My almost completed '31 "A" roadster is a Brookville body on a P&J '32 repro frame. Dropped beam axle in front w/adj. wishbones, Panhard bar, 9 inch rear, also on adj. wishbones, no Panhard. As I did the Mock up, and again on reassembly after painting, I squared stuff up best I could using a tape measure placed where ever I felt I could get a fairly accurate measurement. But now that I'm down in the final stages of completion, I'd like to get it as close as possible as soon as the car is drivable and licensed to drive. We have several pretty good alignment shops around, but they are all oriented to late model stuff, as is their equipment, and Grump Ed tells me that most of the stuff used to re-align after collision repair works only on late model stuff where they have pre-determined measuring points to work with. If I can get front and rear axles to be square with frame and equidistant centered, I stand a much better chance for having a good driving car. If I can figure out some good, accurate measuring points, I can do it with plumb bobs and a tape measure, But where/how to pick up those measuring points? Or should I ask around for a shop with the old style equipment and the knowledge to use it? Dave
I've gotten one reply, by email (much appreciated), nothing on the forum. Just trying to pick up accurate measuring points. On the rear, I can hang plumb bobs to come down from the axle flange, if they're close in diameter. Center of chassis fairly easy to determine and hang plumb bobs, then chalk line. But where in hell can I find a machined surface for measurements? An axle forging isn't accurate except where the king pin and spring perch bolt holes are drilled. Don't really want to pull front axle assembly apart all the way to removing king pins. Any ideas? My theory is that the front axle needs to be square with frame,as well as the rear, before you worry about front wheel alignment. Dave
You might be overthinking it. If you can establish a center line (centers of the front and rear crossmembers) and then take measurements from significant points, ends of crossmembers, centers of axles - and you can get all the dimensions the same side to side and diagonally, then you are good to go. Off the top of my head I'd say anything within 1/8" is ok for a street driven car. If the wheelbase is 3" out side to side you have a problem. If you can get stuff better than 1/8" then great. You don't need to be measuring off machined surfaces to get it good enough for normal road use. Just my opinion, others may differ. Mart. Mart.
Virtually all frame equipment is designed to be universal for uni-body and fully framed vehicles. Even Toyota trucks have frames. The laser style measuring equipment has "targets" that basically sit in holes on the body or frame magnetically, Then measurements are taken with a giant bar code scanner looking thing, Yes that is the technical term. So while they might not have the spec sheet for a Model A frame, they can still measure everything and see if there are any discrepancies, out of square, diamonded, ect. In my opinion, though, You can be very accurate with a plumb bob, chalk and a flat floor. It all comes down to who is doing the measurements. Modern frame measuring equipment is designed to be idiot proof, but then they came out with new and improved idiots.
measure your frame at transmission...divide by 2...put a dot on transmission at this diatance from one side of frame ...measure from a point on the left and right of the front axle to this dot...adjust until they are the same...repeat for rear axle using same dot... helps if car is on a lift or suspended in some fashion...d32
I just pulled a string line down the centre of the frame. Measured the width at front and rear and centred the line. From this line you can measure the rest of the frame and see if anything is tweaked [side to side] I also measured a 3.4.5 [right angle triangle] off of this to check for square. You can determine if your axles are square and centred this way. Along with this use a level front and rear [side to side] to see if there is any twist. Hope this is helpful. Peter
Put the car on stands with the wheels off. Wrap the plum boob string around a wheel stud, always off the rear of the stud. With the level on the top two studs, mark the floor. Measure front to back on each side, and criss cross. Adjust as necessary. Set the toe to 1/16 for radials, or 1/8 to 1/4 for bias plys.
I worked in the trade for many years before a career change. Ideally I would have squared frame up right at the start to ensure everything was true before any body or suspension was fitted. Like building a house, bad foundations and everything that follows won't be right. Firstly check the diagonals to ensure it was square and then run a centre line to see if rail reference points are equidistant from centre line. A chassis jig would be ideal however we all improvise from time to time I did a friends 33 frame and found that the diagonals were correct however the passenger frame rail was not true and slightly flat. I had to wedge in a large 4"x4" in between rails to force them apart and into the right position so cross braces could be welded in to hold everything square so as boxing plates and cross members could be fabricated. In your case I'd look for corresponding holes on the underside of each rail;front, rear and centre. Drop a plumb bob to the ground and mark with chalk. Roll the car away and then measure up and check to ensure length and diagonals are correct. Draw a centre line and your diagonals should cross the centre line at the same spot. Rails could be deformed and off square despite having front and rear cross members there. If you have access to a trammel bar use this as all you need to do is hold the tapered end in one hole and adjust until it drops into the other hole. Swap it over to the other side and measure again. My bar is approx. 12' long with adjustable ends.
The guys here have it right, use plunb bobs from common points and mark your floor and measure twice.
I use a spirit level and a really simple trammel bar for most all of my measuring on chassis jobs. The shop I did my time at had a really cool set of Blackhawk self centreing 'gunsight 'gauges which also worked very well hanging down from various points on the chassis.
How did I forget the spirit level, I use it as a matter of course (Habit). Definitely essential, front middle and back and anywhere else for that matter. Chassis could have a twist or low/high spot in rails.
