DIY alignment experts, please read.
 

Hi,
I made a DIY alignment tool by fishing lines and took some measurements. I am so ancious while waiting for my buddy to take a look, so can you guys look at this pic below?
The car handdles well. I like the way it drives, but right rear tire is eating rubber much faster in the inner edge compare to the right. Front are all ok. But look at the numbers, I feel my alignment is ok.
What do you gus think?
BTW, the car is a 911, with wide body. Wheels are 17"x9" front and 17"x11" rear.
http://forums.pelicanparts.com/uploa...1331022994.jpg

I was never a big fan of home alignments,especially considering the price of good tires as it comes down cheaper in the long run to pay $125.00 to have a good shop do it ...

Although i crew for a friend who races an ex Trans AM car and he strongly believes in home alignments as he adapts for different tracks.Have to admit that he has lots of racing experience and it seems to work for him !

Cheers !
Phil

Did you follow the guidance to set up the fishing lines, the hub measurement out to the fishing lines front to rear and the spacing of the fishing lines front and rear?

That measurement you show is only as accurate as the strings are relative to the center line of the car.

What about camber? I made a simple camber guage with a cheap angle measurer on a piece of aluminum angle, drill two holes in the angle that line up with the edge of the rim, install two identicle bolts with a nut on either side and make the bolts both stick out about an inch, the exact amount they stick out is not important so long as both bolts stick out the same amount. Then hold the bolts to the rim and lay the angle measure device on the flat piece of angle. it wont be super accurate but again as long as the camber is about the same on both sides that is what you are looking for. I usually set both to max negative and then back one off to match. (this is hard to visualize with out a picture...)

Also, if you have stock or tired torsion bars I would do the alignment with bags of concrete or similar in the drivers seat approximating your weight.

The alignment changes with the weight in there.

Also, the rear tires can wear if the front wheels are out of whack, although I would think you would notice a pull.

Finally, a lot of cars come in for alignment that have a worn part. Put the car on jack stands under the body - lay under there and have some one push and pull on the wheel to see if any of the bushings, wheel bearings, tie rods etc. are moving around. It does not take a lot of slop to cause wear.

If you dont go to a top alignment shop they will:

A: align the car when there is warn parts - worthless
B. Charge you to replace parts that are not really bad

A and B are why I like home alignments.

with the age of these cars you can imagine why there is so much talk here about replacing the bushings with Elephant racing or similar - the old bushings are worn out messing up the alignment and the driving feel/precision.

Thought of something else - these cars seem to be real sensitive to corner weight - especially if you have big T bars - if the CW is off enough it could cause the car to lean and one wheel would have a different alignment than the other. I always noticed a pull when my CW was way off but it could depend on a lot of variables, in some cases you may not feel a pull.

we use those inexpensive Craftman laser level tools. how are you measuring center of the car?

$125 for front and back? corner weights too?

You could also check the trust angle. Not sure if that is the technical term, but that's what I call it.

Set up the fishing line on jack stands so you have equal measurements to the front / rear of the rear tire and measure the distance from the line to the center of the front hub. Compare to the other side of the car. These should be real close to equal.

Actually it comes to $300.00 with an alignment and corner balance ... that all depends how much work they put into having to scrape the black tar off the front shock towers and if they have to reindex the Tbars.

In my case, my car is properly set up with the rear eccentrics in the neutral position and at the right height so it's easy for the shop and they (WeTune) in Montreal are one of the better local shops that come to most of our events so we give them a lot of business ...

A regular alignment is $150.00 !

Cheers !
Phil

Alignment
 

I have used the string method wIth great success on my 914. You must insure
measurement are done front and rear before a test drive. You must insure lines
are parallel with true centerline of car.

Wildcat,
$125 is not the case around here. Beside price, there are other reasons that I like to DIY on “my car”. Other cars I have, I just send my wife out to wait for 1 hour or so and pay the price. Believe it or not, on “my car”, most of the time, I always have to re-adjust it the way I like it to drive almost every time they did it, either it drift to one side, tire doesn’t wear right, etc. Do you believe there was an incident that a known/recommended shop did my BMW 5 times then decided to return my money? No, I didn’t request for the refund. He just proposed the refund because he couldn’t fix the jerking. I didn’t take the refund because I was thinking that he spent too much time on it, although I was pissed. The second shop did it twice, then I just decided to try another shop. The third shop did it for 15 mins. The problems were almost gone. I spend another ½ hour or so, then it’s was to the point I can be happy when I drive it. All of them were blaming on my car because it was lowered. After that time on, I almost always DIY on “my car”. Sometimes, I still bring it out for them to do it, when it is completely off, then I re-adjust to refine it after ward.

