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Just one note. Anytime one is comparing alignment settings with numbers, as opposed to degrees, consider they may be meaningless.
I agree. Am I correct in assuming there is nothing for us available to measure degrees with if we are using either of the 2 methods described? We can however convert our individual measurements to degrees so that we could speak a common language such that saying my toe is 2* is meaningful while 1/8" toe is meaningless.
I horizontally centered the strings by setting the front of the string 8.5 inches from the center of the hub on each side and the rear of the string 4 3/16 in from the end of each rear axle shaft.
Your "box" was shifted a tiny bit.
If Bill set up as he states the box can't be shifted. The geometry is sound. I'm thinking it is a positional tedium of measurement problem. Both methods are tedious and manual.
I have problem getting my steering wheel centered but my car always tracks straight. I center my wheel then do front Toe. The I drive the car and see if it is going left or right vs. the wheel level. Then I will swing the toe left or right equally as needed. It is a real pain. Any tips to make that faster?
The box formed by the strings may very well be a trapezoid without having a center reference point on both ends of the car. To check the box for square measure the diagonals to make sure they're equal.
A center point on the car doesn't do too much good without the subframes also being centered IF you are using camber plates which do not allow minute changes. The same plate used on the LCA on both sides may yield a difference in camber. With the base C6 you can't adjust the UCA. So, centering the subframe is the only way to get equal camber at times.
I set R camber, then R toe, and then thrust angle with a laser. To adjust the thrust I tweak the toe toward one side (\\ or //) just as you do for the steering wheel. It takes very little time.
On the F I set caster, then camber, and then toe. Then I tweak the toe to one side to align the steering wheel.
I agree. Am I correct in assuming there is nothing for us available to measure degrees with if we are using either of the 2 methods described? We can however convert our individual measurements to degrees so that we could speak a common language such that saying my toe is 2* is meaningful while 1/8" toe is meaningless.
I made this Excel sheet if I need to figure degrees to compare with others. Usually I only work in inches as it is relative distance I am measuring. Just enter the radius at which you are making your measurements and it will give you degrees and inches.
To check the box for square measure the diagonals to make sure they're equal.
The same plate used on the LCA on both sides may yield a difference in camber. So, centering the subframe is the only way to get equal camber at times.
The way strings are setup with smart strings I don't see how you can clearly measure diagonals. There is too much stuff in the way for a precise measure. Even with a good tape difference in tautness of the tape will yield quite a bit of potential measuring error.
It is common knowledge that moving the subframe is a solution for camber problems. On the C5 there are reference indexing pins where the subframe fits exactly to the frame and both front and rear subs are square to each other. I dabbled in moving the subframe in years past for camber. However, on a lift with clear view and clear access I could not move the subframe without hogging out the subframe holes or altering the referrence pins so I never moved the subframe. After I thought about it, moving the subframe is not a good idea. Making the right sized camber plates or using the adjustable cam is the proper method. I think this moving the subframe idea came from Hardbar's very limited selection of camber plates when racers wanted to max out their camber in the early days of T1 racing. I was there for the early days and that is what racers did to solve the problem. I was lucky my car was new and everything matched up with hardbar's plates plus we were on rubber bushings with known slop and suspension stichion which made it impossible for good solid reproducible numbers. So we got as close as we could.
Trackboss is the first person I have read about who shares my thinking on this subject. And I would add squareness of both sub frames to the chassis centerline is important too.
Originally Posted by trackboss
This doesn't even consider how square ones car is. Often times it is talked about how people shift the rear crossmember to get the camber where they want. IMO, having the front and rear crossmembers (or rear axle in stick axle cars) square to eachother is more important than having a desirable camber number in the rear. There are other ways to correct that. Lastly, when doing all that one must consider the relationship of the lower suspension crossmember with the upper control arm pickup points (independent suspensions). Moving the crossmember can change the relationship and move the instant center left to right (assuming control arm lengths are the same left to right).
