Front Tire Width and Diameter
- Thread starter Neshkoro
- Start date
Neshkoro
Well-Known Member
Fletch,
Thanks for the thoughts.
It seems to wander at all speeds. Naturally, it seems worse at higher speeds like 45-50 MPH. The rear spring is a Model T type spring. There is little movement, if any, other than up and down. I did not have it loaded with driver weight when I aligned it. The brakes seem to be OK. I just replaced the front wheel cylinders as they were getting sticky. I'm going to get rear shocks and take a look at the fronts.
More testing.
Bill
Thanks for the thoughts.
It seems to wander at all speeds. Naturally, it seems worse at higher speeds like 45-50 MPH. The rear spring is a Model T type spring. There is little movement, if any, other than up and down. I did not have it loaded with driver weight when I aligned it. The brakes seem to be OK. I just replaced the front wheel cylinders as they were getting sticky. I'm going to get rear shocks and take a look at the fronts.
More testing.
Bill
Neshkoro
Well-Known Member
The string method was described some years ago. It involved running strings along the outside edges of the rear tires forward beyond the front tires. Then measuring the distance from the left string to the outer edge of the left tire then measuring the distance on the right side, making sure they are the same, making any adjustment as needed. I will try to find the post. Maybe someone else has a copy of it or knows where it is.It assures that things are centered and equal.
Bill
Bill
Lee_in_KC
Active Member
String method... National T-Bucket Alliance - Login
Edit: I forgot, you have to be an NTBA member to access the Tech Pages.
Edit: I forgot, you have to be an NTBA member to access the Tech Pages.
Here's the article:
Seen lots of posts about toe-in/out settings, questions about how much caster , shimmy, wobbles, issues with bump-steer, and ruts/bumps in the road causing handling problems. I wanted to share my experience over last 230k miles, 27 years, numerous wrecks, 3 front axles, bent hairpins/radius rods, no front shocks for 20 years, numerous tires (heights/widths),... What I've found, many problems can be avoided if the bucket is square/straight. This allows the suspension and steering to work, but won't correct or hide poor design geometry. Don't like seeing dampeners or shocks used intentionally to mask or cover up problems. Also allows the bucket to brake and accelerate straighter, run faster, less unusual tire wear, and above all safer and more predictable handling. I'm not an alignment expert/professional but I have found this works for me. Course I'll assume standard straight front and rear axle and the independent suspension guys can modify these comments to fit their needs.
First, make sure the bucket is square (4 wheel alignment). Second, fix suspension geometry problems like steering travel, ride height, spring rates, shock function, suspension travel (watch how things move in an arch), heim movement or binding (use special washers), tightness and wear of parts, driveshaft angles,ackerman angles, ... Third, set the caster of the front axle. LASTLY: adjust the toe-in/out. I often see these steps done in reverse order (toe, caster, fix, finally align). Try not to skip Step 1. The following is my own process, uses very few tools, and works from the center of where the tire patch sits on the road (tire width and backspacing automatically taken into account). These instructions should compliment, not override, the Chassis information found in the Tech Pages.
Aligment step 1- Get it square and straight. Tools needed: 2" Masking tape, string, markers/pen, tape measure, straight edge/yardstick, and a plumb bob (plumb line), a small amount of paint and paper to write measurements (or use the diagram I created in powerpoint).
Find a clear, flat surface to work (garage floor, concrete slab,...) and enough room to drive straight onto this surface. drive the bucket straight in without turning the wheel. Once you feel comfortable that the bucket is sitting straight put it in park-- do not touch the steering and set the emergency brake/chock tires to keep the bucket from moving.
Place a piece of masking tape on the floor, at the front and back of each tire (centered). Front tire example:
Rear tire example:
Note: Precision in finding the center of the tire is crucial to placing the plumb bob (my tires have a centerline groove which makes it simple). Also try to take measurements within a 32nd of an inch on the tape measure.
Next, dip the tip of the plumb bob into the paint, so it will leave a small dot where it touches the masking tape. Hang the plum bob down the center of the tire like this:
Make sure the plum bob hangs straight down and doesn't swing/spin. Slowly lower the plumb bob till the tip touches the masking tape on the floor and leaves a nice little mark. Do this procedure to the front and rear of each tire. Do not rock or move the tires.
