Wow, you certainly meant low profile when you said it! I've done my two rear-engined Renaults front toe-in with pins stuck in the tyres at the rear, measure spacing, push car to rotate pins to front, measure again. Dead easy and gives about the same result as the string line.Lots of great ideas presented here in this thread! And Col, what a simple way to manufacture a toe-in gauge that is IMO as accurate as you need.
I've had a few goes at DIY alignments using bubble levels and string, and given time and a bit of thought to carry it out accurately, the result is as good as any computer aligner. What the tyre dealers computer aligners do, is to get a readout of all the measurements in minutes, and give you a good report, usually including centreline alignment which is handy.
About 20 years ago, my son had just graduated as a mech engineer and had started work at Kinetic Suspensions as a suspension design engineer. He had bought a 1986 series IV Mazda RX7 13B Turbo (the Porsche looking Mazda). It had quite bad wear on one rear inner tyre, and they were pretty expensive then being 16" low profile tyres. I saw it as an opportunity to get him to learn the basics of physical alignments. Bob Janes at the time had free wheel align with 2 or more new tyres. Spreading the cost, we bought 2 new tyres and to get a starting point requested the alignment report only, explaining the "training" situation. Unsurprisingly, it showed excessive negative camber on the left rear, toe-ins all over the place and surprisingly, about 4° difference in front caster.
Down at the Kinetic workshops the next weekend, on a 4 post hoist (nice), we found the left front lower ball joint, which was bolted to the lower wishbone on a sort of outrigger arm, was bent back badly, result of a previous impact we could only guess. Enough that we picked it up by about 10mm difference in wheelbase on each side. So new ball joint obtained and fitted, caster being checked with a Moore&Wright protractor spirit level from the M&W combination square. Using the same M&W protractor we set cambers front and rear as accurately as we could, requiring good eyesight to read the protractor as close as possible to the markings.
Then we set up the parallel string lines each side which allowed us to measure individual toe-ins plus the alignment front to rear.
The boy was pretty impressed with the old methods and I'm sure it gave him a good understanding of the practical basics. BTW that was a magic car for alignments, everything adjustable, and it had a sort of built in rear wheel steering by using double jointed bushes, which induced rear toe-out on the loaded outside when cornering.
Anyway, then we got the second 2 tyres and another wheel alignment report, everything was spot on, son very happy.
Long story, but that's the way it is - a good DIY alignment if you know what you are doing, is fine, just takes an inordinate amount of time and is no longer commercially viable in a retail situation.
Fast forward to June 2022, I get 4 new tyres fitted to my 2004 classic WRX, only half worn but now over 10 years old, I've only done about 12000kms since 2013 including the 3500km drive back to Perth from Melbourne. Rear tyres worn on inside edges but they have been rotated a few times in the past. Removed the wheels and took them to tyre dealer for fitment, don't like leaving the WRX with anyone.
Tyres are 215/45/17 and BJs had a special on Conti Max Contact 6 at $139 each, good price, and suitable tyre for the car.
I do have a nice level area just outside my carport (noting Col's comments above, I'm glad I specified this to my paving contractor years ago, for exactly this reason). Checked ground level with spirit level on 6ft steel screed bar, all good. Checked camber using a digital angle level I have had for a couple of years, just against the tyres, avoiding the tyre bulge at the bottom. Cambers all to spec, 0.25° Neg at front, 1.0 to 1.5 Neg at rear. Now how to do the toe-in? Had read this post and thought about Col's melamine solution, but impatience and tool envy saw me down at the local Revolution Racegear to pick up a set of Longacre toe-in plates, the only ones I could source in WA stock. For info there is a shop in Melbourne making these in steel for under $100, look good too.
Also as discussed in previous posts, and pointed out in the Longacre instructions, is to beware of the bulge. These are really made for quick checks at the track, where most cars have low profile tyres with virtually no bulge. Initial use I found them to be quite accurate with the small bulge on these low profile tyres not really affecting the reading. But for my road cars I have modified the Longacre plates simply by cutting out a hole where the bulge is, large enough to cover the Koleos 225/60/18 and anything in between. They work a treat. The Longacre has a nifty addition, small magnets at the tape tip side plate to stop the tape end slipping off, works well.
So IMO, these plates are accurate and super fast - probably less than 5 minutes per axle.
Found the WRX had 0.0mm toe at the rear - that's to spec. Same spec at front, but found 3.0mm toe-out, which I am assuming was causing the inner tyre wear. Because the car was steering straight, and steering wheel straight, I just adjusted each side by the same amount and it drives perfectly well.
So with any type of toe-in plate there are 2 things to watch:
Tyre Bulge - I have overcome that by cutting the plates out in that area.
Bent rim or runout - I have double checked my readings by marking top of wheel and rolling car forward 180 wheel degrees. If there was a difference, take the average. Mine were exactly same.
View attachment 206074
Out of the box.
View attachment 206075
Holes cut for tyre bulge - should be ex-factory.
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Bricks to hold firmly for one man operation confidence
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Measuring side.
View attachment 206078
Tape end side, magnets hold tape tip securely.
These things are brilliant.
Cheers.
I did get caster measured and adjusted (roughly as neither tyre place nor I had the right spanner), then measured on their you beaut machine. Nearly right, but half a degree different and a hint of drifting to left (even on roads not cambered to the left). I adjusted one side in tiny increments until the drift disappeared - cheap and easy but very slow.....
Not heavy or high performance cars, and nor are they FWD of course. The Scenics are just fine, drive straight, no scrubbing, alignment checked on rare tyre changes.
