After 6 months of thinking, learning, welding and fixing my f***ups, I took my 30 roadster for a short test drive after bracing the frame and installing more comfortable & securely mounted seats. The car no longer has chassis flex. The radiator grille does not shake & twist like it did, telling me I did something right. You can refer to my Album of the roadster for images. This little hot rod does not hold a candle to most of the ones Ive read about on the HAMB, but its mine. I want this car to handle safely at highway speeds. I do have two issues I need help with. The wheel base is 110 but I need to check it to make sure it is parallel & square. I want to make sure the car is tracking right and not dog-legging it. Measuring from the rear frame upright to the C/L of the driver side & pass side axle housing, results in a ¼ shorter distance on the driver side. The frame is a L type design. The frame is square. What is the correct DIY way to check all 4 wheel alignment MYSELF? Is it best to remove all 4 wheels and anchor plumb bobs to the C/L of each hub then measure front/back & cross distance? This car does not have a panard bar to steady the rear end. It does have a 28 long bar attached from the driver side rear axle, running 1 under the diff., to the pass. side frame. It is mounted 17 inward from the drivers side rear wheel flange to the passenger side of the frame, 16 in front of the axle C/L. The bar is level, at an approx. 20 degree angle. I dont know if this track bar is adequate. In order to install a panard bar above the axle housing I would have add a frame extension to the driver side so that it would run parallel to the axle. Does the panard bar have to be parallel to the axle? I have never seen one run diagonally.
I think you are probably pretty close on your adjustments and as long as the car drives straight you should be good. If you were to drive though some water and the drive straight for 50 to 100ft would/do the rear tires track with the front tires? In straight parallel lines that is, showing that the rear end is following on the same line as the front end and not trying to crab off to one side. I'm pre computerized four wheel alignments as far as doing alignment work goes. Still I managed to get cars to drive straight and handle pretty well and not wear the front tires prematurely. If there isn't any adjustment built into the rear suspension you are pretty well set with what you have. That said, how does the car actually drive? does it drive straight and can you take your hands off the wheel on a straight street and have it go in a straight line down the street? After making a turn does the car return it's self to going straight pretty well on it's own? I don't see anything wrong with the way you put the bar on the rear end. it might be a bit unorthodox but as long as it keeps the body and frame from swaying around when you take a corner it should be good.
THIS IS AN EASY WAY TO CHECK THE ALIGNMENT OF YOUR CAR AT HOME ON THE GARAGE FLOOR. You will need some simple tools. masking tape, at least a 20 ft chalk line, carpenter square, tape measure min 6ft., pencil, plumb bob and a small drafting square. Find a smooth level area in your garage floor or concrete pad, black top or dirt don't work well and sweep it clean. Roll your car in position and place on jack stands enabling you to access under the car. After getting your car up in the air, take the carpenter square and mark the center line of the axles perpendicular on the floor, also transfer the mark to the side wall of the tire with chalk. This will help re index the car if you have to move it and return to the same position. To check the axles square to the frame you are now going to choose known points and determine the center line of the vehicle. From the front intersection corner of the front cross member and the frame rail drop a plumb bob down to the floor surface and mark the point on a piece of masking tape applied to the floor surface. Do this for the opposite side and then go to the rear cross member and repeat the process. What you are doing is establishing a reference point for the center line of the car. With your chalk line first connect the lateral, side to side reference points by snapping a line to go parallel to the frame and perpendicular to the axles. After doing this operation measure from the frame rail cross member junction point to the opposite side and divide the measurement in 1/2 exactly and mark the distance on the lateral line between the front and again at the rear cross member points. You can have different numbers front and rear based upon the taper of the frame but they must be exactly 1/2 measurement distance on the axle end that you are measuring. After determining the center line of the vehicle points, snap a chalk line front to rear to represent the center line of the vehicle. With the center line determined now you are ready to check the square of the axles. Repeat the same procedure that you used to determine the frame position as with the axles.Choose the intersection of the radius rod and axle on the front and on each side drop a plumb bob and mark the position. At the rear axle choose a symmetrical locating bracket axle junction and repeat the front process. By snapping a chalk line perpendicular to the frame and connecting the front axle point markings and repeating the process at the rear you are ready to determine the square of your axles. You should have established a grid work that looks like a railroad train track cross hatch pattern. The rails would be the lines representing the frame rails and the ties would be the marking that represented the axles and a hot line front to rear down the center representing the middle of the car. From the line that represents the center line of the vehicle take your carpenter square and strike a right angle to the center line. Approximately mid point between the axle markings extending the chalked line perpendicular to the center line wide than the frame rail width distance..This would be like adding another tie to the railroad track diagram. If you have done this correctly this line will serve as a square reference angle to measure the square of the axles. Measure first forward on side left of central line and then right of the central line and comapre figures. If you have assembled your vehicle correctly and laid this out correctly the two numbers will be the same. Repeat the process measuring to the rear axle, again if the axle is square to the chassis the numbers should match. In either case if the numbers do not match it will tell you that one wheel is ahead or behind the opposite side and you will have to adjust the links to bring the axles to square. You can also use this to check to see if you have centered the axles to the chassis. By dropping a plumb bob from the outer edge of the tire on center, marking on the ground a reference point and measuring back to the center line of the chassis. You can determine if the axle is centered or off set to the right or left of the vehicle as it tracks down the road. If the numbers are equal then the axle is centered if they are not the same then the axle is offset to the right or the left. let us know your results.
