Making Alignment Bars (String Based)

[S. Frebert]

Hey All!
Was hoping to gather some input on this. I have slowly found out that the alignment bars supplied with my FF are...... inferior?


I'd like to make new ones and have so many ideas, but also trying to maintain the mentality K.I.S.S.....




Am I to measure the widest point of the car (Outer portions of the stub axles), then make 2 tubes of the same length?


Pretty excited to race a car with a correct alignment, maybe a straight steering wheel too?
That was some fun at Road Atlanta.


Thanks to all for any help!


Shayne
Van Diemen RF85

[Ray Rivard]

I have bars for a RF99 that I don’t use. PM me if you’re interested.


Sent from my iPhone using Tapatalk

[S. Frebert]

I have bars for a RF99 that I don’t use. PM me if you’re interested.


Sent from my iPhone using Tapatalk

PM Sent

[Purple Frog]

It is not rocket science.

The bars should extend out front and rear wider than the wheels/tires. (duh)
Best if the strings pass through the axle centerlines. (seriously, makes it better)
I use 1" square steel tubing. Weld brackets on to attach it to car. Since i always has FC cars i would use the rear wing struts to hold the rear bar, etc. Build the bars and mount them before you try to find centerlines.
Find the longitudual centerline of the car. I use a laser shooting down up up high so that it hits the gearbox and the front chassis crossmember.
Mark the center of each bar. Important. I like to run the laser beam down the centerline of the gear box, and a point on the center of the front cross member.
Then make marks on the outer ends of each bar exactly the same measurement from that center point, far enough out that the strings will pass outside the wheel/tyre combination. The strings should be parallel to each other. (duh)
I cut in a small notch in the bars at that point so that the strings will always be placed at the same point.
I use 10 lb fishing line.
Label the bars left and right, etc.
Always bolt them up the same way.
Tight strings.
Get a good accurate steel rule to measure from the strings to the rim edge. (don't use sidewall of the tire)

I always do the measurements with driver weight in the car and full tank with tyres at race pressure.
Of course by then I have already measured the circumference of each tire.
Make sure rims have the same off set left and right, and a whole bunch of other anal measurements.

OBTW, I have had some setups take 8 hours start to finish.

But... if you leave the shop with a good setup and wrote everything down, then it's easy at the track to quickly change out a corner and get everything tidy.

[Earley Motorsports]

Like what Frog says but just to add mine has a light throttle spring on one end of the line just to give a little bit of stretch ability in case you should happen to hit the fishing line. Then they have a loop added after that to slip over the tube attached to the car. Mine also have the ends of the tube painted orange just to make them stand out as when I am looking at the car I am not always looking where I am going. Just some pointers.

[EYERACE]

I go to Homey Depot and look down [like how one checks pool cues for straightness] their long 1" X 1" square alum. tubing and buy two absolutely straight ones longer than the width of your car. Let's say the tubes are 8 feet long [96"]. Figure out the track of the front and rear of the car - let's say the widest is 60 inches and your car's total length is 100 inches too. Tape the tubes together and get a hack saw - cut a tiny groove/mark in the corner of the tubing at the same spot on your tubes 16 inches in from one end......measure over 63 inches and then make/cut another groove/mark.....which is now ideally also 16 inches in from the other end but that depends on how honest Homey is at telling you your tubes are 96" long......the main thing is your marks on both tubes are of equal spacing. Get four jack stands and put them past the ends/corners of your car - lay the tubes across the jack stand tops at either end of the car - tie your fishing line into the cut marks on the tubes such that you used let's say exactly 106 inches of string along both sides of the car.....measure over and over again how far the line is from each rear and front axle tip and get those front & back distances from the strings to axle tips equal on either side of the car front & back by moving the tubes sideways - use magazines with the right number of pages torn out as shims under the jack stands to get your strings to the height of your axle tips.

