Tires wear vs suspension setting

[sierra4000]

Hi,
What is your opinion on this tire wear?
This pattern occurs on the front tires only.
on the inner side (right side picture) is rougher and more Significant.

Thanks Radek

 

[sierra4000]

https://fbcdn-sphotos-a-a.akamaihd.net/hphotos-ak-frc3/1398124_660382530659738_1535192979_o.jpg

 

[GregLocock]

I'd invest in a tire thermometer

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[CapriRacer]

I think a little background is in order. This is obviously a race tire. As pointed out, I note the edge is worn more.

What kind of car? What kind of racing? If the car started life as a street car, what modifications have you made? In particular, did you fix the akerman?

Gut feeling is this is an akerman / camber issue.

 

[sierra4000]

GregLocock - Yes,I am planning buy a thermometer.



CapriRacer - What you think: "little background is in order" ?


Is Ford Sierra for hill climb (extremely lowered)
though this wear is after about 20 min run to the circuit


I made modifications knuckle and top mount strut for smooth adjustment camber, caster and KPI
ackerman without modification
I use Avon crossply tires with 0.7-0.8 front / 0-0.2 rear static camber angle

 

[cibachrome]

This is a tread migration characteristic. You can watch it happen on a Flat Trak tester during low slip angle high load tests. Stuff coming off to the right is headed for the land of 'marbles'.

A toe change might help you. I may have some cool videos of this happening during lab testing of race tires. It's kinda normal in oval track.

Search on youTube for "FLIR tire" and you can watch the phenom causation on some F1 tires during tests. The FLIR will show you the rough spots are the cool areas on the 'tread' as the liquid rubber moves there from the opposite (hot) side. As you may guess, these videos show toe out on straights. The negative camber doesn't cause that much glowation (Is that a real word ????)

 

[sierra4000]

OK,
if I understand

This means that more toe-in (now is 0) also will help more front grip?
is right ?

But,
May be occur because of incorrect interpretation tread temperatures toe vs camber correct settings errors?

 

[CapriRacer]

Thanks for the info.

What I think is going on is that the camber curve is a little funny and the inside tire is turned too much and has extreme camber. In other words, the camber curve is causing the tire to ride on that edge and the akerman is putting in too much toe. My Capri did that.

First, take a photo of the car hard cornering. What you are looking for is something the shows what both front tires are doing. If the photo is good enough, it will likely show the inside tire leaning inward at an awkward angle and turned too far.

 

[sierra4000]

CapriRacer-This is what you think? because when running on the circuit are very small steering angle,I also have very small body roll,therefore camber change is not evident at circuit pictures.

 

[CapriRacer]

I took an extra day to think about the photos. Here's what I see:

I think the inside front tire is turned in too sharply - and that is to be expected because you haven't done anything to the akerman and typically street cars are set up with too much akerman for race usage. This is kind of hard to be sure about, so I'd recommend you study more photos and see if this seems to be consistent.

Second, the opposite of what my Capri was doing, the camber appears to be ..... ah ..... uh ...... "uncambering" for the inside tire. This is contradictory to what the tire wear is telling me. Again, you need to look at more photos to see if this is consistent.

And the tire temps are going to tell you a lot. Just be sure you get good readings.

Side thought: I always thought that taking tire temperatures gave an "average answer" and that the important answer was what was happening as the tire was cornering. The latest videos out of F1 showing the thermal imaging camera seems to confirm this. It is amazing how quickly the tire surface cools. I particularly enjoy the fact that you can see the tire cool down after the tire warmers are removed.

 

[NormPeterson]

Any chance that either static or compliance toe (out) are part of the problem? Or overdriving?


Norm

 

[sierra4000]

CapriRacer - what you say "uncambering" is achieved knuckle modification (KPI and caster change)
This is a picture of extreme slow cornering(usually race not this slow corners )
in fast corners is inner wheel camber change minimal (about 0-1 degree positive)


Norm - now I think (thanks for your thoughts, Guys!!)

When I modified the knuckle I probably also unintentionally changed (more)Ackerman oops!

Where to changes start?
Toe change ?Ackerman lower?smaller camber?
thus how much should have correctly ackerman for medium fast corners?(about 100km/h)
how much the toe-in?

One more thanks Guys!

 

[CapriRacer]

I think the first thing you need to do is get a temperature profile of the tires. That will tell you a lot of information about what the tire is doing. Don't make any changes until you do that.

On the other hand, if you aren't going to buy a temperature gauge until later, I would go through the akerman. How much? I think it depends on the characteristics of the tires - and I just do not have any insight into that for bias race tires. What I would do is arrange to go half way to parallel steering and see what happens. If you can do this in steps, so much the better. Hopefully, you'll be able to do this simply. On my Capri, it was a matter of putting washers between the steering arms and the strut.

 

[sierra4000]

Yes,
different small spacer to insert between will be easy

I then try to toe after?
how much maximum? 0.25"?

 

[sierra4000]

But how to interpreting tires temperature?
for example-hot inside tire is equals larger toe-out ?-or large negative camber?

 

[CapriRacer]

Get the temps first, and post them. We'll discuss what needs to be done, but I am of the opinion that high temps on an edge is all about camber.

 

[sierra4000]

Unfortunately in the springtime
car is now winterizing


Thanks gentlemens for stimuli and ideas
Thank You all !!

 

[Tmoose]

I've been thinking I'd be trying to contact the tire manufacturer's racing engineering group.
I'd be interested in their thoughts, even if today they lag a little behind as they did back in the mid 1960s, as reported from 18:30 to 19:30 here-

http://www.youtube.com/watch?v=3Fkk-VbSSvU

 

[sierra4000]

Today I measured (of course is not accurate)Seat Leon CUP-circuit racing car

he has approximately zero ackerman

https://fbcdn-sphotos-g-a.akamaihd.net/hphotos-ak-ash3/1412372_665095050188486_205085202_o.jpg

 

[sierra4000]