Alignment shop cranked my TB's down

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greenrover

greenrover

10 Year
Joined
May 17, 2011
Threads
23
Messages
115
Location
Colorado Springs, CO
When I got my LC a month or so ago it had a pretty bad lean and big time stink bug going on. I cranked the TB's over a couple weeks and had it level side to side and about a 1/2 rake instead of the 1 inch or so rake.
I took it to get aligned yesterday and it's back to having a stink bug 1+ inch rake. Is it normal for the shop to do thing when getting it aligned? Doesn't seem right to me.

Thanks in advance.
 
It's actually part of the spec to measure the height of the control arm IIRC. And with the TBs cranked sometimes the caster is just out of spec.
 
That sucks! I went back to the alignment shop 2 times because I was tweaking my ride height to how I wanted it. If I spent all that time getting it right, just to have them drop it back "into spec," I'd be peeved.


...via IH8MUD app
 
Scuba Jon! In OP's defense, I never would have thought to have to specify such a thing to an alignment shop. I thought their job was to make the wheels straight.


...via IH8MUD app
 
Sounds like you found a shop that is actually worth their salt, from FSM below the first step is to check vehicle height:

FRONT WHEEL ALIGNMENT

INSPECTION

1. MEASURE VEHICLE HEIGHT

Vehicle height:

Front A − B: 71 mm (2.795 in.)

Rear C − D: 51 mm (2.008 in.)

Measuring points:

A: Ground clearance of spindle center

B: Ground clearance of lower suspension arm front bolt center

C: Ground clearance of rear axle shaft center

D: Ground clearance of lower control arm front bolt center

NOTICE:

Before inspecting the wheel alignment, adjust the vehicle

height to the specified value.

If the vehicle height is not the specified value, try to adjust it by

pushing down on or lifting the body.
 
I'm glad they did the job correctly (we've always like Les Schwab here in Boise) just disappointing I lost my time invested and a bit of lift, I can't stand the stink bug look.
I'll stop by and talk to them, maybe they can make it within specs and leave the twist in the bars.
Thanks again for the replies.
 
Let's see some data...as in alignment specs before and after. Then and only then will we be able to save you from searching and reading.
 
Spare me the sarcasm.
Here's the "as in alignment specs before and after" data.

Front left camber before: -0.3* actual: 0.0*
Front left caster before: 1.5* actual: 2.4*
Front left toes before: 1.11* actual: 0.04*
Front right camber before: 0.3* actual: 0.2*
Front right caster before: 2.5* actual: 2.5*
Front right toe before: 1.10* actual: 0.05*
Camber range: -0.7* to 0.8*
Caster range: 1.8* to 3.3*
Toe range: -0.05* to 0.15*
Cross camber before: -0.6* actual: -0.2* Range: -0.5* to 0.5*
Cross caster before: -1.0* actual: -0.1* Range: -0.5* to 0.5*
Total toe before 2.20* actual 0.09* Range: -0.10* to 0.30*
 
greenrover said:
I can't stand the stink bug look.
I'll stop by and talk to them, maybe they can make it within specs and leave the twist in the bars.
Click to expand...

Keep in mind that even if they can dial it in with no rake that the vehicle may not behave correctly on the road. Even though we're full time 4WD, the front lightens up under acceleration (probably more so on the DS) causing the truck to pull slightly right. This goes away under light throttle or braking so you end up correcting /releasing input to keep the vehicle going straight.

When i first got the truck I tried to level it for aesthetics, but a level truck is not a happy truck and the bad road manners overcame the visual style. With my setup I've found that a 1" rake is the best compromise.
 
Last edited:
Good info OregonLC, thank you for the constructive reply.
 
Slickspawn said:
Sounds like you found a shop that is actually worth their salt, from FSM below the first step is to check vehicle height:

FRONT WHEEL ALIGNMENT

INSPECTION

1. MEASURE VEHICLE HEIGHT

Vehicle height:

Front A − B: 71 mm (2.795 in.)

Rear C − D: 51 mm (2.008 in.)

Measuring points:

A: Ground clearance of spindle center

B: Ground clearance of lower suspension arm front bolt center

C: Ground clearance of rear axle shaft center

D: Ground clearance of lower control arm front bolt center

NOTICE:

Before inspecting the wheel alignment, adjust the vehicle

height to the specified value.

If the vehicle height is not the specified value, try to adjust it by

pushing down on or lifting the body.
Click to expand...


well alinement been done and he checked the front heigh FROM ground to Fender end( above the tire) and cranked it with power gun few time to adjust it, is this the right method? what is the specs heigh for the front? didn't get the heigh measurement points!!!!
 
OregonLC said:
Keep in mind that even if they can dial it in with no rake that the vehicle may not behave correctly on the road. Even though we're full time 4WD, the front lightens up under acceleration (probably more so on the DS) causing the truck to pull slightly right. This goes away under light throttle or braking so you end up correcting /releasing input to keep the vehicle going straight.

