Alignment toe in spec Trailing arms
07-24-2008, 07:51 AM
#1
Drifting
Thread Starter
Alignment toe in spec Trailing arms
Assume the wheels are parallel at zero toe in. I then adjust toe such that the front of the tires move in from parallel 1/16". This means that the rear of the tires move out from parallel 1/16". The difference between front of tire and rear of tire would then be 1/8". Do I now have 1/16" or 1/8" toe in?
Does anyone know the relationship between trailing arm shim thickness and the amount of toe in produced by that shim. For example, would a 1/4" shim change the toe 3/16"? I know I can figure this out with simple geometry (I think) but I was wondering if someone already knows.
I plan on aligning the trailing arms myself with the two hole shims and I want to remove that bolt as few times as I can
Thanks.
Gerry
Does anyone know the relationship between trailing arm shim thickness and the amount of toe in produced by that shim. For example, would a 1/4" shim change the toe 3/16"? I know I can figure this out with simple geometry (I think) but I was wondering if someone already knows.
I plan on aligning the trailing arms myself with the two hole shims and I want to remove that bolt as few times as I can
Thanks.
Gerry
07-24-2008, 09:04 AM
#2
Le Mans Master
toe in/out is a relationship between the front of the tire relative to the rear of the tire. lets focus only on ONE rear tire. whatever the existing toe stat is on that wheel is, if you move the front of that rear tire in 1/16", you have increased the toe in on THAT wheel by 1/8". the TOTAL toe spec on the REAR must be equally split on the thrust centerline of the car. (think of a rear wheel steer car) it is possible to have the rear wheels parallel to each other, (a point at which to begin the toe adjustment), yet not symmetrical with the thrust centerline of the car, (not good). the rear of a car with this situation will go in the direction the rear wheels are pointed when you jump on it and take the front end with it. sooo, the first thing you do is get the rear wheels parallel to the thrust centerline, then split the toe figure EQUALLY between the two rear wheels. (the front wheels are much easier to do because the front wheels turn left/right, duh! that is worth mentioning.
to put the rear in perspective, if your target toe in for the rear is 0 to 1/16, you must get the front of each rear wheel pointed in 1/64 " (or less) from the thrust centerline.
regarding the shims, if you plan to use the two hole shims, you would be well served to do your alignment with the slotted shims, then later replace them with your two hole shims. thes pertains whether you do it or have others to do it. modern alignment shops will kick you out the door if you show up with two hole shims installed.
hope this helps,
chuck
to put the rear in perspective, if your target toe in for the rear is 0 to 1/16, you must get the front of each rear wheel pointed in 1/64 " (or less) from the thrust centerline.
regarding the shims, if you plan to use the two hole shims, you would be well served to do your alignment with the slotted shims, then later replace them with your two hole shims. thes pertains whether you do it or have others to do it. modern alignment shops will kick you out the door if you show up with two hole shims installed.
hope this helps,
chuck
07-24-2008, 10:39 AM
#3
Drifting
Thread Starter
toe in/out is a relationship between the front of the tire relative to the rear of the tire. lets focus only on ONE rear tire. whatever the existing toe stat is on that wheel is, if you move the front of that rear tire in 1/16", you have increased the toe in on THAT wheel by 1/8". the TOTAL toe spec on the REAR must be equally split on the thrust centerline of the car. (think of a rear wheel steer car) it is possible to have the rear wheels parallel to each other, (a point at which to begin the toe adjustment), yet not symmetrical with the thrust centerline of the car, (not good). the rear of a car with this situation will go in the direction the rear wheels are pointed when you jump on it and take the front end with it. sooo, the first thing you do is get the rear wheels parallel to the thrust centerline, then split the toe figure EQUALLY between the two rear wheels. (the front wheels are much easier to do because the front wheels turn left/right, duh! that is worth mentioning.
to put the rear in perspective, if your target toe in for the rear is 0 to 1/16, you must get the front of each rear wheel pointed in 1/64 " (or less) from the thrust centerline.
regarding the shims, if you plan to use the two hole shims, you would be well served to do your alignment with the slotted shims, then later replace them with your two hole shims. thes pertains whether you do it or have others to do it. modern alignment shops will kick you out the door if you show up with two hole shims installed.
hope this helps,
chuck
to put the rear in perspective, if your target toe in for the rear is 0 to 1/16, you must get the front of each rear wheel pointed in 1/64 " (or less) from the thrust centerline.
regarding the shims, if you plan to use the two hole shims, you would be well served to do your alignment with the slotted shims, then later replace them with your two hole shims. thes pertains whether you do it or have others to do it. modern alignment shops will kick you out the door if you show up with two hole shims installed.
hope this helps,
chuck
I'll take your advice about aligning with the slotted shims first.
Thanks
Gerry
07-24-2008, 11:01 AM
#4
It is impressive that you want to align the car yourself and a lot of us did it many years ago before the advent of the high quality alignment machines.
But with the new machine and a quality operator, in my opinion the best way to get the correct thrust angle is with the use of the modern alignment machine.
I am the biggest advocate of doing as much work on our cars at home that time and experience will allow, but a professional alignment is the only way to go.
Good luck
But with the new machine and a quality operator, in my opinion the best way to get the correct thrust angle is with the use of the modern alignment machine.
I am the biggest advocate of doing as much work on our cars at home that time and experience will allow, but a professional alignment is the only way to go.
Good luck
07-24-2008, 01:09 PM
#5
Drifting
Thread Starter
It is impressive that you want to align the car yourself and a lot of us did it many years ago before the advent of the high quality alignment machines.
But with the new machine and a quality operator, in my opinion the best way to get the correct thrust angle is with the use of the modern alignment machine.
I am the biggest advocate of doing as much work on our cars at home that time and experience will allow, but a professional alignment is the only way to go.
Good luck
But with the new machine and a quality operator, in my opinion the best way to get the correct thrust angle is with the use of the modern alignment machine.
I am the biggest advocate of doing as much work on our cars at home that time and experience will allow, but a professional alignment is the only way to go.
Good luck
I just had a four wheel alignment done before a rear wheel bearing went bad. I wasn't happy with it, I measured front toe in at 5/16" so I fixed it myself. I don't know what the caster and camber turned out to be. I asked for a printout of the results, but I never got one. I never measured the rear, but I noticed that they never put a wrench on those trailing arm bolts. Maybe they checked out ok and they didn't have to change it. Now the trailing arms are out for rebuild. Anyhow, I want to align it myself and then I will get it checked by a different alignment shop. This time I'll be there watching and I'll be armed with spec sheets from this forum.
Gerry
07-24-2008, 02:23 PM
#6
Good plan Gerry, and this time you will know what to be watching for. I will agree, there alot of shops that wont do the rear toe correctly, and if they know what you expect going in than you have a better chance of getting it done correctly.
07-24-2008, 03:13 PM
#7
Team Owner
Member Since: Oct 2000
Location: Washington Michigan
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toe in/out is a relationship between the front of the tire relative to the rear of the tire. lets focus only on ONE rear tire. whatever the existing toe stat is on that wheel is, if you move the front of that rear tire in 1/16", you have increased the toe in on THAT wheel by 1/8".
Some folks feel that they can do just as accurate a job of setting rear toe at home as a Corvette-knowledgeable tech can do on a modern laser aligner. I doubt it.
