k24556

Got my -V back on the road today and it is really a nice driving car. The last thing I did was a four wheel alignment. The rear was way out on thrust angle and too much negative camber for the street. Here is a list of what was done:

ls7 clutch and slave
transmission rebuild by Texas Drivetrain performance (great job BTW)
drain and refill the rear diff
replace the rear lower control arms
CS motor mounts
new starter
oil and filter
plugs and wires
flush the power steering system
New CS shifter

everything else seems to be fine. the transmission shifts smoother every time I put a few miles on it, so the TDP rebuild was well worth it.

The went well, after I had to saw out the old rear control arms because the bolts rusted in the bushings. I do my own alignments with home made tools and I thought I would pass along an alignment tool DIY and a how-to for aligning a Caddy. Attached.

G-Body

iTrader: (4)

Great write up on the diy alignment. I have been doing my own alignments on my gm G/B bodies and trucks but threw in the towel when it came to the 4 wheel alignment on the V. It actually took 2 tries with the digital alignment machine and the 2nd time they had 2 techs on the car so one could push everything in place while the other tightened. My biggest issue was always spending the time to level the car out on the garage floor but it looks like your 4 post makes that way faster. I like the 1 full spin on the steering wheel to get caster, much easier than trying to measure 20 degrees off of strings. For everyone else reading, another cheap turnplate substitute is to use 8 pieces of standard vinyl 12" floor tile.

ls1247

iTrader: (2)

How are you guys checking wheel runouts?

k24556

I Jack up the car and use a machinist's dial indicator. If it is a wheel bearing as suspect, I will take off the tire and the brake caliper and spin for rough running bearings. Then I put the dial indicator on the bottom of the brake rotor and put a crescent wrench on the top of the rotor and push the top back and forth. That will tell you if you have a bearing going out.

The usual method is to shake the wheel to look for hubs going out, or a noise when that side of the car is loaded, like going around a curve. When you have one that shows runout that you can make happen with your hands you have a bearing that is gone and about had it.

Wheels can be bent too, so I usually run a dial indicator on the rim. The inside usually has a flatter surface at the bead area.

Finally,if you are tracking the car look at the transition between the hub flange and the hub center. Some folks have been reporting finding cracks there, and one driver had damage to her front end at the track when the hub flange decided to part ways with the hub center. Dye Check is the usual method for checking for this crack. Never heard of a street car having that problem.

k24556

I also have a 2-post, but the floor is not level. When the adjusters are really tight, I will do my alignments in that bay. I shim up my turnplate material with plywood to get level. I use HPDE sheets, but you are spot-on G Body vinyl tiles work just fine

Thanks. Hope it helps. Actually a 4-wheel alignment is easy. If you correct thrust angle first, then camber, and finally toe, you are on your way. One trick I did not write about is to shoot the laser on the wall and put a piece of tape on the wall at the laser dot. Then when you make toe changes, you know which way you want the wheel to move and you can watch. you can either have an assistant hold the camber gage on the wheel or use light bungee cords to hold the gage to the wheel.

If anyone wants the excel chart for caster multiplier, PM me with your email. .XLSX is not a supported file for upload. It is the file that i used to create that graph in the writeup.

ls1247

iTrader: (2)

How much runout are you typically seeing on a v1?

k24556

I am seeing .001 at the hub, both lateral and radial
.005-.007 lateral and .010-.013 radial at the wheels (sometimes the force of the tire bead will egg the wheel a scosch). If I put just the wheel on, and no tire, I would expect to see this a bit lower.
.020 lateral, and and .025-.030 radial at the tire

Typical high performance car specs for TIR: (total indicated runout, so max minus min, not the average)

Hub .005 max for both radial and lateral (if I saw that much on a new one I would send it back) They ought to be less than .001 new.
Wheel .040 radial and .045 lateral
Tire .050 radial and .060 lateral.

Now measuring runout on a tire is a sorcerer's game especially one that has seen the road. In the old days with bigger limits on steel wheels which were stamped and welded, (modern high speed cars have machined wheels and they ought to be dead nuts on when new), a lot of people "force-matched" wheel to tire, putting the tire high at the wheel low. Don't see anyone that even knows what that is these days in a tire shop.

ls1247

iTrader: (2)

Thanks for the info...

For alignment purposes, the runout at the surface where you are measuring (as an average of everything that is rotating) is all that really matters but it is important for those reading that you explained it in detail.

You wouldn't feel 1/16th of an inch worth of runout in the steering wheel (probably) but you can see that if both wheel assemblies (the combination of everything rotating as a whole) where a 1/16th out on both sides, it could throw readings off appreciably.

Nice work.

k24556

Thanks. You are correct. A 1/16 runout would make alignments very hard, and likely the cause of of a lot of complaints about alignments that don't seem to fix a condition. After all, a toe spec is usually 0.2deg total toe, so that is a on the order of a 1/16 inch or perhaps less. As you point out, you might not feel it at the steering wheel.

Most runout conditions can actually be hidden with a good dynamic wheel balance, as runout will give a big 1X vibration. Certainly if the runout is within spec, the dynamic balance will absolve a lot of sin.

The wheels on my C5 track car are Speedline C5Z06 wheels and they have about .002 runout. All they have seen is track duty. That being said, there have been an "agricultural event" or two and more than one gator and curb driven over. The Caddy on the other hand has 95k miles and who knows how many potholes, curbs and tire alligators have been hit. That is where most things happen. Then there is dirt under the hub, etc.

Sadly, about the only time runout is ever checked is to silence a complaining customer and put the burden of the condition back on them. The stealerships don't do it, that would cut into the flat rate payback. How many alignment reporting sheets show the recording of runout??? A wiley techincian would at least rotate each wheel with no load and eyeball for runout. You should be able to see .040.

ls1247

iTrader: (2)

I checked runout on every alignment I ever did using several different alignment racks but most of them were optically based.

I thankfully got out of it just when the "report printing" laser based machines became common place but of the one laser I did use, you still went through the motions of checking runout even though you couldn't visually "see" the runout like you could with a machine that was using a light beam on a chart.

While I liked doing alignments on an optical rack because you had a better feel for what was going on, the move away from solid axle, RWD cars made the laser a requirement if you were quickly going to do 4 wheel alignments...

In other words, its all gotten "black box" and its hard to know what they're doing.

k24556

Totally agree, You speak like a gear-head (flattery intended) that cares.

Sadly, more folks today are interested in collecting a check rather than the satisfaction of a job well done. If feels to me that it isn't "cool" to show you care these days. I get this whether it is at a restaurant, stealership, or store. Those that care ARE there, but the minority.

Cars today are black boxes to almost all users, and reliance on the experts is heavy. Mmmmm, no wonder lawyers are plentiful.

Naf

iTrader: (1)

I pop over to my local alignment shop drop 60usd plus 30usd tip and get it to my satisfaction. Level ground, laser precision, and i make sure all the bolts are snug and tight...

If i mess with the alignment to install something i just use two ropes criss cross them under the car and get the wheels pretty straight so i may get to the alignment shop...