Coil-over suspensions for Land Rover Defenders

This page was copied from Chris Hinkle with his permission. Thanks for the great job. Visit his hompage.
Prior to my second trip to Moab in 1997, I added 4.7 gears, a Safari Gard rear bumper and the Safari Gard JE III suspension. After Moab, I started changing things again.
During that second trip to Moab, I did Wipe Out Hill and a couple of other off-camber/ downhill/ one wheel dropoffs with the JE III suspension that really got my adrenaline up - the defender seemed very sensitive to off-camber situations. I came back to Dallas, bought a Corsa data acquisition system and some linear potentiometers, dug a hole in the back yard and started testing spring and shock combinations. Basically what I found is that when the front wheel of a defender comes off an 18" ledge/rock, the soft SG spring(150 lb/in) allows the body to over-rotate considerably - it doesn't feel bad, because of the excellent damping of the Fox racing shocks, but it actually has worse over-rotation than a standard OME setup. As can be seen in Figure 1, the SG JE III suspension actually allows the front end to dive about 1" further than the OME
springs and shocks. In other words, you’re getting better articulation with the SG JE III suspension, but in off-camber situations, you’re degrading off camber performance because of the softer springs.
After visiting the Fox factory, I decided to try a dual shock system in the front. I purchased an MJ Lee dual shock tower and added a position-sensitive shock in combination with the regular Fox racing shock in the JE III suspension. The position-sensitive shock only functions in the first half of itís travel, as it extends beyond the midpoint of itís travel the compression and rebound drop to 0. Taking advantage of this feature allows you to tune the front suspension and have different compression and rebound rates at different extensions of the shocks. As can be seen in Figure 2, when I use a dual shock system in the front of the D90, I can basically eliminate over-rotation completely (the shock setup supplements the soft spring). The dual shock system gives 3" less over-rotation when coming off a drop off when compared to the Safari Gard JE III suspension.
 
Another benefit of my Fox factory visit, was a better understanding of some of the other options available - especially coil-over shocks. I had ramped my yellow D90 several times and it was apparent that the spring was preventing additional droop in the rear (on the Safari Gard JE III suspension the rear spring is clamped to the upper and lower spring mounts- the 19" spring actually stretches to about 24" :). After evaluating the options, I decided I could put coil-over shocks in the rear of the defender and then the only limitation to droop was the shock travel. I had the Off Road Shop rebuild the upper shock mounts for additional strength and to relocate the upper shock mounting point. I ordered 14" Fox racing coil-over racing shocks for the rear. I also ordered Hypercoil springs in ratings from 200 lb/in to 600 lb/in to test the different combinations. (It takes two springs per shock).
After installation of the 14" Fox coil-overs in the rear, the limiting factor in wheel droop became the stock trailing arms and their attachment at the frame. I got one of the local racing shops to fabricate some 36" chromolloy trailing arms with heim jointed rod ends. The Off Road Shop fabricated a new bracket to attach the trailing arms to the frame (total length  
39" with rod ends attached). The greater arc that the axle goes through now, has the added advantage of limiting forward movement of the drooping wheel. Total package yields some awesome articulation in the rear of the defender (see photos below)Because I now had two spare 12" Fox racing shock (they came off the rear), I had MJ Lee fabricate a new dual shock mount for the front which would allow the use of the existing Safari Gard 150 lb/in springs from the JE III suspension together with 12" Fox shocks. Again I went with one regular shock and one position-sensitive shock on each front corner.
As I have stated in the past, I modified a Safari Gard upper shock mount to allow me to stuff a 14" Fox coil-over shock in the rear of my yellow D90. I have included several pictures of the upper shock mount on the coil-over system to show how the mount attaches. Also which bracket and mount it replaces on the frame. The mount pictured on the ground is the SG Stage III mount. In order to accommodate the added stresses of the coil-over and the longer shock, I had a new mount built with thicker tubing and plate. I also moved the attachment point for the shock forward. As you can see, it's a fairly straight forward design. In this situation, materials and construction are very important.

These are photos of my rear 14" Fox coil-over shock. You can see in the photo the A-arm dropping down, the stretched brake line, and the chromemoly trailing arm. The drivers side wheel is on the ground, the disc brake is on the ground on the passenger side and the jack stand is near full extension. The shock, however, is not yet to full extention.

 

Attached is a picture of the 10" dual shock arrangement with a regular Fox shock, a position-sensitive Fox shock, and an MJ Lee dual shock mount. Also, I've scanned the same picture to hopefully give details showing a bracket that allows the use of a Heim jointed shock with a defender.