It's simple to do. To find the center of the frame, just lay a board, piece of angle iron, string, etc. across the frame from one side to the other. Measure the length of your board from where it touches the frame rails (on the inside or outside of the frame); then find the halfway point. That is the middle of the frame. Drop a plumb bob down to the floor and mark it OR mark the center point of the board. Do that at the front and rear. You now have the center of the frame located at the front and rear. You can measure out to the sides and run parallel lines on the floor or clamp pieces of angle iron, tubing etc to your frame for lining everything up.
It doesn't matter if your board that runs from frame rail to frame rail is squared with the frame. It can run at angle. Half way is half way no matter if your board is perpendicular with the frame rails or not.
Since you already have the suspension hung where the frame is located as far as center etc dosn't matter. What you need to do is get the 4 wheels in the right relationship to each other. Do not raise the chassis and hang plumbbobs off it and make a bunch of marks on the floor - i do this for a living and you are past the stage where that info is useful, that info is needed during construction and you need the suspension fully loaded (on the ground, gas in the tank and somebody in the drivers seat). Place some angle iron (2X2 if you have it, taller the better) alongside each tire - a 8' stick at each corner would make it easy. Now you can see how each tire will track and the relationship of front to rear. I'd square the rear to the chassis (just make sure the rear tire angle iron points forward and parallel); align one front tire & angle iron to the rear tire and angle iron, then align the front tires to each other and give your self a 1/16 toein by measuring tread rib to tread rib and make sure steering wheel is centered. The problem you will likely encounter is rear tire toe-in/out. If you welded on the rear housing etc it will likely warp the tube and the tires may not be true to each other. You'll have the angle iron to measure and it won't lie, best you can do is split the different to set the rear but then you'll have to get a theoretical alignment line to set one of the front tires (ie, figure where the rear tire should be).
Dirtyoldman, This in response to your PM inquiry about checking your car. My position on this is similar to other posts. I rely on a plumb bob and chalk line method. It will tell you the relationship of your axles to each other and the frame. I like to use corresponding stock reference points if possible and then to have a repeatable position I mark the 4 tire sidewalls to a perpendicular reference point on the floor so that I can reposition the car in the exact spot if necessary. Start out on a smooth surface floor, jack the vehicle up on equal height jack stands to allow you to slide underneath. This positions you at ride even thought the tires don't touch the ground. The first step is to drop a plumb bob down from the intersection of the front edge of the front cross member and the frame rail at each side rail and mark its position on the ground. ( As a note if you use different color chalks it will make the job easier as you can differentiate between frame and axle points.) Repeat the same procedure at the forward junction of the rear cross member. After droping lines down for chassis reference points repeate the same procedure using a different color chalk for the axle. Using the junction of the wishbone and perch pin as a reference point drop a line from each side to the floor and mark for the front end and use a corresponding point on the rear axle to determine the rear axle location. If you want to check the axle position laterally drop a line down from the 12 o'clock position of each tire and mark for side to side reference. After determining the marking on the floor, Take a chalk line and produce a grid with a chalk line right and left to determine the longitudinal grid mark and a corresponding right to left marking to determine the lateral marking, your pattern should look like a railroad track and ties. At this time you now determine the central axis of the vehicle by measuring and determining the mid point of the lateral axle measurements. Mark the mid point of the lateral axis chalk line both on the front and on the rear lateral and using these two points snap a chalk line to determine the central axis of the car. Now with a carpenter square pick a point about mid point of the central line and make a right angle marking to both the right and left side of the central line. This line is used to reference the square of the axles to the center line of the vehicle and should extend outward of the line used for the longitudinal grid line. Again a different color chalk line is great. At this time recheck all your points. Your first check is to determine if the front axle is square to the frame, this is done by taking a tape measure and measuring from the cental right angle reference line to the points at the perch pin junction in a line that is parrallel to the central axis line. If you measure off square your measurement will be compromised and you will get an incorrect reading. The measurements should be the same and close enough by 1/8th" isnt close enough. Repeat the same procedure in this case to the rear axle and recording the measurements and comparing to square rear ward. Depending on your measurements you may have to adjust the position of the axles by any threaded adjustment you have engineered in your chassis. You can do this by dropping a plump bob to view the change positioning. Some people lower and roll the vehicle out of the way to do this but I would rather crawl around the chassis as it make it easier to recheck the adjustment position. After checking fore and aft adjustments you can then use the center line to address the side to side positioning of the axles by measuring out ward from the center line to the plum bob point dropped from the tires. This will indicate if you have your axles centered side to side and if you have to make any lateral adjustment. This is just a quick way to address alignment issues that can be done with no special equipment and with the help of some friends and in your own garage. You can expand on this by going into further detail as necessary. This should get you going. DS
Thx to all that replied, much appreciated. Mart with the first post and Dick Spadaro with the last post picked up on my main concern, that being accurate points from which to measue, and another post refined my idea of using the axle flange in the rear,as leveling the 2 top lug studs will put another dead center on the bottom. I did some tape measure work on the frame itself before painting it and assembling to the body and it's straight and not in a "diamond". The rear axle housing is straight now, was "crooked as a dog's dick" when I got it. We used a line up bar thru the housing with appropriate doughnut pieces in a dummy carrier and the axle bearing bores, cut the housing and rewelded back straight. I also was figuring on using the juncture of front axle and perch bolts as a reference as Dick suggested to use. Now I gotta go to Wally World and find some colored chalk! Dave
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