210lb/in. front springs

[WhiteOne]

210lb/in. front springs run with stock 350lb/in. rear springs would give our cars a 60% ratio front to rear.(stock are 120lb/in.)
This should improve the front end grip, reduce understeer and cut down on body roll all without sacrificing ride quality.
Stock height springs are all that would be needed to improve the balance and handleing without breaking the bank.
Swift Springs said they will make these for me if I order 10 sets.
Anyone interested?

[Cris]

Price?

[escobar929]

i would be interested if it also lowerd the ride height

what bout the rear? would they also do a rear spring?

[WhiteOne]

Probably under $200. Just checking to see if there is any interest at this point.

[WhiteOne]

Other companies sell sets of springs if you want to lower your car.
The idea here is to improve the balance of the car without altering the ride height.

[mangotangoe]

I would be interested. Assuming that they maintain basically stock ride height and fit a stock or koni strut. Love some more details...

[arrutled]

sounds like a good idea.

[jah29]

Originally Posted by mangotangoe

I would be interested. Assuming that they maintain basically stock ride height and fit a stock or koni strut. Love some more details...

me too. maximum of 1 inch lower would be acceptable.

[larryn]

Wouldn't you need coilovers to be able to use the swift springs? Are you talking about getting stock shaped springs in different rates?

[WhiteOne]

Yes stock shaped springs that are stiffer. 210lb/in. to replace the stock 120lb/in. front springs. We might not even have to do a realignment! In my mind this works. Maybe I'm wrong...

[Lester]

"Yes stock shaped springs that are stiffer. 210lb/in. to replace the stock 120lb/in. front springs. We might not even have to do a realignment! In my mind this works. Maybe I'm wrong..."

If the new springs are the same length unloaded as the original springs, that will raise the front end by quite a bit. The new springs will only compress about 1/2 as much due to the increased spring rate. For example - if each spring is carrying say 600 lbs. then the original springs would compress 5 inches (600/120) whereas the new springs would compress only 2.9 in. (600/210) - effectively raising the front of the car by 2.1 in. at rest.

Someone is going to have to do some engineering here to calculate the effect of these new springs, not to mention the dynamic effects on handling under driving conditions.

[WhiteOne]

3400lbs X 0.51 = 1734
1734 divided by 2 = 867
New springs would have to match installed height of stock springs with 867lbs pressing on them. I think. Maybe? I'm not an engineer. I am just looking for an inexpensive way to achieve the 60% ratio front to rear without lowering or making the car too stiff.

[arrutled]

^I thought its actually 52/48 front to back weight ratio.

[cpt97m3]

I might be interested.

[Lester]

Originally Posted by WhiteOne

3400lbs X 0.51 = 1734
1734 divided by 2 = 867
New springs would have to match installed height of stock springs with 867lbs pressing on them. I think. Maybe? I'm not an engineer. I am just looking for an inexpensive way to achieve the 60% ratio front to rear without lowering or making the car too stiff.

OK - now I think I understand what you are doing. You want to change the front/rear weight ratio to 60/40?

You can't do that with spring rates. You can only do that by changing the center of gravity on the car. So to get more weight on the front compared to the back - you would have to do something drastic - like moving the engine forward 6 inches or something like that.

The springs only react to the weight that is given to them, they don't 'force' a weight back to the car. The only affect spring rates have is how much displacement will occur with a given weight that they 'feel' and have to react to. To illustrate this think about having the car up on blocks with the wheels off. If the blocks could be placed dead center on each spring mount (with the springs off) - that would be what the weight distribution is on the car. Now add the springs on top of the blocks. Does the weight distibution change (ignoring the weight of the springs themselves)? No.

One easy way to move in that direction would be to remove the 50 lbs. of ballast weight that BMW put somewhere under the back bumper to move the center of gravity closer to the middle of the car. I haven't actually seen this ballast weight myself, but read about it on this forum a while back. Of course, doing so will have an effect on the overall handling of the car.

[cpt97m3]

Originally Posted by Lester

OK - now I think I understand what you are doing. You want to change the front/rear weight ratio to 60/40?

