Adjustable Leaf Springs


New Member
May 4, 2013
Hey guys this is my first post on here. I have a 1976 Mustang II Mach 1 that I'm in the process of restoring and heavily modifying. As part of the modifications I'm cutting the rear quarter panels about 4-6 inches higher up into the car so I can fit a larger tire and still have my car sit fairly low to the ground. Essentially when finished the wheel wells will look something like the 05-09's with similar fender flares and ground clearances. With that I will need to drop the rear of my mustang 4-6" as well. I've read a bit on guys who have blocked their leaf springs to achieve 2-4 inches of drop but upon examination of my car I have adjustable leaf springs. What I mean is that on the shackle that the leaf spring attaches to, there are three sets of holes that it can bolt to. This adjusts ride height. I'm currently sitting on the middle adjustment point and could lower it roughly 1.5" going to the next hole, but my question is, can I drill new holes even further up the shackle? I have about 8" of space on the shackle that I could drill into, more than enough to achieve my desired drop. I'm just worried about my drive shaft clearances and any other rubbing or issues I may have with such a dramatic drop in this way. If anyone has tried this could you let me know how it went, how far you dropped your car and any tips that may help me when I get going on this. Thanks
  • Sponsors (?)


5 Year Member
Aug 11, 2013
Cleveland OH Area
I also have aftermarket adjustable shackles on my '78. I'm running on the 2nd of 3 holes as well, which puts it at just a little above the stock shackle height. If anything you're probably elevated right now and dropping to the 1st hole puts you a little closer to stock height -- if you have 8" of drilling room you've got some BIG shackles on there (stock are 3.5" bolt-to-bolt). I don't imagine going even a little lower is going to be any problem for interference. The exhaust and the tires themselves are pretty much the only things in the way, as long as you aren't bottoming the shocks or hitting the bump-stops. My dad's '76 when I was growing up had the rear springs sagging so badly after 10 years and 250K miles that the muffler would routinely scrape the ground, but that was about it.

One thing you might notice it that dropping the rear shackles even substantially isn't going to change your ride-height quite as much as you might want (you might need alternatives such as a flip kit or lowering blocks). When I pulled off my shackles I had the springs resting on the rails temporarily and the car wasn't sitting all that low. Then again I wasn't sitting in the car either so maybe it was. In my case I'm running P245-45-17's on the back at the middle shackle hole with only minor fender rolling so I didn't want much more drop.

Unfortunately your mileage is truly going to vary here, as there's no way to know how you're sitting and the condition of your springs right now, nor how your wheels and exhaust will sit when you lower it. But as you mention, they're adjustable, try a few settings and see how you like it. Usually the 3 holes are on one end of the shackle, you could even flip the shackle over and bolt through two of them just to see how you like it fully dropped.
Last edited: