Alignment Question

txdox21 · June 21, 2010

About three weeks ago, I put a 1.5" leveling kit on my truck. I immediately had an alignment done after the install. The mechanic said everything was still within the specs. I thought it was odd, but the truck seemed to be driving fine. About 2 weeks ago, I decided to swap out the 1.5" rear block for a 2" block. Soon after, I noticed the truck didnt seem to be driving the same. I took it to the shop again this morning to have the alignment checked. They stated that the camber was off on the drivers side, which was causing the truck to drive funny. This is understandable as I drive rough roads to get to my jobsite.

What struck me as odd is the fact that the mechanic told me that due to the leveling kit, it would not be possible to get the caster to meet the factory specs without altering the camber. He stated that they had adjusted the camber and toe to be within the factory specs, because they are the most important to decrease tire wear and increase straight line tracking.

My questions are:

-Has anyone else with a leveling kit been told the same thing, and is it true?

-If I installed the Bilstein leveling shocks, would I still have the same problem?

Matt_ · June 21, 2010

Answers to your questions:

1) With leveling kits, sometimes its hard to even get the camber within spec. Since the camber adjustments are nearly maxed out, you greatly reduce the caster adjustability. Camber takes priority because it more directly relates to tire wear.

2) the type of leveling kit does not matter... upper strut spacers, lower strut spacers and bilsteins all have the same effects on the angles and alignment.

kdixer · June 21, 2010

I am no alignment expert, but you initially had 1-1/2" of front lift in comparison to the rear. Then you added 1/2" to the rear which reduced your effective leveling height to 1" front to rear. That should have made it easier to get your caster within factory spec.

I installed about 1" worth of lift to the front of my 09 and the alignment is totally within spec.

Matt_ · June 21, 2010

changing the height of the rear does not have a measureable effect on the front alignment.

and 1" is usually no problem to align.

also, every truck is different. if your camber is well within spec and the caster is out a bit, dont sweat it... unless the truck is drifting to one side of the road consistently.

kdixer · June 21, 2010

changing the height of the rear does not have a measureable effect on the front alignment.

and 1" is usually no problem to align.

also, every truck is different. if your camber is well within spec and the caster is out a bit, dont sweat it... unless the truck is drifting to one side of the road consistently.

Agreed. My truck alignment was out from the factory. I had some feathering at about 5,000 miles.

But caster is the tilt of pivot axis looking from the side. So in my mind the rear block should have put it closer to stock than it was with the front level only. I imagine the vehicle pivoting about the rear wheels.

Matt_ · June 21, 2010

changing the height of the rear does not have a measurable effect on the front alignment.

and 1" is usually no problem to align.

also, every truck is different. if your camber is well within spec and the caster is out a bit, dont sweat it... unless the truck is drifting to one side of the road consistently.

Agreed. My truck alignment was out from the factory. I had some feathering at about 5,000 miles.

But caster is the tilt of pivot axis looking from the side. So in my mind the rear block should have put it closer to stock than it was with the front level only. I imagine the vehicle pivoting about the rear wheels.

I know what caster is, i've done hundreds of alignments

The caster issue caused by leveling kits is not due to the change in height with relation to the rear (the angle change caused by that is minimal). It's due to the geometry of the control arms and their relative positions to one another.

Edit: To clarify, caster is adjusted using the camber adjustment cams on the upper control arm. On a stock truck I can take the 2" block out of the rear and do a caster sweep and the caster will still be within spec. When adding a 2" leveling kit, the UCA needs to be moved as far outwards as possible to correct the camber. The "trick" that I used to use is to move the UCA as far outwards as possible on both cams and then do a caster sweep, THEN adjust either the front or rear UCA mount, depending on which way the caster was out, to get the caster as close to spec as possible... however I would shy away from going to the end of the allowable camber range since, IMO, it's better to be "well within" the camber spec and slightly out of the caster as opposed to "slightly withing" camber.