After all the tires are marked. Take a break while the paint dries on the masking tape. 15 minutes should be enough time to read the rest of the instructions and prepare.
Back the bucket out of the way. Should have 8 pieces of tape on the floor (front and back of each tire) and each one have a small dot. In picture, the red and black pens indicate the dots on the tape.
Place another piece of masking tape down, connecting the 2 pieces already on the floor. Should look like this
With a straight edge yardstick, draw a line connecting the paint dots (in this picture from the black pen to the red pen). Measure the distance from dot to dot and divide by 2 and put an "+" at that point (location of green marker). This is the center of the tire where the rubber meets the road.
Do this procedure for the remaining tire locations. Should look like this:
Place a piece of masking tape between the center marks "+" of each front tire and the rear tire. This will represent the axles so we can find and mark the centers. Should look like this:
Tape a string (unless you have a straight edge that's 6 feet long) to the floor, from the center of the front driver's tire to the center of the front passenger tire. Measure this distance and divide by 2. Put a mark "+" at the exact center of the axle. Do this for the rear also.
Here's the part where a friend, wife, buddy really helps out. Record all the measurements indicated by the diagram. Lots of measurements but will give you lots of information about your alignment, thrust angles (acceleration/braking), wheelbase, toe-in/out, and could also let you know if the rear axle housing is bent. Be precise on these measurements.
Now for the VISUAL stuff. Tape a string to the floor from the center of the driver's front tire to the center of the passenger rear tire. Then tape a string from the center of the passenger front tire to the center of the driver rear tire. Finally, tape a string from the center of the front axle to the center of the rear axle and find the center (length/2) of this string and put a piece of tape on the floor underneath the string and mark "+" this spot. Should look like this:
If the bucket is square, it should look like this:
Notice the cross "X" strings are just above the center mark "+" of the axle centerline. Because in this example, the centerline of my rear tires are wider than the centerline of the front tires. This is ok in this example since the crossed "X" strings met directly over the centerline string.
Make small adjustments to correct any problems and only make one or two adjustments at a time. When making adjustments, counting threads on a rodend or heim can get you real close (12, 16, 18 threads per inch). Put a date on the Diagram and make a note on the changes you made (example: front passenger hiem on radius rod unscrewed 2 turns, rear panhard lengthend 2 turns).
After making adjustments, drive the bucket and see if the adjustments helped. Then start this procedure over again. Record your new measurements. It may be somewhat time consuming but can avoid or solve many other problems which may save $$ and avoid other issues. Try not to skip step 1.
You'll also find the bucket more enjoyable to drive, safer, and allows you to do things with the bucket you never thought of
Seen lots of posts about toe-in/out settings, questions about how much caster , shimmy, wobbles, issues with bump-steer, and ruts/bumps in the road causing handling problems. I wanted to share my experience over last 230k miles, 27 years, numerous wrecks, 3 front axles, bent hairpins/radius rods, no front shocks for 20 years, numerous tires (heights/widths),... What I've found, many problems can be avoided if the bucket is square/straight. This allows the suspension and steering to work, but won't correct or hide poor design geometry. Don't like seeing dampeners or shocks used intentionally to mask or cover up problems. Also allows the bucket to brake and accelerate straighter, run faster, less unusual tire wear, and above all safer and more predictable handling. I'm not an alignment expert/professional but I have found this works for me. Course I'll assume standard straight front and rear axle and the independent suspension guys can modify these comments to fit their needs.
First, make sure the bucket is square (4 wheel alignment). Second, fix suspension geometry problems like steering travel, ride height, spring rates, shock function, suspension travel (watch how things move in an arch), heim movement or binding (use special washers), tightness and wear of parts, driveshaft angles,ackerman angles, ... Third, set the caster of the front axle. LASTLY: adjust the toe-in/out. I often see these steps done in reverse order (toe, caster, fix, finally align). Try not to skip Step 1. The following is my own process, uses very few tools, and works from the center of where the tire patch sits on the road (tire width and backspacing automatically taken into account). These instructions should compliment, not override, the Chassis information found in the Tech Pages.
