Alignment question.

[A-man930]

I'll add that any concerns with the brakes could be addressed with an on-car lathe if so desired.  

[1stDeuce]

I'll add that any concerns with the brakes could be addressed with an on-car lathe if so desired.  

Actually, no.  The lathe only turns the rotor, not the pad.  These shims require the pad friction material to wear to a slighty (0.5-1.0°) tapered condition.  Not helped at all by turning the rotors, other than that the freshly turned surface will help them seat in to the proper angle faster.   :)

[Eagle]

It was very commonly done on older cars and trucks with manual steering. Lots of them had very little or even negative caster and a degree or so of positive camber to provide return to center. Gm and Toyota trucks still use lower caster numbers with slightly positive camber (like a quarter of a degree) to keep steering efforts down and still have good centering feel.

I'm going to have to call you out on this one. I grew up in the era of muscle cars and standard (non-power) steering. The shop manuals of the day (of which I still have a few) occasionally mentioned that positive caster contributes to tracking and return-to-center of the steering wheel. But the increased return to center meant increased steering effort, so caster was generally specified as less for manual steering than for power steering. Camber was to be zero.

 

For example, here are the alignment specs from a 1966 American Motors factory shop manual:

 

Caster:

. . . . . w/o power steering = 0 to 1/2 degree positive

. . . . . w/ power steering = 3/4 to 1-1/2 degree positive

 

Camber = -1/4 to +1/4 degree, 0 preferred

 

Toe-in = 1/16" to 3/16", 1/8" preferred

 

These specs are typical of that day and age.

[gogmorgo]

 

Unfounded concerns on all accounts. 

1. The difference in cornering grip between -0.3° and +0.2° on a Jeep with lots of sidewall isn't even worth talking about.   Remember, on a vehicle with IFS, you start with whatever you set camber to, but when you corner, the body leans, and so does the tire.  So on IFS, you get better handling by setting things fairly negative.  On a solid axle, the tire doesn't lean at all when cornering, even if the body does, other than deflection of the rubber.    If I was setting it to +2° or something like that, it'd be different, but LOTS of vehicles run with ~+.25° of camber as the preferred setting.   (All Toyota trucks, All GM trucks...)  Neither you or I would be able to tell the slight difference in ultimate handling on a Jeep.  (I did chassis dynamics for a large portion of my career in the auto industry...)

 

2. Pads wear in VERY quickly.  Because they are rotated toward the top slightly, they wear largely across the short dimension of the pad, not the long dimension.  On my Jeep, I noticed a little extra brake travel for the first couple of days, then it was right back up to normal.  (My Jeep has a very high and fast acting pedal for some reason, so it was very easy to tell there was a difference.)

 

3. Even if you rotate it, you're not changing king pin inclination at all.  The shim is outboard of the ball joints, not inboard.  You're only changing camber if you install it correctly, and if you rotate it, you're mostly changing toe.

 

 

I won't by any means profess to be an expert. I certainly do not have years of experience in the field, but I was an FSAE suspension design lead, so I do at least know a little.

 

1. Tire deflection is what camber settings are all about. There is a perfect camber number, which is where the contact patch deflects back to where it has the best grip. Yes, that perfect number is a variable dependent on lateral load, and it of course will vary with tire choice, vehicle weight, roll stiffness, etc. This is beside the point, but if you set up your IFS properly, you can maintain the camber through the wheel's travel, or if you're really good, to match the roll angle and (negative) camber gain to maintain your deflected contact patch. Again, that's IFS and beside the point, but your wheels don't need to lean if you don't want them to. But back to solid axles, I'll agree with you to the point that you won't really notice that small a change in camber on any vehicle until you're at the vehicle's limit of grip, and even slightly positive you'll still have a limit of grip high enough that you shouldn't come close to finding it on public roads, but it does happen. I'll also agree with you that it's not going to be a huge change even at the limit, but it would still be a change in the wrong direction. I like my limit to be higher, and think my MJ's steering is already a little too light.

 

2. I agree. The pads will wear in. But if you need to make a panic stop before they've done that, you could overheat and damage something, but it's still not something most people would notice and it'll take a perfect storm to cause a serious problem. Murphy's law has left a bad taste in my mouth many times in the past. But I still don't think it's all that severe a problem, just something someone considering the product should acknowledge (and probably dismiss) before choosing it.

 

 

3. You're 100% right on that. My bad. It was a bit of an afterthought between "I wonder if you can flip them upside-down for negative camber" (yeah, I only thought about that for a few seconds) and "I wonder if they make them for negative camber" and I obviously didn't think it through. Like I said, I'm not an expert! :thumbsup:

 

 

Beyond that, I've been trying (not very hard) to find a way to adjust camber less permanently than with ball joints without the intensity of going to independent suspension. The SCCA Jeeps accomplished this on a 2wd solid beam simply by bending the axle, but that's not really an option for a 4x4. Going back to point #1, yes they did it with a solid axle, and yes the negative camber was beneficial, because again it's about tire deflection. I wouldn't mind eventually playing with my camber a bit. I recognize I'll never be able to get the same kind of performance from a 4000lb Jeep that we had in our 400lb FSAE car, but that doesn't mean I can't try to make it better. ;)

[A-man930]

 

I'll add that any concerns with the brakes could be addressed with an on-car lathe if so desired.  

