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Spring sag - how much is a concern? (Bilstein B14 related)

CSM

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#1
I've had my Bilsteins installed for about a year and a half now. When They were installed, the measured gap (hub to fender) was 31.5cm all around.

Today I decided to clean and inspect the coilovers, And to my surprise they have sagged/settled quite a bit. Here were the numbers:
- FR (31cm),
- FL (30cm)
- RR (31.5CM)
-RL ( 31.5CM)

I reset everything to 31.5cm

I was really surprised by the drivers side front. I have been rubbing really bad during the last two autocross events and I guess spring sag is the culprit. I need to dial in more camber and get the fenders rolled I think, 225/45/16 is pretty aggressive tire IMO for these cars.

Anyways, is a full 1.5cm drop over 1.5 years normal? Kind of alarmed by this
 


M-Sport fan

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#2
I don't know who makes the springs for Bilstein (Vogtland maybe??), but that is not 'normal' for a quality spring, in that time/mileage frame, even on the worst possible roads (IF you are positive that the perches/rear height adjusters were not set at those heights from the get-go).
 


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#3
Quality springs should never sag. Even in much heavier cars you should not get spring sag. You can have a settle in period to get to spec, especially with new heavier dampers, but it will not change the actual depth dimension of the spring.

Since you are just checking fender to hub, you should take a look at any rubber spring isolator and/or any spring seats or spacers in your setup..
 


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#4
I don't know who makes the springs for Bilstein (Vogtland maybe??), but that is not 'normal' for a quality spring, in that time/mileage frame, even on the worst possible roads (IF you are positive that the perches/rear height adjusters were not set at those heights from the get-go).
I believe the springs in the B14s are H&R.
 


OP
CSM

CSM

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Thread Starter #5
Quality springs should never sag. Even in much heavier cars you should not get spring sag. You can have a settle in period to get to spec, especially with new heavier dampers, but it will not change the actual depth dimension of the spring.

Since you are just checking fender to hub, you should take a look at any rubber spring isolator and/or any spring seats or spacers in your setup..
When I get time I'll reinspect everything, but I didn't notice anything abnormal.
 


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Huntsville, AL, USA
#6
Agreed, you shouldn't see spring sag at all. Quality springs do not sag or settle. They are usually preset at the factory. Vogtland doesn't make springs for Bilstein. I ask them awhile back about their relationship with Bilstein and they said they don't share products or even make parts for each other. Could be H&R. There are no names on the springs here at the shop. They just have Bilstein on them.
 


Dpro

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#7
Spring sag, welcome to the world of Eibach( Ya I know you do not have Eibach) . lol Ya that aside. I feel there are like two good spring companies Hyperco and Swift. Both have been shock dyno tested and proven. Other companies while maybe considered good may be questionable. If I were you I would consider switching out the factory springs on your Bilstein’s for a set of Swifts or Hyperco’s . Both companies make a broad line of coil over springs.
 


M-Sport fan

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#8
Spring sag, welcome to the world of Eibach( Ya I know you do not have Eibach) . lol Ya that aside. I feel there are like two good spring companies Hyperco and Swift. Both have been shock dyno tested and proven. Other companies while maybe considered good may be questionable. If I were you I would consider switching out the factory springs on your Bilstein’s for a set of Swifts or Hyperco’s . Both companies make a broad line of coil over springs.
The problem with that is that the Bilstein coil over dampers are valved specifically for whatever progressive rate springs they use in that kit, and the Swift and Hypercos are exclusively linear rate springs. [:(]
(I know, as I've spoken to Bilstein tech about this back when I was considering the B14s, but wanted to replace their springs from the get-go.)

IF Hyperco offered a linear rate, factory diameter/fitment, roughly factory ride height replacement spring set for our cars with a 30%-35% higher rate than factory, they would be on my car now paired with B6es. [wink]
 


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#10
The problem with that is that the Bilstein coil over dampers are valved specifically for whatever progressive rate springs they use in that kit, and the Swift and Hypercos are exclusively linear rate springs. [:(]
(I know, as I've spoken to Bilstein tech about this back when I was considering the B14s, but wanted to replace their springs from the get-go.)

IF Hyperco offered a linear rate, factory diameter/fitment, roughly factory ride height replacement spring set for our cars with a 30%-35% higher rate than factory, they would be on my car now paired with B6es. [wink]
The front springs on the Bilstein B14 are not linear. Don't care what the guy answering the phone at Bilstein says.The rears are progressive, but those could be swapped out.

Bilstein will tell you they have all kinds of magic valving, but the reality is there is nothing special in the B14 valving. Its street valving designed around their spring rates. If you want to go up or down on the spring rate 10-15% you won't notice a difference in the performance. The nice thing with the B14 is you can revalve them however you want. The B8s and B6s you can't do that, they are a crappy twin tube design.

What spring rate do you want? The ST springs meet your requirements. You can run them on B8s just fine. If I wasn't going to make my own housings to use a Bilstein inverted strut, the B14 would be my choice as a good off the shelf street kit. I would also say you could use different springs with that kit to fine tune the spring rate. You won't be using 2.5in coil springs with the kit, but you can have pretty good success with off the shelf springs.
 


M-Sport fan

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#12
The front springs on the Bilstein B14 are not linear. Don't care what the guy answering the phone at Bilstein says.The rears are progressive, but those could be swapped out.

Bilstein will tell you they have all kinds of magic valving, but the reality is there is nothing special in the B14 valving. Its street valving designed around their spring rates. If you want to go up or down on the spring rate 10-15% you won't notice a difference in the performance. The nice thing with the B14 is you can revalve them however you want. The B8s and B6s you can't do that, they are a crappy twin tube design.