When i first got the truck I tried to level it for aesthetics, but a level truck is not a happy truck and the bad road manners overcame the visual style. With my setup I've found that a 1" rake is the best compromise.
Click to expand...


I am not sure where this info that if the truck does not have rake it drives bad. Rake does not affect alignment or handling. The only affect it has is that it does add or subtract a minute amount of caster from the truck.

Only overall height for the truck and final caster / camber measurements have an effect as does total lift height vs available down travel.

Rake does not have anything to do with it.
 
looking4lc said:
well alinement been done and he checked the front heigh FROM ground to Fender end( above the tire) and cranked it with power gun few time to adjust it, is this the right method? what is the specs heigh for the front? didn't get the heigh measurement points!!!!
Click to expand...
Wheels should be off the ground when adjusting the torsion bars. I would highly recommend not using power tools to adjust them. It's better to drive the Hundy around the block to let the suspension settle before taking a final measurement. I typically get about 1/4" per turn with OME torsion bars.
 
sleeoffroad said:
I am not sure where this info that if the truck does not have rake it drives bad. Rake does not affect alignment or handling. The only affect it has is that it does add or subtract a minute amount of caster from the truck.

Only overall height for the truck and final caster / camber measurements have an effect as does total lift height vs available down travel.

Rake does not have anything to do with it.
Click to expand...
Christo, empirical evidence speaks to the contrary. Your theory holds well in a static scenario. When torque is applied, however, it unweights the front suspension. When rake is less than about 1" the buoyancy from the torsion bars allows the front suspension geometry to change and I suspect this change is asymmetrical resulting in pulling to the right under load. Perhaps this becomes exaggerated as the truck ages and bushings on the steering rack and LCA wear. At any rate, there is a positive correlation between rake and pulling right under load.

I agree that rake per se does not cause the pull. It's how lack of rake performs under load.
 
Well, if the truck is stock with 1" of rake VS 3" of lift with 1" of rake the behavior would be different. So it is not the rake that causes the issue but the initial caster and camber readings at ride height.

I am not disputing the front end unloading and changing the steering / torque steer. It just has nothing to do with rake. Rake is the difference between the front and rear irrespective if lift height.

How does the rake influence the front end changes under acceleration?
 
sleeoffroad said:
How does the rake influence the front end changes under acceleration?
Click to expand...

I suspect the slight difference in spring rates between left and right coupled with the engine torque unloads the left front slightly more that the right. This creates an asymmetrical caster and resulting exaggerated torque steer.

My guess is that as the rake increases the lower front preload reduces nose climb and related caster changes.

At the end of the day for me a 1" rake was the best compromise. It still pulls slightly but much less that when flat.
 
OregonLC said:
I suspect the slight difference in spring rates between left and right coupled with the engine torque unloads the left front slightly more that the right. This creates an asymmetrical caster and resulting exaggerated torque steer.
Click to expand...

The torsion bars are the same rate, but could be preloaded different.

My guess is that as the rake increases the lower front preload reduces nose climb and related caster changes.
Click to expand...

How does the rake pre-load the front?

At the end of the day for me a 1" rake was the best compromise. It still pulls slightly but much less that when flat.
Click to expand...

Yes, but when you introduced the rake you lowered the front and had a better starting point on your alignment. I bet if you maintained the rake but lifted the front and rear both 1" you would experience a different handling.
 
sleeoffroad said:
The torsion bars are the same rate, but could be preloaded different.
Click to expand...

Interesting. I had thought the pink/blue (left/right) were slightly different rates? The OME coils are different heights, I'd assumed the same with the front. They must be biased from the factory for left/right torque. Learn something new every day!

sleeoffroad said:
How does the rake pre-load the front?
Click to expand...

As rake decreases torsion bar buoyant force increases, no?

sleeoffroad said:
Yes, but when you introduced the rake you lowered the front and had a better starting point on your alignment. I bet if you maintained the rake but lifted the front and rear both 1" you would experience a different handling.
Click to expand...
sleeoffroad said:
I am not sure where this info that if the truck does not have rake it drives bad. Rake does not affect alignment or handling.
Click to expand...

This confuses me a bit, but I respect your knowledge and I think I get where you're coming from. Most users don't have the luxury of setting the front and then adjusting the rear. They buy a suspension set and live with what they bought. As gear and other mods get added the weight change will affect the setup over time. From what I've found (and as others have posted) a positive rake of 1" (coupled with a proper alignment) is the best 'shade tree' method of achieving good road manners. A mechanic of Slee-caliber may very well be able to get a level truck to accelerate straight, but for those of us who go to Les Schwab and work with factory alignment settings I think we're better off playing our best hand which starts with the 1" rake. :-)

I do want to try for Dan's recommended 3.5^ caster on my next alignment and see how that runs.
 
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