HotRod_MD

SELECTING ROD ENDS

Story & Photos By Jim Clark (The Hot Rod MD)

 

Suspension kits and linkage for carbs or shifters are usually supplied with the appropriate rods ends for the application.  However, if you are modifying the suspension or creating your own linkage you will have to choose the correct rod end for that application.  This would seem like a simple task but the consequences of choosing the wrong one can be life threatening.  Failure of a rod end in linkage may only leave the vehicle stuck in gear or the throttle inoperative, but failure in a suspension component could send the vehicle out of control.

The first choice to make is whether you want to use a standard OEM style tie rod end or a spherical rod end.
The standard OEM style rod ends are available in steel and stainless steel construction; the stainless version in a sealed (not need greasing) configuration.  They have a threaded shank and a tapered stud on the pivoting portion of the joint.  These are usually used for tie rod, drag link and split wishbone applications.

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The standard OEM style rod ends are available in steel and stainless steel construction; the stainless version in a sealed (not need greasing) configuration.  They have a threaded shank and a tapered stud on the pivoting portion of the joint.  These are usually used for tie rod, drag link and split wishbone applications.

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Ford style tie rod end and steering arm with a tapered hole.

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This diagram shows how to measure for a tie rod or drag link.

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Speedway Weld Bungs
Weld bungs for splitting wishbones.  Choose from RH or LH thread.
Thread sizes available include: 5/8"-18, 11/16"-18, and 3/4"-16.
These weld bungs are 1” O.D. where they slide into the steel 1" I.D. tubing

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Cutting and changing the angle at the front of this split wishbone to accommodate an increase in kingpin angle shortened it.  This necessitated adding some length to the other end at the frame attachment point.

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To add length to the split wishbone a Speedway weld-on bung was modified by cutting off the stepped end and beveling the edges for welding.  A rod end was installed to provide alignment and keep the threads continuous from the bung to the original wishbone insert.

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The rear radius rods are subjected to heavier loads so 3/4”-16 OEM style rod ends are used there

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Once the bung was welded to the wishbone additional welding was done to taper the end.  An 11/16”-18 OEM style rod end is used for the front wishbone mount.

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This weld-on mount from Speedway makes attachment to the frame simple.

Weld-on Shock Eye for Tie Rod Shocks,

Triangular Weld-on 5/8" diameter tapered hole Required for mounting early Ford 1937-48 tie rod ends, 7 taper.
 This shock mount is:
2-1/8" long at the base and 1/2” thick
Overall height with rounded top is 1-9/16" Center of shock hole is 7/8" from base.
7 tapered hole in the middle (5/8" diameter on big side, 9/16" on small side

Speedway also offers the split wishbone kit with spherical rod ends.
Speedway Split Wishbone Kit With Spherical Rod Ends
This kit includes 11/16"-18 weld-in bungs for the wishbones; jam nuts and 11/16"-18 heim joint rod ends.  Heim accepts a 5/8" bolt.  Cutting & welding required.

The second choice when selecting a rod end is the spherical rod end.
Spherical rod ends, also referred to as the Heim Joint named after the inventor Lewis Heim who founded the Heim Bearing Company, can be used for these heavy-duty applications but are also used in linkages where the load is much lighter.  They are available in a wide variety of sizes and construction, so you must choose the one designed for the application you intend to use it for.  This can be quite a challenge because no one wants to be liable for anything that happens to you if the part they recommend is not proper for the application.
The sources that I used for spherical rod ends are placed in two categories:
1-Those primarily serving the aircraft and military / aerospace and industrial markets.  This includes: Aurora Bearing Company and RBC Bearings / Heim.

2-Those who specialize in serving the automotive market.  This includes: QA1, Speedway and DMP Fasteners / FK Rod Ends.

All of these sources were very helpful in supplying technical information and making recommendations for which rod end that I should use for a given application.  However, they must deny any liability for anything that happens as a result of the use of the rod ends because they have no control over the way that you use them.

My roadster project uses both types of rod ends.  The split wishbones utilize the standard OEM style rod ends.  The tie rod, drag link Panhard bars and shock links all use heavy-duty spherical rod ends.  I could have used the spherical rod ends for the split wishbones but the OEM style tie rod ends were part of the original PSI kit.

The original spherical rod ends for the tie rod, drag link and Panhard bars were all installed in the ‘70s, so they were replaced with new stainless heavy-duty rod ends because spherical rod ends have improved considerably in both strength and quality since then.

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