Stumbled on this article on Autospeed below (oddly, I'm not allowed to post links ??)
Does seem the easiest way to do it (D mounts/bushes as clamps). I'd probably just do that on the ends of the bar, and piggy back the chassis D mounts that exist with the new bar/mounts.
Should work in theory. Really need a second bar to 'mock' up against it first.
Adding a Second Sway Bar
Now this is the real bargain approach. What you do is to parallel another sway bar with the original. While that might seem like way overkill, it isn’t necessarily. Let’s take a look.
Take car that runs a 27mm front sway bar. It’s a rear-wheel drive car with plenty of torque and without an LSD, is prone to lift an inside rear wheel in cornering. A bigger front bar will keep the car sitting flatter, providing better traction at possibly the expense of a little loss in front-end grip.
No upsized bar is available from other models of the same car (ie 27mm bar was the largest size used) but what if we add a second 27mm bar to the front? All other things being equal (which they aren’t), that would double the front sway bar stiffness.
Doing the maths above shows that to double the stiffness of the 27mm bar, we’d have to increase its diameter to 32mm. Hmmm, doesn’t sound so great a jump now, does it? Or, by adding a 25mm bar (easily sourced from an earlier model) to the standard 27mm bar, the stiffness increase would be approximately like upsizing the standard bar to just under 30mm.
So how do you add a second sway bar? The exact approach depends on how the sway bar is mounted but one method involves cutting off the mounting ends of the second bar and then clamping it to the original. Strong clamps can be easily gained if you buy a whole bunch of original sway bar mounts – they’ll have the right strength and also come with D-rubbers to suit the sway bar diameter. All you’ll need in addition are some high tensile nuts and bolts... and even including the sway bar, the total of that lot can be under fifty bucks!
Here’s how to do it:
Go to a wrecker and obtain a second standard sway bar. Compare it to another standard bar to check it’s not bent, and make sure it’s not rusty or otherwise stuffed. When you’re doing your comparison, make sure that there’s room to fit it below the standard bar, without it hitting anything even with suspension and steering movement.
Buy eight (yep, eight!) sway bar mounts and rubber bushes. These don’t have to be from the same make and model of car, but make sure the rubber bush is for approximately the same size bar (eg within a few millimetres). These rubber bushes can get chewed-out over time, so inspect the rubber before plonking down the cash. Hold the new sway bar up against the original and work out how the two are to be attached. A couple of approaches can be taken but easiest is to do as is shown here. In this a diagram the black sway bar and red mounts are the originals. The green sway bar has had its ends cut off and is then is clamped to the original using four clamps. Unlike in this diagram, the new sway bar is usually mounted directly below the original.
Each clamp is made by using a pair of sway bar mounts bolted together, mounting faces of one clamp against the mounting faces of the other. The original rubber bushes are retained but the bar no longer swivels within them. To join the clamps make sure that you use high tensile bolts (available from bolt stores and industrial suppliers) and not cheap low quality hardware store nuts and bolts.
The original sway bar is most easily shortened by being cut with a friction saw. Shorten the arms only by the minimum amount to provide clearance to the original suspension mounts. If you shorten the arms too much, you’ll find it hard to retain enough space for adequate clamping. The greater the distance between the clamps on each side, the better will be the security of the system. Again check that nothing touches at full steering lock (front) and with full bump and rebound (front and back).