MustangCollector
Well-Known Member
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Since many members are on the fence with what lowering springs to get and pros and cons I wanted to make this thread from my experience using both of Eibachs offerings, the Sportline and Pro Kit.
I originally based my first decision on photos on the boards of the S550 with new wheels and the Pro kit just didn’t look like what I was after. I will say firsthand DO NOT BASE your choice off photos because I was clearly wrong. Every car and wheel and tire fitment will visually look different on these cars. Also lots of guys are posting photos right after the install with no time to settle the suspensions or after full settling over time, which also can be misleading if your main goal is stance.
My main reason for the spring install was to help with the bouncy nature of the rear IRS and to clean up the fender gap. I also wanted a much firmer car and since no shocks were available I picked the stiffer and lower spring first.
Lets be honest Springs are not an all out high performance upgrade on this car, yes they help handling some but if you think it will make a drastic handling upgrade you may be disappointed. The cars with both springs I think ride more compliant than the stock PP springs under some conditions.
So I had the Sportlines installed and my car was very LOW, actually it lowered about 2 inches all around maybe even more. I think my car settled very quickly because of the bumpy NYC roads I drive on but as time went on I really realized how bad of a choice these were for my car and my driving. My tires front and rear were buried under the fender well and not even a penny would fit as there was Zero gap.
The issue with lowering these cars too much, I mean over 1 inch is the geometry is all screwed up and it cannot easily be dialed back in since there is limited aftermarket support regarding this. So my car had about -2.4 rear camber and -2.2 up front. It handled horrible, it launched unpredictable and just didn’t feel right. I thought it was the lack of new performance shocks but it really was the geometry issue from being so low. I tried aligning the car a few times with various changes and nothing really helped. All in all the Sportlines are great for someone who wants a super low show stance and cruises around on nice roads who does not aggressively drive on twisties. So if your in Florida or So Cal these might be your best choice, if you have poorly paved roads your really in for a treat then. The ride quality of the Sportlines was very good I was actually shocked since there appeared to be almost no suspension travel with the car being so low. Also ground clearance is an issue as my OEM exhaust and Steeda G Brace hit many times in steep driveways. Maybe with proper adj shocks the Sportlines might be excellent but then you still face the geometry limits. If the Geometry can be corrected and sport shocks existed I think this would be a great combination but for now it doesn’t exist.
So I spent time reading up and calling all the vendors out there who all agree that over 1 inch drop severely degrades the S550 handling and behavior so lesson learned and backed up by industry experts.
I guess it all comes down to what you are really after and if you guys have enough experience with very good sports cars to notice these degrading traits of excessive lowering. Youll be surprised how many owners of cars slam them down low and have no clue that their car drives so poorly or they just don’t care and are after the look. Im sure you guys have seen the Massive camber and stretched tire trend which makes me speechless every time I see one of these cars bouncing around NYC
So now on to the Pro kits. Here are some things I noticed between the two spring sets
1. Sportlines seem to be much heavier in weight side by side, the Sportlines also are stiffer and may be made using different type of coil wire. Bumps with the Sportlines were very tight and they seemed to control any shock thrown into the cars chassis quite well. More rebound of the shocks would be magic with these springs. The Sportlines are coiled tighter in the rear only.
2. Pro kits do ride much smoother, actually smoother than the OEM PP springs if you ask me. They feel really neutral as this term best described the Pro Kit for me. Over bad bumps there seems to be less suspension travel as the suspension is soaking up the bumps rather than bumping over them with the Sportlines. The cars geometry is greatly improved as my rear camber is -1.4 now and front -1.1. With the Pro Kit my cars IRS feels perfectly balanced through hard turns and does not feel so uneasy as the Sportline did. Excessive negative camber may be been to blame with the Sportline kit.
3. Both kits come with new front and rear BumpStops and for both kits the Bumpstops are the same part number. According to the spec sheet Eibach created these for up to 10mm of bumpstop compression, believe it or not this is a lot considering how little suspension travel these cars have I think. Some cars are engineered to ride on bumpstops while others are slight touching. I think the S550 does ride on them when being lowered up front but I could be wrong. I still wonder why Eibach upgrades their stops and Steeda does not.
4. Steering, i complained in other threads over bumpsteer and with Sportlines and NYC it sucked. with Pro Kit it is much better, still not perfect but much better. i think this car just has bumpsteer in its configuration and it may or may not be able to be corrected fully. It is the only thing i truly dislike about this car overall.
Also the Pro kit launches perfectly straight and I am happy with this. With the Sportlines it was very skidish off the line hard and just didn’t feel right at all. Also may be from the excessive rear camber.
On the highway at very high speeds the Pro kit feels smooth as glass.
On the highway at anything about 80mph with the Sportlines I did feel minor rear vibration coming through my car, very minor but still there. I think the excessive negative pitch of the axles could have caused this or the excessive drop affected my pinion angle? Not sure but it didn’t bother me because I rarely get to drive over 80 anyways.
As for overall feel, the Pro kits feel neutral the stance is PERFECT imho I would not want anything more. The handling is decent and this car may actually handle better with linear rate springs over progressive but once BMR releases there springs I guess we can all see feedback to compare. I can feel the backend changes during the compression a lot with these Pro kit springs but when pushing harder it feels a bit weird and not confident inspiring., might be the shocks are at their limits really. Overall if you after practicality go Pro kit or Steeda, if you want a show car cruiser and drive on flat Florida style roads go Sportline. I would love to try some BMR springs if they would be willing to send me a set to try out. I still want a true shock and spring combo as I think investing 4k on coilovers is a bad idea for a daily street driver.
