Coilover Spring Rate Help
06-18-18, 11:37 PM
#1
Coilover Spring Rate Help
Hi,
I just ordered a set of BC coilovers from FIGS engineering because I wanted to bundle it together with their front LCA bushing and I customized the spring rates to be 14k/12k but a rep contacted me and recommended going 14k front and rear due to the 3IS having a divorced rear spring and shock set up and that due to the spring being "closer to the pivot point which makes the spring 'feel' lighter than it is" they are recommending a square set up over a staggered one. I have never seen anyone run a square set up when it comes to spring rates so I am just curious as to what other people's inputs are for this situation. Should I go with the square set up they recommend or still run 14k/12k?
I just ordered a set of BC coilovers from FIGS engineering because I wanted to bundle it together with their front LCA bushing and I customized the spring rates to be 14k/12k but a rep contacted me and recommended going 14k front and rear due to the 3IS having a divorced rear spring and shock set up and that due to the spring being "closer to the pivot point which makes the spring 'feel' lighter than it is" they are recommending a square set up over a staggered one. I have never seen anyone run a square set up when it comes to spring rates so I am just curious as to what other people's inputs are for this situation. Should I go with the square set up they recommend or still run 14k/12k?
06-19-18, 12:45 AM
#5
Right? Which is why I thought the rep's recommendation was a bit weird but I don't know too much about coilovers and spring rate selection that's why I wanted to see what other people think. Based on his explanation, the main reasoning seems to be because of the divorced spring and shock set.
06-19-18, 03:09 AM
#6
The stock setup has stiffer springs in the rear than in the front (approx 4.2/6.4 F/R).
Definitely don't go with a stiffer front setup than rear, if that's what you had selected I would recommend against it. At minimum go the same front and rear, but I would probably suggest going with stiffer rear than front. Probably in the 30-50% stiffer range for the rear.
Jeff
Definitely don't go with a stiffer front setup than rear, if that's what you had selected I would recommend against it. At minimum go the same front and rear, but I would probably suggest going with stiffer rear than front. Probably in the 30-50% stiffer range for the rear.
Jeff
06-19-18, 07:03 AM
#7
The stock setup has stiffer springs in the rear than in the front (approx 4.2/6.4 F/R).
Definitely don't go with a stiffer front setup than rear, if that's what you had selected I would recommend against it. At minimum go the same front and rear, but I would probably suggest going with stiffer rear than front. Probably in the 30-50% stiffer range for the rear.
Jeff
Definitely don't go with a stiffer front setup than rear, if that's what you had selected I would recommend against it. At minimum go the same front and rear, but I would probably suggest going with stiffer rear than front. Probably in the 30-50% stiffer range for the rear.
Jeff
BC Racing: 12k/10k
RSR: 10k/ 8.3k
Parts by Max: 20k/16k
KW X Greddy: 11k/8k
I wasn't aware that the stock suspension is stiffer in the rear than the front. The only coilovers that I found with stiffer rears than the front is from Tein which most of their coilovers is 9k/ 11k
Is there a big difference running 14k front and rear as opposed to 14k/ 12k?
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06-19-18, 08:39 AM
#8
Interesting. If that's the case I wonder why so many aftermarket companies sell their coilovers with the front usually stiffer than the rear.
BC Racing: 12k/10k
RSR: 10k/ 8.3k
Parts by Max: 20k/16k
KW X Greddy: 11k/8k
I wasn't aware that the stock suspension is stiffer in the rear than the front. The only coilovers that I found with stiffer rears than the front is from Tein which most of their coilovers is 9k/ 11k
Is there a big difference running 14k front and rear as opposed to 14k/ 12k?
BC Racing: 12k/10k
RSR: 10k/ 8.3k
Parts by Max: 20k/16k
KW X Greddy: 11k/8k
I wasn't aware that the stock suspension is stiffer in the rear than the front. The only coilovers that I found with stiffer rears than the front is from Tein which most of their coilovers is 9k/ 11k
Is there a big difference running 14k front and rear as opposed to 14k/ 12k?
RSR Lowering Springs are 4.6k/8.67k or 5.1k/8.16k, but their coilovers are 10k/8.3k or 18k/10k
Seems odd to me, but I don't know. I've never gone so far as to swap which springs are stiffer front to rear, but apparently companies are doing it with the 3IS, so perhaps there is a benefit to making the front way stiffer than the rear?