Actually, no.  The lathe only turns the rotor, not the pad.  These shims require the pad friction material to wear to a slighty (0.5-1.0°) tapered condition.  Not helped at all by turning the rotors, other than that the freshly turned surface will help them seat in to the proper angle faster.   :)

 

I'm guilty of typing before thinking completely, in this thread anyways  :doh:

 

Turning the rotor on the hub would address any run-out condition of the hub flange itself but these shims would be moving the plane the hub rotates in (hence the camber adjustment).  So yea, the only way to adjust for this would be some kind of tapered shim in the caliper bracket... not worth it  ;)

 

 

 

It was very commonly done on older cars and trucks with manual steering. Lots of them had very little or even negative caster and a degree or so of positive camber to provide return to center. Gm and Toyota trucks still use lower caster numbers with slightly positive camber (like a quarter of a degree) to keep steering efforts down and still have good centering feel.

I'm going to have to call you out on this one. I grew up in the era of muscle cars and standard (non-power) steering. The shop manuals of the day (of which I still have a few) occasionally mentioned that positive caster contributes to tracking and return-to-center of the steering wheel. But the increased return to center meant increased steering effort, so caster was generally specified as less for manual steering than for power steering. Camber was to be zero.

 

For example, here are the alignment specs from a 1966 American Motors factory shop manual:

 

Caster:

. . . . . w/o power steering = 0 to 1/2 degree positive

. . . . . w/ power steering = 3/4 to 1-1/2 degree positive

 

Camber = -1/4 to +1/4 degree, 0 preferred

 

Toe-in = 1/16" to 3/16", 1/8" preferred

 

These specs are typical of that day and age.

 

 

Benefits of positive camber (according to my textbook):

-decreases spindle leverage (vehicle load closer to the inner bearing)

-decreases road shock

 

Benefits of negative camber:

-increases spindle leverage (vehicle load closer to the outer bearing)

-increased road shock

-quicker wear on wheel bearing and suspension components

 

I was in agreement with 1stDuce on his camber comments but the more I read into spindle leverage and its effects I think its backwards.  

 

BTW I've always heard from the old-timers to increase the caster specs when aligning a classic car that now has radial tires on it to maintain directional stability... not sure if that comment adds anything to the discussion but hey.

[1stDeuce]

Fellas, I don't want to beat this to death...  Everything I read above is correct for one case or another.   But alignment is an art in many cases, and every case is different. 

 

Eagle, your manual is correct, and is how most cars in that era were aligned.  But if you look at truck specs from that same era, what you'll see is caster between 1 and 3 degrees, and camber most always at +1.5°.  This was done for the exact reasons your manual outlines... Adding more caster for better centering made the steering difficult or heavy, while using camber added centering without making the steering heavy.   That's why Toyota and GM set the front camber slightly positive, and run fairly low caster...  

 

gogmorgo, positive/negative camber DOES affect "pull" or centering, just like caster does, and it does affect tire tractive capability in corners too, as you suggest.  But the difference in tractive capability in the "near zero" range that we're talking about is not detectable with tires like ours on trucks like ours.   If we were taliking about a FSAE car, you're correct, but for our trucks, you're talking theoretical differences, while I'm speaking in practical terms, that's all.

 

While I agree that for road holding, return to center, and on center feel, Caster is the primiary driver,  I'll still point out that Camber can and does have an effect also.   Oftentimes a "pull" can be attribued to a cross camber situation rather than cross caster, and it can be fixed with cross camber as well, for example on macphereson strut cars, where caster can't be changed, but camber can.   Or our jeeps, where we can't do much about cross caster, but you can use camber shims to correct a slight pull or drift that might even be caused by a cross caster problem that isn't as easy to fix.

 

I'm just saying there are many ways to skin a cat, and sometimes they're effective even if they're not common practice. 

:)

 

Whatever happened to the OP??  I'm still waiting to hear if swapping the tires L-R changed his drift or not...  ???

Perhaps he got scared away...  :)

[A-man930]

Whatever happened to the OP??  I'm still waiting to hear if swapping the tires L-R changed his drift or not...  ???

Perhaps he got scared away...  :)

We did kind of run away with this one, lol

 

A good discussion for sure.  

[chopper35nj]

OK, as far as refreshing the front end is concerned I did not replace the ball joints they checked out fine as did everything that I did not change. No play anywhere, in any axis. I just replaced the upper and lower control arms with Grand units because it was easier than just replacing the bushings in the old ones, and yes I did replace the bushings on the axle. and I made a sway bar re-locator and added Grand end links. It turns out that I did make the mistake (DUHHHH) of tightening the components before I reinstalled the tires and loaded the suspension, I have remedied that situation and it did help some. I don't intend to put on adjustable CA's unless I am out of options. Front brakes are fine and not dragging. I will check my camber to make sure that I haven't bent my axle, but I doubt it, none of this was a problem before the lift and control arm swap. I have not swapped the front tires yet but I will in the morning (life does have a way of getting in the way of such things) and when I do get this sorted (I'm close... I think) I am going to remove 10mm of shims from the left LCA and weld up and re-drill the axle end of the left UCA 10mm back.