DIY Alignment -- Did I do it right?

[charliekwin]

A little back story: last summer I pulled out the entire suspension and replaced the shocks, springs, bushings, sway bars and tie rod ends.  I installed the new tie rod ends on the same number of turns as the old ones, but I know the alignment has been off ever since I bought the car.  This past weekend, I finally spent some hours attempting to correct it myself.

First, I centered the rack as best I could by counting steering wheel revolutions from lock to lock, then putting the wheel back on as close to the middle as I could.

Then, pulled the car into the garage with the steering wheel straight.  Tied strings to jackstands and positioned them parallel to the car by measuring at the front and back of the rear rim.  Then measured at the front and back of the front rim to determine the toe in/out.  As expected, it was way off.

Made adjustments to the tie rod ends and repeated the same process a number of times.  After enough fiddling, I got both left and right wheels to toe out a hair under 1/16".  When driving the car, it tracks straight if I hold the wheel, but if I let it go, the wheel will turn a few degrees to the right and the car follows.

Not sure what to do now to correct it from pulling to the right.  Did I miss a step in the process somewhere?  Or, considering differences between left and right -- the right tire has significantly more tread wear -- might this be as good as I'll get it with what I have to work with?

[Martzedcars]

2 hours ago, charliekwin said:

 When driving the car, it tracks straight if I hold the wheel, but if I let it go, the wheel will turn a few degrees to the right and the car follows.

LMAO 

But seriously.. some things you have to leave to a professional.. with the right tools.

 

[Martzedcars]

3 hours ago, charliekwin said:

then putting the wheel back on as close to the middle as I could.

I always do that...  (Sarcasm... ) 

Sorry but don't they center themselfs anymore??  Time for some new wheels?? and nuts!

[hr369]

3 hours ago, charliekwin said:

Made adjustments to the tie rod ends and repeated the same process a number of times.  After enough fiddling, I got both left and right wheels to toe out a hair under 1/16".  When driving the car, it tracks straight if I hold the wheel, but if I let it go, the wheel will turn a few degrees to the right and the car follows.

Not sure what to do now to correct it from pulling to the right.  Did I miss a step in the process somewhere?  Or, considering differences between left and right -- the right tire has significantly more tread wear -- might this be as good as I'll get it with what I have to work with?

Pulling to right could be tire pressure, caster, crown in the road.  What is the wear pattern on the tire? scalloped, outside worn, inside worn?

 

 

[Captain Obvious]

I'm no suspensions guy, but here are a couple things that caught my eye as I read your post.

 

There is a dot punch mark on the end of the splined steering column shaft where the steering wheel attaches (see page ST-3 of the 78 manual), and that dot is supposed to signify "center of travel". So in theory, unless someone has messed with the steering rack or column U-joints in the past, you should be able to find center of travel of the whole system by putting that dot at top dead center. Of course, you'll have to find which of three steering wheel rotations is the correct one, but that's something you should be able to do by eye.

 

So you can find approx center of travel by counting revolutions or by eye and then fine tune it by putting that punch dot top dead center. Once the dot is top and center, make sure the steering wheel is installed properly such that it's pointing straight when the dot is top and center.

 

Something else that caught my eye is that you set the front wheels for toe OUT instead of toe IN? Like I said, I'm not a suspension guy, but I thought toe OUT is reserved for performance applications and toe IN is what you want for normal driving. From what I understand, toe IN would provide straight line tracking like what you want on your grocery getter and toe OUT is used when you're willing to sacrifice stability for speed of response when entering turns. So if I understand correctly and you have things adjusted toe OUT, it would be no surprise to me for your car to be a little squirrely. I think you should have a little toe IN, not OUT.

 

About your jackstands and strings... I'm not sure how you think you got the strings parallel to the car, but I'd be interested in hearing where you were taking your measurements from to make that claim. If it were me, I'd skip trying to get lines parallel to the car since nothing in the rear really matters (since there's nothing adjustable back there anyway). Unless you've installed some aftermarket adjustable suspension bits in the rear then you should be able to ignore the entire rear of the car and focus simply on the front. I would just measure directly to the front tire treads at front and rear of the tires and use that to dial in appropriate toe-in. Skip the strings completely as the more complicated the measurements, the more sources for error.

 

Park the car, measure the front tire treads for toe, and keep making small adjustments until the steering wheel runs straight up and tracks straight. In theory even if something is a little out of whack in the rear, using that method should adjust the fronts to account for it. In the end, the best you can hope for is:

1) Steering wheel is straight when you're driving down a flat and level road.

2) Car tracks straight when you let go of the wheel and doesn't pull to one side or the other.

3) Your tires wear evenly and don't go bald on the inside edges before everything else.

 

If you can achieve those three things, I think that's about the best you can do without modifications to the rear suspension bits. All that said, however, if there is really a significant difference between tires, you might not be able to get things proper at all. Might be able to get it close enough with unevenly worn tires, but I would revisit it when you get new rubber.

[John Coffey]

http://www.hotrod.com/how-to/chassis-suspension/ctrp-1204-determining-wheel-alignment-string-your-car/

[charliekwin]

Thanks all for the replies, and I'm happy my follies provided some entertainment   At the risk of digging myself deeper into my hole, some attempts at explanation...

I started with the rack and steering wheel because having seen the things that POs had done to the car, I suspected it was off center, which it turned out to be.  I overlooked the center punch, so that's on me, and I'll check to see if I still ended up off center at all.

I went with toe out because John's alignment specs on Hybrid Z were the only ones I could find anywhere, so that was my starting point.

Regarding parallel: I wasn't measuring to get parallel to the car, but measuring to get the strings parallel to rear wheels.  I used the same link that John posted and tried to do that.

The alignment -- used loosely -- that the car started with when I got it was absolutely bonkers.  Visibly bonkers (the numbers are at home, but 5/16" out on the left and 1/4" in on the right are coming to mind), so it would have been impossible to make it worse, and I might even learn something along the way by giving it a shot myself.  

Anyway, both front tires have uneven wear: both are more worn on the righthand side; additionally, the right tire has about 1/8" less tread total than the left.  Considering that alone, I don't know if there's any hope to get things totally right.  And that isn't a terrible problem anyway.  The wheels and tires on the car are rather awful and I'm eager to replace them when the rears finally give out.  At that point, I'll have it properly aligned by someone who knows what they're doing.  For now, I'm happy to fiddle with it myself.  It's already a whole lot better than it was.

Thanks again for the comments.

 

[Captain Obvious]

Well don't get me wrong. I'm not thinking the venture is a folly. In fact, I did my first day alingment on my Z, and it's the car that I'm most satisfied with. Now that I've had such success with that car, I'll do more of it in the future on other cars.

im familiar with that string alignment page and a couple others and if done well, it works. However, on the Z, since there isn't anything on the rear that's adjustable, you may a well ignore it unless you're looking for an issue that you plan to fix.

Look at it this this way... If you're driving on a flat level surface and you let go of the wheel, the car will go where nature and physics dictates. First step is to have the car go straight when you let go. Make sure you have a little toe in (specs in FSM) and get the adjustments such that the car goes straight naturally when you let go of the wheel. After that, adjust the two front sides in unison so the steering wheel is in the correct position when that happens.

im not poo-pooing home diy alignment. I am, however, a believer that most of the people doing that string stuff are kidding themselves. Even that link posted above has pics of people taking measurements off a tire sidewall. Some of them even on the raised lettering. It can be done, but there are pitfalls.

ill try to draw up a couple sketches if I get a chance.

[Zed Head]

I used CO's described method and it's easy and works well.  Pick a spot on the tread and make it the same distance on the front of the tire as the back.  The spec. for toe-in is 0 to 3 mm for a 1976 280Z, so equidistant is in spec.  If you want a bit more stability, add a half-turn or two to the adjustment.

I found also though, that the slightest wheel bearing looseness will magnify the wheels' attempts to track on ruts, and divert over bumps.  I've also found that the factory wheel bearing tightening method of 20 ft-lbs of torque then backing off 60 degrees doesn't work well.  My old worn parts may be part of the problem.  But the methods they describe in the FSM can be conflicting,  60 degrees nut back-off, or wheel turning torque?  The turning torque measuring  method seems most logical but I lost my fish-weighing scale years ago.  I use a wheel shaking method (my own) now, it seems to work.

[charliekwin]

Measuring at the tires makes sense.  Not having any point on the car properly adjusted was throwing my brain for a loop, and using the rear wheels as a reference was something I could grasp.  In my head, at the office, I think I've got it figured out.  Will see how it goes when I'm on the garage floor.

[siteunseen]

I used an adjustable shower curtain rod on mine, top and bottom of the two fronts. They were so off I went to alignment shop. $50, drives like it's on a monorail now.

[Captain Obvious]

I get ya about nothing being adjusted right and being thrown for a loop. And I also get being able to grasp an unadjustable rear wheel as a fixed reference point. But that right there is part of the problem... You just set your front wheel to on an unqualified rear wheel reference source. Who knows what that rear wheel is doing compared to the OTHER rear wheel!

im saying that at SOME front wheel setting, the car will go straight. The absolute details in the rear don't matter unless you've got adjustable stuff back there.

1) Make it go straight.

2) Get the steering wheel to where you like it.

3) Fine front toe in so you don't eat the outside edges.

4) keep an eye on your tire wear all around.

If at some time after that, you find you're eating up a rear tire, then you need to dig deeper into the rear, but if not, then be happy.

One more way to look at it? You asked if you did it right? Answer is no. You probably set everything to a rear wheel that is a little out of whack.  If you did it right, you wouldn't be asking, because it would be driving perfect.