Aligment step 1- Get it square and straight. Tools needed: 2" Masking tape, string, markers/pen, tape measure, straight edge/yardstick, and a plumb bob (plumb line), a small amount of paint and paper to write measurements (or use the diagram I created in powerpoint).
Find a clear, flat surface to work (garage floor, concrete slab,...) and enough room to drive straight onto this surface. drive the bucket straight in without turning the wheel. Once you feel comfortable that the bucket is sitting straight put it in park-- do not touch the steering and set the emergency brake/chock tires to keep the bucket from moving.
Place a piece of masking tape on the floor, at the front and back of each tire (centered). Front tire example:
Rear tire example:
Note: Precision in finding the center of the tire is crucial to placing the plumb bob (my tires have a centerline groove which makes it simple). Also try to take measurements within a 32nd of an inch on the tape measure.
Next, dip the tip of the plumb bob into the paint, so it will leave a small dot where it touches the masking tape. Hang the plum bob down the center of the tire like this:
Make sure the plum bob hangs straight down and doesn't swing/spin. Slowly lower the plumb bob till the tip touches the masking tape on the floor and leaves a nice little mark. Do this procedure to the front and rear of each tire. Do not rock or move the tires.
After all the tires are marked. Take a break while the paint dries on the masking tape. 15 minutes should be enough time to read the rest of the instructions and prepare.
Back the bucket out of the way. Should have 8 pieces of tape on the floor (front and back of each tire) and each one have a small dot. In picture, the red and black pens indicate the dots on the tape.
Place another piece of masking tape down, connecting the 2 pieces already on the floor. Should look like this
With a straight edge yardstick, draw a line connecting the paint dots (in this picture from the black pen to the red pen). Measure the distance from dot to dot and divide by 2 and put an "+" at that point (location of green marker). This is the center of the tire where the rubber meets the road.
Do this procedure for the remaining tire locations. Should look like this:
Place a piece of masking tape between the center marks "+" of each front tire and the rear tire. This will represent the axles so we can find and mark the centers. Should look like this:
Tape a string (unless you have a straight edge that's 6 feet long) to the floor, from the center of the front driver's tire to the center of the front passenger tire. Measure this distance and divide by 2. Put a mark "+" at the exact center of the axle. Do this for the rear also.
Here's the part where a friend, wife, buddy really helps out. Record all the measurements indicated by the diagram. Lots of measurements but will give you lots of information about your alignment, thrust angles (acceleration/braking), wheelbase, toe-in/out, and could also let you know if the rear axle housing is bent. Be precise on these measurements.
Now for the VISUAL stuff. Tape a string to the floor from the center of the driver's front tire to the center of the passenger rear tire. Then tape a string from the center of the passenger front tire to the center of the driver rear tire. Finally, tape a string from the center of the front axle to the center of the rear axle and find the center (length/2) of this string and put a piece of tape on the floor underneath the string and mark "+" this spot. Should look like this:
If the bucket is square, it should look like this:
Notice the cross "X" strings are just above the center mark "+" of the axle centerline. Because in this example, the centerline of my rear tires are wider than the centerline of the front tires. This is ok in this example since the crossed "X" strings met directly over the centerline string.
Make small adjustments to correct any problems and only make one or two adjustments at a time. When making adjustments, counting threads on a rodend or heim can get you real close (12, 16, 18 threads per inch). Put a date on the Diagram and make a note on the changes you made (example: front passenger hiem on radius rod unscrewed 2 turns, rear panhard lengthend 2 turns).
After making adjustments, drive the bucket and see if the adjustments helped. Then start this procedure over again. Record your new measurements. It may be somewhat time consuming but can avoid or solve many other problems which may save $$ and avoid other issues. Try not to skip step 1.
You'll also find the bucket more enjoyable to drive, safer, and allows you to do things with the bucket you never thought of
old round fart
Well-Known Member
A lot of race cars have bolt on tubes front and rear for set up at the track for crash repair. Pretty cool.
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