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SELECTING ROD ENDS              page 2

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

 

Rod Ends MD-12
Rod Ends MD-11

The original rod ends that were installed on my roadster in the ‘70s had a lubrication hole in the shank and grease fitting in the side of the body, which makes them about 20% weaker than a rod end without them

Rod Ends MD-13

This XM series spherical rod end from QA1 was used to replace the original rod ends in the tie rod, drag link and rear Panhard bar.

Rod Ends MD-14
Rod Ends MD-15

These light-duty spherical rod ends were supplied with the Lokar shifter kit so I didn’t need to make any changes there.

However, I was in the process of installing the front lever shocks so I needed to select rod ends to link them to the front suspension.  To make that choice I had to learn more about rod ends and how to select the right ones for this application
 

First I went to the various web sites for the companies that sell rod ends and read their technical data, FAQs and articles that have been written about their products.  Then I reviewed the offerings in their catalogs; noting the recommendations included with the item.  Once I was familiar with what possible items would serve my purpose, I called their tech help / order assistance line and asked for their recommendations.  Here is some of what I learned.

Spherical Rod Ends:
Most rod ends are manufactured utilizing one of two construction styles.  They are of the two or three-piece type.  Both types feature the advantages of metal-to- metal contact between bearing components (PTFE to metal interface may also be incorporated when specified).

The standard two-piece style consists of a body and precision ground oil impregnated sintered steel ball.  This type of construction allows the rod end body to carry a greater radial static load and the oil-impregnated ball is self-lubricating under normal operating conditions.  This unit also offers greater misalignment capabilities.  A variety of material and plating options for the component parts in this series are available.  Any cold- formable steel in stainless and alloy steel categories can be specified for the body, and all harden able alloys such as 52100 and 440 C stainless steel may be employed as options for the ball component.

The three-piece style consists of a body, ball, and race.  This type of unit, offering fully swaged bearing construction, features the advantages of maximum spherical conformity between the ball and race.  It also offers flexibility in that many different types of materials can be interchanged in each component part, providing combinations that can be tailored to meet just about any application requirement.

Lubrication:
Grease

Grease is oil that has synthetic filler, thickener, metallic soap, or a combination of the three added to prevent oil migration from the lubrication site.  The operative properties of grease depend mostly on the base oil.  Metal on metal spherical bearings are supplied with lubrication grooves and holes to provide the ability for lubrication.  Metal on metal rod ends can be furnished with grease fittings along with the lubrication grooves and holes to allow for lubrication.  These bearings could gall without frequent lubrication and a reversing load to keep the grease from being pushed out.  In applications with one direction loading, the grease will tend to be squeezed out of the bearing area.  These types of applications should be evaluated for the use of dry film or Teflon.

Teflon Liners
PTFE (bonded coated PTFE liner) lined races are available in all three-piece bearing units and all spherical bearings.  The steel race has a self-lubricating liner; a PTFE impregnated woven fabric, chemically bonded to the inner diameter of the race.
 

Rod Ends MD-16

Bearing Misalignment
 A rod end or spherical bearing’s ability to misalign is measured by the degree of angle the ball can accommodate without interference.  The angle of misalignment in a rod end is limited by the ball width and head diameter.  If added misalignment is necessary, this can be accomplished by utilizing spacers between the mounting surface and ball face.

Rod Ends MD-17

Speedway Cone Spacers
Cone spacers for obtaining maximum clearance on rod ends.  1" O.D. Choose aluminum or steel with 1/2" or 5/8" hole
.

Tech Tip: When assembling a tube, each heim end adds approximately 1-1/2" to the overall length (assuming the heim is screwed into the tube half way.)  If you have a heim on each end of the tube, the tube will be approximately three inches longer overall.

Assembly Tip: To ease assembly, be sure to run a tap or die through the threads on chrome-plated fasteners and apply an anti-seize compound to prevent galling of the threads.

 

Answers to Frequently Asked Questions at Aurora Bearing:
Q
—What is the minimum thread engagement required to support the advertised load ratings in the Aurora Bearing Company catalog?
A—The minimum thread engagement is 1.5 times the major thread diameter unless otherwise stated.

Q—What maintenance do I need to perform on my rod ends and spherical bearings to keep them operating properly?
A—For metal-to-metal rod ends and spherical bearings, a thin layer of grease applied occasionally to ball outside diameter will assist in extending the life of these products.  Rod ends and spherical bearings that are Teflon lined are self-lubricating and are designed to be maintenance free and should not be lubricated.

Q—What is axial play (endplay)?
A—The measurement of the total range of movement of the ball inside the insert/body in the axial direction or the clearance measured along the axis of the ball bore.

Q—What is radial play?
A—The measurement of the total range of movement of the ball inside the insert/body in the radial direction or the clearance measured along the axis of the shank of the male or female body.

 

Creating links for the lever shocks
I could have used 3/8-inch size rod ends when creating the lever shock links, as they were strong enough for this application.  However, when I looked at the specification charts included with the item in the catalog I found that the center-to-center measurement that I needed when combining a male and female rod end for the link was only available with a 7/16-inch combination

 

Rod Ends MD-18
Rod Ends MD-19

First the shock arms had to be modified by cutting off the pivot ball.

A link was needed to connect the arm on the lever shock to the front suspension

Rod Ends MD-20

After removing the pivot ball, 7/16” holes were drilled in the arms to accommodate bolting of the rod ends

Shock mounting tabs were cut from metal plate, drilled and bolted together so they could be ground and filed to their final shape

Rod Ends MD-21

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