What do others think about moving a subframe and have you found the same problem I have of exact fit from indexing pins to subassembly holes?
Just one note. Anytime one is comparing alignment settings with numbers, as opposed to degrees, consider they may be meaningless. Reason is because different people measure differently. Example, some measure toe at the rim while others measure at the sidewall. All else being equal, identical toe numbers but different measuring locations(distance from hub center) will be completely different in terms of degrees. If someone says that 1/8" toe out works well yet they measured from the sidewall and you set yours using the rim (assuming identical size and shape rim) you will actually have more toe. It can get even more complicated, but this is the easiest way for me to describe it. So always keep that in mind when considering others recommendations. This doesn't even consider how square ones car is. Often times it is talked about how people shift the rear crossmember to get the camber where they want. IMO, having the front and rear crossmembers (or rear axle in stick axle cars) square to eachother is more important than having a desirable camber number in the rear. There are other ways to correct that. Lastly, when doing all that one must consider the relationship of the lower suspension crossmember with the upper control arm pickup points (independent suspensions). Moving the crossmember can change the relationship and move the instant center left to right (assuming control arm lengths are the same left to right).
Very true. That is why I attached the Smart Strings Toe Chart to show how I got the .43 degree toe measurement that I posted above. I have found the chart very helpful over the last few years when calculating toe. When I used toe plates the tapes were 24 inches apart and when I got total toe/thrust as close as possible in inches I would divide the total toe by half (assuming if thrust was as close to zero as possible that each wheel was toed the same amount) and calculate what I had in degrees and compare that to the spec sheets to see how things looked.
The box formed by the strings may very well be a trapezoid without having a center reference point on both ends of the car. To check the box for square measure the diagonals to make sure they're equal.
A center point on the car doesn't do too much good without the subframes also being centered IF you are using camber plates which do not allow minute changes. The same plate used on the LCA on both sides may yield a difference in camber. With the base C6 you can't adjust the UCA. So, centering the subframe is the only way to get equal camber at times.
I set R camber, then R toe, and then thrust angle with a laser. To adjust the thrust I tweak the toe toward one side (\\ or //) just as you do for the steering wheel. It takes very little time.
On the F I set caster, then camber, and then toe. Then I tweak the toe to one side to align the steering wheel.
--Dan
If you are using strings on jack stands you can easily get into the trapezoid problem. The Smart Strings setup tends to avoid that issue. The bars have slots in them to mount the strings so when the front and rear bars are mounted correctly to the car you have a parallelogram with the two long sides parallel to the car's center axis. The bars prevent you from getting a trapezoid.
For a long time I have been thinking of making a home built smart strings setup using plastic pipe but I couldn't figure out how to get it attached to the car to ensure the center line of the box was parallel to the center line of the car.
I can see why Froggy said it took so long to set up the "box" and now understand the importance of the slotted string rods. Jackstands holding strings would be even more difficult and mean you must physically find chassis centerline to measure off of. The smart rods make that not necessary.
I can't understand why Bill is off that 1/16". A 1/16th is pretty big. It is parallax reading the ruler from a different angle error? Is it possible that string on one side is not through the hub center so that camber changes the point at which your ruler hits the hub, thus your measure is longer or shorter due to camber? Or is your ruler not level from center measure point on hub to the string touching the ruler? If your ruler is swinging on an arc to touch the string to read the measure that could account for a 1/16". An error like that can't happen based on my small grasp of how strings work.
That could very well be. I am just using a ruler pulled off a carpenter's adjustable square to make my measurements. It could be at a slight up or down angle from the hub to the string and since I can't get my eyes directly over the ruler and string there could be a slight parallax error. However, I did check those measurements 5 times for each wheel and the numbers are pretty consistent. The big issue with getting the strings equi distance from the hubs is you loosen a set screw holding the rods and slide them back and forth. Just loosening or tightening the set screw tends to move the rod a little and using your hand to tweak the rod left or right a sixteenth is easier said than done. A better way to adjust the rods would be to have some sort of screw adjustment but that would add a lot of extra cost to the tool.
