While hanging out at Circle City Hot Rods recently, we noticed a Model A roadster which had been brought in to have some seriously bent ladder bars replaced. With no braces between the upper and lower tubes, the lower tubes had bent, as had the clevises at the axle brackets. Though Jimmy White and his crew had already fabricated a replacement pair, with two braces for added strength, we thought it'd be cool to show you how to make a set of ladder bars, and followed along the next time the guys at CCHR fabbed a pair of their regular ladder bars, which they fit to most of their builds.
They have a purpose-built jig for this job, but it's nothing that couldn't be replicated easily, and it ensures that every ladder bar made is identical. This is important even if you only intend to build one pair for yourself. We also photographed a pair of front hairpins going together, using a temporary jig, which not only shows how simple such a jig needs to be, but also highlights how to fabricate different styles of bars, as the hairpins have curved ends and a Ford tie rod end to mount them to the chassis, though a urethane bush could be used as a substitute for the tie rod in a rear suspension application.
It should be noted before we start that 7/8-inch diameter, 0.156-inch wall DOM tubing was used for both the ladder bars and hairpins. Don't use solid bar or regular steel tube with threaded bung ends, and especially not cheap steel pipe, unless you want your handiwork to fail catastrophically. Also, don't be tempted to use bolts any smaller in diameter than inch for the front mounts on the ladder bars. These two bolts are all that are holding your rear axle in after all, so ensure they're of sufficient diameter and grade. This isn't the place to use cheap hardware store bolts!
The inspiration for this story...
The inspiration for this story was this Model A roadster that came into Circle City Hot Rods for repair. With no brace between the upper and lower sections of the ladder bars, they'd bent and required replacing. Note even the clevis had bent.
CCHR uses this simple jig...
CCHR uses this simple jig in which they manufacture ladder bars used on many of the cars they build. It's heavy as the base is -inch steel plate, but it's simple and could easily be replicated at home. The "bridge" at the right end is actually a stop for when the jig is mounted on the milling machine.
The first step after cutting...
The first step after cutting the 7/8-inch DOM tube to length is to drill and tap one end of each to 5/8-18 to accept the clevises. This is done on the lathe to ensure perfectly straight threads.
Allen head bolts locate the...
Allen head bolts locate the tubing in the jig at their rearmost ends (Note that the top stop is removable because when the ladder bar is flipped and re-jigged to weld the other side, the longer top tube would otherwise not fit in the jig). Vise-Grips welded to the base of the jig both front and rear ensure nothing's going to move during the welding process. A third Vise-Grip clamps the center brace in place.
With the tubing clamped in...
With the tubing clamped in place, the jig is mounted on the bed of the milling machine and a 1 5/8-inch diameter cutter makes light work of notching the tube ends for the front bushing. The "bridge" previously mentioned is a stop, ensuring the cutter doesn't go any further than required. If you're making these at home you'll likely not have a milling machine, so will have to notch the tubing with a grinder. Take your time and ensure as snug a fit as possible between the tubing and the bushing.
The bushing outer tubing was...
The bushing outer tubing was placed in the milled notch and the tool to the left was inserted through the tubing and bolted to the jig to hold it in place during welding.
If you're making your own...
If you're making your own ladder bars the style of the central brace is entirely up to you. You can opt for a single or double brace, multi-hole plates or even diagonal tubes for a `60s race car vibe.
The 5/8-18 inch clevises and...
The 5/8-18 inch clevises and jam nuts used at the rear end are available from any number of rod parts suppliers, such as Speedway Motors, So-Cal Speed Shop, or Pete & Jakes. They have a -inch hole although 3/8-inch hole versions are used for front hairpins. The slots in the clevises measure 3/8 inch. CCHR fabricate their own axle brackets from 3/8-inch steel though they're available from the same parts suppliers as the clevises.
Whether you use a cross spring...
Whether you use a cross spring as shown here, or coilovers, the best method of mounting the ladder bars is a triangulated arrangement such as in this '32 chassis, offering the minimum amount of bind in the bushings throughout suspension movement.
With the tubing clamped in...
With the tubing clamped in a vise, Matt uses a rotary sander in a die grinder to form curves in the ends of the tubing
Just as the central braces...
Just as the central braces can be your own design, not all ladder bars need to have straight bars. The CCHR crew also builds versions that have curved ends more in the style of a front hairpin, though we've shown their usual style being made. Here's how a pair of hairpins, with those curved ends, are fabricated, using a temporary jig. A length of angle iron and a section of tube were welded to the table as shown. Note the tubing which will become the hairpin is marked to correspond with a mark on the tube former (arrows), ensuring each section of the hairpin will end up at its required length. It's then tack welded to the angle to keep it in place.
With the caster angle set,...
With the caster angle set, a temporary jig using lengths of angle iron was tack welded to the table.
The short "bullet" end sections...
The short "bullet" end sections of the hairpins were machined from solid steel bar, with a point on one end and an 11/16-18 inch thread in the other to accept Ford tie rod ends. The tubes and end were clamped in the temporary jig making sure the curves of the upper and lower tubes perfectly matched on the "bullet," before welding commenced.
Using a Ford tie rod end to...
Using a Ford tie rod end to mount to a tab on a '32 chassis, the hairpins look traditional, and the caster angle is custom set for this chassis, at this ride height, with the tie rod mounting just under the chassis. Making your own parts means you can build these factors in.