Eliminating body roll...

[spic]

After a day off howling the sport round hullavington airfield testing my newly rebuilt toy out i feel the need to tighten things up and reduce body roll, im not ready to go down the coil over route as i have only just replaced springs and shocks ( 40 mill drop on the springs and stock shocks) So whats the best way to go from here, i was thinking of uprated arb's as its a fairly cheap start, will this help much with body roll and if so which is the best set up to go for ?

Many thanks.

Steve.

[Theo]

I had -40mm springs and Bilstein shocks coupled with big H&R anti roll bars and the car still rolled excessively.

I fitted coilovers and the car was totally transformed..

Probably not what you want to hear.

[BadDave]

Stiffer springs/increased damping and stiffer arbs are the only way fella.

If your budget can't stretch that far, how about a diy coilover conversion on the front and a pr of stiffer springs.

Conversion kit + new springs come to <£100

[GeoffBob]

So whats the best way to go from here, i was thinking of uprated arb's as its a fairly cheap start, will this help much with body roll and if so which is the best set up to go for ?

Body-roll is little else other than your cars reaction to the redistribution of its weight while cornering. Stiffening your cars' springs or ARB's reduces your cars reaction to the redistributed weight, but does nothing to combat the redistributed weight itself.

For example: Your cars weight will always shift towards the outside of a corner, reducing traction at your inside wheels. Increasing the stiffness of your springs or ARB's will reduce the amount of associated body-roll, but does little to reduce the traction lost at the inside wheels, since this is a function of the redistributed weight and not a function of the amount of body-roll (ignoring, for the moment, the effect of body-roll upon camber)

If your desire is to reduce body-roll specifically to improve driver comfort or driver confidence, then by all means look at stiffer springs or ARB’s. But if you have specific issues with your cars handling (traction) through corners, then your cheapest option would be to put your car on a diet and strip out as much weight as possible in order that you limit the weight redistributed during cornering.

[N00b]

So whats the best way to go from here, i was thinking of uprated arb's as its a fairly cheap start, will this help much with body roll and if so which is the best set up to go for ?

Body-roll is little else other than your cars reaction to the redistribution of its weight while cornering. Stiffening your cars' springs or ARB's reduces your cars reaction to the redistributed weight, but does nothing to combat the redistributed weight itself.

Exactly, because if the above wasn't true then vehicles like F1 cars would have fixed suspension without any dampeners/springs.
You can stiffen a car to the point where the handling is ruined, it's more difficult to drive quickly and it's slower point to point.

[spic]

I have to say i was quite happy with the way it handled and the car is fully stripped out already so there isnt much i can do on the weight side of things.... it just felt a little boatey so i guess that comes down to driver comfort so it looks like Better ARB's it is then... any recomendations on a kit ?

[GeoffBob]

Exactly, because if the above wasn't true then vehicles like F1 cars would have fixed suspension without any dampeners/springs.
You can stiffen a car to the point where the handling is ruined, it's more difficult to drive quickly and it's slower point to point.

Quite. If it were not for the fact that a) body roll can be both disconcerting and disorienting, b) you can run out of suspension travel on a lowered car, and c) body-roll can result in incorrect camber angles in anything other than the best unequal-length double-wishbone suspensions, then I would advise putting up with body-roll for the sake of having a suspension that can follow the road surface. Sadly, the McPherson struts on the front and semi-trailing arms on the rear of the E30 demand that suspension travel be kept to a minimum in order to keep the shift in camber angle to a minimum. Stiffening up the E30 suspension can, therefore, only be described as a necessary evil.

I have to say i was quite happy with the way it handled and the car is fully stripped out already so there isnt much i can do on the weight side of things.... it just felt a little boatey so i guess that comes down to driver comfort so it looks like Better ARB's it is then... any recomendations on a kit ?

Fair enough. I would suggest, however, that if you have any choice in the matter that you look at stiffer springs first before looking at stiffer ARB's.

Without going into too much detail, a stiffer ARB (as its name suggests) will reduce body-roll, but it does so at the expense of reduced force on the inside wheels while cornering (further reducing traction at the inside wheels). The extra force required to stop the body from rolling is effectively transmitted via the ARB from the outside to the inside wheel, causing the inside wheel to want to lift. Picture a FWD track-car with a natural tendency to under-steer. A common cure is to fit an extra-stiff rear ARB, thus causing the car to pick up its rear inside wheel while cornering, thus reducing rear traction, thus adding over-steer to the under-steer, returning some semblance of overall neutrality to the steering. In truth, stiffer ARB’s are usually reserved for countering the effects under-steer (stiffer rear ARB), or over-steer (stiffer front ARB). Your best bet for countering body-roll (assuming you want to improve, not worsen, your cornering speeds while reducing roll at the same time) is to look at fitting stiffer springs. Just a suggestion.