So far I like the tool. It is setup on the car and I can move the car around with it setup this way. To get in and out of the car to move it all I have to do is release the string from the rear rod and when I get ready to measure toe just reattach the string to the rear rod.
I am instructing at VIR starting the 10th of October so will be doing a complete setup over the next couple of weeks. Hopefully, that will give me plenty of time to be slow/methodical and to compare results between the strings and the toe plate/laser method I used before.
The way strings are setup with smart strings I don't see how you can clearly measure diagonals. There is too much stuff in the way for a precise measure. Even with a good tape difference in tautness of the tape will yield quite a bit of potential measuring error.
It is common knowledge that moving the subframe is a solution for camber problems. On the C5 there are reference indexing pins where the subframe fits exactly to the frame and both front and rear subs are square to each other. I dabbled in moving the subframe in years past for camber. However, on a lift with clear view and clear access I could not move the subframe without hogging out the subframe holes or altering the referrence pins so I never moved the subframe. After I thought about it, moving the subframe is not a good idea. Making the right sized camber plates or using the adjustable cam is the proper method. I think this moving the subframe idea came from Hardbar's very limited selection of camber plates when racers wanted to max out their camber in the early days of T1 racing. I was there for the early days and that is what racers did to solve the problem. I was lucky my car was new and everything matched up with hardbar's plates plus we were on rubber bushings with known slop and suspension stichion which made it impossible for good solid reproducible numbers. So we got as close as we could.
Trackboss is the first person I have read about who shares my thinking on this subject. And I would add squareness of both sub frames to the chassis centerline is important too.
What do others think about moving a subframe and have you found the same problem I have of exact fit from indexing pins to subassembly holes?
I know there is some slop in the rear cradle mount on my Z. When I look up at the pins I can see they are off center toward the passenger side by about .1 inch (eyeball estimate). Which would explain the camber difference between the left and right sides. However, moving the cradle that small amount could be an exercise in futility.
So pizzed, just typed out a bunch of responses & idiots at MS rebooted my computer to do updates automatically & lost it all. Sheesh.
My question with laser is there seems to be a lot of necessary moving around of the laser device & how do you know you get it EXACTLY back in the same spot on the axle each time & the clamps don't shift and the ruler on the other end does not move?
The way I use my laser is I have a piece of long plastic that I have wrapped with cardboard and taped together. The plastic provides some stiffness to the cardboard. I used a ruler to mark off inches and 1/8 inch marks on both sides of the cardboard strip. The end of the cardboard fits nicely into the hub center. The cardboard is taped to a jackstand and I move the jackstand to get the home made ruler in the correct spot.
The first step in the procedure is to measure total toe using the toe plates then measure thrust/steering wheel centering. To measure thrust or to center the steering wheel I lay the 2 ft Sears Laser Level on top of the toe plate with some spacers under one end to make sure the laser beam hits the cardboard where the marks are located. To keep the level from falling off the toe plate I attach a couple of small wrenches to the magnetic side of the level so they are behind the toe plate. This holds the level quite nicely against the side of the tire without depressing the tire (can be a problem if you have a helper holding the level). Once the level is set I record the measurement where the laser beam hits the cardboard. At that distance the laser beam spot is about 1/16 diameter so it is easy to estimate where it is between the 1/8 marks on the cardboard. Then I move the laser to the other side of the car and do the same thing.
