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Discussion Starter #1
At my last track event, I was parked next to an instructor who had a pyrometer and we took some readings off my tires immediately after a session. I don't have all the numbers handy at the moment, but I do remember that the left front tire numbers were:

170 -- 147 -- 150 (outside -- middle -- inner)

I have -1.5 negative front camber (Dinan plates) and was running Dunlop SSRs 265/35/18s at 40-41 lbs. hot.

Obviously, more negative camber is indicated, but how much more? Any guesses based on these numbers?

By way of comparison, the instructor was getting even temps on his 5.0 Mustang with -4 degrees on his left front, and 0 degrees on the right front. Not sure what kind of tires he had.
 

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i can only get 2 1/4-2 1/2 negative with the the GC coilovers (limited by strut clearance) - rear camber is around 2 negative on most cars unless they've been really slammed

3 degrees would be nice (and consistent with the rear camber) but i doubt that it's possible in an M5 without some radical modification
 

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Ed

What track were you at? Where you going clockwise around the track?

I am going to be at Watkins Glen on Monday-Tuesday of next week. I have the GC adjustable camber plates withthe stock suspension - recently installed. They are currently set up with -.4 degrees on the front for street use.

How did your instructor select to only put the negative camber on one tire? Does this mean that at WG where you go around clockwise, that I should only put the negative camber on my front left tire? There are lots of right hand turns that eat away the outside edge of the left front tire.

I am very interested in what I should set my front camber to?
 

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camber should be the same on both sides regardless of track direction to maximize bite in all the turns and make the car steer correctly (assuming you're not doing ovals)

the scale on the GC camber plates is not at all accurate and needs to be set initally with a good alignment

i like 1 degree negative for the street with about 1/16 toe in -- going to maximum front camber of 2 1/4-2 1/2 (i don't really know if you can get this much with the OEM suspension) gives just enough toe-out for nice turn-in on the track without becoming twitchy

in any case you want maximum possible front camber on the M5 for track
 

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2002m5BGM said:
I am going to be at Watkins Glen on Monday-Tuesday of next week. I have the GC adjustable camber plates withthe stock suspension - recently installed. They are currently set up with -.4 degrees on the front for street use.

I am very interested in what I should set my front camber to?
You're the first person I can recall on the board who has the GC camber plates on the stock springs. I'm very interested in how much negative camber you can adjust them to. Do you have any idea? For A-group level driving, you would want to set them to the maximum possible negative amount.

Chuck
 

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Chuck

The scale on them goes to about -2. When they were installed, the Tech did not give me measurements for max settings. He only set them to a street setting. I was charged about 3 hours for labor to install them. The tech did say he liked them as it allows you to dial in the camber where normally there is no adjustment at all.

This weekend, I plan to make the adjustment and push the top of the front strut as far forward in and and then as far to the rear of the car as possible to get max negative camber and max postive caster. I was told if I take some of the weight off the car, they will adjust easier. You just losen the three nuts on top of the strut in the engine compartment and then just push the top of the strut itself to the desired position.

I have no idea how this will change the toe setting - as that is set for a street set up. I think it will change it some. I have tried to apply some paint to the gauge so I can eventually return the settings back to where they are today.

Anyone have any thoughts on how this will change the toe setting when I move this to max negative camber?
 

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Moving the struts toward more negative camber will move the toe toward more toe-out. The best way to check this out is to get it on an alignment rack and move it. Then you will have an idea of how far the toe will move at max negative camber.

Redshift posted some data in this thread where he shows his street camber set at -1.5 degrees with total toe at 0.14 in; then when he moved to max negative camber of -2.2 degrees, the total toe went to -0.10 in.

You may have an even greater toe movement since you are only at -0.4 degrees now.

Chuck
 

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Ed,

I have a few questions for you:

1. Were the temps taken right after several hot laps, did you have any cool down lap?

2. Were the temps taken with a tire pyrometer or an IR.

3. What were your tire pressures cold/hot? I see the hot #'s but what are the cold #'s? are you sure you are getting up to optimum temp? By the looks of it I would say you are not, at least in the middle and inside. 170 is the bottom of the temp range.

4. Did you have an blistering/graining?

5. What tires were you running? I saw Dunlop but which ones?

So you know 1.5 is not enough. Depending on the suspension set up 2.5-3.0 is a general starting point. Your numers also indicate incorrect pressures. Look a tad low, maybe by a pound or two.

If you used an IR pyrometer the numbers are worthless as surface temps don't tell the entire story of the tire.

