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Have a 2013 convertible, ordered a set of Roush lowering kit being delivered today. Hopefully doing the install this weekend. These springs were the only kit I researched that claimed to not degrade the ride quality, and being an old guy, that remains a priority. Started this thread to keep track of this mod from start thru any rabbit holes thru completion.
The benefit I have is automotive service and repair is my profession and have access to tools and equipment to complete this. First off is an alignment check and will post an image of this before starting the process. Curious how this minor mod will move the rear axle from center, along with will it change drive shaft angle along with pinion angle. Roush claims there will be no need to further mod this car. Proof will come as I go further. I hope they are correct.
This is the before alignment check.
After the spring install. Total toe went up a tad bit, front camber increased about .2 degrees more negative on the left side, and the right side .45 degrees more negative.
Last edited by Ryunker; 3/6/22 at 03:45 PM.
Reason: Photos
Having the Roush suspension on my car, I believe you will see difference in your ride with the the Roush lowering springs verses the stock springs. Mine is noticeably stiffer and tighter than a stock Mustang, Definitely handles better. Still I would not say that I would consider a harsh or a rough ride. I too am an older guy and I have back issues, but I enjoy driving mine. Have taken it on a few longer runs on our poorly maintained roads here in Idaho. The addition will improve the stance and handling over the stock setup.
Looking forward to your install, information you find, and your view on the change.
Lowering springs pretty much have to be stiffer, so the suspension won't bottom out all the time . . . hopefully you won't find it "too harsh."
If you check your rear axle right now, you'll probably find that it is already off center a little. The lowering will probably make this a little worse, like Siber said. Unless it is way off, it probably doesn't matter much, unless you are super picky about how it looks from the rear, or you want perfect alignment including thrust angle.
Pinion angle is not a big deal, assuming you have the original two-piece driveshaft. It's more critical with a one-piece driveshaft. You'll also pick up some negative camber in the front, probably will end up borderline on the factory specs. This is also not a big deal; might make the tires wear a little more on the inside, but it's generally good for "handling."
So last night installed new set of tires, standard size 17" as this is a base V6. Went ahead did an alignment check before starting on the Roush lowering kit.
After the lowering kit install, the rear axle is now not centered. It is too far to the left by 3/4". Front camber is on the far side of negative camber at a negative 1.5 degrees, so for every one degree of camber degrades tread life by 20% so as it sits I am in for 30% less tread life. For me this is not going to be OK, I will be having a set of caster camber plates enroute very soon.
As for the finished ride height all else suspension and tires are 100% OE front dropped 15mm (.6 inches) so a tad mor than the advertised 1/2 inch, the rear dropped a tad more at 20mm ( just over 3/4").
The ride quality remains really unchanged, the rear of the car is way more stable, before I would describe it as a bit of body roll in the rear and that is totally gone.
Installation was straight forward with nothing noted as being stupid.
Rear end adjustable control arms and panhead bar from "American Muscle" I went with the "Whiteline" stuff. The lower control arms are on a bit of backorder. This will allow me to get the thrust angle center as right now there is a bit of toe off which I feel can be removed with the adjustable lowers.
Also as long as you are under 2" it is unnecessary to correct the pinion angle by adding a bump steer kit. My "06" GT is lowered by 1.3" front/1.5" rear with Eibach Pro Springs and Koni adj yellow struts/shocks. I also upgraded to the BMR adjustable Panhard bar for recentering the rear axle along with upgrading to Ford Performance GT500 strut mounts and Eibach camber bolts which brought the camber back within Ford OEM specs. Other than that, my suspension remains OEM stock, but plan on upgrading to either Steeda, BMR, or Whiteline LCA's in order to eliminate that dreaded wheel hop. Meanwhile, good to know ride quality remains unchanged with your Roush lowering spring kit, and also welcome aboard
I wouldn't worry too much about the negative camber, I doubt it will make anywhere near that difference in tire wear, but go ahead and correct it, if it makes you feel better. I am running -2 degrees (car is set up for road track) and haven't noticed any bad tire wear at all, but I don't put a lot of miles on the car, so it is hard to say. One track day evens out the tire wear quite nicely (track tends to rip-up the outer edge of the front tires pretty bad, that is the reason for the negative camber)
I'd like to see the front toe dialed in a bit better, I think you want near-zero or maybe a hair toe-out.
The adjustable panhard bar and adjustable rear LCA's should allow you to get the rear toe (aka "thrust angle") dialed in, but I don't know if an alignment shop will spend the time that is needed to do that right. You probably will need to get everything very close yourself, and then just get the alignment shop to do the final tweaks.
3/3/22, 10:24 AM
