Tazman861

iTrader: (2)

I have just bought some second hand Whiteline ARBs and wire droplinks for my classic scooby. However they are 22mm rear adjustable and 24mm front adjustable. That is correct 22mm rear and 24mm front. They were both fitted to the same car.

This seems to fly in the face of conventional wisdom. What difference do the different holes make ie the rear has three holes - if the middle is say 22mm "strength" does that mean that the furthest from the bar is say 20mm and the closest one 24mm or doesn't it work like that? What about the front? is the softest 24mm and the hardest 26mm??

If I put the rear bar on as hardest and the front as softest will that mean they are both the equivalent of 24mm. Or should I just fit the rear bar and sell the front one?

Any help is appreciated.

172sport

iTrader: (6)

You bought the wrong bars, convention says 22mm front and 24/5mm rear.

I guess it depends if you like an understeery car.

I would fit the rear and leave the front std.

Sell the front one on as its of little use to you.

Tazman861

iTrader: (2)

Yes I know that the best sizes are 22F/24R but I remember reading somewhere on this site that for example on the rear bar the middle hole is the 22mm setting but if you use the hardest setting that is equivalent of 24mm, Therefore if I use the hardest rear setting and softest front setting it could be 24F/24R.

And the Eibach ARB kits are 23F/24R. So hence the confusion

And I didn't buy the wrong bars as I knew that at a push I could use the rear and sell the front and still be quids in compared to buying new ones

dunx

iTrader: (3)

You can't add to the bars stiffness, only subtract so a 22mm COULD be 20 or 18...

Fit the rear bar and enjoy.

dunx

P.S. The hole nearest the 90 bends is the stiffest setting.

Flib

iTrader: (2)

http://www.youtube.com/profile?user=.../6/0ISNWRMB6c4

Might help

Tazman861

iTrader: (2)

Oh well guess I have a 24mm Front adjustable ARB and wire droplinks for sale (all Whiteline)

Tazman861

iTrader: (2)

Not actually true, go to the Whiteline web site and all is explained
If the bar has three holes the middle hole is the advetised size and the the holes either side go up or down one, therefore my 22mm rear ARB can be 21, 22 or 23 and if the bar has two holes they half a mm each way therefore my 24mm front ARB can either be 23 1/2 or 24 1/2. Therefore I will fit the bars as 23 1/2mm front and 23mm rear. (Some Whiteline ARBs have 4 holes and for example a 4 hole 24mm ARB will be 23, 24, 25 or 26mm)

I believe this is a better option for an Impreza as despite being 4WD it has a FWD bias and therefore instead of trying to improve handling by making the rear loose grip a thicker front will encourage the front to grip and not understeer - maybe even making the rear 22mm will be even better? someting to try.

172sport

iTrader: (6)

What out for those hedges, it will be an understeery monster.....

You will also find increased front wheelspin from the inside wheel, this was noticable with just the 22mm front!

Tazman861

iTrader: (2)

How will it be an understeery monster? As standard the front ARB is smaller than the rear and the car is renouned for its understeering characteristics. By adding an even bigger rear ARB all that occurs is the rear looses grip and tries to get in front forcing the understeering front to find grip (or not). Surely by beefing up the front ARB closer to the size of the rear ARB the front will not understeer but go where you want it to and the rear won't try and overtake the front?

I have searched ARBs on this site and there is definately a train of thought that follows this logic. It seems that most on this site accept what is said and won't question anything, am I the first to actually find out the correct sizing for ARBs and therefore people aren't actually running the front to rear differences that they think they are running?

172sport

iTrader: (6)

Just going on practical experiance.

Let us know how you get on!

dunx

iTrader: (3)

Thanks for that, it's been many years since I was on the Whiteline site TBH...

