5th Gen suspension, initial impressions
 

My 2008 with 115K and two summers of trail driving, seemed due for a new suspension. The original springs sagged noticeably in the front, and the rear shocks had a hard time passing the static bounce test. Since my friend got a new TRD Off-Road 4R and immediately upgraded his suspension, I got his shocks, springs, and upper control arms for something close to scrap value. His components had about 1500 miles on them, so I decided to give them a try rather than dropping almost two thousand on new OEM 4th gen components.

Since I added about 300 pounds to the Runner so far, in the form a very beefy front skid plate, surprisingly heavy sliders, as well as a fully-stocked drawer system in the back, I thought the TRD Off-Road springs would be a good option as that truck's curb weight data is 400 pounds higher than my '08 SR5's reported curb weight. I anticipate adding more weight to the truck when I install a winch and a rear-mounted second battery at which point I'll surpass the curb weight of the '18 TRD Off-Road truck which donated this suspension.

Having had this suspension for about three weeks now, here are my initial impressions. First, the static observations:

1. The truck sits much higher than it used to. It gained about 1.5 inches in the rear, and about 2 inches in the front. Keep in mind, those are 5th gen wheels and tires you see in the photo, so they're about an inch bigger than what we typically get on 4th gen 4Rs.

2. The much-maligned "forward rake", which I didn't mind, seems to be gone.

3. There is a driver side lean of about 3/4 to 1 inch on front and rear. Both front and rear coils were marked identically, so I don't think that I inadvertently switched sides.


As far as the driving experience goes:

1. The ride is very comfortable, and familiar road bumps and rail track crossings have been greatly diminished.

2. The wheels are firmly planted on the pavement when going over bumps on straight and curved highways, just like with my old suspension.

3. Limited off-pavement testing consists of rough dirt country roads and huge potholes. The results have been quite satisfactory, with the suspension much less prone to engaging bump stops than before. Steering control is retained as expected. Wheeling season hasn't really started in CO yet, as most of my favorite trails are still snowed in or too muddy. More testing to come.

4. The truck feels "springy". More so than it has before. Not in annoying or dangerous way, but certainly different. The springy feel is more apparent at very slow speed, such as engaging the curb cut when entering my driveway, than at higher speed. On the freeway, there is no springy feel. I don't know why this is, and I don't know why it feels springy. I think the springiness is actually lateral in it's range of motion and not vertical as expect from suspension springs.

5. Zero body roll on curves.

6. The shocks don't pass the old-fashioned bounce test. After pressing on bumper corners, the truck rebounds 1.5 times in the rear and 2.0 times in the front. I don't know if this test is relevant to today's modern suspensions, but it seems odd nonetheless. I don't understand why the truck rebounds more than once, considering these are new shocks.

Overall, the 5th gen suspension resulted in a very comfortable ride, which resembles a large sedan in it's feel rather than a truck. I'll continue to research the reasons for the springy feel and the results of the static rebound test. If anyone has insights into these questions, please chime in.

Here's what the 4R looks like now with this accidental lift:

http://i.imgur.com/gIXwTVS.jpg