Thursday, November 19, 2015

Can a tight front end fall apart, with no warning?


We like to think careful inspection will reveal front end problems before they become failures, but that's not always true.  Take a look at these images from a Land Rover Ninety (the predecessor to the Defender)




The photo above shows the ball joint that connects the pitman arm - the output of the steering box - with the drag like (the connection to the wheels.)  There is nothing visibly wrong, and the joint seems tight.  It would pass any quick inspection, like most state safety inspections.  Is it OK?  Not by a long shot, but we have to take it apart to see the real story:



When it's town down we see that water has been seeping into the joint for a long time.  Gradually the grease was displaced and the steel began to rust. The rust swelled the parts, making a worn joint seem tight as new.  Meanwhile, the swelling increased the pressure on the load bearing cup until it split.  When that happened this joint was on borrowed time.  One sharp jolt, and it would come apart.

If that were to happen at highway speed the result would be a nasty crash as the steering wheel disconnected from the road wheels.  Who know which way the car would veer?  Over the years I have seen a number of Land Rovers wrecked from sudden failure through causes like this.

But it's unfair to single out Land Rover.  Any car can fall victim to this.  The pitman arm joint on a old Rover is just particularly vulnerable because the open end of the ball joint cup faces up, so it can fill with water and hold it. And when it come apart - because the cup faces up - the joint falls completely apart.

Cups that face the other way can come apart and the car will still steer as long as the cup isn't knocked off.  Both designs are common. So how do you protect yourself, and your car?  In my opinion, it's not enough to shake the steering joints and check for play.  As these photos show, the joints can be tight as they get ready to snap.  The only sure thing is to replace them on a schedule, which I suggest could be:
- every 50-100,000 miles of use, or any time you buy a car more than 15 years old
- Ten years of service life
- Appearance of any visible rust around the boot, or damage to the rubber boots

And I suggest you change ALL joints at the same time, to be sure.  They see equal stress, after all.

While durability varies, every car has joints like this in the steering, and this advice is fairly universal.

Till next time,
John



(c) 2015 John Elder Robison
John Elder Robison is the general manager of J E Robison Service Company, celebrating 30 years of independent Land Rover, Rolls-Royce and Bentley restoration and repair in Springfield, Massachusetts.  John is a longtime technical consultant to the Land Rover, Rolls-Royce and Bentley clubs, and he’s owned and restored many fine British motorcars.  Find him online at www.robisonservice.com or in the real world at 413-785-1665

Reading this article will make you smarter, especially when it comes to car stuff.  So it's good for you.  But don't take that too far - printing and eating it will probably make you sick.



1 comment:

Marcus Yang said...

These are extremely useful information for anyone driving a car in the country. Will keep these points in mind while driving around in my Toyota, especially during the long drives.