Rods Ends

[openwheeler37]

How often are you changing the rod ends on your car? Only as they loosen? Every so many races?

Story behind my question;

Several years ago I had a front lower control arm rod end (unknown brand / quality) shear off while racing. This $25 part cost $$$$ in damage as it made me run off track and into a tire wall causing the car to roll. Since then I have been changing all the rod ends every other year - all front rod ends one year and all the rears the next year .. and so on. Iv'e been running FK rod ends for years due to their availability to me and price. Well my vendor and rod end sponsor is getting out of the FK line. Im looking at converting to Aurora rod ends but they are close to 2x the price. Any ideas / suggestions how long these can be ran before changing out?

[Rick Kirchner]

My car was an experiment for Aurora. I's covered with a mix of their products. It has taken 10 years for their stuff to show much wear. Disclaimer, I only run about 4 races/year on average and I run mostly vintage and don't bash the curbs.

I had a few FKs in the mix - those have shown a much higher rate of wear with the liner extruding out of the ball socket.

IMHO even the low end of the Aurora line is better than the rest of the stuff out there. I think what is important is to put high-quality part in specific locations and even life them if the situation warrants.

I've found the ends in the rear legs of front a-arms and the front legs of rear a-arms take the most beating. on some cars there's a large rod -end mounted in single shear on the top front, and the top rear (93 VD and earlier). The rear ones must be lifed or expect breakage at the thread/arm interface.

Shock eye uni-balls also seem to have a relatively short life, along with cheap pushrod ends.

Call John McCrory at Aurora and he'll set you up! Great guy, great products.

[Ralph Z.]

I recently changed out all the rod ends on my 1968 Alexis FF. Cars in those days used industrial rod ends and they very heavy duty compared to today's modern rods. Mine will probably last much longer than rod ends on more modern cars. I owned a '94 and '98 Van Diemen and the rods for these cars were half the diameter of the Alexis.

[ghickman]

A modern formula car such as an F1000 that is being driven at its limit say 6-8 race weekends per year should have all critical rod ends replaced yearly. I doubt that most competitors do this with that level of frequency.

This is really more about using the best quality rod ends that are sized appropriately.

Most formula cars you can replace all of them for less than $800. In the big picture not a huge expenditure.

I too have had a rod end fail at speed, luckily I didn't hit anything or anybody else. This is why I replace every season its cheap insurance and it makes the suspension setup very predictable since all the ends are tight.

[JerryH]

Use Aurora......and use only 4130 or 4340 rod ends. What is called alloy steel is mild steel and not nearly strong enough for rod ends that are highly loaded. Mild steel can be used where stresses are low enough....or.if you calculate your stresses and pick a size that will take the load.

The correct aurora part numbers begin with AM or AB if thread and hole is same size.......XAM or XAB if thread is larger than the hole. These are 4130 body. Plenty strong enough. Specify teflon lined by adding T to the part number (AM5-T is 5/16 with teflon lining). AM is right hand thread. AB is left had thread.

HXAM if you need high angulaity versions.

There is no need to go to the more expensive :PRXM. It is polished and usually 4340 body. Looks cool but not needed.

There are also different levels of life span on teflon linings......depending on the fabric the teflon is imbedded in. The lining is rated cycles of movement. You can find it on Auroras website......,along with the strength and fatique life of the various rod ends.

One of the problems with PRXM and some Mil Spec rod ends is the linings last longer than the fatique life of the rod end body.They are built for applications where they are replaced on a schedule. The rod end will often break before the lining gets loose....,.so you have no warning.

The mild steel rod ends have the same problem if teflon lined......and they need to be or they are loose to begin with or get that way very quickly.

The advantage of the AM and XAM rod ends is the teflon lining life is just short of the fatique life of the body.....so when it get loose you replace it and avoid fatique failures. Now it can still break if it exceeds its design strength or the thread is loaded in bending ( common for many years for top front ball joints). In that case use the PRXM and replace every year.

I use AM and XAM on the JDRs and have never had one break.......but I never design anything where the theraded portion is loaded in bending. we use spherical bearings for the outer ball joints.

Hope this helps.

Jerry Hodges
JDR Race Cars
636-399-7060

[openwheeler37]

Use Aurora......and use only 4130 or 4340 rod ends. What is called alloy steel is mild steel and not nearly strong enough for rod ends that are highly loaded. Mild steel can be used where stresses are low enough....or.if you calculate your stresses and pick a size that will take the load.

The correct aurora part numbers begin with AM or AB if thread and hole is same size.......XAM or XAB if thread is larger than the hole. These are 4130 body. Plenty strong enough. Specify teflon lined by adding T to the part number (AM5-T is 5/16 with teflon lining). AM is right hand thread. AB is left had thread.

HXAM if you need high angulaity versions.

There is no need to go to the more expensive :PRXM. It is polished and usually 4340 body. Looks cool but not needed.

There are also different levels of life span on teflon linings......depending on the fabric the teflon is imbedded in. The lining is rated cycles of movement. You can find it on Auroras website......,along with the strength and fatique life of the various rod ends.

One of the problems with PRXM and some Mil Spec rod ends is the linings last longer than the fatique life of the rod end body.They are built for applications where they are replaced on a schedule. The rod end will often break before the lining gets loose....,.so you have no warning.

The mild steel rod ends have the same problem if teflon lined......and they need to be or they are loose to begin with or get that way very quickly.

The advantage of the AM and XAM rod ends is the teflon lining life is just short of the fatique life of the body.....so when it get loose you replace it and avoid fatique failures. Now it can still break if it exceeds its design strength or the thread is loaded in bending ( common for many years for top front ball joints). In that case use the PRXM and replace every year.

I use AM and XAM on the JDRs and have never had one break.......but I never design anything where the theraded portion is loaded in bending. we use spherical bearings for the outer ball joints.

Hope this helps.

Jerry Hodges
JDR Race Cars
636-399-7060

Thank you, great info!