Erik,
I used to set the strings up on jack stands but this time, thanks to draco who gave me the idea, I set the strings on the pipes and mounts the pipe to the car. This way, when I move the car, the strings set up are still in tack.
The 2 strings are parallel to each other. Left and right of each axle are measured to have same distant from center of the wheels to the strings.
On the picture above, the numbers are the measured of the distant between front and rear of each wheel to the strings.
I only did the rear wheel, not front wheel, because I am trying to take care of the uneven wear on the right tire. Since left tire wear is ok. At this step, I am trying to see how much off the right wheel is comparing to the left wheel.
Looking at the numbers, I feel they look ok. Another possibility, as you explained, it can be some worn part\s.

So you're measuring toe rather then camber in that picture?

Yeap Toe

Can you clarify what you are saying? Is the the inside of the right tire wearing out faster than the outside of the right tire? If yes then it's likely due to several reasons. Rear shocks could be worn out, rear sway bars could be set wrong (not sure if yours is adjustable), rear suspension has too much toe and/or camber and lastly corner balance could be off.

I like to use string method although it is time consuming. Always double check the strings and measurements.

Your rear toe looks about right to me. I would say it's normal for a 911 with some negative camber to wear out the inside edges first. Best cure is some track days with lots of cornering loads to get the outside to wear!

-Andy

Sounds like you have too much -ve camber on the right rear for your style of driving. If you are burning up the tire on the inside and not the outside then that may be a camber issue. Do you have a digital camber gauge? They can self level.

don't understand why people invest so much to measure camber.
http://forums.pelicanparts.com/porsche-911-technical-forum/459183-home-built-camber-gauge.html#post4506384

if you do it right - in most cases, be patient and spend enough time double checking - string method is very very accurate.
assuming your strings are parallel and even camber, your toe is just fine or a tad toe-in. dial back to zero toe and see what happens. rear inside wearing is not unusual for a 911?

Not always useful at the track... that would be why we spend some money on the good stuff :P Sometimes you just don't have the time. Toe in is ok for a 911 (rears) since it is rear drive. However it also depends on camber gain and rear suspension travel, weight transfer etc... (all that vehicle dynamics mumbo jumbo...) but for an example, we would set .5mm toe out on the front wheels and 2.5mm toe in on the rears for 997 Cup Cars. Not that we need to be that accurate here... ;)

Another home made camber gauge.

Total cost about $25.

http://forums.pelicanparts.com/uploa...1331146029.jpg

This is the best I can do for now. Can someone check to see if my toe is ok?
Sorry, it's A-B, not B-A.

http://forums.pelicanparts.com/uploa...1443943361.jpg

rnln

just to make sure we are all on the same page.

what are you using for string?

what are your measurements from the string to the hub on all four wheels?

and for grins what is the measurement between the strings on the front and the rear?

If I am reading this right you are slightly toed in at the front. I thought scruggs wants us slightly toed out?

I can usually get the rear toe closer than that with out too much trouble, I think I usually shoot for zero at the rear IIRC but there is a lot of opportunity for error in the measurement.

Ooops I just noticed you are toed out.

Is this with any weight in the drivers seat?

I think I would be pretty satisfied with those settings, why did you not shoot for zero on the rear? Is that better for performance? I cant remember. I think a slight toe in allows the normal flex to allow the rear to go to zero during braking, or is the other way around and you want it straight ahead under acceleration. Have to get my books out.

Can you shoot a "selfie" of yourself measuring the distance from the rim to the string at one spot? I am curious what equipment you are using.

Finally, Have you considered a tri-pod corner balance and doing the alignment with close to your weight in the seat? it can make a pretty big difference.

Tire Alignment Toe-In Conversion Chart

As read your measurements, if B>A, you have toe-out in the rear, which is not good. I'd shoot for a little toe-in in the back.

