Alignment Help

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Ricks70Duster340

Ricks70Duster340

Child of the King
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I am trying to align my car after replacing front end parts. I see the quote:

From Jim Lusk:

"Have them start with the front cam all the way out and the rear cam all the way in. Move the rear cam out until camber is in spec (1/2 deg. neg is good). This is the most positive caster that is available without new parts (offset bushings, tubular upper control arms, etc.). All of this is AFTER setting ride height. I usually set ride height with about an inch between the LCA bumper and the frame, then even the sides up."

My question is this: what does it mean when the front cam is all the way in? Does that mean the high eccentric part of the cam is pointing to the top, side, etc.? Trying to be crystal clear.
 
Move the cams such that you get maximum caster, which puts the upper ball joint behind the lower ball joint.
upload_2021-3-29_16-57-2.jpeg
 
It means you didn't follow Jim's instructions.
 
It means make the front part of the upper control arm as long as possible (rotate front cam lobe inwards) and the rear part as short as possible (rotate rear cam lobe outwards) You'll understand when you see it and manipulate it...Then make the rear a little longer a bit at a time by rotating the rear cam from the full outward position until you get the slight(1/2 degree) negative camber.......Unless you used off-set bushings.
 
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Ricks70Duster340 said:
Less than helpful comment. C'mon man
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I don't know what else you're after. It means you went the opposite way. The wrong way. "All the way in" means you made the front of the control arm "short" and it needs to be "long". The rear of the control arms need to be "short".
 
CFD244 said:
It means make the front part of the upper control arm as long as possible (rotate front cam) and the rear one as short as possible (rotate rear cam) You'll understand when you see it and manipulate it...Then make the rear a little longer a bit at a time until you get the slight(1/2 degree) negative camber.......Unless you used off-set bushings.
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Perfect, that is what I needed.
 
Ricks70Duster340 said:
Not going to belabor this, but was wondering why you have such an edge to you? I mean, as a newcomer to this forum; I thought it was for people like me who read things and have questions. Even dumb ones.
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It wasn't a dumb question. I was just messin with you man. Lighten up Francis.
 
Need to get my front end aligned on my 70 Dart, stock with front discs radial
Tires
What are the specs for alignment ???
 
The general deal is, you want the spindle laid back as far as possible to get max castor in that direction. But you cannot lay it back as far as the adjustments allow because you ALSO must tilt the top of the spindle inwards towards the car to get the camber where you want (with radial tires the tires need to be "in" towards the top. So you have to give up some caster to get the camber. But if you just get the camber "in" you may give up more caster. So try to keep the caster to max while "barely" giving yourself the camber you can live with
 
To the op, if you're doing it at home, one thing that kept biting my ***, was do not jack the car up. It changes everything. Once I drove it around, then onto turn plates, i did what you were told, and perfect. Also, I bought one of those Longacre kits with the digital angle finder. The part that has the legs would never sit repeatedly in the same spot.
 
Here's the SKOSH chart that was mentioned if you don't feel like reading that whole article. The bottom line is that the factory specs were for bias ply tires, so the FSM alignment specs should not be used with radial tires. Ever. The SKOSH chart is a much better place to start, but the caster numbers are pretty conservative. The chart was limited by technology at the time, basically it's limited to the numbers you can get with a set of offset UCA bushings (MOOG K7103). With tubular control arms you can run quite a bit more caster than what's recommended here, although for street use the "Max perf street" is fine. For track and auto-X I'd happily say +5° to +7° caster is just fine, especially if you have power steering.

alignment-specifications-jpg-221767-jpg-jpg-jpg.jpg


furyus2 said:
To the op, if you're doing it at home, one thing that kept biting my ***, was do not jack the car up. It changes everything. Once I drove it around, then onto turn plates, i did what you were told, and perfect. Also, I bought one of those Longacre kits with the digital angle finder. The part that has the legs would never sit repeatedly in the same spot.
Click to expand...

100% true. Do not raise your car with a jack and set it down onto your turn plates. You can "jounce" the bumper all you want, the car will never completely sit down to its real world ride height like that. You need to drive up onto the turn plates. I bought a set of race ramps, I drive up right onto the turn plates. I then use a jack to slide the slip plates under the rear tires. Which is fine, because the rear with its live axle and leaf springs can be "jounced" to return it to ride height. With the front suspension the tires move in an arc as they go through the range of suspension travel, changing the alignment as they move. So the ride height is critical to setting the alignment. Once you make changes, ideally you would drive the car around the block and check it again. If you jack it up and set it down, same thing. If the car doesn't drive you can roll it back a forth a bit, but rolling the front wheels helps the suspension settle.

If you're using a longacre kit, or any of those tripod looking caster/camber gauges, you do need to use the same process each time for installing it onto the wheel and install it on the same place on the wheel each time. It definitely takes some practice to get nice, repeatable numbers. But it can be done!
 
72bluNblu said:
Here's the SKOSH chart that was mentioned if you don't feel like reading that whole article. The bottom line is that the factory specs were for bias ply tires, so the FSM alignment specs should not be used with radial tires. Ever. The SKOSH chart is a much better place to start, but the caster numbers are pretty conservative. The chart was limited by technology at the time, basically it's limited to the numbers you can get with a set of offset UCA bushings (MOOG K7103). With tubular control arms you can run quite a bit more caster than what's recommended here, although for street use the "Max perf street" is fine. For track and auto-X I'd happily say +5° to +7° caster is just fine, especially if you have power steering.

