Bigger Roll bars and uk roads
 

Has anyone felt that there ride quality or road holding on bumpy roads has suffered due to fitting uprated roll bars?

The reason I ask is since fitting 24mm whiteline front and rear roll bars my car doesn't feel as planted on A roads when pushing on a bit.
It's perfectly fine on motorways ect. Just looses its composure on less than perfect roads.

Will be changing them in a week so will see if they are the culprit.

Bigger ARBs are bound to make it more skittish.

I put my 22 mm rear anti roll bar from middle setting to soft yesterday on my classic wagon seems much nicer to drive

I've recently removed my Whiteline AR bars and gone back to standard bars owing to other suspension changes which weren't working as they should have.

The badly choppy ride on the Whiteline bars has now improved quite a bit and it went to prove that the AR bar was adding significantly to the spring rate.

Consequently, I'm now wondering how much the AR bars were contributing to the harsh non compliant ride of my coilovers.

Still experimenting....

I'll be interested in your opinion after your change.

what size were your whiteline bars?

I've read somewhere on here that bigger ARB's will improve MPG :norty:

Possibly 24mm although not totally sure without measuring. They were installed as part of the Powerstation Stage 3 T25 kit.

Really interesting question.

I've been pondering this. What is this fixation with big bars on an awd ROAD car?
I don't really know the answers, but I'll have a go.

Thinking out loud:


It's awd, so traction is very good. If you use a big bar you reduce the side-to-side independence of the suspension. So, a suspension movement on one side of the car, is transmitted to the other. Which reduces traction/grip/comfort!

You approach a corner entry, you've braked to too early/late, your entry speed's too fast: something. You turn-in, and the front washes wide, the more you turn and brake the worse it gets (I know you shouldn't).
So, why do we immediately go and get a bigger rear bar?

We go to the same corner, make the same mistake, the front starts to wash wide, but now the bigger rear bar is doing its job, and causing a decrease in rear grip - we're now going around the corner, with both ends washing wide?! But, the rear is trying to come 'round faster than the front - is that right? We're now going sideways, not forwards; that's not fast, fun, but not fast. We can't apply the throttle, yet, as at best, we've got 2 wheels up the kerb, on a grass verge or in a ditch.

Why don't we do tyre pressures, caster, camber first?

If it still washing wide at the front, why don't we go for just a larger front bar? To stop loss of camber at the front tyres, during turn-in? As the MacPherson strut front suspension is allowing loss of camber, and therefore a smaller tyre contact patch.

Shouldn't we all be using the smallest bars possible, that give us our preferred balance. And shouldn't they be the last thing we touch, not the first?

Why don't we do tyre pressures, caster, camber first?

This is exactly what to do first , a good set of coilovers on Prodrive tarmac angles to start with , 30mm lower , better brakes , powerflex on the bushings and then some decent new rubber, Once you have that sorted , I might be tempted to do something on thicker roll bars , but more than likely only if I were into track days.

I wouldn't have the coilovers for road use, but I might be a bit biased. And I'd only have urethane bushes if they're in compression, not pivot. Other than that, I agree.
So where's this general bigger sta bar fixation come from?

This is really interesting! I've recently purchased a standard classic Turbo 2000 & the 15-year old suspension appears to be in good order although the rear anti-roll bar is corroded & the rear drop links were replaced for the last MoT. The advice I'm getting is "Whiteline rear anti-roll bar, aluminium front & rear drop links,Whiteline front strut mount." Reading this thread I'm not so sure that is the way to go with a classic! 😐

Would need to know something of your set-up to begin to focus on an answer....

What suspension system do you have now? Fixed perch/coilover? What type etc?

Is your car lowered?

What dia wheels, and what tyres?

What power is your car running?

What alignment settings have you dialled into the car?

ARB's should not, on their own make for a more or less compliant ride - there are just too many other variables involved

True. But, they can limit suspension travel and change the "flat-ride" characteristics, by changing suspension frequency.

Ah I see , but where I drive I am biased not you, I don't have to contend with B roads with holes that can trap tigers and elephants.

I run BC's not approved TÜV but IMHO safer than std. In summer I took my 2 kids and my 86 year mother and the luggage to go on holiday and the re-action from the back seat was , "Thanks dad now we don't get sick." But I am spoiled here as even a country lane is better surfaced than best of the UK A roads. It never ceases to amaze me how road councils in the UK fail to get this organised , as Britain (south anyhow ) really isn't that large and certainly does not have the freeze-thaw activity we have in Germany.