I hope this info can be subjectively used by other members in making the right choice and by the polls it seems a majority out there have made the right choice so far. I plan to do another alignment soon once other parts arrive for the rear IRS, toe and vertical links.
I originally based my first decision on photos on the boards of the S550 with new wheels and the Pro kit just didn’t look like what I was after. I will say firsthand DO NOT BASE your choice off photos because I was clearly wrong. Every car and wheel and tire fitment will visually look different on these cars. Also lots of guys are posting photos right after the install with no time to settle the suspensions or after full settling over time, which also can be misleading if your main goal is stance.
My main reason for the spring install was to help with the bouncy nature of the rear IRS and to clean up the fender gap. I also wanted a much firmer car and since no shocks were available I picked the stiffer and lower spring first.
Lets be honest Springs are not an all out high performance upgrade on this car, yes they help handling some but if you think it will make a drastic handling upgrade you may be disappointed. The cars with both springs I think ride more compliant than the stock PP springs under some conditions.
So I had the Sportlines installed and my car was very LOW, actually it lowered about 2 inches all around maybe even more. I think my car settled very quickly because of the bumpy NYC roads I drive on but as time went on I really realized how bad of a choice these were for my car and my driving. My tires front and rear were buried under the fender well and not even a penny would fit as there was Zero gap.
The issue with lowering these cars too much, I mean over 1 inch is the geometry is all screwed up and it cannot easily be dialed back in since there is limited aftermarket support regarding this. So my car had about -2.4 rear camber and -2.2 up front. It handled horrible, it launched unpredictable and just didn’t feel right. I thought it was the lack of new performance shocks but it really was the geometry issue from being so low. I tried aligning the car a few times with various changes and nothing really helped. All in all the Sportlines are great for someone who wants a super low show stance and cruises around on nice roads who does not aggressively drive on twisties. So if your in Florida or So Cal these might be your best choice, if you have poorly paved roads your really in for a treat then. The ride quality of the Sportlines was very good I was actually shocked since there appeared to be almost no suspension travel with the car being so low. Also ground clearance is an issue as my OEM exhaust and Steeda G Brace hit many times in steep driveways. Maybe with proper adj shocks the Sportlines might be excellent but then you still face the geometry limits. If the Geometry can be corrected and sport shocks existed I think this would be a great combination but for now it doesn’t exist.
So I spent time reading up and calling all the vendors out there who all agree that over 1 inch drop severely degrades the S550 handling and behavior so lesson learned and backed up by industry experts.
I guess it all comes down to what you are really after and if you guys have enough experience with very good sports cars to notice these degrading traits of excessive lowering. Youll be surprised how many owners of cars slam them down low and have no clue that their car drives so poorly or they just don’t care and are after the look. Im sure you guys have seen the Massive camber and stretched tire trend which makes me speechless every time I see one of these cars bouncing around NYC
So now on to the Pro kits. Here are some things I noticed between the two spring sets
1. Sportlines seem to be much heavier in weight side by side, the Sportlines also are stiffer and may be made using different type of coil wire. Bumps with the Sportlines were very tight and they seemed to control any shock thrown into the cars chassis quite well. More rebound of the shocks would be magic with these springs. The Sportlines are coiled tighter in the rear only.
2. Pro kits do ride much smoother, actually smoother than the OEM PP springs if you ask me. They feel really neutral as this term best described the Pro Kit for me. Over bad bumps there seems to be less suspension travel as the suspension is soaking up the bumps rather than bumping over them with the Sportlines. The cars geometry is greatly improved as my rear camber is -1.4 now and front -1.1. With the Pro Kit my cars IRS feels perfectly balanced through hard turns and does not feel so uneasy as the Sportline did. Excessive negative camber may be been to blame with the Sportline kit.
3. Both kits come with new front and rear BumpStops and for both kits the Bumpstops are the same part number. According to the spec sheet Eibach created these for up to 10mm of bumpstop compression, believe it or not this is a lot considering how little suspension travel these cars have I think. Some cars are engineered to ride on bumpstops while others are slight touching. I think the S550 does ride on them when being lowered up front but I could be wrong. I still wonder why Eibach upgrades their stops and Steeda does not.
4. Steering, i complained in other threads over bumpsteer and with Sportlines and NYC it sucked. with Pro Kit it is much better, still not perfect but much better. i think this car just has bumpsteer in its configuration and it may or may not be able to be corrected fully. It is the only thing i truly dislike about this car overall.
Also the Pro kit launches perfectly straight and I am happy with this. With the Sportlines it was very skidish off the line hard and just didn’t feel right at all. Also may be from the excessive rear camber.
On the highway at very high speeds the Pro kit feels smooth as glass.
On the highway at anything about 80mph with the Sportlines I did feel minor rear vibration coming through my car, very minor but still there. I think the excessive negative pitch of the axles could have caused this or the excessive drop affected my pinion angle? Not sure but it didn’t bother me because I rarely get to drive over 80 anyways.
As for overall feel, the Pro kits feel neutral the stance is PERFECT imho I would not want anything more. The handling is decent and this car may actually handle better with linear rate springs over progressive but once BMR releases there springs I guess we can all see feedback to compare. I can feel the backend changes during the compression a lot with these Pro kit springs but when pushing harder it feels a bit weird and not confident inspiring., might be the shocks are at their limits really. Overall if you after practicality go Pro kit or Steeda, if you want a show car cruiser and drive on flat Florida style roads go Sportline. I would love to try some BMR springs if they would be willing to send me a set to try out. I still want a true shock and spring combo as I think investing 4k on coilovers is a bad idea for a daily street driver.
I hope this info can be subjectively used by other members in making the right choice and by the polls it seems a majority out there have made the right choice so far. I plan to do another alignment soon once other parts arrive for the rear IRS, toe and vertical links.
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