensure their is no play. Check tie-rods (both inner and outer joints) as maybe the tie rod is pulling out and causing toe out when driving.
BTW.... 3hr is alot of time on the tires. One thing you can do is to rotate the tires (sway left to right on the fronts) to even up the wear some. Won't fix the issue you have, but will cause the tire to last a bit longer. The directional arrows on the RA-1's are not needed unless you are running tread in the wet. The carcass is the same and can be run in either direction.
08-07-2006, 01:23 PM
#6
Rennlist Member
Thread Starter
Originally Posted by M758
Looks like toe out on the RF or way too much camber.
If the static numbers look good then check bushing for play. Something could be shifting or flexing causing a problem. Look at both the left and right front as a problem on the left could be causing the right to suffer.
If the static numbers look good then check bushing for play. Something could be shifting or flexing causing a problem. Look at both the left and right front as a problem on the left could be causing the right to suffer.
Bushings are all new and solid, and everything's tight. I replaced everything on the front this past winter: steering rack, tie rods, control arms, all bushings, caster blocks, coilovers, camber plates.
I will retorque all fasteners on the front just to be sure.
I have no strut brace. Could the shock towers be flexing enough to cause a geometry change and therefore cause the inside tire to "drag" through a turn?
08-07-2006, 01:45 PM
#7
Race Director
Originally Posted by shiners780
I have no strut brace. Could the shock towers be flexing enough to cause a geometry change and therefore cause the inside tire to "drag" through a turn?
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08-07-2006, 01:52 PM
#8
Burning Brakes
What kind of weather conditions and what kind of lap times (real lap times, not "I wish" lap times) were you turning at the Nelsonring ? Absent pyrometer readings, that will tell me the most.
Sorta just looks like too much camber.
Nelson Ledges is pretty hard on the left front tire, regardless of car.
Sorta just looks like too much camber.
Nelson Ledges is pretty hard on the left front tire, regardless of car.
08-07-2006, 02:11 PM
#9
Burning Brakes
Camber or toe problem on the right side. I would vote for toe as the Toyo's like a LOT of camber (3+) where wear should be very good and fairly even accross the tread IF it's not being driven on the street.
Take a good look at the camber eccentric on the right strut and make sure it's holding its settings. These have a tendency to strip on the 944. If you're not club racing (or are willing to run "prepared" - lock it down or tack weld it in place at max camber and get some camber plates for fine adjustments. Car will handle better and one less thing to worry about.
Take a good look at the camber eccentric on the right strut and make sure it's holding its settings. These have a tendency to strip on the 944. If you're not club racing (or are willing to run "prepared" - lock it down or tack weld it in place at max camber and get some camber plates for fine adjustments. Car will handle better and one less thing to worry about.
08-07-2006, 03:01 PM
#11
Rennlist Member
Thread Starter
Thanks for the input guys.
It was my first trip to "Nelsonring," consistent 1.23/1.24 with moderate traffic, 1.22 fastest, I only timed one session while giving "fun rides". It started out around 70, and was in the low 80's in the PM.
No street driving, and this was the first day on these particular tires.
The camber eccentric nut/bolt is tight, I just checked, and I had replaced those with new this past winter when everything else was replaced. I do have camber plates, and we've been using those during alignments instead of the eccentrics.
Only 2 left handers on this track, some of the right handers are fairly fast and although the track is bumpy grip wasn't bad. Weltmeister sways 28F at soft setting/22R at medium setting. Shocks set at 15 clicks F, 10 clicks R, single adjustable Ledas.
I really appreciate the suggestions guys, please keep them coming if you think of anything else.
It was my first trip to "Nelsonring," consistent 1.23/1.24 with moderate traffic, 1.22 fastest, I only timed one session while giving "fun rides". It started out around 70, and was in the low 80's in the PM.
No street driving, and this was the first day on these particular tires.
The camber eccentric nut/bolt is tight, I just checked, and I had replaced those with new this past winter when everything else was replaced. I do have camber plates, and we've been using those during alignments instead of the eccentrics.
Only 2 left handers on this track, some of the right handers are fairly fast and although the track is bumpy grip wasn't bad. Weltmeister sways 28F at soft setting/22R at medium setting. Shocks set at 15 clicks F, 10 clicks R, single adjustable Ledas.
I really appreciate the suggestions guys, please keep them coming if you think of anything else.
08-07-2006, 03:11 PM
#12
Burning Brakes
Next questions: What does the car weigh, total hp and the typical "What does the car feel like ?"
The 'feel like' bit: If you've got a push at all, you'll eat front tires. Does the car feel neutral, pushy or loose on entry, mid-corner and exit ? Once you get to an apex, are you 'unwinding' the wheel, or are you 'opening the steering up' all the way from apex to exit ?
