Ford Powerstroke Diesel Forum banner

21 - 40 of 63 Posts

·
Super Moderator
Joined
·
9,672 Posts
Actually, you need to be careful about what is removed and what is added. If your current bushing is 2*, and you swap it out for a 2.5* bushing you added .5*......

I'd go back to the alignment guys and ask for them to measure caster using 0* caster bushing. That would give you the true reading and what bushing to use to be within spec.
 

·
Registered
Joined
·
1,148 Posts
Discussion Starter #22
Ok.... got some good info from my neighbors dad who is a shop foreman down south. I’ll have to draw some things and post some photos in a sec.
 
  • Like
Reactions: HeavyAssault

·
Registered
Joined
·
36 Posts
My head hurts after reading this. I’m just going to sit here with my factory Michelin’s and hope PB Blaster saves my EGR pipe bolts.
 

·
Registered
Joined
·
1,148 Posts
Discussion Starter #24
Ok, So this is how he explained it....
The bar chart is misleading. They make it look like 2.3 is at the far left and 4.7 is at the far right. That is not the case. While those are the minimum and maximum per manufacturer spec, they really should be at the left and right of the “valley”. Not the bar. Also, the actual measurement ( in my case 0.6) is placed in the middle of the chart and really shouldn’t be. That is misleading as well.
He also said that you lose about a degree per inch of lift with radius arms. I was probably around 2.6 to 3 degrees before the level kit. After the kit, rolling the axle forward as it was moved away from the frame caused an effective loss of caster. The Carli shims will do the trick by adding 2* and giving me a net 2.6* caster. But.... he said that if I could find 3* it would be better. Or, go with 4* and have a shop set it up at 3*. I could eyeball it but that is not as easy as dropping the shim in at the max adjustment.
767961
 

·
Registered
Joined
·
959 Posts
Ok, So this is how he explained it....
The bar chart is misleading. They make it look like 2.3 is at the far left and 4.7 is at the far right. That is not the case. While those are the minimum and maximum per manufacturer spec, they really should be at the left and right of the “valley”. Not the bar. Also, the actual measurement ( in my case 0.6) is placed in the middle of the chart and really shouldn’t be. That is misleading as well.
He also said that you lose about a degree per inch of lift with radius arms. I was probably around 2.6 to 3 degrees before the level kit. After the kit, rolling the axle forward as it was moved away from the frame caused an effective loss of caster. The Carli shims will do the trick by adding 2* and giving me a net 2.6* caster. But.... he said that if I could find 3* it would be better. Or, go with 4* and have a shop set it up at 3*. I could eyeball it but that is not as easy as dropping the shim in at the max adjustment. View attachment 767961
Exactly


Sent from my iPhone using Tapatalk
 

·
Registered
Joined
·
1,148 Posts
Discussion Starter #26
Actually, you need to be careful about what is removed and what is added. If your current bushing is 2*, and you swap it out for a 2.5* bushing you added .5*......

I'd go back to the alignment guys and ask for them to measure caster using 0* caster bushing. That would give you the true reading and what bushing to use to be within spec.
I think I’m actually going to go to my local dealer. They have a shop dedicated to the Super Duty and up Ford trucks. They have been really good to me so far with other odds and ends. Obviously, I will tell them what’s up first and make sure they either have or can get different bushings. They will also know what the truck came with in the beginning. Provided it has not been changed. But I got it at 28k so doubtful it has been messed with.
 
  • Like
Reactions: HeavyAssault

·
Registered
Joined
·
1,148 Posts
Discussion Starter #27
Follow up.... my head hurts. Lol.
So I got the truck back from the dealer. I have to say that the steering is 100% better. Tighter, not as twitchy feeling and does not wander when you hit grooves in the asphalt.
What hurts my noggin is the data sheet. Unless the other shop was jerking around while setting it up (possible), the measurements did not change by much. At least not to these novice eyes.
768652
 

·
Registered
Joined
·
959 Posts
The middle line is 0 on every spec. Each increment to the left or right of that line you, are adding or subtracting from the number.

the 0 is the midpoint, calculating the midpoint is adding both numbers together and dividing it by 2 so the first sheet,

Is 4.7 + 2.3 = 7* divided by 2 is 3.5
3.5 is the centre which would read 0.

