Build FatherSonSJ45 Troopy

[RevISK]

And that discrepancy seems fishy too...

 

[Kmehr]

Ok here are the measurements as it sits right now:
Passenger side:

Drivers side

 

[RevISK]

Looks like -1.6 and -1.5…

Concur?

4* shims should put you in the hood, or even 5*.

I like to measure the ground level from tire to tire. For instance, a straight, 6’ 2x4 will even out the grounds “level” to give you a slightly more accurate reading.

 

[Kmehr]

Looks like -1.6 and -1.5…

Concur?

4* shims should put you in the hood, or even 5*.

I like to measure the ground level from tire to tire. For instance, a straight, 6’ 2x4 will even out the grounds “level” to give you a slightly more accurate reading.

I’ve got 4* in there now, looking like I need some 8* shims?

Seems really bizarre to need that much, don’t think I’ve ever heard of anyone installing that big on a 40 series?

 

[RevISK]

I’ve got 4* in there now, looking like I need some 8* shims?

Seems really bizarre to need that much, don’t think I’ve ever heard of anyone installing that big on a 40 series?

Ok, I was pretty sure you did so either they’re installed backwards or something else is up that we aren’t seeing.

 

[pb4ugo]

I installed 6* shims and netted 3* positive caster, but that was with a 4" Skyjacker lift. If you install shims that big, make sure the driveshaft spins freely at full droop.

 

[dmtfab]

Did you zero out your angle finder before taking the measurement? My Wixey angle finder is not a level and only shows angles relative to the plane that the finder was last zeroed to.

Edit: looks like the Klein 935DAG does have a digital level function.


Your driver side has negative caster 3.1 degrees relative to the ground surface and your passenger side has positive 2 degrees relative to the ground surface. If you zero your gauge on the ground under the knuckle then take your measurement, it will be less confusing. Maybe I am screwing something up there, but if that is accurate then it would indicate a twisted axle housing IMHO.

I’ll have to go back and look to see if you posted it, but what direction are your shims facing?

 

[dmtfab]

I went back and read some more. By putting the fat end of the wedge forward, you rotate your caster angle toward negative or neutral

 

[rlong]

“If you zero your gauge on the ground under the knuckle then take your measurement, it will be less confusing.”

Yes more “accurater”. And you’re imputing a lot of potential error using the square on the (not so) flat side in all four locations. l can see it. Likely need something that is an actual “straight edge”.. (if the blade of the framing square is hitting you likely need something like the steel rule from a tri-square)

 

[Kmehr]

Here’s my measurement while on my lift right after the spring install, so no shims, using the similarly inaccurate technique (I only took one side):

 

[dmtfab]

Here’s my measurement while on my lift right after the spring install, so no shims, using the similarly inaccurate technique (I only took one side):

View attachment 4210529

View attachment 4210530

That shows a net of positve 2.5 degrees of caster. Your measurements here compared to the previous ones show that your methods are introducing error.

With the angle gauge sitting on the surface you are measuring relative to, press and hold the power button to zero the gauge (probably, this is how a Wixey model works) then take the measurement at the knuckle. No math needed in this approach.

Edit: disregard this post. I made an ASSumption and did not read that those pics were from before shims.

 

[Kmehr]

Ok, pulled it into my garage, used the zero feature, and a speed square that is “more straighter”:

 

[Kmehr]

And some photos of the new vs old shackle, steering and leafs in case I’m missing something obvious:

 

[dmtfab]

yeah, that's wonky for sure. I am not sure what amount of variance is acceptable, but you have one positive caster knuckle (passenger) and one negative caster knuckle (driver). I would bet that an alignment rack would show slightly different numbers because it is going to be much more accurate compared to these tools. In my opinion shims are not going to change a 1.9 degree twist. Maybe @Pin_Head can chime in here

 

[Kmehr]

yeah, that's wonky for sure. I am not sure what amount of variance is acceptable, but you have one positive caster knuckle (passenger) and one negative caster knuckle (driver). I would bet that an alignment rack would show slightly different numbers because it is going to be much more accurate compared to these tools. In my opinion shims are not going to change a 1.9 degree twist. Maybe @Pin_Head can chime in here

Well I think the twist is really only .3*. Since the little arrow on the angle finder is pointing up on one side and down on the other, they’re oriented the same way because the way I’ve taken the photos has the angle finder in a mirror image situation. Setting it to zero on my work bench, then putting the angle finder on a spare shim shows the same degree measurement, but the little arrow is pointing in the opposite direction when the angle finder is facing 180degrees differently. Man this angle stuff makes my brain hurt.