Say I get a total toe measurement of 1/16 in with a measurement of of 4 1/8 thrust on the driver's side and 5 1/8 thrust on the passenger side. That tells me I the right rear is toed out more than the left rear. If I want to keep my 1/16 toe that means I have to adjust toe on both sides an equal amount to the left which usually means turning the left side tie rod 3 flats in and the right side tie rod 3 flats out. Once that is done I remove the laser, tape measures, toe plates, cardboard ruler and move the car backward to the end of the driveway and forward to where it was before (the last motion of the car always has to be forward before you measure toe). Then I put the tools back into place and measure everything to see where my adjustments got me. Once you do this a couple of times you get to know how much to turn the tie rod ends to get a certain amount of movement of the laser beam so you can narrow in on the setting. It can take 4 or 5 shots to get thrust close to zero and still have the toe setting you want. I have done checks to see how repeatable this is by just taking measurements, moving the plates/laser/cardboard and then putting them back into position and I get the same reading. Of course once I move the car the irregularities on the tire sidewall could change things but that is an issue with the toe plate method. I am hoping the strings can simplify this part of the job.
Bill
Last edited by Bill Dearborn; Sep 13, 2014 at 12:38 PM.
Your eyeballs & brain reading the ruler is a VERY critical part of the whole process & probably why alignment racks & systems were invented to eliminate the "human" error. If you can do it you can be as good or better than the machine IMO, but if you blink/sneeze/get interrupted/ etc you can end up with crap. This process needs you to be VERY focused on the task.
VERY focused and not to make inny and outy mistakes like I did in my previous post. One little thing not done correctly and you definitely have crap.
If Bill set up as he states the box can't be shifted. The geometry is sound. I'm thinking it is a positional tedium of measurement problem. Both methods are tedious and manual.
I have problem getting my steering wheel centered but my car always tracks straight. I center my wheel then do front Toe. The I drive the car and see if it is going left or right vs. the wheel level. Then I will swing the toe left or right equally as needed. It is a real pain. Any tips to make that faster?
Yes, definitely true you can have a straight tracking car with a crooked wheel, previous to my last two alignments I would get that. I think I got better with my measuring is all. I just center the wheel & my column lock (still have that) holds it.
If Bill set up as he states the box can't be shifted. The geometry is sound. I'm thinking it is a positional tedium of measurement problem. Both methods are tedious and manual.
I have problem getting my steering wheel centered but my car always tracks straight. I center my wheel then do front Toe. The I drive the car and see if it is going left or right vs. the wheel level. Then I will swing the toe left or right equally as needed. It is a real pain. Any tips to make that faster?
I'm not sure on Bill's question, need to reread & rethink it.
I know that reading the ruler is a crtical skill for this whole process. Just the way your body bends down, or if you lean your shoulder into the car on one side and not the other, or even how your shop lights illuminate each corner of the car differently (shadows on the ruler/string) all can make at least a 64th or 32nd differenc, but probably not a 16th.
Last edited by froggy47; Sep 13, 2014 at 01:51 PM.
That could very well be. I am just using a ruler pulled off a carpenter's adjustable square to make my measurements. It could be at a slight up or down angle from the hub to the string and since I can't get my eyes directly over the ruler and string there could be a slight parallax error. However, I did check those measurements 5 times for each wheel and the numbers are pretty consistent. The big issue with getting the strings equi distance from the hubs is you loosen a set screw holding the rods and slide them back and forth. Just loosening or tightening the set screw tends to move the rod a little and using your hand to tweak the rod left or right a sixteenth is easier said than done. A better way to adjust the rods would be to have some sort of screw adjustment but that would add a lot of extra cost to the tool.
I leave the set screw off until the final string alignment is in place, also to move the rod a tiny bit just twist it with a gentle pull at the same time.
So far I like the tool. It is setup on the car and I can move the car around with it setup this way. To get in and out of the car to move it all I have to do is release the string from the rear rod and when I get ready to measure toe just reattach the string to the rear rod.
With the bungee setup you can just push the string down and carefully open the door & the string slides under the door & pops back to proper position when the door is closed.