[N00b]

Stuff

Depending on how hardcore the OP wants his car to be, an option could be stiffer springs on standard (but brand new, obviously) shockers.

[GeoffBob]

Stuff

Oddly misquoted, but I'm flattered nonetheless

[spic]

Thanks GeoffBob that makes for very intresting reading .... But can i just confirm that realy arb's will help with body roll slightly but are mainly used to remove over and under-steer ?

[GeoffBob]

can i just confirm that realy arb's will help with body roll slightly but are mainly used to remove over and under-steer ?

Depending on how much stiffer the ARB's you fit you will go a long way to eliminating body-roll, but at a price!

The problem is the knock on effect that stiffer ARB's will have on your cars dynamic weight distribution while cornering. With stiffer ARB's you will shift more weight to your outside wheels, causing your inside wheels to lose traction sooner. Sounds odd, I know, but that's the physics of how an ARB works. It works as a lever that connects your two wheels together. As a general rule, the stiffer your ARB’s the slower your cornering speeds will be before the onset of either over-steer or under-steer (depending upon which your car arrives at first).

On a daily-driver, keeping the car level for the sake of comfort is considered important. The effect of a stiffer ARB upon the cars dynamic weight distribution while cornering is of little consequence. On a track car, however, it is of utmost importance!

Another problem you will face with stiffer ARB’s is that if you don’t get the balance between the front and rear correct, you can bring on the onset of chronic over-steer or under-steer. Drifters, for example, deliberately fit a stiffer rear ARB in order to bring on over-steer. Conversely, a stiffer front ARB would cause under-steer (and how much fun that would be).

I’ll say it again for clarity, stiffening up your coil-springs is by far the best route to follow if you want to reduce body-roll, since this will cause you to maintain or improve your cornering speeds, not reduce them. Simple skip-pad (roundabout) tests confirm this.

[spic]

That dose make sense so i think arb's our off the list for now... i was thinking of moving to Billy B6's , what springs would you guys recomend for less roll ? or should i just fit a H&R Cup kit ?

[Rusty_McRusty]

All depends if it's a fast road car that gets used on track occasionally or a track car that you drive to and from a number of track days. For a road car, you'll want some ride comfort and suspension travel, for a track car you sacrifice comfort for performance and ride comfort on the road isn't a consideration, it's all about the balance and confidence on track.

A decent set of upgraded ARBs are over £300 so it wouldn't appear to be a particularly cheap upgrade, especially if you need some proper dampers and even some springs too, getting towards another £500 for decent kit there. Better to put the money towards something proper, if it suits your usage.

You'll notice that Eibach ARBs are no larger up front and the rear bar is fractionally larger than the OE item - hardly a massive upgrade - HnR are better but will still not do the job of properly stiff springs. Ireland Engineering do some seriously large bars and there are some others on DT, ebay and the like that are upgrades. However, be aware of the balance of whatever setup you choose, too large up front will induce understeer, too large at the rear, oversteer. Think of ARBs as a way to tune a road-compliant chassis rather than a fix for a track car.

Lowering springs on the E30 seem to be IIR 150-200lb/in fronts, 250-300lb/in rear and these rates still allow for movement. I've recently gone from Eibach to Apex and there is a marked improvement in handling and confidence but they're still a road spring rather than a track spring.

At the risk of repeating what's written above, it's worth remembering that an ARB does nothing until it's twisted whereas a spring's effect is instant, best option is to get the car working as you want it to and either balance a set of road springs with upgraded ARBs or just get the coilover spring rates correct.

Finally, when I was choosing my springs, I asked the manufacturers for spring rates so that I could compare and contrast. Eibach, Apex and HnR all revealed their spring rates and the Apex were the more aggressive, softer up front, stiffer at the rear than the HnRs. I have found them to work very well and at £80 delivered, they were a no-brainer for a low cost car IMO. Could complete with an adjustable RARB and have a fairly aggressive setup for about £300. My dampers are Bilstein B8s, they're good but I'd expect Koni adjustables to be stiffer, useful for direction change, not so great for ride comfort or big bumps.

[billgatese30]

A decent set of upgraded ARBs are over £300 so it wouldn't appear to be a particularly cheap upgrade, especially if you need some proper dampers and even some springs too, getting towards another £500 for decent kit there. Better to put the money towards something proper, if it suits your usage.

