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DIY wheel alignment vs Alignment shop


mender
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I decided to take the Civic to my local 4 wheel alignment shop to see how close I'm getting with my cheap tools. Also, I have cheap aftermarket upper control arms and I've heard interesting stories about the amount of caster that can result. And of course, the car has taken a few hits over the years, including the last race where one of my drivers tried a kamikaze dive bomb, hit the right rear corner of the other car with our left front, broke our wheel and launched the rear of the other car about three feet into the air. They didn't continue, we did after quick repairs and a short visit to the penalty box. What would have cost us at the most three seconds by waiting until the next straight to make that pass ended up dropping us from a likely second overall finish to fourth. Very disproportionate risk/reward ratio.

 

The left inner steering link got bent, changing our front 1/8" toe-out to 1/2" toe-in for the remainder of the race (about four more hours). I replaced the right outer tie rod as it was showing signs of wear, did a very rough toe check (two 8 foot long 1x2 rectangular tubes resting against the front and rear tire sidewalls) then off to the alignment shop with their expensive laser alignment stuff. Results were surprisingly close to what I had set things at before our last race.

 

Front camber: -2 degrees 15' (-2.25 degrees) left, -2 degrees 17' (-2.28 degrees) right. Target was -2.25 degrees on both

Caster: 0.65 degrees left, 0.07 degrees right. Well within reason and close enough for me. I know some FWD guys use lots of caster but I don't, another topic in itself.

Toe: 1/2" out. Checked it with my toe plates and tape measures after, also says exactly 1/2". I have to swap out the steering rack so wasn't overly concerned with the toe for now.

 

Rear camber: -1 degree 10' (-1.17 degrees) left, -0 degrees 56' (-0.93 degrees) right. Target was -1.0 degrees on both

Toe: 1/4" in. Target was 1/8" in. Also found that the upper camber links that I replaced just before the last race were missing the left hand thread jam nuts and had play.

 

I "knew" about the jam nuts but was working on my axle popping out issue (fixed!) and forgot to take care of it before the race weekend. Figures!   

 

Okay, so I checked my alignment against the results from the alignment shop and I'm quite pleased with the accuracy of my methods and tools. I use toe plates and two identical tape measures for the toe, and a camber tool that has an adjustable bubble level. I also have a SmartTool (digital) as a back-up for the camber.  Every so often I'll string the car and make sure my toe adjustments aren't resulting in a bias to one side or the other. I use the SmartTool and the long rectangular tubing to level my floor before setting corner weights and wheel alignment. To get the car level, I use 1/8" thick sheet material as shims on the floor beneath where the tires will be.  

 

TL;DR: DIY alignments when done carefully are more than sufficient for racing. 

Edited by mender
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Yes, yes they are.

 

Even more so when you consider that the alignment done in the shop is the baseline.

 

we then change our alignment based on tire temps and laptimes and driver feedback.  None of those changes are measured until everything is set where everybody is happy.

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I build high end alignment systems for pro race teams, and the string based systems are as good as any laser system out there. 
The big advantage to laser systems is being able to do all sorts of vehicles and sizes.   But you are correct in that a big factor is taking the time to get things setup correct.   If using strings, ensuring they are parallel is crucial for accurate readings. Proper initial setup really makes this easier each time. 

0287526F-C73D-4A8B-A642-65D2C38A085D.jpeg

CA46B105-8CDE-4DC6-9894-DC1626AFED36.jpeg

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Agree 100%   You can get pretty darn close with reasonably crude tools.   Setup and taking your time seems to be key.   

I've (as most of us have) seen some pretty crazy stuff post race that makes one wonder just how important this meticulous setup stuff is.  One of my favorites was an Autocross car many years ago that blew a double adjustable shock on day one, they replaced it with a parts store monroe special and ran day two.....and it was fast.  Go figure.   I guess 3 good shocks is better than none.   

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We had contact day one at the most recent Sebring, we change the tire and kept going, day two the car seemed a little off but we had used tires… got a 7 And a fifth place. We did find some weak bushings in the front end and slapped lower control arm and radius arm on, forgot to check the alignment…. Onto Road Atlanta from the back up to fourth to lose that spot in the last five minutes because the car was really off, it was found the right rear completely bald on the inside with a ton of Toe from a bent link.

