Sub8

Hi all. A friend owns a garage with a hunter 4 wheel laser alignment ramp. He's happy to let me use it.

I know what the settings mean, I know what settings I want.

Could anyone help with practical adjustment steps?

It's a c5 z06 with delrin bushes. No shims under front upper arms.

I believe best practice is start at rear. I guess camber and then toe?

Front? Camber then toe then check castor? Or camber, then check caster and end with toe?

What's the lowdown on lower arm front and rear camber bolts with regards caster vs camber?

Many thanks!

fatbillybob

Is laser alignment rig calibrated?
Then is your corner balancing done?
1/2 fuel load in car
tires at hot pressures
your weight in driver's seat
then: rear thrust angle to zero
rear camber
rear toe
front camber
front toe
caster
verify as going for 1 setting can slightly change another.

Sub8

Hi - when you say set rear thrust angle to zero as a first step. Is that just setting rear toe to zero?

Understand the need to go round the loop a few times.

What about lower arm bolts? Set them both in an equal position for required camber and then lock front bolt and use rear to adjust castor?

Thanks.

davidfarmer

you have to make sure your rear toe is not only set propery, but symmetric to the vehicle. Thrust angle is the relative mis-alignment. Your friends rig will show this to you.

As for front, if you care about castor at all, you'll do castor and camber together, then set toe last. No reason to set the toe then check castor, as if you change the castor you'd F-up the toe.

Lower control arm adjusters swing the bottom of the upright forward to create castor. If you can't visualize this, then you should just pay your friend to do it for you.

SocalC5Z

David brings up a good point here. Set the toe wrong or thrust angle and the car will be wicked to drive and with your level of experience probably not something you can address in the pits at your next track event. Think of the alignment cost in terms of what you spend to do a track day.

. . I've used a modern alignment rack a few times and it's a joy, but you still need to understand how adjustment affects the others. I started out with a Smart Camber, toe gauges and homemade turn plates and worked my way thought lots of mistakes. If you're asking for practical alignment steps I'd pay the man and get the job done right and worry about other stuff.

Nowanker

If you can't visualize this, then you should just pay your friend to do it for you.

My procedure (after doing >1K alignments...)
Race car: Ballast to race condition (driver weight/fuel)
Set tire pressure. Irrelevant if it's what you race at, but they MUST be even side/side
General recommendation is to set the rear camber and toe first. Setting even rear toe on each side drives the car straight ahead, while skewed rear toe (thrust angle) will drive the car sideways.
Camber changes generally affect toe readings and vice-versa, but to a WAY smaller amount
Jounce the car to settle the suspension between adjustments
Then move to the front...
Camber adjustments affect caster readings and vice versa, the adjustment cams tie them together directly.
Visualizing what each cam does to the angle of the spindle (caster) helps the process.
When making camber adjustments, set the wheel that you're working on close to straight ahead. With our high caster angles, the farther away from straight ahead, the wronger your camber reading will be.
After Cam/Cas are set, lock the steering wheel straight ahead and set front toe evenly both sides.
Jounce the car again, recheck/fine tune your adjustments.... repeat as needed.
Patience is your friend, and it's awesome that you have a late style digital aligner to use!

Sub8

Thanks all. Some of you guys do make me laugh.....

Sub8

So in detail: rotating the cam bolts to push the bottom of the wheel out obvious adds negative camber. But does it also add castor? What is the effect of just the front bolt vs the rear?