You'll notice that Eibach ARBs are no larger up front and the rear bar is fractionally larger than the OE item - hardly a massive upgrade - HnR are better but will still not do the job of properly stiff springs. Ireland Engineering do some seriously large bars and there are some others on DT, ebay and the like that are upgrades. However, be aware of the balance of whatever setup you choose, too large up front will induce understeer, too large at the rear, oversteer. Think of ARBs as a way to tune a road-compliant chassis rather than a fix for a track car.

Going any bigger than the Eibach/H&R ARB's is overkill in my opinion, especially for a track car. I have Ebach's on the track car which are on the softest rear setting, and the middle front setting. It will still lift a front wheel in certain corners and I can feel that the rear bar is still a little too stiff on tight corners as the car just doesn't like putting the power down at all. In the wet (on the track) I disconnect it altogether just so I can get some drive out of the corners. I have B8's and H&R -35mm springs on there. As a road car, it handles great like that, but for the track I would up the springs and reduce the ARB's.

Think of ARBs as a way to tune a road-compliant chassis rather than a fix for a track car.

As you say, get your suspension correct and it should only be there to fine tune what you already have, but they do make a good compromise if the car is still a road car.

[GeoffBob]

That dose make sense so i think arb's our off the list for now... i was thinking of moving to Billy B6's , what springs would you guys recomend for less roll ? or should i just fit a H&R Cup kit ?

Regardless of whether you are fitting full-on coil-overs or just changing the stock springs, so long as they are stiffer (more lbs of force to get the spring to displace a unit distance) they will reduce body-roll.

Going any bigger than the Eibach/H&R ARB's is overkill in my opinion, especially for a track car.

Fully agreed Chris.

”¦ As a road car, it handles great like that, but for the track I would up the springs and reduce the ARB's.

I removed both the front and rear ARB’s from my car and stiffened up the springs. Simple as that. I kept the mounting points intact and always maintained that if ever the car shows a defined tendency towards over-steer or under-steer, I will put one or the other ARB back. I haven’t needed to thus far.

I’ll say it again for the sake of anyone who thinks that ARB’s are performance enhancing items, they reduce body roll, but at the expense of reduced traction at the inside wheels while cornering. On an E30 that means reduced steering response at the front (in the case of a larger front ARB) and reduced power transfer at the rear (in the case of a larger rear ARB). Don’t be fooled into thinking that something that looks bigger and stronger must, by definition, be better.

[Rusty_McRusty]

I have a mere 150 4 pot ponies so traction in the dry isn't an issue, you need to really want to get oversteer for it to happen - or clutch kick it. In the wet it's a little easier to play at being naughty, especially in the slower corners. Anything over 3rd gear and traction issues are very uncommon.

Looking at your sig picture, our cars (unsurprisingly) look to roll about the same amount. As I said above, the Eibach front bar is no larger than stock, the rear is 16mm vs. 14.5. Roll bars basically work on a d^4 principle (material variation is minimal and obviously hollow bars need the centre section to be subtracted from any calculation) so going from 14.5mm to 16mm gives you an ARB approx. 1.5 times as stiff. This means that the balance will have been shifted towards more front grip and this might explain your slight issues with traction from a 200+bhp engine. If you were to fit a 22mm whiteline FARB instead of the 20mm Eibach then that would address the balance, giving you a front and rear stiffness upgrade of ~1.5 and a better balance with less roll.

The HnR kit is 22mm front, 18mm rear so that again will shift the balance of grip frontwards somewhat as the rear bar is @~2.4 times stiffer to the front's ~1.5. The adjusters ususlly give a +/- 10% or so change in leverage and this is a direct relationship. As above, stiffer ARB removes axle articulation and so reduces grip when cornering and also makes reaction to bumps on one side worse as the load is transferred to the unaffected wheel. The balance between the amount that the grip is affected front and rear determines the change in the car's handling characteristics. I am tempted to get an upgraded rear bar to give more front grip but that's a balance thing and I can do that with my modest power. A 200bhp 2.1 would be a different story, unless you aim for neutral drift everywhere in a 1960s F1 style.

From speaking to HnR and Apex, the HnR springs are approx 10% stiffer up front and 5% softer at the back so they should be helping you a little there, compared to the Apex.

Another much overlooked thing is tyre pressures... you can use this to help balance the chassis for conditions and track layout, there's usually a couple of PSI that can be added or taken away with small changes in grip achieved. I like to start the rears a little higher and take any weight in the boot out, it makes the car more pointy but with any more power, it would require a delicate right foot... but that's not relevant to this thread.

