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Alignment String Jig

                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         


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Alignment String Jig


I have read a lot of good things about doing my own alignments.  It can save money and should allow me to do custom alignments to my Miatas.  I looked at the different alignment tools and processes to get ideas on how I could make my own tools.  I get much more satisfaction from making my own.


The first alignment tool I decided to attempt was a string jig.  Use of jack stands to hold strings parallel to the car just seemed to me to be too much trouble, especially if it needed adjustment.  There were several string jigs that hung on the car and that appeared to be simpler to me.  So, I made my own string jig.


I looked around my shop for materials.  Aluminum is a good choice but I did not have enough aluminum strapping and I don’t know how to weld aluminum very well.  I found some steel strapping at Tractor Supply.  This is a list of the pieces I purchased. 


National Hardware® 4063BC 1 in. x 48” Flat 3/16” Plain Steel (Green)

(2) @ $7.99


National Hardware® 4063BC 1-1/4 in. x 48” Flat 3/16” Plain Steel (Green)

(2) @ $8.49


National Hardware® 4063BC 3/4 in. x 36” Solid Flat 3/16” Plain Steel (Green)

(4) @ $5.99


I already had two sticks of ½” electrical conduit that I cut to 72”.  I then made a small slit with my hacksaw to allow the string to be positioned at the same distance apart each time the jig is used.  This will ensure the strings are parallel as long as the two conduits are kept close to parallel when mounted.


I needed some clamps to hold the conduits and found these Halex 3/8” – ½” Conduit and Pipe Hangers (5 Pack) at Home Depot.

(1) @ $2.48.



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I purchased some ¼” x ¾” carriage bolts, some fender washers and wing nuts for less than $2.00 at the local hardware store.  I had to file a square opening into the mounting holes to accept the carriage bolt, but made sure it was kept small so I could drive the bolt into the hole to hold it in place.  I could spot weld them, but I don’t think that will be necessary.


Then I started working on how to mount the jigs.  Most of the ones I saw for sale looked like they just hooked onto the front and rear.  I made the one in front fit the radiator clamp bolts so it will bolt on for a sturdy attachment.  I was going to bolt the rear one also, but I could not find a suitable attachment point.  I did not want to drill any holes in my cars, so the rear one is made to hook on the trunk panel.



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I sanded, degreased and painted the steel mounts with silver wheel paint.  I already had the paint on the shelf.



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This is the completed string jig mounted on my 00 SE Miata.  I added some pipe insulation for padding.  


I used some white braided fishing line.  It is small but easy to see while measuring.


The string is adjusted to cross at about wheel hub height.  The two round things are old timing belt idler pulleys that held the string in the groove at the front.  The string was tied in the rear to stay in the groove.


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Notice the conduit is adjustable side to side and up and down.



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This is how I made the measurements.  


I used a tape measure to center the car hubs to the strings.  I tried to measure the toe with a tape measure, but it was not as accurate as I wanted.  So, I used this dial caliper.  It worked well adjusted to touch the flat area on the outside of the wheel and just touching the string.  


I recorded the numbers and checked the difference to get the toe.  The rear has about 1/16" toe out per side.  I will probably be changing that to zero later.


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While the alignment jig was on the car, I adjusted the front toe.  It was off as I figured since the car was pulling hard to the right.  I adjusted the driver's side to 1/16" toe in and the passenger side was very close to 1/16" so I left it alone.


All it takes is getting the car onto ramps to access the steering rods.  I chocked the car before getting under it.  Safety always!  


I was able to drive onto the ramps without removing or bumping the jig.  I needed a 21 mm, 17 mm and 12 mm wrench to adjust the steering rod.


Notice the Flyin' Miata Sway bar.  I installed it yesterday.  I bought it used and ordered the heavy duty end links and 1" bushings from Flyin' Miata.


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The road test revealed a slight drift to the right, but the front toe is very close now.  


I also moved the steering wheel one tooth to make it level while going straight ahead.


I will be doing more on the alignment once I get a level place to do it so I can set the caster, camber front and rear and rear toe.  I know I will have to recheck the front toe, but for now it is much better.


Another successful tool for about the cost of a regular alignment!



 


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