So if the black line in the first camber spec sheet was directly in the middle it would read 0 but the actual measurement would be 3.5* total. Make sense?

Like the first one is 0.6 to the LEFT of 2.3 so add that and it’s 2.9* see how it’s to the RIGHT of the centreline which is 3.5...

Keep moving it to the left and it would of read 0 but actually been 3.5

The second one is a lot easier, it automatically find the centreline and just adjusts it - or + to what it needs. You are looking at -5* total of negative camber, but it’s impossible to have negative camber.. or else the wheel would be behind the centreline (vertically) of the coil spring. It just took it to -5 of what the actual spec put in the computer reads of what the actual spec the wheel is.

Actual camber is 1.5*
 

·
Registered
Joined
·
1,148 Posts
Discussion Starter #29
So my true caster was 2.9* and is now 2.5??
 

·
Super Moderator
Joined
·
9,672 Posts
Why does the top of the form read "Modified Specification"?

Didn't the other report someone posted show a different spec range for Caster???
 

·
Super Moderator
Joined
·
9,672 Posts
Yea..the first sheet.......4.7*-2.3* is the accepted range that a measurement needs to be found to be Green "in range, in spec".

Your first round was 0.6* which threw the RED shade which is "out of range, out of spec".

Now the "range' is +3.0*- (-1.0*).....WTF.....
 

·
Registered
Joined
·
959 Posts
Modified because the vehicle is modified, which the first shop didn’t account for.


Sent from my iPhone using Tapatalk
 

·
Super Moderator
Joined
·
9,672 Posts
LOL.....jeez....So he's still sitting at +0.5* Caster then.........Cause a range of +3.0*- (-1.0*) would have a middle of +1*...to which he is -0.5* off "middle" of that which is +0.5* Caster......

At least that's what I've picked up thru all this.....I think....LOL
 

·
Super Moderator
Joined
·
9,672 Posts
I've learned way to much at this point and to STILL be confused is hard for me to grasp.....IF I'm confused!?!!????? LOL
 

·
Super Moderator
Joined
·
9,672 Posts
Not to mention IF the Caster specs listed on the "Modified Specifications" are true then HOW can there be a reading of less than 0* Caster??????????

Cause:
Because negative is impossible
Negative caster angle isn’t a setting used by modern road cars. The self-aligning torque and straight-line stability that is characteristic of positive caster are absent in a negative caster setting. In fact, a “loose” steering wheel and immense front wheel instability would result from a negative caster setup”
 

·
Registered
Joined
·
1,148 Posts
Discussion Starter #37
The first sheet I posted was from a local shop that didn't correct the caster. I then took it to the dealer because I was a little irritated with the local place since they did not address my primary concern of caster. That is probably why the min/ max on the sheets are different.
As for where the hell my truck sits, I have no idea. It seems Roccafella explanation makes sense. If the dealer sheet has 3.5 in the center, then -1 to +3 from that center, it makes sense. Total span 2.5 to 6.5. But by my new math, it is still the same total csster angle.
I need a beer.
 

·
Super Moderator
Joined
·
9,672 Posts
Well....You can't have a negative value for caster.....

As far as the sheet....the number shown in the "middle" is the measurement....The arrow just shows to which side of the range it's measured. That's stated in the video as well.

YES....your caster is still reading +0.5*.....
 

·
Super Moderator
Joined
·
9,672 Posts
I would expect the following:
1) Shop sets up machine to read OE specs. NO adjustments for modifications.
2) Truck is on stand and measurements are taken.
3) Report would show current measurement, to include if it was in spec or out of spec.
4) Shop would adjust the truck alignment (hence Caster bushings) to be within OE spec range.

How on earth would the shop know how to set the machine measurement specs to "correct" for the lift??? Too many variables with lift kits and parts in my mind.
To which we know there's NO WAY those spec values would/should be negative for Caster. IF the shop did correct the specs, and it's report is showing a negative spec range number....the adjusted specs and machine isn't right to me.

Some things just aren't coming together 100% for me.
 

·
Registered
Joined
·
1,148 Posts
Discussion Starter #40
So I stopped by the shop on my way home today. The mechanics were already gone. The front stays open later for pick up/ drop off. The service writer told me that the high and low #s were the min and max for my truck based on VIN from Ford. I have a hard time believing that.
 
21 - 40 of 63 Posts
Top