I need to go out and take another drive and check out all your suggestions. Car steers and turns well. I'll check out your drive thru water idea. I get a little vibration around 50 MPH but that could be due to the bias-ply tires. Right now I'm nursing a sciatic nerve flareup from working on my mower. On vacation this past week thinking I'd get a lot done. Just laid around. Done whining.
Thanks Dick. I'll get out the tools, do some limbering up, take my meds. and hit the garage Sunday morning. I'll let you know what I find.
After plotting out all the intersection points you requested, I found out the driver side wheel base is 111.125”, measured from the C/L of the front spindle bearing to the center of the rear axle hub. The passenger wheel base is 111.312”. Checking the front axle sqaure to the frame, I found the intersection point of the front cross member and the frame rail. I located the C/L of the driver & passenger side spindle, then plotted lines or ties, perpendicular to the frame C/L. Please note the cross member is in FRONT of the axle. The driver side axle measured .500” closer to the rear of the car than the passenger side. Performing this task at the rear of the car, keeping in mind the frame is an “L” design with the rear axle assembly located to the rear of the frame. The driver side is .250” further away from the rear cross member point than the passenger side. The front axle is offset approx. .250” toward the driver side, measuring from the C/L to the inside brake backing plates on each side. The rear axle is approx. .375” offset toward the passenger side holding the plumb bob against the rear brake backing plate. I also determined the rear of the body is positioned approx. 1” closer the C/L of the frame on the driver. This is why there is a 1” wide wheel spacer between the brake drum and the wheel on this side. only. I will have to try to find a better way to center this, after making the final adjustments to the wheel base and front hairpin radius rods. I will run thru this procedure a few more times to make sure my measurements are correct and repeatable. What is the correct procedure when adjusting the front hairpin radius rods?
1 key I want to remind you is make sure your floor is level . This is a good excuse to buy a 4-6 foot level. We used to do our own racecars. the key thing was 4 spots in the floor that were perfect and repeatable. use wood shims if needed The wheelbase being square is a big deal here. . There are a couple of good chassis books that are good to read . just curious if you unbolt the panard bar does the rear axle shift ? I would love to see a pic of the rear suspension. a quick and dirty way to check wheel base is center of axle shaft to center of spindle with string .
Whiskerz Good point about requiring the floor to be level. I did lay a level lengthwise parallel to the frame and got it close. I did not check level side to side though. Unbolting the cross-link bar does not shift the rear axle. With the car supported on stands, the bar does contact the rear axle diff. housing. As statd, I will re-check all measurements again. Positioning the plumb bob & marking all the points takes the most time.
Drove the car yesterday just to see how it handled. Tracked a little to the right on a level road. Getting measurable vibration thru the wheel & ass end at speeds above 45 MPH. It's up on jacks again. Remeasuring everything again tonight, including diagonally.
Thanks a lot! Really useful for a begginer mechanic enthusiast like me. Any advice regarding oil changes and brake repairs? ____________ Adam Worth pneu hiver alignement roue
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