Edit #2: I find it ironic that I started that last edit with "To clarify"... but if you've never done an alignment then you probably have no clue wtf i just said

cerbomark · June 21, 2010

kdixer · June 21, 2010

I know what caster is, i've done hundreds of alignments

WTF.

I am simply trying to explain myself, not question your abilities. He stated it was within spec with just the front leveling kit. It was not until the addition of the rear block that it could not be brought into spec. So if you can explain to me how the position of the rear axle does not pertain to the front geometry I would certainly appreciate it.

I was under the impression the reason they do 4 wheel alignments is because it does matter. Now here I go with my opinion but, both upper and lower control arms are connected to the frame at a certain angle from vertical (side view). If you raise or lower the rear of the frame, then that angle of the control arms is changed from vertical. And since the slope (side view) of the frame is closer to the stock slope of the frame, the caster spec should be more atainable with the rear block than without it.

I could make more of a case if I could use my hands...LOL

REF. Caster angle^[1] or castor angle^[2] is the angular displacement from the vertical axis of the suspension of a steered wheel in a car, bicycle or other vehicle, measured in the longitudinal direction. It is the angle between the pivot line (in a car - an imaginary line that runs through the center of the upper ball joint to the center of the lower ball joint) and vertical

Edit 1:

If you look at a clock with no numbers, and the big hand is straight up and the little hand is straight down. you would know that it is 6 o'clock. But if you rotated the clock (similar to raising the rear of a truck), the time would in fact appear to be different.

Edit 2:

It might be ironic to speak of a clock with no numbers if infact you have never seen one. Because chances are that if you have never seen one, you might have no idea how to determine what time it is.

Matt_ · June 22, 2010

I would say that the first mechanic didn't do a good job. Why he felt the difference after changing the rear of the truck by 1/2" in height is anyone's guess, but i guarantee you it was not because his front end alignment changed due to the new block in the back.

We all know what you're saying with the angle changing... but what im telling you is that the difference of that 1/2" height in the rear does not affect the caster as much as you think. Not to mention it would have zero effect on camber, which was "off after" he replaced the block (again, thats not how it works... the camber was not thrown off from the block change).

Here, i'll explain it in terms you may be able to visualize:

Take your clock with the time being 6:00. Now we all know there are 360 degrees in the clock. Rotate that clock 1/2 degree clockwise... what time does the clock say?

kdixer · June 22, 2010

My entire point was that the addional 1/2" in rear height would have helped his caster situation. Even if it was a very tiny bit.

And pherhaps his alignment was on the ragged edge of "within spec".

The time would be 6:00:05

Not enough info to determine AM or PM.

Matt_ · June 22, 2010

The time would be 6:00:05

Not enough info to determine AM or PM.

kdixer · June 22, 2010

The time would be 6:00:05

Not enough info to determine AM or PM.

I have a lil bit of book learn'n...LOL

Blue2500CC · June 22, 2010

The time would be 6:00:05.Not enough info to determine AM or PM.

Are you sure? By my calculation, if the WHOLE clock was rotated, it is still 6:00! He didn't say the hands were rotated, but the clock.

On a serious note, is there an issue sometimes (more often than not, or once in a great while) trying to get an alignment? I am thinking about a leveling kit, and rear blocks also, for the beast. But I don't want any steering problems.

Chris

Matt_ · June 22, 2010

On a serious note, is there an issue sometimes (more often than not, or once in a great while) trying to get an alignment? I am thinking about a leveling kit, and rear blocks also, for the beast. But I don't want any steering problems.

Keep it at or under 2" and you'll be fine.

kdixer · June 22, 2010

The time would be 6:00:05.Not enough info to determine AM or PM.

Are you sure? By my calculation, if the WHOLE clock was rotated, it is still 6:00! He didn't say the hands were rotated, but the clock.

The reference was to a clock with no numbers. Therefore the only references as to what time it is would be vertical and horizontal. If the whole clock is rotated the hands are rotated from true vertical. The clock would definately show a different time.

However if the clock was rotated 90° clockwise it would have the appearance of being broken. The hands of a clock should never be in the 3 and 9 o'clock position at the same time.