H&R anti roll bars vs Stock anti roll bars

[Ahbengdriver]

Installed for a week now the H&R ARBs.

Feeling is car is more steady and less bouncy especially when I want to catapult the car. Ok I also weighed both of them - H&R front n rear in total weighs about 19 kg, stock ones only about 9kg(10kg less) bcos rear ARB is thinner than H&R and front is hollow whereas H&R front is solid and rear is thicker.

Also my question - if BMW knows why would they not do like H&R? Weight saving is what I can think of. Others told me the stock bars may 'flex', really? I dont think so leh.

So heavier = more steady, why so? but 10kg more weight added to the car (I am beginning to think like some star wars characters)

 

[satinGHOST|r!der]

Re: H&R anti roll bars vs Stock anti roll bars

Installed for a week now the H&R ARBs.

Feeling is car is more steady and less bouncy especially when I want to catapult the car. Ok I also weighed both of them - H&R front n rear in total weighs about 19 kg, stock ones only about 9kg(10kg less) bcos rear ARB is thinner than H&R and front is hollow whereas H&R front is solid and rear is thicker.

Also my question - if BMW knows why would they not do like H&R? Weight saving is what I can think of. Others told me the stock bars may 'flex', really? I dont think so leh.

So heavier = more steady, why so? but 10kg more weight added to the car (I am beginning to think like some star wars characters)

ABD,

The best is if you strip the car like this if you wanna remove weight. Sure 10x faster.

Our cars are meant to be luxurious and fast. I honestly dont see why you should be worrying about weight much where infinitely you are getting much more from the after market modifications. Infact, adding a lil more weight helps the ride to be much more distributed. Weight can be bad if its unnecessary but extremely good if you know how to use it. For example, the 335 battery is the heaviest thing in our cars. I feel like changing it but doing all this major weight savings will and defintiely upset the balance of a perfectly well balanced car. Unless we are any smarter and more genius than the german engineers, I dont think its safe to save more weight on areas where the car requires it the most, especially when you are rolling on more power.

 

[Darth Vader]

Re: H&R anti roll bars vs Stock anti roll bars

i save 10kg on SS exhaust but add another 10kg on H&R sway bars.really LPPL.
but the H&R sway bars sits below the centre of gravity of the car,so still ok.
maybe i will have to lower the car more to negate the weight of the H&R sway bars.

the battery sits in the driver side and weighs 50 lbs getting a lighter battery at 21 lbs with half the ampere hours actually helps to balance the car better because RHD bmw are heavier on the right side.

only problem is will half the ampere hours be sufficient for the car.

 

[louis]

Re: H&R anti roll bars vs Stock anti roll bars

are ARBs part of sprung or unsprung weight of the car?

 

[phil]

Re: H&R anti roll bars vs Stock anti roll bars

put that battery on the left side to compensate for your fat ass on the right side

 

[centurion]

Re: H&R anti roll bars vs Stock anti roll bars

It is expensive to consider to get an ARB for weight savings! Not to mention that the savings are small....

ARB is to link your L-R suspensions for flatter cornering I always thought.... so your experience of `less bouncy' during a straightline launch/catapault is very interesting.

 

[TripleM]

Re: H&R anti roll bars vs Stock anti roll bars

shud be unsprung I'd think.

 

[louis]

Re: H&R anti roll bars vs Stock anti roll bars

shud be unsprung I'd think.

thanks!

seems counterproductive to spend thousands on lightweight rims, only to put the weight back on with heavier ARBs... never knew they could be that much heavier than stock.... that strikes one mod off my list.

 

[TripleM]

Re: H&R anti roll bars vs Stock anti roll bars

in a way yes but it sits v low to the ground and it's static, not rotational like wheels where the effect is felt much more.

 

[Shaun]

Re: H&R anti roll bars vs Stock anti roll bars

In this application, ARBs are mostly sprung mass. Roughly compare combined length of arms vs length that spans the cars width (very conservatively 1:3), so also that proportion unsprung to sprung. Where those arms bolt to along the suspension also matters but in this case it is much closer to hub so straight ratio works.

In some other applications they are upwards of 90% sprung mass.

==

For given application and roughly same materials and construction (affordable steel alloys, solid vs solid, hollow vs hollow), you can't increase bar stiffness without increasing weight. Same thing with other types of springs.

