Tripoding, Is It Bad?

[Garry 1]

Following on from the discussion in V8ish's eliminating understeer thread, I have started think about the dynamics of my own car.

Mine will tripod on most corners:

 

 

This is from Anglesey last year.

 

I have been told by those who have followed me that that I get a fair bit of 'air' when cornering.

 

Is tripoding bad?

Obviously it means I am only using and subsequently getting grip form 3 wheels, but how much benefit does the inside rear wheel give as it unloaded anyway?

I remember Jon Murgie asking a similar question a few years ago, but can't recal if it was ever resolved.

 

My highly inexperienced analysis of my cars handling is that it is pretty neutral leaning to understeer in the dry and a oversteer monster in the wet!

 

The spec of the car is

 

Full weld in cage

195/50/R15 Toyo R888's

 

Front

 

Leda 24 point coilovers

300lb springs

309 wishbones

Eccentric top mounts

Std ARB

Strut brace

Slight toe out

 

Rear

 

309 beam and trailing arms

23mm Torsion bars

25mm ARB

Bilstein tarmac dampers

Solid mounts

[Baz 421]

car's have done it for years, the fronts of rear-drivers do it often, and is basically just the result of good grip on the remaining 3 wheels, and perhaps a slightly stiffer setup.

 

As you say, the inside undriven wheel is doing next to nothing anyway, certainly no benefit without a load/weight on it, hence if it stayed down perhaps grip would be only very slightly better, but at the expense of bodyroll, it's a cast off between the 2! It's certainly not detrimental to the handling IMO.

 

You could negate it by stiffening the front, or reducing the size/removing the rear ARB, but then you'd find you have more understeer, so i'd rather they cock a wheel and grip, than lose adhesion anywhere!

Edited February 21, 2009 by Baz

[tom_m 0]

it's a function of the stiff rear anti-roll bar, as the car rolls around the softer front one the rear arb stops the unloaded rear suspension drooping becasue the loaded wheel is under compression. i'm not a suspension dynamics expert in the slightest, but if you're happy with the handling i wouldn't worry about it. if the inside rear didn't have enough grip to sustain it you would be sliding so it follows there is no shortage of mechanical grip, as shown by the very different handling in the wet, when there isn't enough mechanical grip and the rear slides instead.

 

if you watch any front drive racing series you'll see they all cock an inside rear most of the time, the clio cup cars for example and the btcc. i don't think it's something to worry about.

 

edit: damn beaten to it, must have been typing as baz was posting!

Edited February 21, 2009 by tom_m

[Garry 1]

Link to the old Jon Murgie thread

 

It seems the outcome of that discussion was to raise the front a little.......

[Garry 1]

Thanks Baz and Tom, I am quite happy with the handling.

My car just seems to tripod more than other cars on track.

 

Maybe coz I is soooo fast!

[Baz 421]

Tbh mine does what i thought a little excessively too...

 

 

Even in the wet;

 

 

But this topic shows it quite a lot on 205's, and i'm starting to think my slowing down by scrubbing the speed off mid corner rather than braking driving style probably doesn't help either...

[AdamP 0]

Baz, what springs are you running and are you running a front ARB?

[Baz 421]

Standard springs on konis and front ARB (Std. prod. class)

[James_R 3]

As tom&baz said, all FWD will do it when set up correctly and the reverse is true of race set up RWD cars they c*ck the front wheel before the rear, keeps the power going down.

 

That said too much isn't a good thing as you get a momentum effect when the car rolls back making things unstable, I'd suggest trying a 309 ARB on the nose to reduce the front roll, that or try a 22 rear ARB all takes a bit of trial and error

[TT205 42]

Bearing in mind that you have fitted whopping great 23mm rear torsion bars + a 309 beam, I think your 25mm ARB is probably over the top, I'd be very suprised if you couldn't drop to 23mm or less and your handling would actually improve and be less 'snappy', you might even then be able to drop your front spring rates a little as you aren't running full slicks

 

You say yourself it's an oversteer monster in the wet - the fat arb deffo will be encouraging this

 

That said, iirc this is just for fun? - you don't race it? - if you are happy with it and enjoying it - why bother changing it?

 

Dave

[Cameron 16]

Essentially its a bad thing. In an ideal world all 4 wheels will carry an equal load, but in practise this is almost impossible unless you literally paint everything on the floor. It happens because the centre of gravity and roll centre are quite high up, so the force created by cornering at speed basically pushes the car over. Normally this would be seen as boat-like body roll but on cars with stiff chassis (i.e. with roll cages) and stiff anti-roll bars it will lift the inside wheel. This is because by fitting a very stiff ARB you aren't actually stopping the weight transfer, you are just using the ARB to stop the weight transfer from causing body roll and adversely affecting your suspension geometry. The ARB puts all of that load onto the outside wheel, increasing grip, and lifts the inside wheel.