Thinking it through, I’m seeing 1.1 degrees positive caster on the passenger side, and .8 degrees positive on the driver side. I’m feeling a little better about this with everyone’s input. I ordered some 6 and 8 degree shims to try out.

Here is what I mean about the arrow, (also these photos show the impact of dirt as the reading are different numerals, but the shim is pretty dirty:

 

[dmtfab]

Well I think the twist is really only .3*. Since the little arrow on the angle finder is pointing up on one side and down on the other, they’re oriented the same way because the way I’ve taken the photos has the angle finder in a mirror image situation. Setting it to zero on my work bench, then putting the angle finder on a spare shim shows the same degree measurement, but the little arrow is pointing in the opposite direction when the angle finder is facing 180degrees differently. Man this angle stuff makes my brain hurt.

Thinking it through, I’m seeing 1.1 degrees positive caster on the passenger side, and .8 degrees positive on the driver side. I’m feeling a little better about this with everyone’s input. I ordered some 6 and 8 degree shims to try out.

Here is what I mean about the arrow, (also these photos show the impact of dirt as the reading are different numerals, but the shim is pretty dirty:

View attachment 4210615

View attachment 4210616

Agree to disagree. Did you zero out under each knuckle?

You can’t rotate/mirror the angle gauge after you zero it. Your shim experiment proves that.

Edit: I’ll be at my shop in a few hours and try what you are doing with my angle finder. If I'm wrong, I’ll eat my words.

 

[Kmehr]

Agree to disagree. Did you zero out under each knuckle?

You can’t rotate/mirror the angle gauge after you zero it. Your shim experiment proves that.

Edit: I’ll be at my shop in a few hours and try what you are doing with my angle finder. If I'm wrong, I’ll eat my words.

I definitely would appreciate someone checking my work here!

I did zero the gauge under each knuckle, which is definitely a variable from my spare shim bench test, which I didn't zero it between flipping it.

My understanding of the angle gauge is that it is always measuring the the leading edge, i.e. the right side of the gauge as you look at the read out, with relationship to level. Maybe this is incorrect? I'm going to have to think about this more.

 

[Kmehr]

Here is some helpful info from the instruction to my angle finder. Man, I should have read these first. The little arrow indicates the direction in which the gauge needs to be rotated to reach level:

 

[dmtfab]

not trying to beat a dead horse, hopefully this is helpful:

I set this up as an example. Plate is sitting at approximately 7.1 degree angle relative to the table surface. I zero out the gauge on the 7.1 degree plane. Rotate the gauge and you get 14.2 degrees, 2x the angle.

The instructions you posted which explain the arrows and how to read the gauge are part of what I think you were initially misinterpreting.

Obviously any measurement you take in a garage with this type of tool is going to be less accurate than what an alignment shop is going to read on the same vehicle. This is a crude approach comparatively, but it is going to get you in the right ballpark. I would still do the adjustment based of measurements just like you are taking, but know that it’s not going to be super precise.

You mention that you did zero the gauge at each knuckle before reading the angle of the knuckle. That would indicate to me that there is either a twist in the housing of a couple degrees or the machined surfaces are off or something. If I were working on your truck, using these tools and this method of measuring, I change the wedge angle to get as close to the desired caster angle you are aiming for. I am not an alignment expert by any means, so take my advice with grain of salt.

 

[Kmehr]

Man that makes my brain hurt. I get it, but also dont haha.

As to my caster, as measured by me and my certainly far from exactly precise tooling, I do think that the zero'd under the knuckle measurements reflect roughly 1* positive caster on each side +/- maybe some dirt or my fingers not holding it exactly still.