Heim Joint failure
- Thread starter RPM
- Start date
old round fart
Well-Known Member
I had a girl run a stop sign as I was going by and she contacted my left rear wheel and rotated the rear end out of the car and it sat down on the oil pan and slid to a stop. The rear axle housing was bent and 2 5/8 heim ends were broken at the jam nuts. The balls were not pulled out of the socket.
So the part itself under normal use did not fail.
Mike
Well-Known Member
Ron, I used to keep a box of trashed 3/4 chrome moly heims at the counter, to remind racers to check them after each race. In this area, we had a lot of guys running NHRA's old G/MP class, which was a 13.5 lb. class, so it was nothing to see guys running Camaros tipping the scales at 3700+ lbs. Put a 278 CID motor with a 40 lb. flywheel in a car that heavy, zing it to the stratosphere and then try to rotate the earth when the Tree went green. Dana 60 ring and pinions were generally good for 8-12 passes before the teeth started laying over. We had to use struts and braces to keep axle tubes straight and to keep 9" Ford center sections from deforming enough to break ring gears. I don't know if you remember Bob's 67 Corvette F/G car, but I watched him switch feet at Columbus one year and the car moved about 2 inches off the starting line. He had a Richmond style quick change under that car and it exploded the center section, the side bells and the axle tubes.
That old junk box had joints that were bent at the base of the socket, joints that had deformed the socket to a point where the ball would no longer budge and joints that were broken in the threads at the jam nut. But you have to remember, you can give a racer a rubber hammer, a chrome moly heim, put him in a sandbox and he will find a way to break the heim. :nod:
As for a heim in a street rod application, I've never seen one fail.
That old junk box had joints that were bent at the base of the socket, joints that had deformed the socket to a point where the ball would no longer budge and joints that were broken in the threads at the jam nut. But you have to remember, you can give a racer a rubber hammer, a chrome moly heim, put him in a sandbox and he will find a way to break the heim. :nod:
As for a heim in a street rod application, I've never seen one fail.
I have abused these 7075 aluminum bodied rod ends for many years in sprint car racing. never a failure except crash damage. Most of the bucket plans I have access to spec. out 5/8 x 5/8 rod ends, way overkill to me. I have dozens of these in 5/8 x 1/2 and plan on using them. A good grade 1/2" bolt is seriously strong even in single shear.
old round fart
Well-Known Member
Differen T
Member
I have over 20 years in the bearing industry. The type of bearing being discussed is a spherical plain bearing. As with any other type of rolling element bearing, there are different levels of quality available, depending on material used and construction design. Heim is a brand name usually associated with very good quality, but they manufacture several different types and strength depends on the design if I remember correctly.
Basically this type of bearing is designed to work best in tension and compression at low rotational speeds of the center section. Some misalignment can be tolerated, usually about 15 degrees from the bearing center line. Beyond that the potential for center section failure increases rapidly. They are available with teflon linings, seals to help prevent dirt from entering the race and grease fittings. The bearings with grease fittings have less strength than the same bearing without a grease fitting. One of the dangers of lower quality bearings is the method of manufacture allows the ball to be pulled from the race at much lower misalignment loadings.
As with everything else available in our country there are also spherical plain bearings from foreign countries that are not as strong as the USA manufactured Heim bearings.
You can find the the acceptable loadings for bearings on the web sites of reputable manufacturers.
Al
Basically this type of bearing is designed to work best in tension and compression at low rotational speeds of the center section. Some misalignment can be tolerated, usually about 15 degrees from the bearing center line. Beyond that the potential for center section failure increases rapidly. They are available with teflon linings, seals to help prevent dirt from entering the race and grease fittings. The bearings with grease fittings have less strength than the same bearing without a grease fitting. One of the dangers of lower quality bearings is the method of manufacture allows the ball to be pulled from the race at much lower misalignment loadings.
As with everything else available in our country there are also spherical plain bearings from foreign countries that are not as strong as the USA manufactured Heim bearings.
You can find the the acceptable loadings for bearings on the web sites of reputable manufacturers.
Al
