Tire Gauge and Pyrometer

[flaboy]

I just bought a basic laser pyrometer last weekend to help set my camber settings.I thought it helped out a great deal.We only checked the inside, middle,and outside temps to see if we had to much camber.When we would see more than 50-60 degress difference in temp on the inside we knew we had to much camber.

But we only got the plates in the car on Friday night at the track and din't want to spend the big money for a camber gauge at the track.But i will always take it with me to fine tune the adjustments at the track since different tracks will require some slight changes to help handling.


I may be full of sh*t on all of this...but sounds good to me.


Tim

[ddewhurst]

***We read tires and measure treadwear much more than measure temps. This is for my ITB car and Mathis' GP car.***

Chris, I understand who the G car is. Please explain when you put new tires on the car what you read of the tire surface after 4 to 6 laps to tell in the psi is correct.

Thanks
David

[JimLill]

As I already had a thermocouple device in the form of a Fluke 16, which also serves as a general DVM/VOM



I bought one of these for tires:



http://www.intercompracing.com/detail.cfm?ItemID=113

[RSTPerformance]

I disagree with Dave here, and challange anyone at the track to "look at my tires" after a session and tell me what I need... More or less Camber. I will even set the car up with to much or to little on purpose and show how the temps will show me the difference even after a semi cool down lap that I try to do as fast as possible. I would be very interested to see how you would be able to look at the tire and know what change was needed.

However just to add a little more fire to this discussion, I do not think that a basic laser pyrometer gives you a good reading. It might be all in my head, but to me it makes sence. The outside edge/layer/compound of the tire cools much faster than the inner portions where a probe will read from. An example of this would be, when you have any camber the outside edge of the tire is in "in the air" and cools off. If the outside layers of the tire cool faster than the reading/tempatures will be further off with a laser vs. a probe.

Raymond

[pfcs49]

There is a tool available (circle track) that cuts a shallow/uniform depth rectangular groove across the tread of the tire (similar to that microscopic tread on a new GSCS and just as revealing as examining a gscs after it's fist session). The appearance of the tread surface also tells hugely about if the tire is "working" (car balance/driver working? etc) Non contact pyrometers are useless for tire apps. I tell anyone taking my temps to jab in the probe as if they were trying to give me a flat. phil

[JohnRW]

Tire pressure gauges that use mechanical 'Borden tube' gauges (the most common), are the most evil and treacherous devices you'll ever own. Never trust them. Compare against other gauges regularly. I've seen them read 20-30+% off. Why ? It's a mechanical gauge that uses the 'flexing' of a thin metal tube to move the gauge needle. One drop and the calibration is suspect.

Been burned once too many times. Went to a digital pressure gauge a few years ago...piezo-electric sensor that isn't prone to shocks.

That 'trusty old tire gauge' might be screwing you big-time.

You have now been warned.

[pballance]

As I already had a thermocouple device in the form of a Fluke 16, which also serves as a general DVM/VOM


I bought one of these for tires:

http://www.intercompracing.com/detail.cfm?ItemID=113
[/b]

Now why didn't I think of that before. I already have the Fluke meter, albeit a different model, but the probe is compatible. THANKS for the tip.

Paul

[tom_sprecher]

Based on my experience in the Formula group I can not see how you could have any idea what is happening with your tires with regard to optimum camber or pressure settings w/o a good pyrometer with pin probe. Laser pyrometers are good for making sure the beer is cold enough, and things like that, but not tire temps. To do it effectively you need a 2 man crew shouting out readings (first temps then pressure at each tire) utilizing the driver to record the results on a proper chart. Also, with temps don't bother to shout the hundreds place as it is already assumed and can lead to confusion.

Take them immediately after a hot lap in the first pit box you can get starting w/LF and working counter clockwise around the car. Stick the probe down into the core as there you will find more stable temps that aren't as affected by the most recent track surface. Take 3 readings per tire, moving the probe from the inside out starting no more than 1" in from the inner side wall, then one at dead center and finishing at about 1" from outer sidewall. Give the probe time to settle (2-5 sec on first reading but is gets less as you work around the car) before you shout out. The second crew member takes and calls out the pressure as the first guy is moving to the next tire. When the car comes back to the paddock make a hash mark on the sidewall to record another heat cycle, put the car up on stands and clean off any pick up (staying on line while entering the pits and paddock helps minimize this).

Without having done this for longer than you want, merely "looking" at the tires can only tell you if the driver has worked them enough for the compound being run or if it's time to pitch them due to excessive wear resulting in a bad profile (inside section of tread on LF or outside of RF surface is worn beyond serviceable limit.) If you do the above procedure consistently and keep good records you will quickly gain valuable knowledge and experience. Only at that point (if there have been no off track excursions that day) you can "look" at the tires and only to decide if you need to take more readings. These readings in turn will help decide if you need to make adjustment in either the set-up or the driver. What kind of adjustment fills books.

[lateapex911]

I can't make claim to being a wizard at setup, or engineering, but it IS interesting to see the gulf of opinion, and the strength of it.
I have talked to very respected career chassis engineers who design race suspensions, and they are not pyrometer fans. (And they run at the very front of one model classes that have considerable suspension adjustability, so they must be doing something right...)

And I've talked to engineers who would be lost without them.

Both apparently, can yeild results in competitive environments.

[shwah]

***We read tires and measure treadwear much more than measure temps. This is for my ITB car and Mathis' GP car.***

Chris, I understand who the G car is. Please explain when you put new tires on the car what you read of the tire surface after 4 to 6 laps to tell in the psi is correct.

Thanks
David
[/b]

If you have to do it in 4 to 6 laps, the pyro is the best tool IF you have no historical setup data. The better way to do it IMO is to run a full session, and pull the wheels to measure treadwear indiction holes afterwards.

