Bilstein B14 vs B6 good watch

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NISFAN
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Bilstein B14 vs B6 good watch

Post by NISFAN »

Spotted this on YouTube earlier and found it an interesting watch. Shows the differences between the two units and also some interesting stuff about the Bilstein spring design.

It also shows why I much prefer mono tube dampers to the more common twin tube variety. Note the big diameter part of the damper body is used for support in the outer housing in an inverted orientation. Twin tube uses the thin bit sticking up in the normal orientation.

Enjoy!!!!






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Trojantrow
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Re: Bilstein B14 vs B6 good watch

Post by Trojantrow »

So from what he is saying it looks to me that the ride height of the b14 at its highest setting would be the same as a b8 damper.? Not seen any confirmation of this elsewhere.

It also seems that although the spring rate is more or less double of the M3 spring, the M3 spring is compressed from the off. Would this mean a higher spring rate than 200lb in reality, where as the progressive spring is not loaded at all so may not be as stiff as it suggests.?

Reason I’m talking about this is, I’ve not actually seen any comparisons of a b12 kit to b14/b16 regarding ride comfort.

Is the b12 more comfortable? Or is that not the case.

Just going by the spring rates it reads like an m135i would be unbearably stiff compared to say eibach pro kit.

But I’ve never heard any complaints from b14/b17 owners.

It would be good to confirm these points if anyone knows .

Also. Less droop. Is that a good thing? Or bad? Basically means the wheel can’t fall away form the car as much. Does that mean less contact with the road in those conditions? Or that actually the body of the car floats less / wants to rise less? So this is better.?




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NISFAN
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Re: Bilstein B14 vs B6 good watch

Post by NISFAN »

Trojantrow wrote:So from what he is saying it looks to me that the ride height of the b14 at its highest setting would be the same as a b8 damper.? Not seen any confirmation of this elsewhere.
It looks like that would be the case in the body part, but of course the B14 comes with its own springs, which would change the ride height, like for like setting on the body.
Trojantrow wrote: It also seems that although the spring rate is more or less double of the M3 spring, the M3 spring is compressed from the off. Would this mean a higher spring rate than 200lb in reality, where as the progressive spring is not loaded at all so may not be as stiff as it suggests.?
I’m not quite following what you mean. The M3 has a softer spring rate, effective over a longer portion of the spring. But the length doesn’t matter, an increase of 200lb weight will compress the spring one inch. The Bilstein 400lb spring will deflect half as much. Needed because the effective spring length is shorter, once you delete the coils in bind portion at the top.
Trojantrow wrote: Reason I’m talking about this is, I’ve not actually seen any comparisons of a b12 kit to b14/b16 regarding ride comfort.

Is the b12 more comfortable? Or is that not the case.

Just going by the spring rates it reads like an m135i would be unbearably stiff compared to say eibach pro kit.

But I’ve never heard any complaints from b14/b17 owners.

It would be good to confirm these points if anyone knows .

Also. Less droop. Is that a good thing? Or bad? Basically means the wheel can’t fall away form the car as much. Does that mean less contact with the road in those conditions? Or that actually the body of the car floats less / wants to rise less? So this is better.?




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Droop is good for rally cars, but doesn’t make too much difference on road cars. The only time I benefit from less droop is when jacking the car up. I don’t have to jack it as high to clear the tyres.


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Re: Bilstein B14 vs B6 good watch

Post by stevesurrey »

Seems to me like you would need to get a car almost airborne to suffer from too little droop.
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Trojantrow
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Re: Bilstein B14 vs B6 good watch

Post by Trojantrow »

Thanks for the reply. So basically what your saying is the spring rate is continuous regardless of preloading if the spring. It will always be 200lb per every inch of compression.

So what I can’t understand is. If wanting to upgrade the stock suspension to one that’s better quality and more compliant than stock, the b14 or b16 is not the way to go?

Better to stick to the b12 kit. Or is it not that simple.?



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Re: Bilstein B14 vs B6 good watch

Post by nastypoker »

Trojantrow wrote:
Thu Feb 20, 2020 7:38 pm
So what I can’t understand is. If wanting to upgrade the stock suspension to one that’s better quality and more compliant than stock, the b14 or b16 is not the way to go?

Better to stick to the b12 kit. Or is it not that simple.?
I had the same dilemma but 2 points swayed me to the B12.

1. The B12 is fantastic value
2. I feel like if the system was adjustable, I would be forever thinking it wasn't set quite right and it would probably drive me mad.
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Re: Bilstein B14 vs B6 good watch

Post by NISFAN »

Trojantrow wrote:Thanks for the reply. So basically what your saying is the spring rate is continuous regardless of preloading if the spring. It will always be 200lb per every inch of compression.

So what I can’t understand is. If wanting to upgrade the stock suspension to one that’s better quality and more compliant than stock, the b14 or b16 is not the way to go?

Better to stick to the b12 kit. Or is it not that simple.?



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Yes that’s right, for every 200lb you add, the spring will get compressed by 1 inch. In his example of course.

I don’t necessarily agree with his 400lb only simplification of the spring rate on the B14 he has. It discounts what actually happens in the real world. For example, go over a bump and the car with rise off the ‘settled’ coils, and will give you a softly cushioned return back to ‘settled’. So the soft rate is in play in actual driving. There are also some element of the softer part of the spring in play. That has the effect of progression from softer than maybe the 200lb rate to the final 400lb rate. But yes if you hit a bump, the initial compression will be harsher.
Compare to a stock damper though, and the Bilstein gives a much more controlled movement in my view.



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Re: Bilstein B14 vs B6 good watch

Post by Trojantrow »

Then there is the consensus that the progressive springs actually reduce body roll rather than the linear springs that theoretically don’t.

I can’t remember exactly why. Something to do with if you go around a right hand corner, the left spring will compress but the right of the car will not lift up as much due to fact that the spring is not under compression like a linear spring.

I don’t know if this is exactly true but if it is, then the b14 should handle a fair bit better than stock or b12


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Re: Bilstein B14 vs B6 good watch

Post by NISFAN »

Trojantrow wrote:Then there is the consensus that the progressive springs actually reduce body roll rather than the linear springs that theoretically don’t.

I can’t remember exactly why. Something to do with if you go around a right hand corner, the left spring will compress but the right of the car will not lift up as much due to fact that the spring is not under compression like a linear spring.

I don’t know if this is exactly true but if it is, then the b14 should handle a fair bit better than stock or b12


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Makes sense, on a uniformly progressive rate spring, as the weight transfers in the corner, the loaded outside spring will deflect less as it takes more and more weight to compress it. Whilst on the other side, the spring pressure upwards reduces as it rises. Nett result, slightly flatter through the corners.


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