[GeoffBob]

[Rusty_McRusty]

I was referring to my car, driven by me - I don't find traction in the dry an issue. I was also making a reference to the different characteristics of my M42/4 hybrid vs. an M50 conversion in billgatese30's, which I can imagine is somewhat less forgiving to a heavy right foot mid-corner. Fair enough, if you want to get all ham fisted and drive far beyond the limits of the car and the driver then that might not be the case but as this is the trackday / motorsport section, I'd assumed that a basic standard of driving would be a prerequisite... perhaps not.

[billgatese30]

Heavy right foot or not, certain corners (hairpins typically) I loose out to standard saxo's and 316i's due to the fact that they can get the power down better due to my rear roll bar being too stiff for the track. I only tried driving it on a dry track with the rear ARB disconnected once (had started wet earlier on in the day) and it did make a difference at the hairpin at Croft, much better drive, but then I also found that I had to trail brake more into a few corners as I then found myself with more understeer on turn in and whilst I don't mind trail braking, having to do it heavier and heavier at 90mph certainly can get the bum twitching

[Rusty_McRusty]

Right, that's not ideal then. What about the rear camber? If the car is lowered and has the usual E30 increased rear camber that results then that won't help in terms of contact patch size and thus traction. Sounds like some properly setup coilovers are what's required to tame the car. I'll be interested to try a stiffer rear bar and see how I get on, early days playing with the E30 so interesting to hear different experiences as I don't want to be wasting money on 'tuning' parts that don't work.

[N00b]

How much power you have, or which engine you've fitted makes no difference. If your ARB is too stiff the car will partially, or completely, lift a wheel.....and that cuts your traction.

[GeoffBob]

I'd assumed that a basic standard of driving would be a prerequisite... perhaps not.

Rusty, I'm not going to go down this road. I'm not here to make enemies, and I value the few friends that have made here too much to go banging on ad infinitum at their expense. Your response is out of order.

[Rusty_McRusty]

Fair enough, no offence intended. My initial comment was reduced to basics and taken out of context, hardly necessary given this forum or nature of my post.

[billgatese30]

I don't think it was anyone's intentions to cause any offence to anyone.

Sorry if it seemed like my post was taking your comments out of context, I was merely stating some of my experience's about my setup seeing as the OP was looking for something similar (i.e. some road based shocks and springs, rather than coilovers) similar to what I have driven on various tracks in various weather conditions. I wouldn't have wanted to OP to go out an buy arb's that were too large for his setup if he could have something that suited the rest of his suspension setup better, I feel your comment of "Think of ARBs as a way to tune a road-compliant chassis rather than a fix for a track car." couldn't have been worded better. The fact that his suspension wasn't a good match for some of the thicker roll bars such as the IE or whiteline bars was all I was trying to say. Again, sorry if it seemed like I was reducing your input or indeed attacking you personally.

I always feel that suspension is normally down the list on mods to do if a budget is tight, but that's only my opinion.

Tuition, followed by brakes, followed by suspension and tyres comes next, but thats for a totally different thread.

[Rusty_McRusty]

Spic / Steve, feel free to let me know if you're doing another MSE day locally, they're damned good VFM I just do a morning @ £65, if you get on with it you can do 1 hour+ including some fuel stops for the driver. LOL. Be good to compare cars too, might be interesting for sure.

[spic]

Thanks for all the replys chaps, they all make for intresting reading and from what i can see you are all singing from the same hymn sheet realy, My car is realy for use at the ring where i do most of my track miles and even though its a drive away comfort is far from the top of my list, infact the E30 is like a bently compared to the tiger cat i used to drive over in which had no roof, windscreen or heater and rock solid suspension, the car is already fitted with Apex springs but with the stock sport tech 2 shocks, none of the bushes under the car have been replaced lately so thats at the top of my list... and while i was experiencing quite abit of under steer and over steer in the sharp corners due to me pushing the car to its limits as i felt this was the only way to get a feel for where these points were... overall i was very happy with the way it performed and soaked-up the days abuse and to be fair when im in germany i never push that hard in fear of having to buy a load of already damaged armco and a long walk home... so if i could remove the body roll i would be more than happy, BUT just to throw another spanner in the works i was about to change boots to R888's but surely this will only increase body roll even more ... ? if i had the budget then i would just go and buy coilovers but im in the middle of buying another house and my Mrs is watching out the corner of her at my bank balance so i realy need to keep costs down

[Rusty_McRusty]

I've got some offset poly front arm bushes that I was planning to sell on, should help a bit. Also thinking of selling on my m1144s, chuck me a PM if you like.

Apex springs are pretty decent rates so stick with them for now. Some 'stiffer' dampers will help, if we meet at a track day you can test the difference with the B8 dampers.