If you were on R compounds we need to know the brand/modle as each brand requires different camber settings dependent on sidewall stiffness.

You instructors' #'s seen very starnge as well. No camber on one side and -5 on the other. Were you on an oval?

Jordan
 

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Discussion Starter #9
1. Were the temps taken right after several hot laps, did you have any cool down lap?

This was a BMWCCA event at Lime Rock Park, clockwise 1.5 mile track, only one left-hand turn. Temps were taken after a 20-minute second session with a cool-down lap. Traffic was decent, meaning that I was generally able to string together several good laps before having to slow down for other cars and wait to pass. Lime Rock is relatively tight in terms of passing zones.

2. Were the temps taken with a tire pyrometer or an IR.

IR.

3. What were your tire pressures cold/hot? I see the hot #'s but what are the cold #'s? are you sure you are getting up to optimum temp? By the looks of it I would say you are not, at least in the middle and inside. 170 is the bottom of the temp range.

For the first session, I went out at 33 cold. Immediately after that session, my left front tire pressure was around 44-45, which I believe is too high for these tires. I lowered them before the second session. This has happened before with these tires, where the grip really seems to fall off at these higher pressures, but I've been reluctant to start with, say 29 cold, since that seems so low.

4. Did you have an blistering/graining?

No blistering. Not sure what graining would look like.

5. What tires were you running? I saw Dunlop but which ones?

Dunlop Super Sport Race (DOT competition)

If you used an IR pyrometer the numbers are worthless as surface temps don't tell the entire story of the tire.

But they're some indication, no? I've heard different opinions on this and still don't know where to come out. At other CCA events, the classroom instructor has recommended getting even the IR numbers to have at least some information, albeit imperfect, to work with.

This is relatively new to me and I'm trying to learn as much as I can, so I appreciate all the feedback.
 

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Discussion Starter #10
stever said:
i can only get 2 1/4-2 1/2 negative with the the GC coilovers (limited by strut clearance) - rear camber is around 2 negative on most cars unless they've been really slammed

3 degrees would be nice (and consistent with the rear camber) but i doubt that it's possible in an M5 without some radical modification
good point, I guess that makes the discussion somewhat academic.
 

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Discussion Starter #11
2002m5BGM said:
Ed
I am going to be at Watkins Glen on Monday-Tuesday of next week ....

I am very interested in what I should set my front camber to?
Which WG event is next week? I had hoped to go next month, but had to change my plans.

I think the consensus is maximum possible, whether that is -2.25 or -2.5. I am wearing down the shoulder of my left front tire at -1.5. It helps, but it clearly is not enough. I've done four events so far this season, and if I were not able to rotate the wheels to balance out the wear, I probably would have corded a tire by now.

I had been under the impression that it was o.k. to have different camber settings left vs. right, so I'd be interested in learning more about why that is not recommended.
 

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Ok.

The IR as I said is worthless. You need to get into the tread to get the correct readings. As the saying goes; use the correct tool for the job. Since you had a cool down lap the readings you got have no real value and I would not want you to chase a solution based on those #'s. I have messed around with an IR and they give readings that are just plain wrong as compared to a probe pyromerter.

How was the car driving? How was initial turn in, push, overstear or neutral? Did you have any mid corner or exit push?

I would contact Dunlop and ask them for any camber recomendations as well as tire pressures. This is good for a baseline setting.

Blistering is somewhat hard to see if it is minor. Look at the tread and see if you can see and small lifting of the tread. Graining will generally occur on the outer edge of the tire and looks like very small "waves" in the tread. Like if you were to drag the tire across the asphalt. Take a picture and I may be able to see it. I will take a picture tonight so you can see it on one of my tires.

I have run at Lime Rock, used to be my home track. The left you are talking about is after Big Bend. Makes a little more sense now.

Best,

Jordan
 

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I am going to a PCA event at the Glen.

http://www.theglen.com/track/TrackSchedule.jsp


<TABLE style="WIDTH: 100%; BORDER-COLLAPSE: collapse" cellSpacing=0 cellPadding=2 width=694 border=0><TBODY><TR><TD>Mon & Tue</TD><TD>5/30/2005</TD><TD align=middle>-</TD><TD>5/31/2005</TD><TD>PCA - Niagara Region</TD></TR></TBODY></TABLE>


The PCA events are a good deal at $280 for the two day event.
 

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You can have different settings for camber side to side. I have not seen them that drastic though.

