another wheel alignment thread

[Alan L]

So I have need to be able to do this stuff myself, frequently. I did a search here looking for some inspiration and avoid the string lines if possible. They are awkward when you have to make any adjustments.


I have shamelessly borrowed some bits from the following thread posted by Tony some years back
https://forums.pelicanparts.com/porsche-911-technical-forum/581498-stringless-wheel-alignment-diyers.html?highlight=stringless+toe+adjustment

I never quite got to grips with the whole concept, but saw enough inspiration to set off on my own course to solve the task. I am really happy with the results - it has delivered a real simple system to do measurements very quickly.
I used the laser system - I already had an el cheapo laser from previous efforts at this task. Basically I used a plug in the hub with a measuring bracket to provide for the reference points and alignment measurements.
The laser is fitted to the other hub as seen next

The tool for mounting is in next pic

There is a bit of a difference here from Tony's system. I used a steel box section - I found the Al one I started with was flexing in the mid point, even with light tension. If your laser spanned the whole length it may not matter - but mine went about half distance. Also I was using RUF hubs - which have a lip inside the inner hub. This makes the mounting a bit simpler. Tony devised a system to work with Fuchs hubs - which don't have the lip.
So the technique I developed is different to Tony's. What I set out to do is determine the measurement at the other hub that would give me a parallel line. A string line without a string. I did this two ways - firstly measuring the beam along the sill line (above the rocker trim strip) and secondly against an actual string line. Once I had one reference point - eg front right hub, I reversed everything and did the rear hub measurement. I now had 2 reference points for one side. Rinse and repeat for other side. These are forever reference marks. And it turns out I only need the front hub marks, but the rear hub distance marks serve as a backup check.
Now that I have these confident marks, all I need to do, to find the toe on front and rear hubs is as follows.
Mount the laser to the rear hub and take the measurement on the marker on the front hub. If there is any toe in the rear hub (known or unknown) it will show as a deviation from the reference value (parallel line) for that front hub value. That deviation is measured over the distance of the wheelbase of the car (set the laser beam at the center of the rear hub). That wheelbase distance is around 5 plus x that of your rim diameter. That value will depend on your car and rim size. But divide the deviation by that number and you have your rear toe. Done. EG if the deviation is 10mm, you have approx 2mm toe on that rear wheel (depending on the exact ratio value of the calc).
For the front toe, now you shim the laser to hit the reference mark (if it is not at zero toe already on the rear). Small shims around 10 thou are all you need. Now you are back on your previously determined reference mark. You now have a parallel laser line past the front hub. Remove the measuring plug and measure the distances from the beam to the front and rear of the rim. Now you have your front toe. Done.
Repeat on the other side of the car. Takes about 5 minutes to get front and rear toe this way. So it is easy to make adjustments and re measure.
I use a speedway weight checker for corner balancing (works well). I tried that to settle each wheel after adjustments, rather than running the car round the block. Worked well. Finally as a final check I ran the car around the block and compared again to the weight checker results. Very close, so you could do all but maybe your very last tweek without leaving the shed. You may in fact find it unnecessary to run the car.
For camber I have a very simple system using a spirit level - set it vertical off the bottom of the rim, and measure the gap at the top. To do that I have a screw threaded in to the level. Set the screw til the spirit bubble at top is centered, and measure the length of the screw. Some trig calcs give you the angle from that length. In my case for 17" rims I multiply the mm x 0.12 = degrees camber.

My laser is a cheapo and has a dot for a beam and that dot was a bit large at the other end of the wheelbase. I used some electrical tape to make a small slit and ended up with a dot around 1-2mm at the other end. Easy to find the mid point of that.
This method gave me repeatable measurements to 1-2mm over the length of the wheelbase, which translates to an error of a fraction of a mm at the wheel rim.
My car had just had an alignment, but it had a ride height issue for reasons unknown (was recovering from track damage). So I had to correct the ride height and return it for a final alignment. I chose to do this instead. So I had some current alignment numbers to check my method against and it proved reliable.
Hopefully explained it well enough. But it is so simple, it is easy to remove the wheel, tweek the alignment, and repeat the measurement.
Alan

[mark houghton]

Absolutely awesome! This thread along with Tony's link is worthy of its own sticky.

[nickelplated5s]

Why didn't you just put the level on a tripod? Mine shoots 90's and you can cross check for toe.

[Alan L]

I don't have a tripod and using the hub gives me a constant reference point , so I can re use my referance mark without having to re set parallel lines again. The tripod is independant of any previous settings - so start all over again.
Alan