[tom_sprecher]

I have talked to very respected career chassis engineers who design race suspensions, and they are not pyrometer fans. (And they run at the very front of one model classes that have considerable suspension adjustability, so they must be doing something right...)
[/b]

Jake,

Out of curiosity, what do they use to fine tune their setup? Inquiring minds want to know.

[lateapex911]

Jake,

Out of curiosity, what do they use to fine tune their setup? Inquiring minds want to know.



[/b]

Well, I'm one of those "inquiring minds" too.....

For me, a pyrometer is pretty useless, as it takes humans to operate, and I have none of those, LOL.

But the "other way" is black magic to me. He said, "Well you can tell a lot by looking at the patterns, and the graining of the tire". I'm sure some can...just not me!.

Seems to work though....for him at least, LOL.

[gran racing]

For me, a pyrometer is pretty useless, as it takes humans to operate, and I have none of those, LOL. [/b]

Maybe you could speak with one of your friends who races in another class such as ITB and ask them to do it? Then, maybe you'd be willing to help them take the reading on their car? Brilliant!

[lateapex911]

yea, I had such a friend, but the guy wrecked his car and was never seen nor heard from again,...

Kidding!!!

Consider yourself "tapped"...good thing Jake Fisher doesn't need the same help, eh?

[gran racing]

He is one of the people who tunes by reading tires. Just because he and others run mid-pack, doesn't mean those same people don't know what they're doing. Last year he finally bought a pyrometer, but it was just to test for max. temp using autocross tires.

Jake, he's moved onto the dark side and bought a 240sx, dropping some silly big motor in it, and doing drifting. Besides, he does a significant amount of his tuning at his work's track. Jerk!

[backformore]

A good use of a pyrometer for someone just starting out is to measure how much of the car/tire potential is being used and determining when tires have gone over the hill.

While this requires some historical and comparitive data, it can be really useful.

By comparing your temps to someone running a similar car on the same brand or tires(during the same session), you can tell if you are pushing the car hard enough (i.e. signigicantly colder temps means you need to put your foot into it grandma).

Similarly, if you have been recording data for several events and you see a consistent reduciton in max temps, it may be time to buy new shoes.

[pfcs49]

VERY INTERESTING EXERCISE: (that I've done for a long time now): take the sums of (3) temps for each tire and express them like corner weights. If you've been scaling the car, youll be suprised at the diagonals ("cross-temps"?) (add the diagonal sums and compare them/express them as % of each other.
The results will look like good crossweights when the car setup is good/chassis working. phil

[kthomas]

Well lessee, during my "active" period as a Crew Chief, my drivers won something like 41 races in 69 starts, 2 SARRC Championships and 4 ARRC's. That doesn't mean I know anything, but IMHO (and I mean that sincerely) here's my take on pyrometers/gages.

I use a pressure gage to set the first cold pressure of the day, and each time we mount another set or rotate. I record pressures after the tires have cooled (as well as the ambient temp) for setups that we are happy with. In 15 years of ITS I may have checked pressures hot a couple times just for yuks. They mean nothing to me. The pyrometer is my primary tuning tool. In fact, the last two years I worked regularly I never unpacked my camber gage, and couldn't tell you what camber we were running. In the first few years with the Z's, however, we tracked and recorded so much data I think we should have owned stock in Weyerhauser. After enough years on the same tracks you sorta learn what you don't need.

In the bias ply Hoosier days a 1/2 lb of air made a significant and repeatable difference in the temperature distribution. Ditto my days on slicks with sports racers and prod cars. As already noted, the bias of temperature for optimum grip varies with suspension and tire type. Pre IT radials I'd shoot for even or 10 degrees max depending on which car we're talking about. On radials its more like 25 degrees hot to the inside. We seem to get a lot of benefit from camber thrust in radials, and curiously that kind of bias still results in pretty even wear (although wear in general has a LOT to do with shocks). Radials are not near as sensitive to pressure as bias ply's, although being basically a race carcass the Hoosier is pretty close. You're not losing because your tire pressure is off a pound or two.

I never make a setup change until two sessions produce the same temps, unless of course we have something way wrong (this is usually indicated by the driver running over your feet on the way to the paddock while your in pit lane waiting for him to stop for temps). If you think temps only reflect the last couple of corners then you're not sticking the probe in deep enough. Because of the huge camber most IT cars run now (eh, the ones with not enough spring and shock anyway ) the corners of the tires usually have a pretty big temperature gradient so to be repeatable you have to be careful and consistent about which locations along the tread you're taking temps. I always measure hottest tire first, followed by next hottest etc. The hotter the tire, the more heat loss while you're measuring.

While I can't say enough good things about Bruce Foss and Rodney Perry of Hoosier, I always do my own temps even when I also have them do them. They're usually pretty close to right.

[tom_sprecher]

Oh yeah, well when I was the Crew Chief for 4 years we won I don't know how many races in CFC, 2 SARRC championships and set track records at Roebling and CMP, so there. That doens't mean I know anything but I felt like bragging.

Seriously, katman, that was a great post, but you lost me when you said in 15 years you only took hot temps a couple of times yet the pyro was your primary tuning tool. What gives? The cold pressure method is the best once you have the setup you want, but hot pressure with temps can tell a lot too.

All of my experience is with Hoosier bias ply slicks (25's & 35's) so the DOT radials (Toyos, at that) will be something new (which is a good thing as I bore very easily). I appreciate your info and it looks like I might need to bone up on the differences before getting too serious.

Thanks again,

[ddewhurst]

I read this post earlier this a.m & surmised katman might have oop's a word. I don't argue with folks who WIN.

***In 15 years of ITS I may have checked temps hot a couple times just for yuks.***


Have Fun
David