Anti Roll Bars

Hi all,

I am currently reading into different ARB setups and was wondering if I could pick some of your brains on this one...

Digging around the Leon FAQs I came across RuddMeister's suspension guide, which was a good read and pointed to an interesting chat about ARB theory: http://www.geocities.com/MotorCity/1108/shine.html

The car in question is a different model but the theory seems sound. Please try to read the whole thing if possible even if it is a little dry.

From what I can ascertain, body roll is greater at the front of a vehicle (e.g. when cornering all weight is transferred to front outside wheel); and it seems SEAT put a 19mm ARB on the front of the LCR to combat this.

To reduce this roll further a stiffer (thicker) anti-roll bar should be fitted to the front of the car.

(Fitting a large ARB to the rear and a small ARB to the front seems to be a big no-no which will create snap oversteer due to the front rolling and making the stiff rear more likely to raise on one side.)

The next stage seems to be regarding balancing the rear to match the front, so if a really stiff bar is fitted up front then the rear will need stiffening up to allow the rear to keep up with the front.

What is everyone elses thoughts on this? What have you tried on your car?

The LCR is stock 19/0 (f/r) from what I am led to believe. What would a good setup be to change to: (f/r)
22/0
22/25
25/0
25/25
25/28

From what I have been reading having something like 19/28 or 22/28 would make the rear too stiff and liable to oversteer. Snappy overstear is really not something I want from the Leon and would prefer mild understeer as a predictable setup is much more confidence inspiring for me.

Just to add that I will be sticking with the OEM spring/dampers.

Thanks again for your time,
Rob.

Phillc said:

You can also go for 23/25 which is what i will be doing, i have the 25MM rear on along with a rear strut brace and its realy good, i think having the strut brace adds a bit more stifness, the 23mm front will be from the R32, the LC front is 21mm as standard

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The only problem I'd have with a rear strut brace is that I don't want to affect the load space when I have to carry a bike or load up the car with ikea stuff.

What made you go for the 23/25 over a 25/25 setup? Is it due to the price diff between neuspeed and the R32 part? Do you think you could benefit from the extra 2mm at the front?

Willie said:

Rob, think you pretty much know my thoughts on this.
I had 23mm front, 28mm rear (set on mid point) and S3 strutt brace all with new wish bone bushes and uprated engine mounts and 92,000 miles OEM springs and shocks.
I loved this set up and if it hadn't been for the coilovers coming up I would still be on this set up.
I had this set up for about 23 months and loved the way the car felt.
I never really got to explore the limits of this due to getting to crazy speeds and still not finding the limit.
There's not alot of people on here got the same set up as the above(if any) but the Octavia VRS guys swear by it. They have the same suspension set up as us.
I've just been on the track with an instructor today, I no have the above set up (with rear set to hardest setting) and coilovers, the instructor said the car felt perfect. It is very difficult to induce over steer in this set up.

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I just wonder if going for a 28mm rear is a little stiff against a 23mm front. Perhaps you don't run into issues because it is adjustable and in affect is is acting as a smaller ARB on the rear. Do you think 23/25 would have been just as good a setup for your car?

Also, do you think there are benefits to be had for going up as far as 25mm on the front. I don't doubt that roll will be greatly reduced with a thick bar up front, but do you think the ride would be badly affected at all? Would 25mm be better paired with 25 or 28mm at the rear? I don't want an overly stiff rear, but don't want one which lags behind the stiffened front end.

My current setup is just the standard OEM 19mm ARB, but when I added the upper strut brace I found the front end so much sharper for the better. Haven't had a problem with the backend keeping up and that's without a rear ARB. I'm really just thinking out loud but wondering whether having a rear ARB thinker than the front is really necessary.

Phillc said:

Rob,
I asked Willie the same question about the extra 2mm and he thinks it will make the difference, and yes it is the cost of the neuspeen that made me choose the R32, also the rear strut brace i have can easily be removed if i want to use the boot. (no tools required)

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Did the 23mm ARB make the ride less comfortable. I think I'd prefer to go 25mm front if the ride is fine. Quite good with the rear strut brace being removable then, but I've never felt the rear needed stiffening in the same way as the front. The front strut towers seemed to wobble or move when pushing on, which the front brace sorted out nicely. I guess rear strut braces must have uses in certain cars as nissan always use them in the 300 series.

Willie said:

TBH for a purely road car I think 25mm would be fine.
For my car as you said, i have the adjustability to balance things out. There is a 32mm one, lol.
I do plan to play with the settings a bit more but need to get me trained first before messing with the car because TBH just now I am the weakest link no the car.
Rob,

What you will find is that the bars stiffen the car up. With a rally driver driving the car you wouldn't need these as he can get the car to handle how he wants with the accelerator.
What the bars will do is give you more confidence to push on more.
On another point the GYE F1 Asymmetrics are fan feckin tastic on the track.
Guys in Scoobies were running 452 Falkens at the weekend were all over the place, even with active diffs etc

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Yeah I read that there's a 32mm one - now that will be stiff. That's the great thing about those track days, really getting to learn about you and your car. If I went to 25mm front would have to consider whether 25mm or 28mm rear would be a better match (considering that my car currently handles great with a 19mm front and no rear ARB).

Yeah wouldn't fancy budget tyres out of choice. You thinking of trying out some track tyres, maybe on a second set of (lighter) wheels?

Willie said:

I did notice the stiffer front end did magnify the weaker points of the OEM suspension
Would worry that a 25mm would do so more

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Mmm more food for thought. Doesn't the ARB also help to spread the loading to the opposite side in a way that simply putting on harder suspension doesn't?

I'm sure I'll be asking these questions for a while as the SCN forum hasn't got quite so many members with different ARB setups to dig out of the search...

Willie, with the 23mm ARB how much roll do you get now out of interest. Is the roll anyway reduced to s2000, lotus levels or does it still lean a bit too much for you?

Edit: Basically my aim is to find a front ARB that reduces the roll to a level that I'm absolutely happy with, then get a rear ARB which matches nicely to the front.