Alignment after lift

[jsalbre]

Background: My truck was previously aligned using Thuren specs, and drove great.

As some here have seen, I installed a Thuren suspension this weekend. 2" front lift coils, 0.5" rear lift. During the install I had to mess with the front caster cams to get the lower shock bolts in. I took pictures of them before adjusting, and put them back where they were afterwards.

I took it in to the alignment shop yesterday because with the lift I know the caster would have changed, and I'm not 100% I got the cams back exactly where they were by eyeball anyway.

Thuren specs say left caster 2.40-2.80º, right caster a 3.40-4.80º, and total toe at 0-0.05".

Their before number show left caster at 2.40º, right caster at 2.60º, and total toe at -.07". Their after numbers show caster the same and total toe dead on at 0". This tells me they didn't adjust caster at all. Technically the left caster is in the range, but the right is out by almost a full degree. With this much of a difference on one side from being "equal" (there's 1º of cross caster welded in, so the right should be about 1) higher than the left) I'd expect a lean or a pull, but the truck is level and drives straight. It is a bit "darty" though, which I'd attribute to the caster being relatively low. The cams are both very close to straight down, with the right cam at slightly forward of down.

Thuren themselves suggests starting from one mark back from vertical, so I'm no where near that.

So here's the question: Do I take it back to them and have them fix it since they obviously didn't change the caster at all, or do I adjust in my driveway since I now know the current angle and I can calculate the change myself with an angle finder? Also, should I aim for something closer to the center of that range (about 3.1L 4.1R) to reduce the "dartiness"?

 

[Crusty old shellback]

Take it back and make them do the alingment YOU paid for.
They did half a alignment

 

[jsalbre]

Yeah, that’s what I should do. I just hate losing a couple hours to them.

 

[Rockcrawlindude]

I set mine with a magnetic angle finder after my 1” lift and been riding that way 4 years no complaints

Post in thread 'Home brew alignment theory'

Apr 10, 2021

Ok so I tackled my 1” front lift today

here is the starting “caster” angle on the top of the ball joint. I put caster in parenthesis because this is not necessarily a perfect caster angle measurement but it does give me an idea of the axles spatial orientation underneath the rig. I zeroed the angle finder on the garage floor



here is the changes I made to compensate for the 1” lift. The factory caster alignment was the same on both sides and it was indicated by the yellow mark. I moved the setting to the silver mark.



here is the after measurement of the angle...

• Rockcrawlindude

• 

 

[ErikTheRed]

I agree with Crusty-- you paid him to align the truck to the customer's specs, so he needs to align it to the customer's specs. Even if he thinks its wrong.

 

[jsalbre]

I set mine with a magnetic angle finder after my 1” lift and been riding that way 4 years no complaints

Post in thread 'Home brew alignment theory'

Apr 10, 2021

Ok so I tackled my 1” front lift today

here is the starting “caster” angle on the top of the ball joint. I put caster in parenthesis because this is not necessarily a perfect caster angle measurement but it does give me an idea of the axles spatial orientation underneath the rig. I zeroed the angle finder on the garage floor



here is the changes I made to compensate for the 1” lift. The factory caster alignment was the same on both sides and it was indicated by the yellow mark. I moved the setting to the silver mark.



here is the after measurement of the angle...

• Rockcrawlindude

• 

I’ve got an appointment with the same place tomorrow morning. I’ll make them fix it since I already paid, but next time I’ll just deal with it on my own.

I’ll probably use the results from this combined with the info from your post to get an offset from the caster angle to an angle I can directly measure, then it’ll be easy to set it accurately in the future.

 

[Rockcrawlindude]

I’ve got an appointment with the same place tomorrow morning. I’ll make them fix it since I already paid, but next time I’ll just deal with it on my own.

I’ll probably use the results from this combined with the info from your post to get an offset from the caster angle to an angle I can directly measure, then it’ll be easy to set it accurately in the future.

I like learning so if you find out that I’m completely wrong please let me know lol could be pure dumb luck that my truck drives well

 

[jsalbre]

Waiting for the shop to realign it right now. They’re doing it, but giving me some attitude. The guy tried to explain to me how a solid axle works, and what caster cams are and that they need to be the same. I had to tell him that I know they’re not the same, because I took pictures of them being not the same before I brought it in the first time, which is how I know it’s wrong! If it’s not where I want after this it I’ll just fix it myself.

 

[Rockcrawlindude]

Waiting for the shop to realign it right now. They’re doing it, but giving me some attitude. The guy tried to explain to me how a solid axle works, and what caster cams are and that they need to be the same. I had to tell him that I know they’re not the same, because I took pictures of them being not the same before I brought it in the first time, which is how I know it’s wrong! If it’s not where I want after this it I’ll just fix it myself.

I believe he is correct if he is saying you don’t want any cross caster. On mine, both sides were the same from factory and when I set them both to ~4° they were mirrored still but a notch or two from start point.

I suppose it’s possible to have the cams set differently and still have no cross caster, the cams exist for a reason because variances happen ?

Realistically, you cannot end up with any cross caster because those cams aren’t going to twist the axle housing but you could end up with bound up bushings in your arms

 

[G Mcpherson]

These are the Factory settings on mine with thuren 2" coils. Toe I set to 0. I sent these pics to Don at Thuren and he said if it drives fine its all good and no adjustment is needed. My Truck drives perfect and tire wear is also good. Caster Cams he said should be mirrored but some cross caster is fine.