[spic]

Thanks Rusty_McRusty.... dose anyone know whats the stiffest Dampers on the market, i was thinking of changing to Bilstien B 6's due to the drop of the car 50/40 i think or 60/50... so was going for the shorter to remove any chance of it being permanently compressed, but i have been looking at the cup kit which, has anyone compared the two as the price isnt that different and im going to be getting dirty hands anyhow, the only saving i would make with the billys is i wouldnt need to change springs again !

[Theo]

You'd be MUCH better off going for something like these: http://www.pistonheads.com/sales/2290275.htm

[Rusty_McRusty]

HnRs are something like 188lb front, 288lb rear, Apex are 165 / 297 so little difference. The x low kit needs shortened dampers so B8s are a good option, they are also inverted up front so improve rigidity for steering. Don't get the B12 kit as it uses Eibachs and they're not stiff enough for track use at 110/250 approximately.

Konis may be stiffer on full adjustment and will allow for some chassis fine tuning, Gaz do some adjustable shocks too. Obviously tuning dampers to a number of factors is the key to a properly setup car - the 'ring will differ from a billiard smooth UK track...

I've been pleased with the Apex / B8 setup if that helps. It rolls but is well controlled and adjustable, helped by the Z3 rack to minimise arm twirling.

[spic]

You'd be MUCH better off going for something like these: http://www.pistonheads.com/sales/2290275.htm

Thanks for the heads up on these but i dont realy want secound equipment due to the exspense and grief of having to them overhauled or re-valved...

Do people mix there springs, say H&R 188llb's on the front and Apex 297llb's on the rear...

[Rusty_McRusty]

Springs are generally matched for rideheight but if it sits OK then worth a try. Stiffer front springs will increase understeer though so will need to try it.

[Theo]

You'd be MUCH better off going for something like these: http://www.pistonheads.com/sales/2290275.htm

Thanks for the heads up on these but i dont realy want secound equipment due to the exspense and grief of having to them overhauled or re-valved...

Do people mix there springs, say H&R 188llb's on the front and Apex 297llb's on the rear...

The coilovers belong to a mate of mine, they don't need overhauling or re-valving - it was just mentioned as many people (wrongly) believe that Leda no longer trade.

[N00b]

Thanks Rusty_McRusty.... dose anyone know whats the stiffest Dampers on the market, i was thinking of changing to Bilstien B 6's due to the drop of the car 50/40 i think or 60/50... so was going for the shorter to remove any chance of it being permanently compressed, but i have been looking at the cup kit which, has anyone compared the two as the price isnt that different and im going to be getting dirty hands anyhow, the only saving i would make with the billys is i wouldnt need to change springs again !

If good handling is what you're after, I'd suggest that your car is too low. Lowering more than around 35-40 mm does more for the aesthetics than it does for the cars ability to corner.

[GeoffBob]

Thanks Rusty_McRusty.... dose anyone know whats the stiffest Dampers on the market, i was thinking of changing to Bilstien B 6's due to the drop of the car 50/40 i think or 60/50... so was going for the shorter to remove any chance of it being permanently compressed, but i have been looking at the cup kit which, has anyone compared the two as the price isnt that different and im going to be getting dirty hands anyhow, the only saving i would make with the billys is i wouldnt need to change springs again !

If good handling is what you're after, I'd suggest that your car is too low. Lowering more than around 35-40 mm does more for the aesthetics than it does for the cars ability to corner.

+1

Not to mention that you are already in trouble if your car is that much lower on standard dampers.

Condsider a damper with 120mm of stroke (typical). The damper rod is intended to extend to near enough half its stroke while standing (static) upon the OEM specified springs. That means the damper offers approximately 60mm stroke in either direction (compression and extension, or jounce and rebound depending upon your preferred terminology).

Now, lower you car by 50mm (by fitting shorter springs) and you will reduce your stroke to 10mm on compression, while increasing your stroke to 110mm on extension. A far from ideal position for your suspension to be in.

Sure, by fitting stiffer springs you will reduce the liklihood that the car will ever require a full 60mm of stroke in either direction (which is why a 35 - 40mm drop may be tolerated on stiffer springs) but it beggers belief that stiffer springs would be fitted purely to combat the fact that the dampers have limited stroke while in compression (jounce) rather than fitting the correct stiffness springs to achieve a suspension that provides the car with the desired/required degree of compliance to the road surface (while making sure that the dampers are located correctly).

Spic, whatever springs and dampers you should eventually choose, make sure that your dampers aren't near the limits of their stroke after you have fitted/adjusted your springs. Even with coil-overs with height adjustable spring-seats, it is still very easy to adjust the seat height while overlooking the position of the damper rod relative to the limits of the stroke.