Its good because you get slightly more grip on the outside wheel, but its bad because you have none on the inside wheel. What's more is that tyre load isn't directly proportional to grip. Yes, as load increases grip increases, but the relationship isn't linear. Its far far better to have 300kg distributed over 2 tyres, so 150kg each, than it is to have 300kg on one.

Hope that makes sense.

[projectpug 0]

TT205 sums it up well , if it isn't being raced and you enjoy the handling characteristics then why change? Mines the same as soon as its wet even with good rain tyres on it will still snap lots, but in the dry it gives very sharp turn in which i like .

[Garry 1]

Thanks chaps.

 

In the wet I disconnect the rear ARB which helps alot.

 

As said it is a fun car, I was just interested to get some discussuion on the subject.

[Rippthrough 98]

As tom&baz said, all FWD will do it when set up correctly and the reverse is true of race set up RWD cars they c*ck the front wheel before the rear, keeps the power going down.

 

 

[Alastairh 47]

Completely agree with Tom'm.

 

Al

[Toddy 7]

From my understanding as soon as the car has cocked a rear wheel, the ARB has zero effect as it now has no resistance on the opposite side, the only part left to control the rear end is the t/b and damper on the outside wheel.

 

Would have thought ride height was important here as a stiff rear end has v. little droop travel ( if thats the correct term?) so as soon as you have compressed the front suspension by say 40mm, as an example, it will lift the diagonally opposite rear wheel, smaller T/bs and ARB may help to keep all four wheels in contact.

 

 

Just my thoughts, where is eeyore or miles when you need them!

Edited February 22, 2009 by Toddy

[Henry 1.9GTi 36]

combination of small amounts of droop on your rear end witht the stiff bars, a flimsy french chassis (shell) and going very fast

 

wouldn't worry about it unless it unbalances the car when coming back down, as said all clio cup cars do it and they are of a similar ilk.

 

Also was a bit of a trick for controlling rear roll centre as per eliminating understeer thread.

 

plus it looks kool! lol

[Batfink 201]

Isnt this where you need to look at running a wider front track width?

0 offset wheels should help

[tom_m 0]

Also was a bit of a trick for controlling rear roll centre as per eliminating understeer thread.

 

you can't change the rear roll centre, by virture of the fact that it's a torsion bar rear beam the roll centre is on the floor already.

[niklas 1]

You should make the front end stiffer, reducing overall roll. That will improve the grip of the front outside tyre which does most of the job of keeping you on the track.

 

As you see, the car is rolling quite a lot. With the typical pug mcpherson front suspension the camber gain is something like 0.2 degree per degree body roll. If you have a body roll of 7-8 degrees and running 309 track control arms gaining you 1-1.5 degree neg camber, you end up with the tyre contact patch of the front outside tyre being at least 4.5 degrees off plus tyre deflection. Not optimal!

And running 6 degree neg camber is not really suitable nor easily achievable...

Making the car roll less is the answer. Increasing castor and steering axis inclination (SAI) obviously improves camber gain, but physical limitations makes it a bit difficult.

Body roll is the only thing we can easily control by ride height and more importantly spring/antiroll bar rates. (Eventually we run into physical limitations here too as the the rear beam only accepts up to a moderate size of bars.)

[Henry 1.9GTi 36]

my understanding is that if one wheel lifts of the floor then all the load (ignoring front) is on the other wheel, therefore the roll center becomes the contact patch of the wheel still on the tarmac. It will stay at the contact patch untill the inside wheel has some load on it again. It wont move around as the car rolls and twists.

[C_W 3 1 Cars]

But I suppose even if it's not visually lifted, there might not necessariyl be any load on that tyre.

 

Hot Clios tend to lift a rear wheels as do older Golf GTis really easily in standard form.

[welshpug 1,655]

Clio's have a beam axle not independent suspension, as do many VW's which means they do it even more than a pug.

[VisaGTi16v 1]

Yes I was quite offended when I got under my 172 to find it had a ugly beam, give me fully independant like on the Visa any day heh

Edited April 8, 2009 by VisaGTi16v

[Paul_13 212 1 Cars]

Tripoding.... Pfft you haven't seen anything

 

:lol: :lol:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Please tilt head 90 degrees

 

 

 

Sorry it's dark

 

Me being an idiot and not looked where I was reversing, some kind bloke stopped to tow me out... with his Fiesta.

 

Tow rope attached him in reverse I started moving then bang flew back further into the ditch, turns out i'd just ripped his bumper and front lights completely off the car.

Edited November 20, 2009 by pugtorque
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