You may have a combination of 'pushy car' and 'too much camber in the RF'. Shock and bar settings don't translate, unless we've driven YOUR car, with your spring rates and your suspension setup. You gotta tell us what it feels like, as cars get tuned for drivers, not the other way around.
If you've got a big push in Oak Tree, it will absolutely chew the RF to shreds. Go walk around on that pavement...the grip in there is incredible.
Loose cars make tires live longer.
The 'feel like' bit: If you've got a push at all, you'll eat front tires. Does the car feel neutral, pushy or loose on entry, mid-corner and exit ? Once you get to an apex, are you 'unwinding' the wheel, or are you 'opening the steering up' all the way from apex to exit ?
You may have a combination of 'pushy car' and 'too much camber in the RF'. Shock and bar settings don't translate, unless we've driven YOUR car, with your spring rates and your suspension setup. You gotta tell us what it feels like, as cars get tuned for drivers, not the other way around.
If you've got a big push in Oak Tree, it will absolutely chew the RF to shreds. Go walk around on that pavement...the grip in there is incredible.
Loose cars make tires live longer.
08-07-2006, 04:12 PM
#13
Rennlist Member
Thread Starter
Originally Posted by Professor Helmüt Tester
Next questions: What does the car weigh, total hp and the typical "What does the car feel like ?"
The 'feel like' bit: If you've got a push at all, you'll eat front tires. Does the car feel neutral, pushy or loose on entry, mid-corner and exit ? Once you get to an apex, are you 'unwinding' the wheel, or are you 'opening the steering up' all the way from apex to exit ?
You may have a combination of 'pushy car' and 'too much camber in the RF'. Shock and bar settings don't translate, unless we've driven YOUR car, with your spring rates and your suspension setup. You gotta tell us what it feels like, as cars get tuned for drivers, not the other way around.
If you've got a big push in Oak Tree, it will absolutely chew the RF to shreds. Go walk around on that pavement...the grip in there is incredible.
Loose cars make tires live longer.
The 'feel like' bit: If you've got a push at all, you'll eat front tires. Does the car feel neutral, pushy or loose on entry, mid-corner and exit ? Once you get to an apex, are you 'unwinding' the wheel, or are you 'opening the steering up' all the way from apex to exit ?
You may have a combination of 'pushy car' and 'too much camber in the RF'. Shock and bar settings don't translate, unless we've driven YOUR car, with your spring rates and your suspension setup. You gotta tell us what it feels like, as cars get tuned for drivers, not the other way around.
If you've got a big push in Oak Tree, it will absolutely chew the RF to shreds. Go walk around on that pavement...the grip in there is incredible.
Loose cars make tires live longer.
Overall the car feels a little pushy in turn entry. Once the car gets set into a turn, it's neutral through the middle and exit. I tend to use trailbraking to assist turn initiation to help get the car rotated.
**At NL: Turn 1/2, trail braked in, neutral throughout, able to unwind from apex.
**Turn 3 slight lift to rotate then full throttle through apex, neutral, able to unwind at apex.
**Turn 4/5 (Oak Tree) brake early, car a little tight on entry, feather throttle through first apex then full through second apex, probably could have taken 4/5 much faster. Car was not very settled in Oak Tree.
**Carousel, neutral throughout while scrubbing off speed during first half (decreasing radius turn), consistent feedback from tires (humming) all the way around assists throttle steering with audible cues, able to get on throttle early toward end of turn and unwind to trackout.
**Kink, lift to rotate then full throttle once settled in right direction, car felt neutral considering the bumps.
**Turn 12, brake hard straight toward inside of turn and hugged the inside edge to setup for 13 while hard on throttle, car took 12 great.
**Turn 13, trailbraked in to get LOTS of rotation, I was kicking the back end right around then full throttle through slightly early very tight apex while unwinding. Turns 12 and 13 I was able to take lots faster with my line than everyone else in my group that were all taking the same line as eachother.
I'm not sure if the above info helps much.
What is my diagnosis? Other than pokey-peter syndrome.
08-07-2006, 04:42 PM
#14
Burning Brakes
No offense intended, but it sounds like you've got a pushy pig on your hands. There mere fact that your rears look GREAT should tell you that they're just following you around, without much to do. You really need to loosen the car up, if you want the front tires to live a while.
Other diagnostic things to check: Ever whack a corner ? You could have bent a tie-rod arm on the 'whacked' knuckle, which could be 'aligned' back to straight with the tie rod adjusters, but would present some weird Ackermann angles when steering was cranked in (seen this myself). Find, or make some slip plates (greased linoleum tiles or aluminum plates), get a protractor and see what happens to each front with steering input (0-30 degrees).