View attachment 1715716339



100% true. Do not raise your car with a jack and set it down onto your turn plates. You can "jounce" the bumper all you want, the car will never completely sit down to its real world ride height like that. You need to drive up onto the turn plates. I bought a set of race ramps, I drive up right onto the turn plates. I then use a jack to slide the slip plates under the rear tires. Which is fine, because the rear with its live axle and leaf springs can be "jounced" to return it to ride height. With the front suspension the tires move in an arc as they go through the range of suspension travel, changing the alignment as they move. So the ride height is critical to setting the alignment. Once you make changes, ideally you would drive the car around the block and check it again. If you jack it up and set it down, same thing. If the car doesn't drive you can roll it back a forth a bit, but rolling the front wheels helps the suspension settle.

If you're using a longacre kit, or any of those tripod looking caster/camber gauges, you do need to use the same process each time for installing it onto the wheel and install it on the same place on the wheel each time. It definitely takes some practice to get nice, repeatable numbers. But it can be done!
Click to expand...

It depends on what type turn plates you have. I have an old set of Hunter turn plates I rebuilt that allow complete jounce and rebound, so the front end can be jacked up and set back down fine. It makes adjusting the cams much easier.
 
When I was taught alignment, the thing that helped me the most, was my mentor emphasizing
- A bicycle HAS + Caster .
I would picture that, and swing the top ball joint rearward.
Hope it helps someone else .
 
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RustyRatRod said:
It depends on what type turn plates you have. I have an old set of Hunter turn plates I rebuilt that allow complete jounce and rebound, so the front end can be jacked up and set back down fine. It makes adjusting the cams much easier.
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Most of the turn plates out there that are affordable enough for home use are just that, turn plates. They do not have a sliding component, just rotating. For those plates, “jouncing” the bumper will never fully settle the car. The plates have to slip for that to work.

The problem is that the wheels make contact with the plate/ground when the suspension is fully extended. At that point, the wheels have a ton of positive camber. As the the suspension sits down, the track width increases slightly and the camber changes with the decreasing ride height. But the tires are on the ground, and the resistance you get from the tires not sliding on the ground holds the suspension up. So unless you have it on slip plates in the front, you have roll the wheels to let the suspension settle. That’s why when you put the car on the ground after jacking it up it stays higher than the ride height has been set.

If you run skinny, hard front tires they may reduce that effect and make “jouncing” the suspension more effective because the tires may slide on the ground. If you run wide, soft front tires they’re not gonna slide, enhancing the ride height change and making the “jouncing” thing useless.

inertia said:
When I was taught alignment, the thing that helped me the most, was my mentor emphasizing
- A bicycle HAS + Caster .
Hope it helps someone else .
Click to expand...

Yup. And a shopping cart wheel has negative caster. Which is why you want positive caster.

With the UCA you want to move the top of the spindle as far back as you can get it. So you adjust the front leg of the UCA so it moves away from the frame, pushing the ball joint backward. And you adjust the rear leg of the UCA so it moves toward the frame, pulling the ball joint back. That’s max caster.

Then you adjust the camber. If you don’t have enough negative camber, use the front adjuster to pull the ball joint back in a little. If you have too much negative camber, use the rear adjuster to push it out. Both adjusters should have been maxed out, so you only have one direction left to move anyway.
 
72bluNblu said:
Most of the turn plates out there that are affordable enough for home use are just that, turn plates. They do not have a sliding component, just rotating. For those plates, “jouncing” the bumper will never fully settle the car. The plates have to slip for that to work.

The problem is that the wheels make contact with the plate/ground when the suspension is fully extended. At that point, the wheels have a ton of positive camber. As the the suspension sits down, the track width increases slightly and the camber changes with the decreasing ride height. But the tires are on the ground, and the resistance you get from the tires not sliding on the ground holds the suspension up. So unless you have it on slip plates in the front, you have roll the wheels to let the suspension settle. That’s why when you put the car on the ground after jacking it up it stays higher than the ride height has been set.

If you run skinny, hard front tires they may reduce that effect and make “jouncing” the suspension more effective because the tires may slide on the ground. If you run wide, soft front tires they’re not gonna slide, enhancing the ride height change and making the “jouncing” thing useless.



Yup. And a shopping cart wheel has negative caster. Which is why you want positive caster.

With the UCA you want to move the top of the spindle as far back as you can get it. So you adjust the front leg of the UCA so it moves away from the frame, pushing the ball joint backward. And you adjust the rear leg of the UCA so it moves toward the frame, pulling the ball joint back. That’s max caster.

Then you adjust the camber. If you don’t have enough negative camber, use the front adjuster to pull the ball joint back in a little. If you have too much negative camber, use the rear adjuster to push it out. Both adjusters should have been maxed out, so you only have one direction left to move anyway.
Click to expand...
I got lucky at one of the garages I worked for years ago and was given an old set of Hunter turn plates. I got rebuild kits for them and they are nice now. Work really good.
 
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