I am instructing at VIR starting the 10th of October so will be doing a complete setup over the next couple of weeks. Hopefully, that will give me plenty of time to be slow/methodical and to compare results between the strings and the toe plate/laser method I used before.
The box formed by the strings may very well be a trapezoid without having a center reference point on both ends of the car. To check the box for square measure the diagonals to make sure they're equal.
I think if the car is square (not a wreck/rebuild) and you are EXACT off the axles with the string measurement then it's not a trapezoid. But I have no proof of that other than good results.
A center point on the car doesn't do too much good without the subframes also being centered IF you are using camber plates which do not allow minute changes. The same plate used on the LCA on both sides may yield a difference in camber. With the base C6 you can't adjust the UCA. So, centering the subframe is the only way to get equal camber at times.
I set R camber, then R toe, and then thrust angle with a laser. To adjust the thrust I tweak the toe toward one side (\\ or //) just as you do for the steering wheel. It takes very little time.
On the F I set caster, then camber, and then toe. Then I tweak the toe to one side to align the steering wheel.
If you are using strings on jack stands you can easily get into the trapezoid problem. The Smart Strings setup tends to avoid that issue. The bars have slots in them to mount the strings so when the front and rear bars are mounted correctly to the car you have a parallelogram with the two long sides parallel to the car's center axis. The bars prevent you from getting a trapezoid.
For a long time I have been thinking of making a home built smart strings setup using plastic pipe but I couldn't figure out how to get it attached to the car to ensure the center line of the box was parallel to the center line of the car.
Bill
From the little I know about Smart Strings having not used them it seems that to use them effectively and set them up quickly you need to start with the centerline of the car. The centerline is then used to position the front and rear rods that support the strings. The strings are equal distance out from the centerline and ideally in a notch that can't move.
In this way, you know you have a rectangular box around the car that can be used to measure into a wheel or hub. -- F or R.
Without referencing a centerline on the car how are the strings placed? Measuring off the F & R hubs does not account for camber differences from side to side, I believe, or worse, having only one wheel way off after say moving an eccentric.
I found this DIY that better explains what I am saying --
Circle Track String Alignment -- where they say to set one side and then measure off that side to set the other parallel string and not use the car to determine both sides as camber changes the wheelbase. Mouse over the text on the images to see the full explanation. This also saves the cost of the process by bringing us back to jack stands.
The tripod laser is also a sweet way of doing this. I may give it a try as this one is cheap -- Laser w/Tripod.
Better yet, I just looked and my Stanley Fat Max laser has the built in threads for my tripod so I will try that.
I don't want to derail this thread, but chassis setup is pretty demanding on the brain when it is discussed in depth, like this. So to lighten things up, for those of you who race on a very limited budget (like I used to) I'll remind you of this.The alignment perfection doesn't matter so much anymore when on sunday your competition, who can afford fresh tires while you are on worn out 3 weekend old rubber, mounts them you are hoping for a mistake up front otherwise first place is almost out of reach.
Some info from Smart Strings user manual especially 4-6.
If anyone on the thread has actually done an alignment from true centerline, please, describe how you determine it & then how you use strings or lasers coming off true centerline. I don't see how it's possible on a street car on a garage floor.
Last edited by froggy47; Sep 13, 2014 at 09:16 PM.
I don't want to derail this thread, but chassis setup is pretty demanding on the brain when it is discussed in depth, like this. So to lighten things up, for those of you who race on a very limited budget (like I used to) I'll remind you of this.The alignment perfection doesn't matter so much anymore when on sunday your competition, who can afford fresh tires while you are on worn out 3 weekend old rubber, mounts them you are hoping for a mistake up front otherwise first place is almost out of reach.
LOL! So true. I'm going to Runoffs for the very first time because it is on the West coast and I'm tagging along with a front runner multiple championship guy who can point me to where start/finish is. I'm an unoptimized driver with a silly unoptimized car with the very huge goal of finishing the championship race not last. But my alignment will be perfect.
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