Installation Time: Weekend
May 08, 2017
Nice, trickier install than expected
A friend and I installed the full set of Koni STR.T shocks and struts in my '11 Mustang GT convertible over the course of a weekend. I had been unhappy with the stock damping-- the car floated and bounced on the highway, squatted and dove accelerating and braking, and swayed and wobbled alarmingly when cornering. With the large tires and relatively soft springs the grip level was actually pretty high, I'm sure, but I was never comfortable using it since it always *felt* so unstable.
With the Koni STR.Ts installed the difference is obvious. First the downside-- on rough pavement at lower speeds, you will definitely notice that it rides harder. The soft stock setup could absorb this kind of situation and yield a smooth ride. With the STR.Ts it's definitely firmer and you'll feel the bumps. It's not bad at all, plenty of cars are this firm stock, but there is a difference.
The good part of the ride quality comes at higher speed, particularly on the highway. The increased energy being imparted to the springs at higher speeds was just too much for the stock dampers to tame, leading to the bouncing and heaving that was driving me crazy. It's a night and day difference with these new ones-- driving an asphalt highway onto a concrete overpass where the pavement is at different heights, there's now just a fwup fwup and hardly any body movement, whereas stock it pitched and bobbed up and down like a pogo stick with a blown shock. *Huge* improvement in ride quality here. Likewise dips in the road on fast two lanes are now handled smoothly without the deep body motions of the stock suspension.
Finally handling; I doubt the limits are really much if any different than before, but because the car is more stable and feels more planted, I now feel like I can come closer to them. This is a street setup anyway; I was never on the limit and don't plan to go there now. But it makes brisk 8/10 driving much more pleasurable and confidence inspiring. So all in all, a definite improvement in enjoyment, although I can't attest to what if anything it would do in terms of a skidpad or lap times.
So no doubt the pros and old hands will laugh at me here. I'm not much of a mechanic. I can change my oil and spark plugs, but I had never tackled a job like this before. Youtube install videos made it look reasonably straightforward though, and a much more experienced friend agreed to help out, so I decided to tackle it.
The first gotcha we encountered was removing the shocks. If you just turn the nut on the top of the shock mount, it simply spins the shaft inside the shock. The top of the shaft has flat sides, so you need to use those to hold it still. It proved easier said than done, however. Even a 6mm wrench (smallest I had) was a bit too big. Vice grips kept letting go. Eventually we went out and bought the biggest strongest set of vice grips we could find, and that did the trick. Most of the videos showed using an impact wrench, which might have made it easy to remove, but my car being a convertible has very little room above the shock mounts (the well for the top when it's folded down intrudes) so the impact wouldn't fit.
Retightening this nut once the new shocks were in was also difficult. You are supposed to torque them to a specific setting, but putting a socket on the nut covers the flat sides on the shaft, so once again the shaft just spins and the nut doesn't tighten. We had to get a crow-foot socket for the torque wrench so that the top of the shaft would not be obstructed and we could get the vice grips on it.
The bottom of the shocks was pretty straightforward removing the bolt with an impact and tightening with the torque wrench.
The next surprise was on the struts at the front. The brake line is held to the back of the strut with a bracket and what is essentially a large screw. The hole for this on the factory strut is threaded, so there is no nut. But the Koni was not threaded, and so the bolt wouldn't go in. We had to run out and buy a tap to make our own threads (8mmx1.25 is the size you need) which worked fine. I was very surprised by this oversight though, and this is why I'm dinging it one star for "Fit".
The nut holding down the top of the strut gave us the same issue as the one on the shock-- turning it just spins the whole rod that the nut threads onto. We eventually managed to hold this in place somewhat using a strap wrench. This was not enough to hold it when slowly turning it with a torque wrench, but it did provide enough resistance to tighten it with an impact. The factory service manual gives a torque spec for this nut, but in all the howto videos they just go at it with an impact, so we did the same. Maybe I'm just uptight, but the fact that we couldn't be sure of the torque here left me a bit uneasy, but it seems to be fine.
Only other thing to be aware of is that the Koni's come with a different size nut for the top of the strut. This was under a protective plastic cap and we almost discarded it as just part of the shipping protection. But the original Ford nut won't thread on, so we realized we had to use the new one here.
I'm sure someone more experienced would have an easier time, and we did eventually get it done, but it took a full weekend, including a lot of time running around to parts stores looking for things that we hadn't known we would need.
All in all I'm happy with the result. The installation is certainly doable if you know what you're doing, and even if you don't, but don't expect it to be a cake walk in the latter case. Recommended.