This is why you need a probe pyrometer. I can't stress it enough that the temps must be taken HOT, with no cool down lap. So you come down the hill and go straight into the pits with someone standing there ready to take your temps and writes them down. Now yopu can make adjustments based on those #'s.

You may loose some track time but this information is very valuable for you set up notes and your future track days at lime rock. You also need to know the track surface temp. This is what the IR is great for.

Jordan
 

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Discussion Starter #15
Thanks Jordan.

Except during the first session, the car felt fine. I don't really have enough seat time to make the most useful observations, but to me, it feels like the car still understeers a bit, even with the 265/35 rubber on all four corners and the Dinan suspension. Turn in (like at the second appex in Big Bend) can be a little slow, but I'm sure I'd see some improvement through better trail braking. I am only a B-group driver at this point, albeit usually the fastest in that group thanks in large part to the car. My biggest, semi-legitimate gripe with the suspension is that it's too softly sprung, but that is another well-worn thread topic.

I'm pretty sure the high pressures were too blame for the way the car felt during the first session, as it's happened before. Some sloppy driving on my part during that session didn't help matters. But I had an instructor with me for that session who also felt that the grip had gone out of the tires. Felt very greasy and loose. I've looked for a phone number for Dunlop to get pressure recommendations, but haven't found one.

I will try to take a picture of one of my tires, though the few times I've tried to shoot tires I've found it difficult to get a good picture.

Thanks again.
 

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Discussion Starter #16 (Edited)
2002m5BGM said:
I am going to a PCA event at the Glen.
Nice. Thanks for the link. I guess that it one of the few PCA chapters that doesn't require p/car ownership and a secret handshake to get in :rolleyes: Let us know how it goes.
 

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i'm not sure 44-45 is much too high in front for an M5 -- the RA1s like 42-44 and i think almost everything else does too except for the Michelin Cups

i've pretty much given up on the pyrometer as once you've cranked in maximum camber you can only fiddle a bit with tire pressure, and unless the pressures are way off, it's very difficult to come in hot and get temps measured consistently enough to tell you about a 2 psi difference

i've run into a couple people running the Dunlops because they're so cheap, but on substantially lighter cars. These tires may go "off" relatively quickly on the M5. 33 to 45 psi is a 120F temp rise -- a very big temp rise for a 1st session -- assuming it was 60F ambient, that's 180F tire air temp -- the most i've seen on RA1s is 100-110F rise after multiple sessions and fairly quick laps.

be sure to keep an eye on treadwear and rotate the tires every track day --increased front camber will reduce the outside wear but you can't get close to enough camber to offset the soft springs -- if the Dunlops are directional, you can re-mount them flipped after 4 or 5 track days -- if they last that long

i personally think it's better to invest in RA1s which will have good life and consistent behavior - fighting tire problems is very frustrating and time consuming and not helpful learning to drive fast
 

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Discussion Starter #19
stever said:
i've run into a couple people running the Dunlops because they're so cheap, but on substantially lighter cars. These tires may go "off" relatively quickly on the M5. 33 to 45 psi is a 120F temp rise -- a very big temp rise for a 1st session -- assuming it was 60F ambient, that's 180F tire air temp -- the most i've seen on RA1s is 100-110F rise after multiple sessions and fairly quick laps.
1 psi = 10 degrees ? is that a basic rule of thumb? 180F is not far from the 170F we got with the IR. Ambient temp was about 60F. I consistently see big temp increases with these tires. I should note that I am running them at full tread depth (and they squeal like mad). Is that a contributing factor?
 

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Wow. I guess you can do what you want regarding tire temps and the pyrometer. This is the only way to determine your camber settings/tire pressures. You gave up on it because why? Can't adjust your camber?

I make it a point to do this stuff throughout the first session of every event I do. This comes from my racing experience and makes for a much better weekend. Use the first session to dial in the set up and then have fun the rest of the weekend. Sometimes it will take 2 sessions but no more than that. It is very easy to get accurate measurments after a hot lap..... I don't get it.

Also I am running an E30 M3 on the track with a fully adjustable suspension front and rear.

I think it is bad advice to disregard the pyrometer. And yes a 1 pound difference can be the difference between a good weekend and a great weekend. Maybe you can't feel it????? I can when I make that adjustment and I do make 1 pound adjustments as they are for fine tuning. I know guys that can feel 1/2 pound changes.

Also as you change tire presures you may even be able to dial out some camber which is better for braking and high speed stabilty.

To each his own. Good luck.

Jordan
 
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