I wanted to add a (long) update to this thread with some recent changes in suspension, tires, and other. Also, some things you might want to check if you are experiencing extreme body roll or bump steering after installing a Rancho lift or similar.
About 2 months ago my R51 started having bad bump steering issues. The Pathy always had a bit of an ass wiggle, but was never uncomfortable or dangerous like many people describe. But in a short period of time it had become very bad. Every time I hit a bump, ripple or ridge in the road, the ass-end would try to jump out from under the truck. It was happening at all speeds, but was extremely un-nerving at 70+mph... downright scary.
I suspected alignment, but also felt the big BFGoodrich A/T 285/65/18 tires where putting extra strain on the suspension. After 15k miles the tires looked brand new, almost zero wear! The downside of this was, these tires weighed about 60lbs each (without rims) and even at 35psi, they were hard as a rock. Rated at almost 5000lbs per tire, I was convinced they were just too much for my needs... 80% highway speeds, 10% city, 10% rural roads and trails daily. Even before the bump-steering started, I needed to keep the ranchos tuned stiff to get the best highway ride, but sharp bumps would jar the entire vehicle.
So here is what I did, what I found wrong, and a surprise issue I found..
First, I found that the bushings on the lower control links were bad. I had checked these a few months back at a tire rotation and they seemed fine, but this time they were not. The left had obvious play and even though the right side looked & felt good, it showed to be bad after we took it apart and un-sprung the suspension. The frame side of the lower link has a non-removable bushing, so I had to buy new lower links with bushings installed. About $35 ea. from Nissan.
That might have been the end of the story, but once on the lift without tires, I noticed that the right side suspension was not hanging level. Even if I pushed the right side up, (which pushes the left lower), it would return to an uneven level. I found two issues. First, when they installed my Rancho spring spacers, the right spacer was not seated into the upper spring cavity 100%. The spacer is a pretty snug fit into the cavity that holds the top of each rear spring. If the spacer is tilted, even a little, it will stop before it seats. I'm not talking a lot, the slightest angle will jam the spacer. In my case it was about 1/2" lower, inside the cavity. You would have thought that after a year of driving it would have seated. But until un-sprung, it remained jammed and unseated. This was not easily seen from below the vehicle as most of the spacer is hidden inside the spring cavity.
So if your having sway or bump steering issues and are using spring spacers, try lifting the vehicle and insuring your rear axels hang level without the tires, and insure they return to level if push one side up or down. Because on the ground the vehicle was still sitting straight as the suspension compensated for the 1/2" spring height difference. Also make sure the springs are in the same alignment. That is, after 100k miles my springs have a slight lean or curve when they are set on the ground. In my case they were both were curving right as installed. But if aligned the springs on the ground with the factory "paint marks" both facing rear, the springs had a more uniformed curve, left curving left & right curving right.
Since I had my lift installed immediately after purchase, and installed at a big box store, I was not present during install. The rear lift spacer seating and spring alignment is where they dropped the ball. I believe the uneven compression on the rear springs made the Pathy much more unstable in the rear, especially at high speed, even though the vehicle sat level and straight.
I also, replaced the rear shocks with Bilsteins. I had read that the Bilsteins worked smoother on mixed driving and was tired of constantly search for the best setting on the Ranchos. The Ranchos were great on soft (1-3) in the dirt, and smooth at firm (7-9) on the highway or while towing, but I could not find a happy medium. I now know the spring alignment and spacer issue may have caused some of that, but I had already purchased the Bilsteins, so I installed them.
Here are a few shots of the lower link removal and the springs setting on the level floor.
I also decided to replace those heavy (60lbs) BFGoodrich A/T 285/65/18 tires with the (40lbs) Goodyear A/T Adventure w/Kevlar 275/65/R18. These lowered my height by about 1" and when combined with the below roof rack mod, which lowered my overall height by another 4", it now allows me to enter parking garages with a 7' clearance. Before I sat at 7'2" to top of rack. Not having to park on the street in the city is a big plus. Most garages I use are 7'.
Here are a few pics of the rake mod. I cut 4" out of the center of the basket of a standard "Rage" roof rack so that it would fit inside the factory rails. After welding it back together in the center, I used rubber heater & fuel line tubbing to wrap the contact points on the basket, since it now sits on top of roof. This seems to be working well, as it is more secure than factory attachments and can hold more weight without moving or squeaking now that rack is secure by both rails and roof.
The Ride Change:
Even though I lost an inch in body height, and the Goodyears don't look as aggressive as the BFG, the ride is fantastic. Not only did my sudden bump steering go away, but almost all ass-end sway and jerkiness disappeared as well. And as for traction, last week I took it into the muddiest conditions it has been in, soft, slick red clay mud, up to the axels, and even though there was times I though it was stuck, 4x4 low just walked it through the muck.
On the highway, it rides better than my wife's new 14 Jeep Grand Cherokee, something it has never done in the last 18 months, since I bought it. Lastly, I went from about 15mpg on highway to almost 18mpg, same speed, same roads..!!
Hopefully this might help others that are chasing sway or bump-steering issues... Or who are evaluating big heavy tires. I miss the taller beefier look of the BFGs but I love the performance of a lighter more street friendly tire/lift setup.
A few shots of the stance after tire & rack changes.
Before & After :