Your point on the Urethane is a good one and I agree , that's why Id use powerflex ( its a mix with silcon rubber compound) on any pivot.

I recently fitted a bigger (22mm - middle setting) whiteline arb to my 99 uk wagon and I think it's a huge improvement. I'm still on stock suspension.
I don't think the ride has been compromised. But, the car now has a clunk coming from somewhere in the rear but I can't work where from.....

Mines a MY05 but if its an eractic clunk sound even at low speed sounds like rear shocks could be done , had that T shirt.

So took them out , rather than replace again.

Well I finally had both my roll bars replaced on Tuesday. I did a straight swap from 24mm front and rear, to 22mm front and rear.
I've done a fair few miles since then and the car is more compliant over uneven roads and does handle bumps better. But still not where I want the car to be in terms of control while on our A/b roads.

I've not noticed any increase in roll either. Maybe it's not pushed hard enough on the road to see the benefit of having a larger bar.

I've also been able to increase my dampers two clicks this before would of made the car to nervous on a less than perfect A or B road.

Although this has been an improvement I still think think there is more to be done. might try fitting the original front bar at some point to see if that helps things further.

Hi Bonesettter. Here is my set up see what you think.

The cars on Bc type ra coilovers with adjustable top mounts and rubber rear mounts

The ride height centre of wheel to arch is 360mm front 350mm rear
Think this maybe a bit low!

Car now has 22mm front and rear bars rear is set to middle

Anti lift kit also fitted

Wheels are 17'' oem Sti
Tyres are Goodyear eagle F1 asymmetric 2's

Front camber is 1.15
Front toe 0.03
Rear camber is 1.30
Rear toe 0.06

Power is circa 375 bhp 440 ft lbs

Well first off, your set-up has a good few positives

Ride height looks fine, which always can be a big stumbling block. Nothing worse than an over-lowered scooby

Geo settings look spot on

As for the rolls bars, I have always settled on 24 rear, set to middle setting and 22mm front on firm. This for both the classic and new age (up to Hatch).

You have a little extra compliancey in 17" dia wheels (the best size IMO), and the F1 tyres which have a medium/soft side wall

You can 'see how it goes' with what you have now, or, for the time it takes, swap out the rear bar again for the 24 to see how you like that

But all in all, I think you shouldn't be too far away now. When you say you think there's more that can be done, what aspects of the car's handling do you think is lacking?

Just lacks the confidence at higher speeds. Even more so on a road with undulations and bumps. it's kind of a unstable feeling.

Also tried a few tyre different tyre pressures currently running 36 front 34 rear powerstations recommendations
I was also thinking of increasing the ride height. Both front a rear control arms look parallel to the floor.

What you're describing there is normally down to insufficient damper/spring travel, bump steer, or over-lowering (in the main)

360/350 should be fine, but you say your control arms are horizontal??

Do you have a pic of your car - preferably side on, but not crucial?

Yeah I had it up on the ramp at Powerstation the other day and the arms are horizontal. But ride height doesn't look slammed and its 360 front 350 rear as I said.

Maybe the spring is set too low on the strut body causing a lack of damper travel

Don't have a pic with the coilovers fitted. Might take a pic tomorrow and one of the strut

What did PS say re set-up?

Um not much. Just that the alignment is ok and that I should lower it more.
And what I need is some Ast Coilovers.
I did mention about the control arms being horizontal but they have never had any problems with the arms being like that. Also asked about roll centre and they had no idea what I was on about.

That bears out the level of help & advice I and many others have had from them over the years too :rolleyes:

Edit to your edit: That's total bull****

Well what would you suggest? Am I right in thinking there should be some sort of angle to the lower arm.
what would be the ideal ride height for a Sti with out roll centre correction.

Try and post a pic of your car. You may indeed need to raise it a little, looking back over my info the '05 on has an 'ideal' height of 380/360.

Your control arms should not be level

Thanks for your input. I'll try and get a pic tomorrow.

InTurbo, just out of interest... what front brake setup are you running?


Sam

Sti Brembos, drilled discs, black diamond predator pads. Dot 5.1

Why do you ask?