Once your rectangle of string and tubing is in place....you can practice bumping the tubing or stands out of place with your shoes or your leg or your knee or your favorite tool when you're hunched over the car or walking around it !!!..............which you will do multiple times while you actually set up the car. Which explains why others prefer to attach their tubes to the car after going to the trouble to find the car's centerline front and back and figuring out how to attach the tube midpoints at exactly those places - that way you can someday bump into those tubes hard enough and bend them.

[problemchild]

It is not rocket science.

The bars should extend out front and rear wider than the wheels/tires. (duh)

Duh?
Why would that be?

If on a formula car, I much prefer to have the bars 3' long than 6' long.
I put the strings between the body and wheels.

Some advantages.....
Less cost for material
Less storage space required
Less space required for the process (I have done it in trailer)
Harder to trip over strings

Also values are real rather than inverted, so less likely to get confused, when you are trying to set toe when you should have been sleeping 10 hours before.

Also, Mike says to measure on the wheel not the tire. That is assuming your wheels are straight enough and regular enough to do it. Generally, the inside of the wheels is better in that regard, which may be another reason for the narrow string setup. If I am concerned about wheel straightness, I roll the car fore and aft so that I am measuring the same one point on the wheel. With the right string and right scale (ruler for non-trades people) you can certainly measure more accurately than the run-out variances on very serviceable wheels, so be aware of wheel run-out. If I start getting unexplained inconsistencies, I immediately check that I am not on a bad section of wheel.

[DanW]

Duh?
Why would that be?

If on a formula car, I much prefer to have the bars 3' long than 6' long.
I put the strings between the body and wheels.

Some advantages.....
Less cost for material
Less storage space required
Less space required for the process (I have done it in trailer)
Harder to trip over strings

Also values are real rather than inverted, so less likely to get confused, when you are trying to set toe when you should have been sleeping 10 hours before.

Also, Mike says to measure on the wheel not the tire. That is assuming your wheels are straight enough and regular enough to do it. Generally, the inside of the wheels is better in that regard, which may be another reason for the narrow string setup. If I am concerned about wheel straightness, I roll the car fore and aft so that I am measuring the same one point on the wheel. With the right string and right scale (ruler for non-trades people) you can certainly measure more accurately than the run-out variances on very serviceable wheels, so be aware of wheel run-out. If I start getting unexplained inconsistencies, I immediately check that I am not on a bad section of wheel.

Brilliant!

[Purple Frog]

Only problem with Greg's "inside method" is that I like to measure at axle centerline. Hard to run a string through the rear axle on the inside of the wheel.

To each his own. Either way you are comfy, go for it.

[lch Racing]

What laser do you use? MOunted on the ceiling of the shop or some higher vantage point. Thanks for the advice.
Larry

QUOTE=Purple Frog;555740]It is not rocket science.

The bars should extend out front and rear wider than the wheels/tires. (duh)
Best if the strings pass through the axle centerlines. (seriously, makes it better)
I use 1" square steel tubing. Weld brackets on to attach it to car. Since i always has FC cars i would use the rear wing struts to hold the rear bar, etc. Build the bars and mount them before you try to find centerlines.
Find the longitudual centerline of the car. I use a laser shooting down up up high so that it hits the gearbox and the front chassis crossmember.
Mark the center of each bar. Important. I like to run the laser beam down the centerline of the gear box, and a point on the center of the front cross member.
Then make marks on the outer ends of each bar exactly the same measurement from that center point, far enough out that the strings will pass outside the wheel/tyre combination. The strings should be parallel to each other. (duh)
I cut in a small notch in the bars at that point so that the strings will always be placed at the same point.
I use 10 lb fishing line.
Label the bars left and right, etc.
Always bolt them up the same way.
Tight strings.
Get a good accurate steel rule to measure from the strings to the rim edge. (don't use sidewall of the tire)

I always do the measurements with driver weight in the car and full tank with tyres at race pressure.
Of course by then I have already measured the circumference of each tire.
Make sure rims have the same off set left and right, and a whole bunch of other anal measurements.

OBTW, I have had some setups take 8 hours start to finish.