Nelson tips: You shouldn't have to trail-brake into T1...just a quick pop on the pedal as you initiate turn-in to set the nose, then give it as much throttle as it will take. T1 is a naturally late apex, which isn't really obvious unless you spend a lot of time at Nelson Legistan...(I've spent a LOT of time there). Somebody may have been preaching the 'drive Oak Tree as a double-apex' sermon...but you need some skepticism here. Single apex is much easier on your front tires. You mentioned that your car feels unsettled there...Oak Tree has a HUGE amount of positive camber, which you should use as much as possible - the only place it should feel 'unsettled' is at the pavement change on the way out, where the patches will give you a big wiggle if you still have some steering cranked it (and you should, IMO). Carousel - if you spend a lot of time feathering the throttle on the way 'in' (i.e. before you get to the big black splotch and the pavement change), then you're giving up lap time. Cut a big diagonal outside left to right edge back to 2/3rds out at the 'splotch', bang the brakes and then back on the throttle before the pavement change. Kink - if you have to lift to get the car to rotate, you have a suspension problem. I've never driven anything at Nelson that wasn't flat-flat-flat-no lift-flat-no lift-flat-flat-flat-flat thru the kink, unless it was wet.
Just for some perspective - 100hp Miata, 2350lbs. wet, going 1:21's at 'enduro pace' at Nelson Ledges, down into the low 1:20's for sprint races, can get 12 hours+ out of a set of Toyo RA1's, and the only the LF tire is pretty trashed at the end...you can sprint race the other three for many more weekends.
You need to loosen that pig up.
Other diagnostic things to check: Ever whack a corner ? You could have bent a tie-rod arm on the 'whacked' knuckle, which could be 'aligned' back to straight with the tie rod adjusters, but would present some weird Ackermann angles when steering was cranked in (seen this myself). Find, or make some slip plates (greased linoleum tiles or aluminum plates), get a protractor and see what happens to each front with steering input (0-30 degrees).
Nelson tips: You shouldn't have to trail-brake into T1...just a quick pop on the pedal as you initiate turn-in to set the nose, then give it as much throttle as it will take. T1 is a naturally late apex, which isn't really obvious unless you spend a lot of time at Nelson Legistan...(I've spent a LOT of time there). Somebody may have been preaching the 'drive Oak Tree as a double-apex' sermon...but you need some skepticism here. Single apex is much easier on your front tires. You mentioned that your car feels unsettled there...Oak Tree has a HUGE amount of positive camber, which you should use as much as possible - the only place it should feel 'unsettled' is at the pavement change on the way out, where the patches will give you a big wiggle if you still have some steering cranked it (and you should, IMO). Carousel - if you spend a lot of time feathering the throttle on the way 'in' (i.e. before you get to the big black splotch and the pavement change), then you're giving up lap time. Cut a big diagonal outside left to right edge back to 2/3rds out at the 'splotch', bang the brakes and then back on the throttle before the pavement change. Kink - if you have to lift to get the car to rotate, you have a suspension problem. I've never driven anything at Nelson that wasn't flat-flat-flat-no lift-flat-no lift-flat-flat-flat-flat thru the kink, unless it was wet.
Just for some perspective - 100hp Miata, 2350lbs. wet, going 1:21's at 'enduro pace' at Nelson Ledges, down into the low 1:20's for sprint races, can get 12 hours+ out of a set of Toyo RA1's, and the only the LF tire is pretty trashed at the end...you can sprint race the other three for many more weekends.
You need to loosen that pig up.
08-07-2006, 06:50 PM
#15
Rennlist Member
Thread Starter
No offense taken at all, I really appreciate your insight.
Your slip plate suggestion is interesting, I may give that a try. If nothing else (tie rods turn out to be truly straight), it will be an education in suspension & steering relationships.
The car can probably make it through the Kink flat out, another day there and I may have nailed it. It is my strong sense of self-preservation that inhibits me from accepting such personal challenges quicker. In other words, I'm a puss (not that there's anything wrong with that.
)
I had no previous information on NL before this event, I will print out your driving instructions above and put them with my track notes for next time.
You stated 1:21s at enduro pace and low 1:20s during sprints? Did you write those numbers correctly? I would think sprint times would be faster than enduro times.
When you say loosen it up, I'm assuming you mean to loosen it up during turn entry? As it seems mid-turn and exit are solid.
Thanks again for taking the time to address this issue.
Your slip plate suggestion is interesting, I may give that a try. If nothing else (tie rods turn out to be truly straight), it will be an education in suspension & steering relationships.
The car can probably make it through the Kink flat out, another day there and I may have nailed it. It is my strong sense of self-preservation that inhibits me from accepting such personal challenges quicker. In other words, I'm a puss (not that there's anything wrong with that.
)I had no previous information on NL before this event, I will print out your driving instructions above and put them with my track notes for next time.
You stated 1:21s at enduro pace and low 1:20s during sprints? Did you write those numbers correctly? I would think sprint times would be faster than enduro times.
When you say loosen it up, I'm assuming you mean to loosen it up during turn entry? As it seems mid-turn and exit are solid.
Thanks again for taking the time to address this issue.