TECH: Suspension Geometry, Alignment Specs, and Shakedown Run
Alignment and Suspension Tech:
With summit just a little over a week away, I thought that it was time to shake this booty around and see what falls off *crosses fingers*.
First off, my alignment specs and some suspension geometry tech.
Before I put the Solo gear on my Sequoia, I was using (keyword search) DJs Specs for my alignment specs. And they were great. My car tracked straight, tires wore evenly, and steering control was predictable.
With the Solo gear, not so much. I mentioned before that the Solo gear changes the suspension dynamics. Because of the way the outer heim steering mounts to the lower uniball housing, the point where the rod reacts to the joint is physically lower compared to OEM. This means that the length of the steering arm from the steering rack mount to the ball joint housing mount is longer by ~3/8" comparing Solo to OEM.
I'm not going to bore you with the math and geometry, but the added length of the steering rod makes a huge difference when the suspension loads/unloads, thus affecting steering/tracking. The suspension doesn't follow a completely up/down motion. It actually moves in an arc. What this means is that when the suspension moves up/down, the tires toe in/out as the steering arm moves radially. The added length in the steering rod results in an additional +/- 4deg of toe in/out when the suspension cycles over OEM.
To compensate for this change, I had to do a few things.
I changed the lift with an additional 5/8" of pre-load bring my lift to ~1-3/4". This puts my suspension to favor more uptravel and less downtravel. That way, the amount the suspension can toe out when it cycles downward is minimized.
Next, the alignment needed to be dialed in. This took trial and error. Thankfully, the shop I had do the job was super cool about it.
Alignment Specs:
Camber: L<-0.1> R<0.0> Cross <-0.2>
Caster: L<2.3> R<3.1> Cross <-0.8>
Toe: L<0.05> R<0.00> Cross<0.05>
This gave me back the driveability and predictably I needed up to 75mph. Tracks straight, no shimmy, and only "normal" steering corrections.
For the chagrins of it, I tried highway driving w/o front swaybar. That's a no go, especially on paved backroads with lots of twisties. All the added weight requires the front swaybar for controlability purposes.
Shakedown Run:
After sorting this whole deal out, it was time to take her out. I didn't want summit to be the first road trip since the rebuild and going out without really knowing if I missed anything just seemed like a bad idea. Thankfully, she did great. I didn't beat on her, but I wasn't gentle either. I made sure to bottom out the suspension when I could and tires were fully inflated to street pressure. This way, maximum shock loads were experienced.
Washboards were a breeze, but the front shocks faded quickly compared to the rear. The rear shocks held up great and stayed controlled. It reinforced the notion that the added weight in the suspension, front bumper, winch, and gear had exceeded the 2.5 coilover shock performance range. It's just not equipped to handle all the additional weight. So that will need addressing. Despite that, the fronts barely kept up.
I thought I heard some rubbing on the passenger side, but could not find wear marks. I hope I don't have to re-tub that side.
My impressions off-road can be summed up in one word. This kit is awesome. Steering response was tight. No slop. Turns on a dime. I am glad I took the time to dial this all in. The rear setup also held up great. My rear cargo was carrying extra weight to simulate camping gear and coolers, etc. The Dobinson shocks soaked up everything I threw at it.
All in all, she's ready for Sequoia Summit.
I had planned to commemorate the moment with a summit golden hour photo shoot, but was denied. Oh well...
Alignment and Suspension Tech:
With summit just a little over a week away, I thought that it was time to shake this booty around and see what falls off *crosses fingers*.
First off, my alignment specs and some suspension geometry tech.
Before I put the Solo gear on my Sequoia, I was using (keyword search) DJs Specs for my alignment specs. And they were great. My car tracked straight, tires wore evenly, and steering control was predictable.
With the Solo gear, not so much. I mentioned before that the Solo gear changes the suspension dynamics. Because of the way the outer heim steering mounts to the lower uniball housing, the point where the rod reacts to the joint is physically lower compared to OEM. This means that the length of the steering arm from the steering rack mount to the ball joint housing mount is longer by ~3/8" comparing Solo to OEM.
I'm not going to bore you with the math and geometry, but the added length of the steering rod makes a huge difference when the suspension loads/unloads, thus affecting steering/tracking. The suspension doesn't follow a completely up/down motion. It actually moves in an arc. What this means is that when the suspension moves up/down, the tires toe in/out as the steering arm moves radially. The added length in the steering rod results in an additional +/- 4deg of toe in/out when the suspension cycles over OEM.
To compensate for this change, I had to do a few things.
I changed the lift with an additional 5/8" of pre-load bring my lift to ~1-3/4". This puts my suspension to favor more uptravel and less downtravel. That way, the amount the suspension can toe out when it cycles downward is minimized.
Next, the alignment needed to be dialed in. This took trial and error. Thankfully, the shop I had do the job was super cool about it.
Alignment Specs:
Camber: L<-0.1> R<0.0> Cross <-0.2>
Caster: L<2.3> R<3.1> Cross <-0.8>
Toe: L<0.05> R<0.00> Cross<0.05>
This gave me back the driveability and predictably I needed up to 75mph. Tracks straight, no shimmy, and only "normal" steering corrections.
For the chagrins of it, I tried highway driving w/o front swaybar. That's a no go, especially on paved backroads with lots of twisties. All the added weight requires the front swaybar for controlability purposes.
Shakedown Run:
After sorting this whole deal out, it was time to take her out. I didn't want summit to be the first road trip since the rebuild and going out without really knowing if I missed anything just seemed like a bad idea. Thankfully, she did great. I didn't beat on her, but I wasn't gentle either. I made sure to bottom out the suspension when I could and tires were fully inflated to street pressure. This way, maximum shock loads were experienced.
Washboards were a breeze, but the front shocks faded quickly compared to the rear. The rear shocks held up great and stayed controlled. It reinforced the notion that the added weight in the suspension, front bumper, winch, and gear had exceeded the 2.5 coilover shock performance range. It's just not equipped to handle all the additional weight. So that will need addressing. Despite that, the fronts barely kept up.
I thought I heard some rubbing on the passenger side, but could not find wear marks. I hope I don't have to re-tub that side.
My impressions off-road can be summed up in one word. This kit is awesome. Steering response was tight. No slop. Turns on a dime. I am glad I took the time to dial this all in. The rear setup also held up great. My rear cargo was carrying extra weight to simulate camping gear and coolers, etc. The Dobinson shocks soaked up everything I threw at it.
All in all, she's ready for Sequoia Summit.
I had planned to commemorate the moment with a summit golden hour photo shoot, but was denied. Oh well...