toe in toe out thats the question

[Phill1978]

ok crap shakespear reference.

right so i was playing rallisportchallenge2 (just bought it cheap) and on the advanced tuning section it claimed toe`ing out on the front gave quicker turn in but at the expense of stability under breaking.

can anyone explain the relative merits of toeing in or out and is this another term for camber adjustment (i.e will i be able to control this toe`in via camber bolts like the ones from ktec)

whats the best for fast road ? i would guess rear toe in on a cup for stability and toe out on the front a bit ?

its just that both 172`s ive owned have handled great at speed but even though its not understeer it doesnt seem as crisp and as acurate to turn in i.e point and it will go exactly where your wheel is pointed or a crisp as the new shape mondeo i drove or the ford focus i drove, it improves with speed but at mid speed bends it doesnt display any REAL accuracy and my car is stock and setup correctly as was my other 172, i improved this with modified suspension in my last 172 but perhaps at the expense of ride comfort and tyre wear.

anyways back on question, whats toe in/out ??

cheers

--phill--

 

[Phill1978]

just to add i think the steering is lifeless in MKII 172 rs`s dunno if the 182 is any better but can improve this

 

[MarkM]

looking at the wheels from the front of the car, camber is the difference between the distance between the top of the two wheels and the bottom. Less distance at the top is negative camber.

looking from above the car onto the top of the bonnet, toe is again the difference between the top of the wheel and the bottom.

A bit hard to explain in words if only I could be arsed to draw a picture!

You want negative camber and toe out for handling. I am running -1.5deg camber and slight toe out on my car.

 

[benji&eka]

how much toe are you running ^

 

[BenR]

toe out, your wheels are of a negative offset so the centreline is inside of the steering steering axis.

The generic things you read on games mean jack.

If you want better steering 'feel' then get a lower offset wheels for the front, this will increase the torque moment from the castor offset/scrub radius increase.

 

[jas1]

toe out on front will give more straight line stability, better initial turn in, but less steering on corner exit, toe in does the opposite
toe in on the rear gives better rear end traction but takes steering away, the less toe in you use the more straight line speed and acceleration but at a cost
the basics of castor, the larger the kingpin angle the more high speed steering you get (at higher speeds in corners your suspension compressors more and with more castor more of the tyre is in contact with the ground)

this is all from a radio control car perpective, which i now what i'm talkin about, whether it works in the real world i wouldn't know

 

[BenR]

doesnt really translate, the technical geometry is the same, but RC cars do not encounter the same forces or react in the same way due to weight majorly.

Most of the stuff above wont work on a road car, unless the geometry is exactly the same as your RC car.

 

[George k]

Ben R; If a car has a negative scrub radius then reducing the ET (offset) will actually reduce the offset and thus the self aligning torque. What is worse is that with modern wide flat treads and the average lumpy English road the actual centre of contact can move laterally so on one side you have negative scrub radius and on the other positive scrub - this is why changing the offset make some cars much less stable. Interestingly enough a bit more negative camber will tend to stabilise this lateral movement although it will change the effective scrub radius. As an aside I tried to calculate/measure the scrub radius on my 182 Trophy and it came out at 4 mm positive which really surprised me. This was using the dealer supplied KPI of 11.30' and the track of 1430 mm. If you have more info it could help to clarify this. As we have had a recent somewhat technical discussion I am happy for you to e-mail me direct if you think that would be more appropriate.
Regards

 

[fizzy_drink]

^^

Question then:

By changing my wheels from ET45 to ET37: what essentially have I done technically?

(i have noticed that turn isn't as sharp at lower speeds, but other aspects of hadling and grip have improved)

 

[almaghrbi]

I found that for best handling I set my car toe out both front and rear. It will feel like skidding even at sraight line but it is the fastest on track.

 

[George k]

Omar, As a new comer to the Clio world my comments are based on theory and practical experience with other cars. If as Ben R says the Clio has a negative scrub radius, which despite my comments, I would expect, then reducing the ET from 45 to 37 will reduce the scrub radius, which in turn will reduce the self aligning torque and steering feel by making the steering lighter, as well as creating straight line instability and weaving, and possibly increase the bending loads on the bearings - but will not affect the grip once you have turned in. I would guess that when you chnaged the wheels you probably increased the rim width and fitted different/new tyres, all of which will affect the overall handling characteristics.
Years ago we had a special deal for Fondmetal wheels and when fitted to Astras and Corsas found the cars were a nightmare to drive - the reason was that the standard ET was 49 and the Fondmetals only came at about 38. We spoke to the Vauxhall rally dept who confirmed that this was the problem and that if anything they tried to run more offset. We found that by machining the back of the wheel hub by about 5mm thinfg improved quite a lot and that by runing more toe-in the car felt much more stable.

I have talked to may people who done what Almaghrbi suggests (toe out all round)and they agree that it done in moderation it can be quicker, but that the cars is so unstable on the straight that it is impossible to race in close company because the car is so unpredictable. Rather like a badly set-up LSD in the wet!! The americans love lots of front toe-out for autotests but that is a very specialist application.