Edited by Team Infiniti
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We have the crude solution for alignment but it seems to work fine.  The setup check takes the longest but I've taken some time out of that process by just having some dedicated conduit, strings, etc.  4 jack stands, 2 lengths of conduit, string, 6 oz bank sinkers (for ends of the string), steel rule, tape measure, and couple of plastic garbage bags for the fronts.  I fold the bags over (doubled) and they slide easily when adjusting front toe, no binding.  Rear is a challenge - lot of down/up - adjust/down - recheck all the squares - rinse and repeat.  Acura Integra for reference.  I've never had it checked at a shop but the tire wear for the races we have run last year seemed fine.  None of my drivers have complained about the handling but maybe they're not as sophisticated / experienced in providing that level of feedback.  Yet.

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14 minutes ago, Team Infiniti said:

We had contact day one at the most recent Sebring, we change the tire and kept going, day two the car seemed a little off but we had used tires… got a 7 And a fifth place. We did find some weak bushings in the front end and slapped lower control arm and radius arm on, forgot to check the alignment…. Onto Road Atlanta from the back up to fourth to lose that spot in the last five minutes because the car was really off, it was found the right rear completely bald on the inside with a ton of Tow from a bent link.

Had a fairly big hit into the wall on an oval with a stock car, had it back on track in 43 minutes, right front had probably more than 5 degrees negative camber and unknown toe, went through right front tires  but kept rotating tires to that corner. The driver was running faster times after the hit than he was during qualifying but that was because he was no longer worried about tearing up the car. :)

 

Having the alignment out seems to show up as tire wear rather than a slower car, although things can get exciting at the limit. Most drivers adapt.

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27 minutes ago, Todd K said:

4 jack stands, 2 lengths of conduit, string, 6 oz bank sinkers (for ends of the string), steel rule, tape measure, and couple of plastic garbage bags...

 

Was already using jack stands and conduit, but hadn't thought of sinkers and trash bags.  Will add those to the setup.  Thanks!

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I wrap the string around the top of the jack stands and move the jack stands to get the spacing. I also place a pair of floor tiles with grease between them under each of the front tires for toe adjustments. I tried that for caster checks but I didn't think it was accurate enough; turns out that it was.  :)

Edited by mender
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16 hours ago, petawawarace said:

I build high end alignment systems for pro race teams, and the string based systems are as good as any laser system out there. 
The big advantage to laser systems is being able to do all sorts of vehicles and sizes.   But you are correct in that a big factor is taking the time to get things setup correct.   If using strings, ensuring they are parallel is crucial for accurate readings. Proper initial setup really makes this easier each time. 

0287526F-C73D-4A8B-A642-65D2C38A085D.jpeg

CA46B105-8CDE-4DC6-9894-DC1626AFED36.jpeg

Nice setup

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I have spent quite a bit of time on a good 4 wheel alignment rack since one of our guys owns a shop and what has surprised me is how you move one parameter it affects all of the others.  The crude/DIY instruments work sufficiently as long as you repeat all checks against each other multiple times since you are checking one at a time whereas the good racks give you instant feedback on all of them at once.  You can really dial it in with a good rack and is obviously preferable but most people don't have that luxury.  

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28 minutes ago, Rodger Coan-Burningham said:

I have spent quite a bit of time on a good 4 wheel alignment rack since one of our guys owns a shop and what has surprised me is how you move one parameter it affects all of the others.  The crude/DIY instruments work sufficiently as long as you repeat all checks against each other multiple times since you are checking one at a time whereas the good racks give you instant feedback on all of them at once.  You can really dial it in with a good rack and is obviously preferable but most people don't have that luxury.  

Caster/camber first, toe last.

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My experience is that floor level is not too important until you start doing corner weights, then you need to be about +/- 1/16" of an inch.  I have a manometer to check this and leveling shims. 

 

Now that may sound expensive and complicated, but the manometer is a old paint can with a length of tygon tubing RTV'd into the bottom of it.  The tygon tubing has a Tee fitting and I tape the open ends of the tubing to a jack stand and measure the height of the water column.  As long as there is no air in the system, the water in the tubes are the same height.  Shims are VCT/linoleum flooring squares that you can get as color samples.

 

Since I have a dedicated location to do this, I also have marks on the floor with shim amounts noted so I just put the scales in the same spot each time.

