Mustang Drift Suspension- My Experiences with the Solid Rear Axle

So here it is based only on my personal observations. I preface it in this way because everyone has his or her own opinions and I have no need to debate what works better under these conditions or that. What my opinions are based on is my past 6-years of experience drifting MY sn95 chassis in all types of events across the country from grassroots to Formula Drift Pro-1.

So with that said; the standard 1979-2004 4-link/SLA suspension is what I started with. The second day I owned the car I was up at Summit Point for my very first HyperFest. This event should be on everyone’s “must do” list as it is so much fun. Back then, drifting was an all-import show and I think when I pulled into the paddock next to all the 240’s, you could actually hear the laughter over the sound of the engine. I actually got “boo’d at events back in those days but those are stories for another day…

Mustang LS 7-10-04

After coming home from this first outing I knew I had to start with the basics: Lower & Stiffer… First move was to cut the coil springs. I think I cut-off 1 ½ if I remember and this lowered the car a couple of inches and stiffened up the spring a bit so it was a good start. At the time, I was on a pretty-tight budget so cutting my springs was a good way to go as long as I only cut a little bit at a time. I knew that I could always cut off more but I couldn’t add any back so. I then used a big rose-bud torch to heat and re-shape the end s the spring sat down in it’s perch properly.

During this process I ditched the Quad-shocks too because I just thought the idea was a Band-Aid and sure enough, the wheel-hop was terrible. I then switched pretty quickly to Kenny Brown upper and lower Control Arms with heims on one end and urethane bushings on the other. These got rid of all of the wheel hop, period… (Quad shocks— whatever Ford!) because his arms did not flex. I also at this point added some shorter Vogtland springs that offered a lower ride height and stiffer than stock rates. All good things!

Quad Shock 99-04

As I got more proficient with the car I felt like the rear suspension was too-stiff in the rear in terms of anti-roll and I was looking for more grip. It seemed like I’d start the slide, everything was find (off power) and then as I’d add throttle and the car would start to hook-up around mid-corner, all of a sudden it would just hop-loose and it was all I could do (and sometimes not) to catch it and not spin out. I concluded at the time that I had too much roll stiffness…

KBP_Rear Suspension_Package

I tried a couple of smaller factory-style sway bars and this made it somewhat better. I then “just for the fun of it” tried a few runs with no rear SB at all… This seamed to help in some ways but I didn’t really like it on light-transitions because as one could imagine, the rear just “wallered-around” too much from side-to-side. At the time I felt the car was better enough to leave it off so I ran without a stock bar from there on out.

I then was talked into adding a Kenny Brown Panhard Rod… This I came to see was really not what I wanted at all as all it did was bind-up the suspension more than it already was. In other words, sure it located the axle from side-to-side but the more the body rolled, the more the PHR would bind everything up. I found this out one day by simply using a floor jack under the right-side spring plate. When I jacked it up a few inches, I expected the tire to tuck itself up into the wheel-well and leave the left tire down on the ground. What happened however was the right tire went up about two inches and then the left-side came up as well lifting the whole back of the car up with it.

I then started to understand why the car sometimes would go into a “snap-oversteer” condition because as the body would roll, it would lift the inside tire off the ground essentially leaving me with “a 3-wheeled” race car. Needless to say, this made the car very unpredictable and made me feel like I couldn’t catch a slide at times! Not good for driver-confidence… So with the PHR removed I did the same “floor jack test” and still found some binding but not nearly as much so I ran the car this way for a good while.

I then went through a period of shock & spring changes eventually going to coilovers.

KBP_Rear Suspension

The next step was to build my own control arms with heims at each end. This made an immediate improvement in the car as it helped the suspension “articulate” further before it bound-up. Yes it still did bind but it took more body-roll to get it to that point.

KBP_RLCA_79-04

At this point I’m sure you’re wondering, why not just get rid of the body-roll, then it won’t bind and everything will be good! As you may or may not know, contrary to the casual-observer’s thought, in drifting you need the rear suspension to be “free moving” and supple so as to gain as much grip as possible. This then allows you to stay on the power harder putting up more tire smoke, makes the car more controllable and ultimately, makes it faster so you can leave your pursuers in the dust (or smoke as it were)…

From the time I got involved with the Mustang, I knew about these things called “Torque Arms” and I fully understood why they worked as well as they did. Problem was, they are completely against all rules in drifting because you have to add a cross-member up by the transmission and there-bye you are “changing your original pick-up points”… Big No-No in the world of competitive drifting, they want things to remain somewhat OEM… I can go into a long talk about the pluses and minuses of this thinking but I’ll save that for another day.

So while I knew the TA would do the trick, I wanted to compete in FD and at the time the rules was, as long as you didn’t change your “pick-up points”, you were good. So how could I get the benefits of a TA but not add a cross member to my chassis???

With inspiration and a few parts from a few different sources (in particular Evolution which is now out of business), I devised a method of attaching 1-link in the center of the car which when combined with my existing double-heim lower arms gave me a sweet little 3-link set-up that worked at my desired super-low ride height. Naturally with now nothing to support the axle laterally I needed to re-install my Panhard Rod, which worked well until I folded it in half one day testing up at Englishtown. As they say, when you make one part stronger, the failure shows up somewhere else down the line…