Strings work great, racers have been using them for decades. The attention to detail will pay off. Corner balance is the next big issue. If your weights are off, you can adjust the toe and camber until you are blue in the face, to no avail. Change ride heights, corner balance is a must do, per the FSM. I use strings and a set of electronic scales add a Dunlop camber guage and its all good, really good. I can run 65mph and brake, hands off with no pulling or diving to either side. I got my FSM online as a PDF and also have the paper ones as well, guess which ones I use the most....PDF on the iPad.

Damned acronyms, we don't need no stinkin acronyms! LOL What the heck is an
FSM?

Flying Spaghetti Monster

Factory Shop Manual.......

l recently paid $150,000 her in Atlanta to get my wheels aligned. Of course they needed it because it had been years since they were aligned.

Later on that month I went and replaced my tie rod ends because I wanted to change them out to Turbo. I know I should have waited on the alignment but apparently there was a reason for this happening.

Near the house is a oil change shop that does alignments. Stopped by there to talk to them about doing an alignment on the Porsche and the specialists there said it shouldn't be a problem after I explained to him what I did.

When I brought the P-car over I also brought the specs from the shop where I paid $150.00. So, I gave the sheet to the mechanic, he looked at it and then dialed in the specs on his machine for the Porsche, which BTW was the same exact machine that the other shop used.

Well he pulled up the specs and they were exactly the same specs as the other shop. The display was exactly the same. So I had him do just the front end although he did check everything and when it was all said and done the alignment came out perfect.

The great thing about this is - I always get my oil changed over there and never gave them a though about getting an alignment. So, when I asked what the price was he initially quoted $60.00. However because he only did the front end he charged me $39.00

So I have to say there are alignment shops out there that can do an excellent alignment on the P-cars as long as they have the proper computerized equipment and the specs for the car.

I have to lower it later on this year so when I complete it I will take it back. The nice thing about it was I could stand and watch what was going on and ask questions if need be.

So I would say for a little over $50.00 it's worth having a computer do the alignment. Prices are subject to change depending on the location of the shop.

HaHA, have worked on 911s for 45yrs but never heard the FSM acronym.
However, at times I have used the acronym RTFM when folks have asked me a technical question that they should have researched themselves! LOL

I use big fishing line for string.
I create a jig by big PVC pipe in front and rear of the car. The 2 strings are parallel, then setting them up by measuring the same lengths on 2 rear space (from the line to the center of the wheels. And same for front.

All my my 4 wheels are toed in, but right rear is a little more than other 3 wheels.

No no, as I explained in the text area, B is < A. It was a mistaken when I did the drawing. All whels are toed in, but right rear is toed in a little more than other 3 wheels.

Just double checking - both pieces of string have to be the exact same length and the distance they are apart have to be exactly the same F&R. The whole string alignment is based on having a perfect parallelogram.

If that's correct, to me your toe doesn't look too bad. I think the spec is 0-20' (0.333°) in per side. If my math is right (questionable) guessing you are measuring about 24" apart on the tire:

24 sin .333 = .1396". 1/8" is 0.125".

According to that you are in spec, dead in the middle on the left rear and near the upper end of it on the right rear.

With how much of a PITA adjusting the rear alignment is, might not be worth trying to tweak it any closer IMO. How bad is the tire wear exactly? 911s in general eat up rear tires much faster than the fronts, and if you have them set for optimal performance with modern tires, the insides will go first. Do you know how to "read" a tire for alignment issues? Toe wear makes a distinctive pattern on the edges of the tread blocks - if you rub you hand inboard and outboard across the tread, they'll feel "smooth" one way and "sharp" the other.

To the OP, you should have slight toe out in the front, however your issue is incorrect camber in the rear.

I thought that it is not perfect, but not too bad. I do have a little pull to the right when taking my hands off the steering wheel.
Before this, I had almost 0 (zero) toe in the front, very little. The front tires wears bad. They wear more on the inside 1/3 of the tire, and is un-even. But in the mean time, my struts are bad too . I just flipped the the front tires (inside out, and outside in) and gave it a little more toed in up front (as the diagram above). Let see how it goes.
Thanks all.