You can't do that with spring rates. You can only do that by changing the center of gravity on the car. So to get more weight on the front compared to the back - you would have to do something drastic - like moving the engine forward 6 inches or something like that.

The springs only react to the weight that is given to them, they don't 'force' a weight back to the car. The only affect spring rates have is how much displacement will occur with a given weight that they 'feel' and have to react to. To illustrate this think about having the car up on blocks with the wheels off. If the blocks could be placed dead center on each spring mount (with the springs off) - that would be what the weight distribution is on the car. Now add the springs on top of the blocks. Does the weight distibution change (ignoring the weight of the springs themselves)? No.

One easy way to move in that direction would be to remove the 50 lbs. of ballast weight that BMW put somewhere under the back bumper to move the center of gravity closer to the middle of the car. I haven't actually seen this ballast weight myself, but read about it on this forum a while back. Of course, doing so will have an effect on the overall handling of the car.

Nope. He is just trying to get the front spring rate to be 60% of the rear rate, so 0.6*350=210. This should help the handling some but still have a reasonable ride quality. Note you can do this with off the shelf springs, but they all lower the car various amounts. The OP wants the extra rate, but at stock ride hight. You are correct on the weight distribution. To change that you have to move things around, and that's not usually easy on a street car.

[Lester]

OK - well to do that you would have to experiment - but the new springs would have to be shorter than the stock springs to maintain stock height - and that changes how all the other components work together.

[WhiteOne]

I believe the installed height of the springs should be the same as stock.
The range of motion should be the same also.
Would stiffer springs require different struts?

[Lester]

Originally Posted by WhiteOne

I believe the installed height of the springs should be the same as stock.
The range of motion should be the same also.
Would stiffer springs require different struts?

That is the issue. When you say installed height, do you mean after loading? Or before loading?

If the stiffer springs are the same dimensions as the stock springs at rest - the stiffer springs won't compress as much under the same loading. So the car will sit higher. In order to accomodate this, the stiffer springs would have to be shorter at rest. When you put shorter springs in, this will change the geometry and the fitment of the rest of the suspension.

Your last question is also appropriate, will the stock struts still be effective, or would they cause the car to be 'bouncier'? Stiffer springs probably need stiffer shocks.

How would this new setup ride? In my opinion, more like a truck than a car. Doubling the spring rate is quite a drastic modification. I guess it all depends on what you are looking for.

[WhiteOne]

I have read on this and other forums, that running lowered springs with stock shocks is not a good idea. It seems the shocks wear out because they do not operate in there normal range of motion. So stock ride height should not hurt the struts?
BMW Performance runs about 195lb/in. springs on the front.
KW Street Comfort runs 285lb/in. springs on the front.
Bilstein PSS10 runs 385lb/in. springs on the front.
210lb/in. should ride pretty good.
The real question: Is more dampening really required?

[cpt97m3]

Originally Posted by WhiteOne

I have read on this and other forums, that running lowered springs with stock shocks is not a good idea. It seems the shocks wear out because they do not operate in there normal range of motion. So stock ride height should not hurt the struts?
BMW Performance runs about 195lb/in. springs on the front.
KW Street Comfort runs 285lb/in. springs on the front.
Bilstein PSS10 runs 385lb/in. springs on the front.
210lb/in. should ride pretty good.
The real question: Is more dampening really required?

The stock struts are valved to support the stock springs, which I think are around 120 lbs/in. When you increase the spring rate, you need to increase the rebound rate of the shock to match the new spring rate. So anytime you go stiffer springs, you really need stiffer shocks. That's why most of the aftermarket shocks have adjustable rebound so they can match a variety of spring rates.

So if you got these springs that would be at stock ride height, or any of the ones that lower the car, you really should have shocks that have stiffer rebound settings.

[arrutled]

I have been doing a lot of reading lately on suspension and everything I read seems to agree that increasing the spring rate in the front will increase understeer. So you might be compromising understeer for body roll with this. Unless macpherson strut's are magically opposite than everything else. opinions?