Basic Alignment and Setup Questions - IRS

[TTimmy]

Now that my Gen 3 coupe can travel under its own power (what a great milestone!) I have found the alignment is abysmal at best... crabwalks, etc. It’s tough to drive around at speeds over 10-15 MPH.

I am looking for input regarding the sequence of steps I should follow for roughing in the alignment. I realize it will need a final alignment once the car is completed. I am considering handling the final alignment myself as I have found great resources here on the forum. If my work is not adequate I can take it to a pro. I have power steering, IRS, front and rear sway bars and the basic red Konis.

So, as a starter, I am thinking these basic steps in this order:

0. Purchase some basic alignment gear for camber and caster?
1. Unload the sway bars
2. Set ride height on level surface
3. Adjust rear wheels (Gen 3 IRS) to be centered and square to the frame using jack stands and string
4. Adjust rear camber and then toe
5. Adjust front steering wheel/rack to approximate "center"
6. Adjust front caster - power steering
7. Adjust front camber
8. Adjust front toe - total
9. Fine tune front toe (distribute left/right) to keep steering wheel centered
10. Reconnect the sway bars

[weendoggy]

Reverse step 6 & 7. Camber is set first.

[edwardb]

Yes you will need some tools. I've done my own alignment on all my builds. I started basic and have gradually added more tools in search of a better (and easier...) job. For starters, you will need a caster/camber gauge. I started with an SPC FasTrax tool. Many others use it as well. It's OK and is a good place to start. I've since upgraded to a Longacre digital caster camber gauge which I believe provides more accurate and repeatable results. But well over twice the money. For toe adjustments, I tried the toe adapters that SPC sells for the FasTrax. I just couldn't get repeatable results. I now use toe plates which I highly recommend. The last thing I added was turnplates. There are lots of ideas out there for DIY methods to allow the wheels to turn while you're doing the alignment. Trash bags, greased floor tiles, etc. They can work, but the biggest challenge I found is getting the right angle left and right when setting caster. The angles need to be accurate to get the proper results.

As for sequence, your list is OK. Ride height is absolutely first. I agree camber is set before caster. But in all cases, the camber/caster/toe settings interact. Don't think it's one and done for each setting. So you have to go around and around checking one, adjusting, checking the next, adjusting, etc. When they get close, the interactions reduce and eventually everything will be to spec. It will try you patience on a new build when everything is way off. But follow-on checks and/or minor adjustments are much easier. Good luck!

[F500guy]

I think your list is great, I would set caster first and add, as Paul said, rinse and repeat. IMHO caster is the least critical, if you are off .5 deg, probably not notice and even if it is off side to side .5 deg. The other toe/camber will really impact each other so will require multiple retest. Toe is critical and rear toe probably the hardest to ensure there is no "rear steer" and rear is centered. Toe plates are great and easy to use. I also use toe plates in the vertical (rested against the wheel) to measure camber with a a digital angle gauge Roll car to take a couple measures). Make sure your string is set up square. Also, try and bounce the suspension in between measurements to settle it, surprising how well the springs and shocks will hold a preset.

Will need to corner weight after that for an optimal alignment, a little harder to do with out expensive scales, but quick check is to center the jack on front or rear and as you lift the chassis, it will twist if a corner is heavier, if that is significant, it can be corrected by adjusting ride height at different corners.

Quality turn plates are expensive and large equipment to store, so I think the plastic bag or tile and grease works fine
Good toe plates are money well spent
Angle gauge that can be zero'ed
String and 4 jack stands

This is the minimum, the rest is more expense and may make the process faster or easier, not always better.