June 17, 2002
by Matt Moe
Here I provide some information on a recent suspension change that I have worked on in the past months. For about a year and half I had been running Bearmach 3 springs with N44 shocks in the front and extended N45 shocks in the rear. I was quite happy with this setup as it provided good flex off road, but as I added weight with front and rear bumpers, a heavy winch, and sliders, the springs proved to be too soft. So I decided to make a change toward a full OME setup that would provide a solid 2-½ under a good load.
This suspension setup is still in its trial stage. Much advice and most of my suspension products were found at Expedition Exchange. On the front end I matched OME 764 springs to N73 shocks. For the rear, OME 762 springs were matched to N76 shocks. The rear end also required a 1 inch spacer and new lower shock mounts. The 762 springs are rated at 220lbs/in and the rear springs are rated from 300 to 340lbs/in. The front and rear shocks, N73 and N76, are close to 3 longer than the standard OME shocks for the Discovery.
When installing taller springs and longer shocks a number of common issues emerge that need addressing. First the angles in the front and rear drive lines change dramatically, which often result in vibrations either in the front or rear or both. With my old suspension setup, I had already changed to a front double carden drive shaft sold by Great Basin Rovers and rear bottom links made by Rovertym Engineering. This combination helps compensate for the changes in the pinion angle and the RTE links provide more strength compared to the stock links. A second and related issue is the change in castor angle (basically, the steering geometry) will likely result in some loss in self-centering or tracking of the steering. Some people choose to put up with it, others install castor corrected radius arms, and others (like myself) have the luxury of a True Trac limited slip differential, which helps the steering to track straight. A third issue to consider is that taller shocks are likely to unseat the rear springs and the stock brake lines will be stretched to their limit, if they dont fail altogether. To address these issues, I previously had installed ExpeditionWare spring retainers and extended brake lines also sold by EE. Other people prefer cones rather than retainers for the rear springs.
For the standard install instructions follow the well-used spring and shock install. There are two other points to keep in mind when installing the taller 764s in the front and the 1 spaced 762s in the rear.
For the front end, I had already removed my panhard rod and sent it to a local shop to have the bushings replaced. This made it far easier to install the taller springs without a spring compressor, although the stock Land Rover bottle jack was used to help push the radius arm away from the frame. Even though I upgraded my brake lines, judging from how far the stock brake lines this stretched, longer brake lines might not be necessary in the front.
For the rear end, when I previously ran the Bearmach 3 springs I had made a small 1 bracket attached to the top of the diff housing to sneak the most out of the stock brake lines. This seemed to look ok under static conditions and held up off road, although I was constantly worried that a rear wheel would get stuck in a hole or caught against a ledge, allowing it to be leveraged downward and then shearing the brake lines. When I changed out my rear springs, I still had the stock brake lines in place. By unbolting the bracket that joins the solid to the flexible lines, you should be able to just squeeze the rear springs and 1 spacer into place without a spring compressor. Soon after installing the springs, I switched to longer lines in the rear.
Joshua Weinstein, who has installed a similar suspension setup, found a local shop that cuts 4-inch diameter aluminum rod, which we used as rear spacers. Josh provides information here in his article. I did three things slightly different. I drilled smaller 3/8 inch holes and reamed them a little. The bolts I used were 3/8 by 2-Ό inch instead of 2-½. And after grinding down the sharp edges, I painted my spacers black.
To accommodate the rear N76 shocks, I needed to make or buy new rear mounts. I chose to make my own out of piece of Ό x 2 x 3 angle iron and a piece of Ό strap. I welded these two pieces together to form a U. On the underneath of the U, I welded a large nut to act as a spacer. I had previously drilled a Ύ inch hole to accommodate the Ύ x 2-Ό inch grade 8 bolt that would be used to hold the mount in place.
In the photo below, you can see the rear suspension including the spring spacer and lower shock mount. You will notice that the way the shock is setup there is not a lot of up travel. I initially thought this would be an issue and have kept an eye on it and so far it does not appear to be bottoming out.
Compared to the previous Bearmach springs, I now have lot more stability on road and feel more comfortable during off camber situations off road. Even though I have only had about 350lbs in the rear cargo area, the vehicle definitely handles a load much better. My only complaint is that the rear N76 shocks could be slightly stiffer. The N76s appear to be very close to the regular OME N45in the upstroke but are definitely softer on the down stroke. In general I am very satisfied with the new suspension. It works well off road and provides great flex for heavy duty springs. The two photos below provide an idea of how much flex the suspension provides.
I recently took two measurements of my vehicle. The first was taken with a full tank, empty cargo, and highlift jack. The rear measured between 21" to 21-1/4" and the front between 20-3/4" to 21+". Weeks ago with a moderate load of about 300+lbs, I measured around 21" in the rear and 20-3/4+" in the front. On that occasion, most of that weight sat slightly forward of the rear axle. It seems as though my front passenger side is a little lower by close to 1/4", while the driver side is a solid 21". When I first considered this suspension setup, I wanted a good 2-½ inch lift. If you consider the baseline being close to 18-½, I might have achieved that goal. Keep in mind when making comparisons, I have heavy rear bumper including a skid plate, RTE sliders, and a modified ARB holding a 135lb winch in the front.