Also I thought castor is effectively measured by change in camber when you swing the wheel +-20degs? So do you get a direct reading of castor from the machine as you move the bolts? Or do you have to set camber, turn wheel, get the castor and repeat? Does that make sense?

c5racr1

Nowanker

I've never used the feature, but supposedly the late machines can tell you what is happening to the caster when you adjust camber.
I wouldn't trust it.... but that's just me.
"insert dinosaur picture here"

Bill Dearborn

When you turn the cams you will affect camber no matter what. If you can possibly turn both the front and rear cams exactly the same you won't affect caster. Using the front cam to move the lower control arm increases camber and decreases caster. Using the rear cam to push the lower control arm out increases camber and increases caster. OP: Since you don't have any shims behind the upper control arm dog bones you could add shims behind the front dog bone to increase caster but that also decreases camber. When I was setting up my C5s for the track I found that it was easier to get close to the negative camber value I wanted if I just forgot about caster and let it fall where it would fall. I pushed the LCAs out as far as possible and removed all shims from behind the UCAs. When I ran the GM Camber Plates I was able to get the following settings in the front of my C5Z:

Front:
==Left: ==================================== Right: Camber -2.4 ============================== Camber -2.7
Caster +5.1 ============================== Caster +6.3

Bill

Sub8

I was hoping you might chime in! And pretty much exactly the info was looking for.

I think last question..... What's the score with 'overclocking' the cam bolts, so going over centre and having the cams in the top of the slot? I'm led to believe this makes them more secure, short of using the locking plate type.

Any idea if you get less adjustment this way? Does it affect bump steer as it looks like it moves the LCA pivot point up slightly?

I had an alignment 3weeks ago, ran a track day, something moved. Went to a shop a week later, rear left had 1.5deg toe in!

They couldn't get better than 3degs castor delta with only 1.5deg front camber.

Car doesn't drive nicely.

Hence pretty fedup with shop 'experts'. I use MPSCup2.

Many thanks.

Nowanker

Uneven caster will induce a pull, toward the side with the least amount.
Unknown what specifically that caster spread will do to on track behavior, but I always find it disturbing needing to hold the car on a straight path.
I aim to keep it within 1/2 degree side-side. No reason it should be dramatically off, except something is bent or bushings are squished.
I've never experimented with delrin bushings, but rumor has it they are so rigid as to limit the amount of caster available.

Sub8

Well the `first` alignment prior to the track day had ~1/2deg difference side to side. So no reason I can't replicate that. The last alignment place clearly didn't really know what they doing!

Thanks.

Nowanker

Alignments are frequently seen as a cash cow. A butcher shop alignment can usually be done in around 20min, and is frequently given to an apprentice level tech.
The typical mass-market alignment shop motto is "if all the readings are green, it must be right!"
Adjustment tolerances are wide, cars are pretty forgiving, drivers aren't discerning...and most customers are so thoroughly ignorant that the printout looks like Greek anyway.
It pays to use a performance shop, if you can find one, and also pays to be specific in the settings you're after. If they can't reach them, they should be able to explain why in simple, plain English.
Not too tough to do an alignment at home. Takes a lot of patience though.
Good luck!

paul69camaro

I was once in the same situation as you. Got tired of alignment shops doing half *** alignments so two buddies and I bought our own alignment machine and 4 post lift with turn tables and sliding plates in the rear. There is good advice here and the only thing I would add is if you are going to keep tracking the car, invest in a alignment camber kit, I'm talking about the ones that replace the cam bolts. My experience is that the cam bolts will move on you if you track it. Take advantage of the fact that you have access to an alignment rack and spend the time to install these. Also, Like David said, adjust toe last and caster and camber together.

Sub8

Well that's the thing. To do it properly at home you really need the 2/4poster. With the 'sticky' ride height on our cars jacking the car between adjustment puts more error into the process.

The other interesting option is the hub stands... But again $$$. Agree about proper alignment plates vs the camber bolts.

Thanks again all....

paul69camaro

There is no need to lift the car off the rack unless you need to put washers behind the upper control arm mounts. I am a huge fan of rachet straps.... Hook one onto the lower control arm and tighten it towards the center of the car to take the load off the camber bolt so you can replace it with the alignment plate. Obviously only do one at a time. Makes the process really easy.

Paul

Sub8

..... Yeah. If its on a lift and not 3inches off your garage floor.

paul69camaro