 

[jsalbre]

Got it back, 3.75º on the left and 4.00º on the right now, so technically within specs, but I feel like that's closer than it should be given the welded in cross-caster. There's about a half an inch lean to the left now though. I'm guessing they didn't loosen the upper radius arm-axle bolts. Didn't have time to crawl underneath and look at the adjusters to see if they're equal. I'll look at it this afternoon and check the adjuster markings and the upper bolts.

 

[Rockcrawlindude]

View attachment 84733View attachment 84734 These are the Factory settings on mine with thuren 2" coils. Toe I set to 0. I sent these pics to Don at Thuren and he said if it drives fine its all good and no adjustment is needed. My Truck drives perfect and tire wear is also good. Caster Cams he said should be mirrored but some cross caster is fine.

You’re saying you tossed 2” coils in there and left the alignment alone? GLWS

 

[G Mcpherson]

All I did was set the TOE to 0. It drives straight with no wander and the Cams are Set back close to even.

 

[Rockcrawlindude]

All I did was set the TOE to 0. It drives straight with no wander and the Cams are Set back close to even.

I guess caster is fairly forgiving but mine required more than expected for just 1” lift. I suppose if it drives straight it’s mostly fine

 

[G Mcpherson]

I have asked Don several questions about it. Sent pics also showing Cams. He said if it drives nice good to go.

 

[jsalbre]

Well I was right about them not touching the upper radius arm to axle bolts, or the radius arm to frame bolts. None of them had any marks from tools on them. Both adjusters are dead even on 2 notches behind center though. I loosened everything, bounced and rocked the front suspension, and then retorqued it all. Still a nearly 3/4" lean to one side though. I'm annoyed by that, but I'll drive it a bit tomorrow and if it tracks straight probably just let it be.

Torquing all those bolts to 240 ft-lbs from underneath is not fun!

@Rockcrawlindude: I wasn't able to find a good place to check angle where I could get a consistent reading. Measurements from the top of the ball joints were closer between the two sides (only 0.1º difference) than what the alignment shop said they were (0.25º difference). I checked a few other spots and had similar struggles. My adjusters are both in the same spot yours were when you did your self-alignment though.

 

[Pearce]

Lean, or maybe track bar not adjusted correct? Change in sway bar adjustments? Coils set in right orientation, seated? Just throwing out ideas. Been drag racing?

 

[Rockcrawlindude]

Well I was right about them not touching the upper radius arm to axle bolts, or the radius arm to frame bolts. None of them had any marks from tools on them. Both adjusters are dead even on 2 notches behind center though. I loosened everything, bounced and rocked the front suspension, and then retorqued it all. Still a nearly 3/4" lean to one side though. I'm annoyed by that, but I'll drive it a bit tomorrow and if it tracks straight probably just let it be.

Torquing all those bolts to 240 ft-lbs from underneath is not fun!

@Rockcrawlindude: I wasn't able to find a good place to check angle where I could get a consistent reading. Measurements from the top of the ball joints were closer between the two sides (only 0.1º difference) than what the alignment shop said they were (0.25º difference). I checked a few other spots and had similar struggles. My adjusters are both in the same spot yours were when you did your self-alignment though.

What was your alignment end number for caster ° ?

Does this match (or even close to) what an angle finder says on the top of the ball joint like I measured mine?

I’m pretty curious to see the answer but not curious enough to pay for an alignment.

 

[jsalbre]

Lean, or maybe track bar not adjusted correct? Change in sway bar adjustments? Coils set in right orientation, seated? Just throwing out ideas. Been drag racing?

View attachment 84771

Track bar wouldn’t affect the lean, just push the axle to one side or the other. I don’t have a front sway bar, so that’s not affecting anything. Coils are straight, but good question. No drag racing lately, but man, that’s some torque on that truck!

What was your alignment end number for caster ° ?

Does this match (or even close to) what an angle finder says on the top of the ball joint like I measured mine?

I’m pretty curious to see the answer but not curious enough to pay for an alignment.

Actual numbers from the alignment shop were 3.75 L, 4.00 R. On top of the balljoints I was getting 4.5 L and 4.6 R . I feel like that should be a reliable spot to measure from, but I’m confused as to why the numbers are closer to each other than the caster specs from the alignment shop. I suppose my angle finder could be off, but it’s a brand new Klein, so I’d expect it to be good. Maybe I’m not getting the rotation of the angle finder right? It’s hard to tell if it’s straight from under the truck.

I did have to drive across town this morning but I couldn’t tell if it was driving straight because we have 40mph winds today.

 

[johnmyster]

My truck also has less cross caster welded into the front axle than Don's specs would lead you to believe is normal. I think it's like yours, only 0.25 deg or so. Don't worry about it. You can't change it and you'll only mess things up trying. Let the axle rest natural/neutral where it wants and move on. Pay attention to average caster. Move on.

FWIW, my alignment guy (whom I trust) says you want as much caster as possible on solid axle vehicles. (He's mostly worried about avoiding death wobble, which isn't going to be a problem on my truck.) That said, I brought my truck to him with 6 deg caster and he really encouraged me to leave it alone. I'm mostly happy. It tends to really want to follow crown, but it returns to center well. If I get tired of it I'll dial some out myself.