The one thing I know for sure is it is the original 2001 front ARB that came with my car as a PD100? There are 16mm, 18mm and 19mm bars. What would a PD100 TDI have come with?

As an aside, are there also any aftermarket complete ARBs out there for the fabia? Not heard this talked about before on here.

Try this - pretty.

http://www.awesome-gti.co.uk/product.php?xProd=11913&xSec=1166

Think it's an 18mm on the PD100 Jason.

I know there was a replacement Eibach one available for the front, but people had issues with clearance and it fouling as it ended up sitting pretty low.

I'd leave the standard one in, or pop a fresh vRS 19mm in there TBH. I wouldn't want to be dialling in more understeer by fitting a beefier front bar, unless you're feeling that the front is a bit too light and unplanted? That's the only time I'd fit a larger front bar.

Steve

Yeah, no kidding! MORE understeer is something no Fabia needs!

Why does everyone think that making the front roll less induces understeer? Surly it just keeps the car flatter through bends and helps it change direction with less drama.

Why does everyone think that making the front roll less induces understeer? Surly it just keeps the car flatter through bends and helps it change direction with less drama.

it does tend to be the case with the great British weather

in the dry tho it should be better !

Why does everyone think that making the front roll less induces understeer? Surly it just keeps the car flatter through bends and helps it change direction with less drama.

Because a stiffer ARB actually REDUCES grip, by reducing weight transfer to the outside (traction determining) wheel - until or unless the inside wheel eventually lifts. As my surname isn't Duke, I don't fancy this, which is why I don't have a RARB fitted!

Although the increased negative camber that comes with lowered MacPherson struts goes some way to improving traction when cornering, this isn't particularly significant unless you go spine-shatteringly low - certainly not enough to over-ride the reduced traction from a stiffer FARB.

HTH

Maybe I should look out for a decent ARB from a vRS? Tempted by the powerflex ARB bushes which can be had for about £30 for the pair. 18mm bar is likely to be adequate

"Light and unplanted" is exactly how I would describe the feeling above 100 (km/h again of course )

Because a stiffer ARB actually REDUCES grip, by reducing weight transfer to the outside (traction determining) wheel - until or unless the inside wheel eventually lifts. As my surname isn't Duke, I don't fancy this, which is why I don't have a RARB fitted!

Although the increased negative camber that comes with lowered MacPherson struts goes some way to improving traction when cornering, this isn't particularly significant unless you go spine-shatteringly low - certainly not enough to over-ride the reduced traction from a stiffer FARB.

HTH

ok. but if you are reducing weight transfer to the outside (traction determining) wheel then surly you would get more lateral grip as the weight is spread better over all four tyres? And sorry but tbh the fabia handles better with a RARB fitted so I dont really understand why you think it doesn't :S Can't say I've ever had mine on three wheels either

Weight is key as far as grip goes: less weight = less traction. And traction is traction, whether it's lateral or axial - this is why you see hillclimbers bouncing up and down on the back of their cars, and indeed why F1 cars make so much use of downforce due to the cars only weighing 620kg or so fully-laden!

I'm not saying that a RARB it doesn't make the handling more neutral on the Fabia vRS; I'm saying that I'd rather NOT reduce the grip at the rear, because I'm more comfortable controlling understeer than a four-wheel drift or even a spin. With a RARB, all you're doing is reducing the grip at the rear so that it's closer to the grip at the front in a bend. This is fine, provided you never reach the limit of grip...

Weight is key as far as grip goes: less weight = less traction. And traction is traction, whether it's lateral or axial - this is why you see hillclimbers bouncing up and down on the back of their cars, and indeed why F1 cars make so much use of downforce due to the cars only weighing 620kg or so fully-laden!