But... if you leave the shop with a good setup and wrote everything down, then it's easy at the track to quickly change out a corner and get everything tidy.[/QUOTE]

[problemchild]

Only problem with Greg's "inside method" is that I like to measure at axle centerline. Hard to run a string through the rear axle on the inside of the wheel.

To each his own. Either way you are comfy, go for it.

My axles are only an inch thick, so 5/8" up or down is not my concern. By the time I make mounts for the bars, I am usually happy if I end up with my strings within an inch, plus or minus, of the axle centerline. When I have a choice, I prefer them on the low side so I can set toe on stands in the air. That requires doing an initial comparison to determine the differences, much like setting ride height to a point on the car. I believe ease of process offsets any comparison variances, and provides more consistent values over time, with less chance of errors.

[S. Frebert]

Duh?
Why would that be?

If on a formula car, I much prefer to have the bars 3' long than 6' long.
I put the strings between the body and wheels.

Some advantages.....
Less cost for material
Less storage space required
Less space required for the process (I have done it in trailer)
Harder to trip over strings

Also values are real rather than inverted, so less likely to get confused, when you are trying to set toe when you should have been sleeping 10 hours before.

Also, Mike says to measure on the wheel not the tire. That is assuming your wheels are straight enough and regular enough to do it. Generally, the inside of the wheels is better in that regard, which may be another reason for the narrow string setup. If I am concerned about wheel straightness, I roll the car fore and aft so that I am measuring the same one point on the wheel. With the right string and right scale (ruler for non-trades people) you can certainly measure more accurately than the run-out variances on very serviceable wheels, so be aware of wheel run-out. If I start getting unexplained inconsistencies, I immediately check that I am not on a bad section of wheel.

Greg,
Any pictures of this setup? Haven't seen this before. Curious to see this

[Purple Frog]

I have a Bosch laser that i use in my construction job most days. About $100 unit. Projects a horizontal beam and a vertical beam.
I sit it on a six or eight foot ladder behind the car. I aim down the center of the gearbox and it usually shoots over or through the rollhoop to hit the front frame member and alignment bar. I have already marked the center of the front chassis. Once i get the beam hitting both center of gearbox and center of front, then I can mark the alignment bars.

I have heard that perfectionists say the beam is actually too thick to be super accurate. It's about 1/16" wide. I just use a single blade razor and try to mark everything on the center of the beam.

[Rick Kirchner]

laser width can be an issue - I built a set of pad leveling "gauges" with some nice precision scales epoxied to some machined blocks, and the laser (admittedly a cheap one) made those pretty useless. For one, it has to have a really good leveling feature, which mine didn't. Froggies is likely much better.

A trick I've learned when working with the lasers is that any time you have to stare at the beam reflection to make a measurement use sunglasses. Even dim lasers will bug you if you have to stare at that spot and focus for more than a few seconds. IMHO, you want to observe as little of the reflection as possible.

[SEComposites]

I wouldn’t bother with lasers. There’s nothing wrong with string!

[Fred Michael]

We use a laser to rough in our setup patches but that is all it is good for, a rough in. We do our final set with a precision level. There is no way it is accurate enough for toe. Stick with string.

[lch Racing]

Thank you. My challenge is transferring chassis center line on the top frame components to the frame bottom. It seems that with the laser picking up the top points as you suggest I would get a mark on the floor to run a string thru to get a better point to translate with a square/level back to the bottom frame. I am learning to get these points defined real well before assembling the car.
Larry

I have a Bosch laser that i use in my construction job most days. About $100 unit. Projects a horizontal beam and a vertical beam.
I sit it on a six or eight foot ladder behind the car. I aim down the center of the gearbox and it usually shoots over or through the rollhoop to hit the front frame member and alignment bar. I have already marked the center of the front chassis. Once i get the beam hitting both center of gearbox and center of front, then I can mark the alignment bars.

I have heard that perfectionists say the beam is actually too thick to be super accurate. It's about 1/16" wide. I just use a single blade razor and try to mark everything on the center of the beam.