Caster Correction (1 Viewer)

[knuckle47]

Not to pile on but the moment you had mentioned new alignment machine, my brain is screaming, “ someone does not know how to use it properly”. . . . And that has been mentioned here already 4 other times.

I have discovered when I wind up with data that tells me something is out of adjustment, my immediate reaction is always to triple check the source.

It sucks that you’re trying to improve conditions and will wind up getting mixed up further than when you started

 

[-MaTTi-]

The lead guy at Midas said I can only correct Caster on the vehicle by moving the axle forward and that a shim rotating the caster angle would not do it.

He should not be in lead, he don’t understand how the caster is created in the solid axle.

If he were the guy sitting next to me at the bar I would dismiss this, but since he has 20 years at Midas, I am looking to see if his impresssion that Caster can not be corrected with an axle shim is correct.

Like said, he don’t understand what he is saying.

Last piece of advice sought: I could put in a different thinkness shim on each side, though to more closely align the left and right side caster. E.g., 2* on the left and 3* on the left. What are your thoughts?

You can’t, you have a solid axle with solid king pin angles. If your knuckle bearings are in good shape, the axle is bent or the alignment machine results are not correct.

 

[Grayscale]

You can't simply shim an axle for caster correction on a live-beam front axle 4x4, if the data suggests that it is off-target on just one side. What would you do, install a shim just on the passenger side?

Or, if you install shims for positive caster beyond factory specs., because the steering is acting funny after installing 'tall skinnies' on stock wheels, which threw-off the scrub radius, and peer-know-how says that caster shims up front will help), you mess with the driveline regarding the pinon flange orientation in relation to the transfercase, which could be fine driving in 2wd, but the amount of bend that the lift already imposes on the driveshaft u-joints, particularly with a 4-inch lift, will still be an observed, or sub-clincal, vibration and weakness when you need the 4wd traction.

Wedge-shaped shims, at the front spring perches, might be okay for correcting just caster because of running with extended shackles. But, the data from the machine suggest that shims, especially on the driver's side, are not called for in this case. There are other issues to consider when choosing to run longer shackles, like issues with shackle-inversion.

 

[Skter505]

Caster is absolutely set different on each side on purpose. It is a common practice for a quality alignment guy to set drivers side a couple tenths not more that 1/2 degree lower than the passenger side. Helps the car to track straight ahead and is not some myth or poor quality at the factory. Thread kinda died off but I've seen this posted multiple times and people saying it's a myth or not knowing the true answer.

 

[-MaTTi-]

Caster is absolutely set different on each side on purpose.

Set? It’s solid axle. Cut & weld is the only option to do that.

 

[Skter505]

Set? It’s solid axle. Cut & weld is the only option to do that.

You're right. The factory didn't set it they just threw the tubes on and welded wherever they felt like it.

 

[pb4ugo]

You're right. The factory didn't set it they just threw the tubes on and welded wherever they felt like it.

BS, the Toyota diff housing are an assembled steel housing. There are no tubes. My guess, the assembled housings were put in a jig then the balls and perches were adapted in their proper orientation for caster and pinion angle.

 

[Skter505]

BS, the Toyota diff housing are an assembled steel housing. There are no tubes. My guess, the assembled housings were put in a jig then the balls and perches were adapted in their proper orientation for caster and pinion angle.

You are arguing semantics. Of course they used a jig. My point is the caster is different side to side on purpose. How many have you measured caster on and how many are the same side to side?

I'm out. Just clarifying some things not trying to argue with strangers on the Internet.

 

[Grayscale]

Caster is absolutely set different on each side on purpose. It is a common practice for a quality alignment guy to set drivers side a couple tenths not more that 1/2 degree lower than the passenger side. Helps the car to track straight ahead and is not some myth or poor quality at the factory. Thread kinda died off but I've seen this posted multiple times and people saying it's a myth or not knowing the true answer.

The FSM suggests something different.

 

[65swb45]

You're right. The factory didn't set it they just threw the tubes on and welded wherever they felt like it.

If I’d been online when you posted, I would have jumped in to offer you a napkin for your dripping sarcasm! I could tell you were being facetious.

IN THIS PARTICULAR CASE, the FSM does not indicate a difference between right and left on the question of caster. And that is what we have to go with.

The timing of this discussion is interesting to me because I am currently daydreaming about cleaning out the service bay of my shop to bring in my FJ45 for a cut and turn. As @Grayscale mentioned, I do not find the driveline angles created by the caster shims to be satisfactory.

 

[peesalot]

Curious, if it's factory take measures before of driver & pass side trunions, if you would, I'm guessing 1/2 deg diff.