If a car really needs more roll stiffness and other means at reaching it don't give the compromise that suits the application, then gaining some weight is necessary to come up with outright grip or handling net gain.

 

[Shaun]

Re: H&R anti roll bars vs Stock anti roll bars

Oh and angle of those arms too. If they're parallel to ground then roughly only half of their length or mass (if uniform cross section) is unsprung. In which case the ratio changes to 1:6 unsprung : sprung.

If there is a linkage or some sort of suspension that starts with the arms normal to ground, then it starts of as pure sprung mass, then as the wheel rises in suspension compression, then it starts to become a little bit unsprung, from 0 up to a max of ~17% (1:6) at parallel to ground... so it is negligible unsprung mass.

 

[Shaun]

Re: H&R anti roll bars vs Stock anti roll bars

Also if you want, you can measure it on a car with just some setup pads and 3 jacks. 30 min

 

[Darth Vader]

Re: H&R anti roll bars vs Stock anti roll bars

increase in corner handling negates the 10kg increase in weight.
i am quite happy with mine,so i can live with 10kg more.

 

[louis]

Re: H&R anti roll bars vs Stock anti roll bars

couldn't you have achieved the same thing with stiffer springs?

 

[Shaun]

Re: H&R anti roll bars vs Stock anti roll bars

Yes but the same limitations as listed earlier apply. The coil springs will each be heavier as well. You can vary pitch but you lose linearity in the spring, gain travel before coil bind. All compromises, but you'll find that spring companies always go up on weight and keep the other parameters optimal since they're more mission critical. If you look through say a Hyperco catalog or any other top tier spring manufacturer spring specs, that's what you'll find.

But above isn't really a concern because in these street car applications, the primary reasons for going with bars instead of springs will be to keep as much ride comfort as possible while reaching desired roll stiffness. To reach it with springs will mean the car will be stiffer in heave and pitch which affects ride on all roads. Individual wheel bumps or significant magnitude will still be affected, but this is fairly rare on normal roads.

 

[TripleM]

Re: H&R anti roll bars vs Stock anti roll bars

couldn't you have achieved the same thing with stiffer springs?

Springs affect comfort level directly
ARB regardless of setting, don't.

So quite a diff end result.

Wot u hv now suspension wise ?

 

[louis]

Re: H&R anti roll bars vs Stock anti roll bars

Yes but the same limitations as listed earlier apply. The coil springs will each be heavier as well. You can vary pitch but you lose linearity in the spring, gain travel before coil bind. All compromises, but you'll find that spring companies always go up on weight and keep the other parameters optimal since they're more mission critical. If you look through say a Hyperco catalog or any other top tier spring manufacturer spring specs, that's what you'll find.

But above isn't really a concern because in these street car applications, the primary reasons for going with bars instead of springs will be to keep as much ride comfort as possible while reaching desired roll stiffness. To reach it with springs will mean the car will be stiffer in heave and pitch which affects ride on all roads. Individual wheel bumps or significant magnitude will still be affected, but this is fairly rare on normal roads.

thanks for the insight shaun!

Springs affect comfort level directly
ARB regardless of setting, don't.

So quite a diff end result.

Wot u hv now suspension wise ?

still trying to figure out what to get, hence the questions.

 

[Shaun]

Re: H&R anti roll bars vs Stock anti roll bars

Yes but the same limitations as listed earlier apply. The coil springs will each be heavier as well. You can vary pitch but you lose linearity in the spring, gain travel before coil bind. All compromises, but you'll find that spring companies always go up on weight and keep the other parameters optimal since they're more mission critical. If you look through say a Hyperco catalog or any other top tier spring manufacturer spring specs, that's what you'll find.

To clarify, I'm not saying the total mass gain in all 4 springs equals or exceeds that seen in both bars, just that the spring will have to gain mass too. It depends on the suspension type and vehicle width. In typical road car application, to stiffen the bar up across that typical width requires considerable mass gain, but the priority is still ride comfort.

Even on some narrow body width cars there the suspension arms make up a large portion of overall vehicle width, allowing very short ARBs that are concentrated on the vehicle centerline since they work off the inboard rockers, the mass of ARB system still matches or exceeds mass gain if you were to just go up on springs. It's around a 10 pound max total diff. So even in racing the mass gain is tolerated in exchange for tire grip and life, handling balance, and body orientation control for optimal aero. Just like road cars it's the net performance gain that's sought.