I'm not saying that a RARB it doesn't make the handling more neutral on the Fabia vRS; I'm saying that I'd rather NOT reduce the grip at the rear, because I'm more comfortable controlling understeer than a four-wheel drift or even a spin. With a RARB, all you're doing is reducing the grip at the rear so that it's closer to the grip at the front in a bend. This is fine, provided you never reach the limit of grip...

Ok less weight = less traction, but less weight also means the car will be pulled out of corners via lateral g's less as less mass/weight = less lateral g's trying to pull you away from the bend.

To get a bit mathematical - when a car is cornering at speed, the car's weight transfers from the inside wheel to the outside wheel. The rate of change is proportional to the height of center of gravity (CG), the lateral acceleration ( in g ) and inversely proportional to the track width. As this :

Weight transfer = ( Lateral acceleration x Weight x Height of CG ) / Track width

For example, a Porsche Boxster is cornering at 0.85 g. Assuming its track width is 1600 mm, height of CG is 500 mm and it weighs 1250 kg, then we can calculate the weight transfer is 332 kg. Assuming the car has a perfect 50 / 50 weight distribution between front and rear, then we can see each inside wheel takes 146.5 kg while the outside 478.5 kg.

When weight transfers to the outside wheel, the grip on the outside wheel is increased, but does not increase as much as the grip loss on the inside wheel.

Therefore the total grip decreases as weight transfer occurs. The more weight transfer, the less the total grip becomes.

Body roll also introduces weight transfer and thus a reduction of total grip.

Edited 5 August, 201015 yr by Thirdtimeluck

Stiffer front ARB = more understeer

Have a read of this - it gives a good description of how it all works

Don't forget that the 'weight' of the car remains the same - at no point does the mass of the car change. There is always m×g acting in the vertical direction - what causes you to slide when cornering hard is the force provide by mass × acceleration in the HORIZONTAL direction exceeding the traction force provided by the tyres (essentially from electrostatic forces at the molecular level).

Take a look through the relevant bit of Don Palmer's handbook if you want to know more on the theory:

Clicky Linky

Off topic I know but:

Can't say I've ever had mine on three wheels either

As demonstrated thus

I've also seen jonny5ive's car do it through the chicanes at Castle Combe

I like to "push on" on the road but had never experienced any oversteer from having the Jabba bar fitted

However on a damp track last October with 99% bald tyres, and the rear lightened by removing the rear seats, tool kit & spare wheel "moments" were easy to come by

Add a big downhill stop into a tight left hander and I know one Fabia ended up facing the wrong way onthe infield!

On Topic - when the plastic collars on my old style bar came adrift and it needing replacing an OEM VRS bar was about £50 - which is why i ruled out the Eibach one at 3 times the price!

Off topic I know but:

As demonstrated thus

I've also seen jonny5ive's car do it through the chicanes at Castle Combe

I like to "push on" on the road but had never experienced any oversteer from having the Jabba bar fitted

However on a damp track last October with 99% bald tyres, and the rear lightened by removing the rear seats, tool kit & spare wheel "moments" were easy to come by

Add a big downhill stop into a tight left hander and I know one Fabia ended up facing the wrong way onthe infield!

On Topic - when the plastic collars on my old style bar came adrift and it needing replacing an OEM VRS bar was about £50 - which is why i ruled out the Eibach one at 3 times the price!

nice one. That photo is pure win.

Maybe I should look out for a decent ARB from a vRS? Tempted by the powerflex ARB bushes which can be had for about £30 for the pair. 18mm bar is likely to be adequate

"Light and unplanted" is exactly how I would describe the feeling above 100 (km/h again of course )

I got a replacement on Fabia #2 as the shims and bushes were shot. Don't think it was that expensive direct - maybe £70ish?

If light and unplanted was in a straight line Jason, it's the brick-like Fabia aerodynamics you need to address there :p

As far as the Fabia front end is concerned, give some money to Powerflex and Seat for bushes, fit proper suspension and then stand back and leave well alone

Good point on the aerodynamics. Front splitter like this should see you right: