3IS F Sport Springs
07-28-15, 02:02 PM
#62
I am going to take some very close measurements, as I always do, and go from there. Something is amiss.
07-28-15, 03:56 PM
#65
07-29-15, 04:26 PM
#68
F Sport vs. Swift Spring comparison with pic...
Ok so my curiosity got the best of me after reading this thread, and seeing a 3IS that had been lowered with F Sport springs and sat substantially lower than the OP's car pictured.
Since I already had the F Sport springs, I purchased a set of 4T912 Swift springs to compare side by side. What I found was an eye opener. Pic may not be that great, but the stats are as follows:
F Sports:
Front 12.0" free length, .538 wire, 7 1/8 coils with a linear design
Rear 12.0" free length, .588 wire, 8 7/8 coils with a progressive design
Spring rate on these are apparently proprietary, so your guess is as good as mine.
Swifts:
Front 10.812" free length, .532 wire, 6 1/4 coils with a spring rate of 5.2 kg/mm
Rear 12.375" free length, .550 wire, 9 1/8 coils with a spring rate of 7.2 kg/mm
Both F/R appear to be linear
Just from the front spring free length difference alone (taking into consideration they are both linear and with approximately the same diameter wire), the drop difference between the two would be quite substantial. In fact, if the advertised drop for the Swifts is 1.1", basic math (again taking into consideration wire diameter, and similar spring rates) will show you the F Sports will result in negligible drop.
Not sure what is going on with the F Sports, but it sure appears the R&D (or the manufacturing/marking of this batch) is out of whack.
As the OP noted, I would not be happy with this spring and the lack of drop. They are going back and the Swifts are going on. I have had nothing but great experiences with them previously.
Since I already had the F Sport springs, I purchased a set of 4T912 Swift springs to compare side by side. What I found was an eye opener. Pic may not be that great, but the stats are as follows:
F Sports:
Front 12.0" free length, .538 wire, 7 1/8 coils with a linear design
Rear 12.0" free length, .588 wire, 8 7/8 coils with a progressive design
Spring rate on these are apparently proprietary, so your guess is as good as mine.
Swifts:
Front 10.812" free length, .532 wire, 6 1/4 coils with a spring rate of 5.2 kg/mm
Rear 12.375" free length, .550 wire, 9 1/8 coils with a spring rate of 7.2 kg/mm
Both F/R appear to be linear
Just from the front spring free length difference alone (taking into consideration they are both linear and with approximately the same diameter wire), the drop difference between the two would be quite substantial. In fact, if the advertised drop for the Swifts is 1.1", basic math (again taking into consideration wire diameter, and similar spring rates) will show you the F Sports will result in negligible drop.
Not sure what is going on with the F Sports, but it sure appears the R&D (or the manufacturing/marking of this batch) is out of whack.
As the OP noted, I would not be happy with this spring and the lack of drop. They are going back and the Swifts are going on. I have had nothing but great experiences with them previously.
Last edited by SoCalISF; 07-29-15 at 04:36 PM.
07-29-15, 04:42 PM
#69
Thanks for your observation. I'm leaning towards the Swift's as well. Please post pictures once installed!
Ok so my curiosity got the best of me after reading this thread, and seeing a 3IS that had been lowered with F Sport springs and sat substantially lower than the OP's car pictured.
Since I already had the F Sport springs, I purchased a set of 4T912 Swift springs to compare side by side. What I found was an eye opener. Pic may not be that great, but the stats are as follows:
F Sports:
Front 12.0" free length, .538 wire, 7 1/8 coils with a linear design
Rear 12.0" free length, .588 wire, 8 7/8 coils with a progressive design
Spring rate on these are apparently proprietary, so your guess is as good as mine.
Swifts:
Front 10.812" free length, .532 wire, 6 1/4 coils with a spring rate of 5.2 kg/mm
Rear 12.375" free length, .550 wire, 9 1/8 coils with a spring rate of 7.2 kg/mm
Both F/R appear to be linear
Just from the front spring free length difference alone (taking into consideration they are both linear and with approximately the same diameter wire), the drop difference between the two would be quite substantial. In fact, if the advertised drop for the Swifts is 1.1", basic math (again taking into consideration wire diameter, and similar spring rates) will show you the F Sports will result in negligible drop.
Not sure what is going on with the F Sports, but it sure appears the R&D (or the manufacturing/marking of this batch) is out of whack.
As the OP noted, I would not be happy with this spring and the lack of drop. They are going back and the Swifts are going on. I have had nothing but great experiences with them previously.
Since I already had the F Sport springs, I purchased a set of 4T912 Swift springs to compare side by side. What I found was an eye opener. Pic may not be that great, but the stats are as follows:
F Sports:
Front 12.0" free length, .538 wire, 7 1/8 coils with a linear design
Rear 12.0" free length, .588 wire, 8 7/8 coils with a progressive design
Spring rate on these are apparently proprietary, so your guess is as good as mine.
Swifts:
Front 10.812" free length, .532 wire, 6 1/4 coils with a spring rate of 5.2 kg/mm
Rear 12.375" free length, .550 wire, 9 1/8 coils with a spring rate of 7.2 kg/mm
Both F/R appear to be linear
Just from the front spring free length difference alone (taking into consideration they are both linear and with approximately the same diameter wire), the drop difference between the two would be quite substantial. In fact, if the advertised drop for the Swifts is 1.1", basic math (again taking into consideration wire diameter, and similar spring rates) will show you the F Sports will result in negligible drop.
Not sure what is going on with the F Sports, but it sure appears the R&D (or the manufacturing/marking of this batch) is out of whack.
As the OP noted, I would not be happy with this spring and the lack of drop. They are going back and the Swifts are going on. I have had nothing but great experiences with them previously.
07-29-15, 06:03 PM
#71
That is exactly what they look like! I am going to measure the free length, wire diameter, and number of coils on the stockers for comparison.
07-29-15, 06:42 PM
#72
Update day #3
It seems the springs did settle but not by much. I think it settled about a 1/4-1/2 inch or at least it looks that way. I still think the front still too high but I like the drop on the rear.
It seems the springs did settle but not by much. I think it settled about a 1/4-1/2 inch or at least it looks that way. I still think the front still too high but I like the drop on the rear.
07-29-15, 07:52 PM
#73
That does looks better. I agree the front can go another 1/2-3/4".
07-29-15, 08:36 PM
#74
If the fronts only settle 1/4"-1/3" more I would say it's just about what I'd expect. Looks much better on day 3!