 

Another way to check is to put the car on the scales and record the numbers.  Spin the car 180 on the scale set up (much easier with go karts).  If the scales are out of level, the individual weights will be different (remember you have to transpose them).  LF should weigh the same regardless of orientation in the shop.

 

 

As others have said, strings and tape measures get you pretty close.  Since most of us are still using rubber bushings, the car maybe the least accurate item in the mix.  Biggest thing is repeatability.  Doesn't matter what the method you need to be able to set it up, measure, take it down, put it back up, measure and get the same number. 

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18 hours ago, petawawarace said:

What theory are you using for this?  There is literally nothing connecting the front to the rear.  

 

Actually there is something to what he says.  I have had it described as starting with a square box, you start with the back to keep the box square, then set the front.  Now somebody smarter than me or at least somebody with more time will have to explain that better.  I do know in practice, if you set the front on a precision 4 wheel alignment machine and then set the back, the front will have to be moved again slightly in a lot of cases.  For what we are doing here, I am sure that is all negligible and is just an academic discussion at best.  

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3 minutes ago, Rodger Coan-Burningham said:

 

Actually there is something to what he says.  I have had it described as starting with a square box, you start with the back to keep the box square, then set the front.  Now somebody smarter than me or at least somebody with more time will have to explain that better.  I do know in practice, if you set the front on a precision 4 wheel alignment machine and then set the back, the front will have to be moved again slightly in a lot of cases.  For what we are doing here, I am sure that is all negligible and is just an academic discussion at best.  

The same thing could be said if you do the front first, then move to the rear.  So it really doesn’t matter.   The only thing that I could see, is the front sway bar putting a load into the chassis and affecting the rear alignment slightly.  But you really should be doing your alignment with the swaybar disconnected anyway.   

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5 hours ago, petawawarace said:

The same thing could be said if you do the front first, then move to the rear.  So it really doesn’t matter.   The only thing that I could see, is the front sway bar putting a load into the chassis and affecting the rear alignment slightly.  But you really should be doing your alignment with the swaybar disconnected anyway.   

Starting with the rear is necessary with alignment machines because the front toe and steering wheel being level is dependent on rear toe final settings, if you don't and adjust the rear toe after the front is set the steering wheel will not be straight.

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8 hours ago, petawawarace said:

The same thing could be said if you do the front first, then move to the rear.  So it really doesn’t matter.   The only thing that I could see, is the front sway bar putting a load into the chassis and affecting the rear alignment slightly.  But you really should be doing your alignment with the swaybar disconnected anyway.   

2 hours ago, Timothy G. Elliott said:

Starting with the rear is necessary with alignment machines because the front toe and steering wheel being level is dependent on rear toe final settings, if you don't and adjust the rear toe after the front is set the steering wheel will not be straight.

 

It's more than just the steering wheel won't be straight.  But like so many of my posts, don't take my word for it, go read about it from people who know.

 

From Les Schwab:

Four-Wheel Alignment: This is done on vehicles with adjustable rear suspension, to bring all four wheels of your vehicle back into your vehicle’s original specifications. All four wheels are aligned to the center of the vehicle. First, the rear axle angles are measured and adjusted, then the front. This is the best, most accurate, manufacturer-recommended alignment for vehicles with adjustable rear suspension.

 

From Sun Auto:

A 4-wheel alignment is usually only performed on vehicles with four wheel independent suspension systems. The technician will adjust all four wheels however, the adjustment varies from front to rear. On the front wheels, the adjustment includes the toe, caster, and camber whereas the rear will have the toe and camber. All are adjusted to the center of the vehicle by first measuring the rear axle angles, then the front.

 

From Nissantechnicianinfo.mobi:

Thrust angle is the direction that the rear wheels are pointing in relation to the center line of the vehicle. If the thrust angle is not zero, the centerlines of the rear wheels will not be parallel to the centerline of the vehicle. Thrust alignment is measured by calculating the difference between the centerline of the front and rear wheels. Improper thrust angle may cause the vehicle to drift or the steering wheel to be off center. During a four-wheel alignment if the rear toe is adjustable, adjust it and then the front toe. If the rear toe is not adjustable, set the front toe to compensate for the thrust angle allowing the steering to be centered.

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