[Gubi]

Just wanted to plug this caster/camber gauge I bought off of Amazon. Definitely the easiest option I've found for doing this: it works a lot better than the bubble levels I've tried in the past, it fits a wide variety of wheels, and it's not stupid expensive. In a clever touch it has the appropriate angle cut into it to measure proper wheel rotation when you're setting caster.

Amazon.com: Tenhulzen Auto 1100 Hand-Held Camber/Caster Gauge with 0.1 Degrees Accuracy: Automotive

Buy Tenhulzen Auto 1100 Hand-Held Camber/Caster Gauge with 0.1 Degrees Accuracy: Wheel Alignment & Balancing Tools - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

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You can make swivel plates by using stick on vinyl floor tiles: put them face to face with some lithium grease between them and the wheels will swivel easily. With this and the digital tool it's very easy to set camber and caster.

 

[marpat]

I too am DIYing this, and I am wondering about the measurements. I think the "20 degrees left, then 20 degrees right, measuring camber at each position" method is problematic because of the offset attachment of the caster-adjusting arm to the upper control arm. That is, the normal formula assumes symmetry that the Alfa geometry doesn't have. See https://disco3.co.uk/gallery/albums/userpics/24543/steering-geometry-and-caster-measurement.pdf.

I have a simple bubble camber gauge like this one: https://www.amazon.com/gp/product/B01EPL6BB6. I'm pretty happy with it, because its measurements seem very repeatable, but it doesn't have a separate way to measure caster directly. I think I can probably figure something out, but I'm wondering if others have a suggestion.

My technique to substitute for swivel plates is two pieces of wax paper, which work quite well, even without grease. They also allow markings to measure angles (though now I'm doubting whether those angle measurements are useful).

 

[Gubi]

I'm not sure you're thinking about that right? All that really matters for caster and camber are the positions in space of the top and bottom ball joints, and those are fixed relative to each other when you lock the camber adjuster. It doesn't matter if the camber arm is offset or not.

If you read page 8 of the doc you referenced I can't see why conditions (1) and (2) wouldn't hold. In any case, I've never had any steering pull at all doing caster by the angle method on the Alfas, which also suggests that turn asymmetry is a non-issue.

If you're saying there are interactions when you adjust camber, caster, and toe, then that's correct, and that's why you might need to do a second iteration to dial things in if you were way off at the beginning.

 

[marpat]

Thanks for the reply, and, yes, I think you're right. It shouldn't matter how or where the arm adjusting caster is attached to the upper control arm, because none of that should move. As you say, that's all fixed (or almost fixed) once the camber is fixed.

That said, I'm getting odd results when I adjust caster. The camber at the +20 degrees and -20 degrees positions doesn't change as I would expect. But I will experiment and ponder further.

 

[Gubi]

You should make sure you do caster last. First toe, then camber, then caster. Then check and adjust again in that order.

For caster (at least with a digital gauge) you turn the front of the tire in 20 degrees, then zero the gauge. Then turn the front of the tire out 20 degrees, measure camber angle, and multiply by 2 [edit: should be 1.5x for 20 degrees], that's your caster.

 

[marpat]

For caster (at least with a digital gauge) you turn the front of the tire in 20 degrees, then zero the gauge. Then turn the front of the tire out 20 degrees, measure camber angle, and multiply by 2, that's your caster.

I’m measuring the difference in camber between the two positions, but it’s the same thing. And I think 1.5 is the multiple for +/- 20 degrees, with 2 for +/- 15 degrees. That’s what (8) on page 5 of that article would produce, and what seems to be the consensus on the web.

 

[Gubi]

Yep, you're right: I was going by my digital tool's instructions and it uses 15 degrees.

 

[Gubi]

I have a simple bubble camber gauge like this one: https://www.amazon.com/gp/product/B01EPL6BB6. I'm pretty happy with it, because its measurements seem very repeatable, but it doesn't have a separate way to measure caster directly. I think I can probably figure something out, but I'm wondering if others have a suggestion.

Also, just some advice: I tried one like that at first and it was pretty crappy. Especially on a 115 Alfa where you're targeting relatively small 1.5 degrees caster, it's just not precise enough to really do it right. I'd suggest either the digital gauge or a better bubble gauge.

The other problem is there's no easy way to mount a magnetic bubble gauge to most Alfa wheels. What I did was use a piece of flat steel across the middle of the wheel from rim edge to rim edge, but this was kind of a pain. The digital one is easy to adjust so that you can hold it consistently against the rim.

Anyway, if you want to use the one you have then you shouldn't be trying to manually calculate the difference between the two angles: it's got a zeroing knob. Point the front of the wheel in, zero it with the knob, and then point the front of the wheel out. Then the gauge will directly register the camber difference. Make sure you use the other bubble to level it horizontally for each measurement.

 

[marpat]

“you shouldn’t be trying to manually calculate the difference”

“Trying”? Subtraction isn’t that hard. I think I’m up to it, though I realize I might have given you reason to doubt.

I actually think the gauge is ok. As I said, I’ve checked its repeatability. I’m using the same metal-plate approach, and it’s a bit of a hassle, but not so very bad. But thanks for the suggestions.

And I think I’ve figured out the cause of my original problem. I’ll check tomorrow.

 

[Gubi]

“Trying”? Subtraction isn’t that hard. I think I’m up to it, though I realize I might have given you reason to doubt.

I don't doubt your ability to subtract. But you're trying to measure a delta of one degree (assuming you're targeting 1.5 caster) on a fairly imprecise scale.

It'll be easier to get a repeatable measurement if you zero the first measurement with the wheel, then target the 1 degree line for your second measurement. It'll also make it more immediately obvious which way you're moving things and how much.