It's less of a problem on a New-age car with R888's, no traction or understeer problems, but then I selected a 22mm bar anyway...

dunx

budd

iTrader: (5)

Simply sticking a thicker ARB on the rear will not cure the Imprezas awful handling, sure traditional thinking has long held that if you want to fix understeer you want the rear to step out more. While this does appear to work to some extent to improve balance it doesn't reduce understeer so I feel this is the wrong way to approach.
Sure CONTROLLABLE oversteer with the back stepping out is fun, and a good thing, but the front is still going wide. As part of this traditional thinking folks scream get a bigger rear bar, and leave the front alone or go smaller. I have to disagree on this. Here's why -

First, let's look at the technical reason. The dynamic camber curve for the mc'pherson strut setup is very poor it's a basic design problem. all setups have their good and bad points. What happens is this - you enter a turn at speed. Your ourside front corner gets loaded with weight. That weight compresses the suspension. When the suspension compresses the camber of that wheel, where that tire is loaded, rolls toward positive camber. If you're running very little static negative camber this will actually start to make the inside edge of the tire light, reducing the width of your effective contact patch that resists lateral acceleration. This lose of traction results in that "push" or understeer condition. This is why folks who are more into performance run a decent amount of negative front camber. Sure, they give up some straight line accel and decel grip doing this, but that's more than offset by the fact that they can maximize the width of the contact patch in turns to help resist higher slip angles due to lateral acceleration. If you lower the car any with springs or coilovers that camber curve gets worse as does bumpsteer.

A thicker FRONT front swaybar will increase the effective spring rate of the wheel without effecting the ride spring rate. In other words, it will help keep the suspension from compressing so much at the loaded corner. Less compression means less loss of camber. Less loss of camber means that you can tune to, and maximize the contact patch of the tire to resist that push. Now, one of the things you need to consider - just like you can't make something from nothing, you can't make a good contact patch if you have nothing to give it to begin. Because the suspension will still compress some you need some negative camber in the front to start with.See, this stems from my philosophy that move oversteer does not necessarily mean less understeer. The front is still pushing. I feel the fix for this is to setup the front end of the car to truly reduce understeer as much as possible. This will make the front tuck in more, and while your tires will be resisting more lateral acceleration taking more grip from straight line acceleration (think traction circle), you'll be able to unwind from the turn faster thus getting you back toward the acceleration portion sooner than your competition. In other words, you'll be able to drive a tighter, and more controlled line.

Additionally, by reducing understeer as much as possible you won't have to set up the car for so much oversteer. This will also lead to more control, a tighter line, and the ability to accelerate sooner.

Now, that's great an all, but if you're looking for a simple answer as to what size bar to get then here it is (I'm giving these in terms of whiteline bars as I am most familiar with them):

Rear - 22mm to 24mm, but if you go to 24mm then you really want to think hard about upgrading your springs. If you go higher than 24mm then you are taking the wrong approach and trying to fix shortcomings of your springs with swaybars, and this is not the right way to do it. Get a proper spring for what you do, and then fine tune with a swaybar.

Front - for the street and mild autocross, and mild track work look at 24mm up front. If you start to get into it more then 26mm is good (WL makes a 24-26 adjustable front). These are also very good sizes if you are not a smooth driver as they won't make things too "darty" with super quick tuck of the front end into the apex. For autocross junkies or track ****** who are smooth overall and can anticipate the "dartiness" then look at the 27 to 29mm front bar.

The above info comes from the yank site NASIOC which seems to have a different way of looking at and sorting problems, before doing anything i'd reccomend a a trawl through their suspension FAQs there is some great stuff on there.

dunx

iTrader: (3)

So in reality, for OEM fit a bar to tweak it.
Change the suspension to alter it's handling, then fine tune with ARB setting.

dunx

budd

iTrader: (5)

basically OEM (Subaru) WANT to create understeer because it's easier for most drivers to deal with than snap oversteer it's just with the Impreza they went a bit to far so yes a slightly thicker rear ARB will improve balance because it creates the illusion of less understeer which is fine for most road cars, but if you really want to improve the handling (grip, turn in, feel,steering responce etc etc) then you need to look at the system as an whole, each part as an effect on the next, only by considering things like spring rates, roll centres, ride heights and indeed what you are using the car for will you end up with a car that truly handles well, it's no good dailing in 3 degreees of deg camber and then using for your motorway commute or to go to the shops.
In most cases a simple ARB swap will be fine but it's not a proper solution just a sticking plaster

RetroMk1

iTrader: (1)

Awesome Info