What spring rate do you want? The ST springs meet your requirements. You can run them on B8s just fine. If I wasn't going to make my own housings to use a Bilstein inverted strut, the B14 would be my choice as a good off the shelf street kit. I would also say you could use different springs with that kit to fine tune the spring rate. You won't be using 2.5in coil springs with the kit, but you can have pretty good success with off the shelf springs.
You're looking at this from the viewpoint of exclusively tracking the car and using it on mostly glass smooth streets, which is about as far from my needs as could be possible.

NO, the ST springs most definitely DO NOT 'meet my requirements'. [nono]

Bilstein may not use any special 'magic' to valve their B14 dampers, but they absolutely can set it up for the progressive springs they use without too much more effort.

Sorry, but I have to take what the people who actually manufacture these coil overs, and source the springs for them, tell me about their product, over what you have deduced by merely looking at their front springs (unless you've actually had them on a spring 'dyno'?? [dunno]).

Besides, the B14 dampers are of no use to me anyway since they can only go to the factory ride height at best, possibly, and even that is pushing it.
Some of us have to, and yes even choose to take our cars on not just horrid condition paved roads, but also bombed-out, rutted, high centered, cratered, 'baby's head' rock embedded, gravel forestry roads.

The one road I took out of the last stage of NEFR last year would have taken the whole bottom of the car out in a half mile if I had one of the fave on here, slammin' 'coils' on this car, even at rock crawling speeds.
I had a skid plate on, and it got dented and dinged from just that one 2 mile stretch alone, and I was on factory suspension!

All of these 'slammer', or even a decent, not ridiculously low road course style coil over setup just will not cut it on those surfaces.
 


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#13
I will be happy to dyno a set of springs if someone will send me a front and rear from their Bilstein kit. Will also dyno their shock/strut for free.

I am going to be taking measurements for construction of a strut housing for the front that will theortically allow any combination of spring and strut valving and ride height. If you were so inclined, this setup could use a 2.5in spring or a stock type coil spring/lowering spring of whatever rate you want. Ride height can be set for your proposed ride height. I also don't see why I can't make a ride height adjuster for the rear that puts a lowering spring back in the range you would need for a light rally type setup, then just valve some rear shocks for that arrangement instead.

So lets say you wanted a stock or slightly lower ride height (remember droop is an important factor in what you are trying to achieve), do you have a spring manufacture in mind for the rates you want? (obviously using a 2.5in spring you can use Hyperco or Swift)
 


M-Sport fan

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#14
EITHER of those companies are exactly what I would use for 2.5' coil over springs.

I would want ~250 lb. in. in front, and ~225 lb. in. in back (I don't use, or understand, the import K measurements [wink]), about the factory wheel travel specs, and adjustability from about a half inch below factory ride height (at MOST) to about a half inch ABOVE that height (at LEAST).

Truth be told, IF I knew for certain that I could trust Panda Motorworks 150%, to NOT take my coin, and then not send me their product (as has happened to some others on here for other items), I would just order their 'rough tarmac rally' spec/valved coil overs based on the monotube Neo Max Silver dampers, and be done with it. [:(]
 


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#15
Why do you want a 2.5in coil spring other than the ability to quickly change rates? The nice thing with the front springs is they are offset from the strut axis to lower the side loading on the strut tube. This cuts friction and enhances steering feel. Thats why I'm looking at making an adjustable perch using the stock type coil springs (different rates).

These?
https://silvers-na.com/collections/...ilvers-neomax-coilover-kit-ford-fiesta-6-2011
They sure look a lot like BC,Megan, or other Chiwanese coil over kits.
 


M-Sport fan

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#16
That is what they are based off of, but they are completely re-valved for gravel/rough surfaces, with taller spring options, and higher perch adjustment capability, and even have a 3 way/remote reservoir, adjustable option planned.

I don't necessarily want, nor need 2.5" springs, nor even coil overs for that matter.

But NO ONE makes even close to a factory height/wheel travel/fitment linear spring (or even a progressive spring for that matter) with even a slightly higher rate than factory, at all, anywhere, nada, period. (The Swifts Spec Rs still claim about a 1" drop, even if those who pair them with the B6es say it ends up being less than that.)

Yes, Hyperco would produce them (maybe Swift as well?) IF I get another 399 people to commit to buying them. LOFL

Maybe I just do not understand what it is that you are proposing for a solution?
But, from what I do understand, you are suggesting using something like the Swift Spec Rs on an adjustable platform/perch, but otherwise factory strut setup, in order to get back to, or above, the factory ride height? [dunno]

Will the geometry/travel still be correct with that type of setup?

MCS offers something like that for those who 'must have' a coil over, but still be legal for H/Street SCCA competition (it actually uses the OEM factory springs), but it is exorbitantly priced, and it is valved specifically for smooth pavement.
 


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#17
Its a custom strut it can be valved for whatever you want. If you want it to be the same height as the stock setup give or take a bit, it can. You could use whatever lowering spring or 2.5in spring. It can be made with whatever perch and height you want. So yeah, it could have the necessary amount of travel you need for off road/higher than stock ride height.

The geometry will change the more you raise and lower the car over the OE ride height. so yes there will be a bit of a geometry change. No idea the effect as I have never contemplated running the car higher than stock. There could be a bumpsteer issue that might need to be corrected. No idea with some analysis of the geometry or real world testing.

I'm just speculating on what I was going to build for my car. If yours could benefit from it, I can keep that in mind when working out the dimensions.
 


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