Can we talk Rear Anti Roll Bars?

Django x2 · 3 Jul 2019 at 09:13

So, funny thing, basically I'm enjoying the Ibiza too much and for no other reason that lols, I want to tweak it slightly starting with the handling.

It's already a pretty pointy car, but it likes to understeer when pushed. There is, a front ARB (I suspect 19mm). There are two stiffer ARBs available 20 and 21mm which I assume were reserved for the sportier models, not the 1.6TDI ST. Anyway, I am yet to confirm that I have 19mm, as I say, it's speculative.

In any case, adding a rear ARB will balance the handling back to almost oversteer characteristics. What I would like to know is, with a Rear ARB, would keeping the 19mm front ARB induce snap oversteer moreso than the 21 or 22mm Front ARBs? If so, I would upgrade the front ARB to keep the balance. The rear ARB available is 3 stage adjustable, but not sure if that's enough to get the balance I want. Obviously a beefier front ARB would reduce roll more too.

Thoughts?

adam cool dude · 3 Jul 2019 at 10:32

I have an upgraded whiteline anti roll bar on my ST205 GT-Four. Like the one you are looking at it has 3 adjustable positions. The difference was night and day when i fitted it. Roundabout test is a good indication. Mine has been on the hardest setting since day one and have left it like that. It helps a lot with the inherent under steer of a 4WD car. I have even managed to spin the car a couple of times but have got used to it now and can catch it pretty good. Easily get the rear end out on a wet day pulling out of a junction.

People always seem to underestimate anti roll bar upgrades and go straight to coilovers for improved steer. I went in a Saab 9-5 recently with uprated SAS anti roll bars on standard dampers and it was pure bliss compared to my standard ones. Still have that comforting ride on terrible uk roads but feels so much more planted when pushing on.

vanpeebles · 3 Jul 2019 at 10:38

If you add one to the back, you will need a bigger one on the front. I took the rear one off my mgb, as they can make it snap oversteer, swap ends etc.

Django x2 · 3 Jul 2019 at 10:40

That's what I'm thinking. I'll measure the one I have, as I say, I suspect it's the poverty spec 19mm, and the get the 21mm version found in the FR/Cupra, etc.

vanpeebles · 3 Jul 2019 at 10:47

I think mine is 22mm (7/8") on the front.

adam cool dude · 3 Jul 2019 at 11:02

vanpeebles said:
If you add one to the back, you will need a bigger one on the front. I took the rear one off my mgb, as they can make it snap oversteer, swap ends etc.

It depends entirely on the drivetrain. RWD cars lend heavily to having softer rear anti roll bars. FWD the exact opposite.

vanpeebles · 3 Jul 2019 at 11:06

All depends on the car really, I'd still prefer a softer set up with predictable handling, your Celica sounds unstable to me

adam cool dude · 3 Jul 2019 at 11:55

vanpeebles said:
All depends on the car really, I'd still prefer a softer set up with predictable handling, your Celica sounds unstable to me

It's not unstable as it is very predictable. It is just a lot of cars come out of factory with neutral leading to under steer handling characteristics.

Doobedoo · 3 Jul 2019 at 12:30

I’ve fitted a H&R rear anti roll bar to my Fabia only on the medium setting and it eradicated a fair bit of understeer. It’s probably the best bang for buck handling mod you can do on a Fabia.

Didn’t bother with the front I’d imagine by increasing the stiffness of the front you are cancelling out some of the effect of upgrading the rear.

Django x2 · 3 Jul 2019 at 12:56

Doobedoo said:
I’ve fitted a H&R rear anti roll bar to my Fabia only on the medium setting and it eradicated a fair bit of understeer. It’s probably the best bang for buck handling mod you can do on a Fabia.

Didn’t bother with the front I’d imagine by increasing the stiffness of the front you are cancelling out some of the effect of upgrading the rear.

That's exactly what I was thinking, but it seems like most people do this mod to FRs or Cupras which have the stiffer front bar as OEM. As mine is probably the 19mm poverty spec, I could induce too much snap oversteer. I guess the best thing is to buy the RARB and go through the different settings to find the sweet spot. If it still tends to OS, then think about upgrading the FARB

Diagro · 3 Jul 2019 at 13:07

I have a 27mm Rear ARB on my MPS.
Unfortunately it's very hard on drop links. I've gone through 6 sets within 24 months.

I now have whiteline drop links, and they already started knocking. So... Yea. Don't go crazy

Nasher · 3 Jul 2019 at 13:38

A big reason for the understeer on VAG cars is where the engine is mounted, it's really far forward. I'm not sure you'll ever get it quite right and properly balanced tbh. It may not be worth the battle.

Liquidfox · 3 Jul 2019 at 14:06

Not the same car, but fitting a thicker RARB to my Focus ST225 made a huge difference, I left the front one stock.

sovietspybob · 3 Jul 2019 at 14:33

I'd probably buy it and use it on the softest setting and just see where you are, i've only upgraded them on imprezas which like the Celica above really tend to under steer so it makes them far more neutral.

Doobedoo · 3 Jul 2019 at 14:46

I would just buy the rear for the minute and fit it on a medium setting and go from there. It made quite a difference to my car and it’s much more balanced than it was and more predictable, I’d expect it to make the same difference to yours.

jellybeard999 · 3 Jul 2019 at 19:57

I fitted a whiteline rear ARB on my Octavia VRS and it made a massive difference. Stock front, rear on the hardest setting. Before, you could defintely tell it was a larger car and the rear was very vague and wallowy. After it has much less understeer and a much more direct/precise feel; the rear feels tight and the car feels much smaller and more nimble.

rodenal · 3 Jul 2019 at 20:23

I noticed little difference to my Octavia with a rear ARB tbh, but I can't remember where it was set, possibly middle

encephalopathy · 3 Jul 2019 at 23:43

i fitted thicker front and rear ARB to my octavia vRS and it has made a massive improvement to cornering and handling - much flatter. Also fitted a front strut brace - much more subtle effect - cut down on the chatter from the steering going round corners that had an uneven surface

HummuH1 · 4 Jul 2019 at 13:29

Under what circumstances are you getting under-steer in the Ibiza? Turn in? Mid-corner? On throttle?

What's the rest of your suspension set up? What tyres do you run? What geometry?

I'd focus on the front end if you've got issues, just whacking on a rear anti-roll bar could be a complete waste of time.

Django x2 · 5 Jul 2019 at 15:03

HummuH1 said:
Under what circumstances are you getting under-steer in the Ibiza? Turn in? Mid-corner? On throttle?

What's the rest of your suspension set up? What tyres do you run? What geometry?

I'd focus on the front end if you've got issues, just whacking on a rear anti-roll bar could be a complete waste of time.

Adding a RARB is focusing on the front end. It's entirely what a rear ARB is designed to do, improve turn in and reduce understeer. The front is all completely stock running 15" alloys on Goodyear tyres.