Jeff
06-19-18, 08:50 AM
#9
Interesting, I'm seeing differences in some of their offerings.
RSR Lowering Springs are 4.6k/8.67k or 5.1k/8.16k, but their coilovers are 10k/8.3k or 18k/10k
Seems odd to me, but I don't know. I've never gone so far as to swap which springs are stiffer front to rear, but apparently companies are doing it with the 3IS, so perhaps there is a benefit to making the front way stiffer than the rear?
Jeff
RSR Lowering Springs are 4.6k/8.67k or 5.1k/8.16k, but their coilovers are 10k/8.3k or 18k/10k
Seems odd to me, but I don't know. I've never gone so far as to swap which springs are stiffer front to rear, but apparently companies are doing it with the 3IS, so perhaps there is a benefit to making the front way stiffer than the rear?
Jeff
06-21-18, 02:10 PM
#12
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Check what rates performance brand springs use as your starting point. For instance, I see all Tanabe springs have a higher rear spring rate. Unless you have Research and Development experience and/or racing feedback .. I would stick with the top brand recommended rates depending on the drop.
06-21-18, 04:32 PM
#13
Suspension tuning is a well known black magic...there's so much to think about. Eerything affects everything and there's usually a lot of math involved. Check out this very informative link if you want the long answer: http://speed.academy/how-to-choose-s...h-koni-marcor/
Short/lazy answer is 2K difference isn't much and won't be very noticeable on the street. Either 14/14 or 14/12 will be fine, nether setup will help you get to work faster nor make you crash on the highway ramp. Springs are cheap. If you don't like your choice, you can always change it later.
On the topic of different manufacturers offering different rates and front/rear bias: The easiest explanation for a softer rear rate is less oversteer. Oversteer can be dangerous, so manufacturers like to play it safe. Also, wheel/tire choice makes a difference--R comp or street tire--staggered or square wheels/tires, vehicle weight, etc etc. Going from divorced spring and shock to true coilover also affects spring rate choice. As I said above, everything affects everything lol
Short/lazy answer is 2K difference isn't much and won't be very noticeable on the street. Either 14/14 or 14/12 will be fine, nether setup will help you get to work faster nor make you crash on the highway ramp. Springs are cheap. If you don't like your choice, you can always change it later.
On the topic of different manufacturers offering different rates and front/rear bias: The easiest explanation for a softer rear rate is less oversteer. Oversteer can be dangerous, so manufacturers like to play it safe. Also, wheel/tire choice makes a difference--R comp or street tire--staggered or square wheels/tires, vehicle weight, etc etc. Going from divorced spring and shock to true coilover also affects spring rate choice. As I said above, everything affects everything lol
06-21-18, 09:55 PM
#14
Suspension tuning is a well known black magic...there's so much to think about. Eerything affects everything and there's usually a lot of math involved. Check out this very informative link if you want the long answer: http://speed.academy/how-to-choose-s...h-koni-marcor/
Short/lazy answer is 2K difference isn't much and won't be very noticeable on the street. Either 14/14 or 14/12 will be fine, nether setup will help you get to work faster nor make you crash on the highway ramp. Springs are cheap. If you don't like your choice, you can always change it later.
On the topic of different manufacturers offering different rates and front/rear bias: The easiest explanation for a softer rear rate is less oversteer. Oversteer can be dangerous, so manufacturers like to play it safe. Also, wheel/tire choice makes a difference--R comp or street tire--staggered or square wheels/tires, vehicle weight, etc etc. Going from divorced spring and shock to true coilover also affects spring rate choice. As I said above, everything affects everything lol
Short/lazy answer is 2K difference isn't much and won't be very noticeable on the street. Either 14/14 or 14/12 will be fine, nether setup will help you get to work faster nor make you crash on the highway ramp. Springs are cheap. If you don't like your choice, you can always change it later.
On the topic of different manufacturers offering different rates and front/rear bias: The easiest explanation for a softer rear rate is less oversteer. Oversteer can be dangerous, so manufacturers like to play it safe. Also, wheel/tire choice makes a difference--R comp or street tire--staggered or square wheels/tires, vehicle weight, etc etc. Going from divorced spring and shock to true coilover also affects spring rate choice. As I said above, everything affects everything lol