So, you’re heading off to work in the crisp cool morning and you hear a new strange “ping” noise when engaging reverse. There are many reasons for a metallic noise when you do this, but let’s just explore some of the most likely causes.
At times, this noise is just driver error, such as engaging a stick shift gearbox in gear too quickly or without depressing the clutch enough. Other causes for example, can be gearbox, differential, giubo, or center support bearings. However, the high note of the “ping” sound usually points to the most likely mechanical source for this kind of noise, which is a worn universal joint. If this is the case, wind down your window and/or have someone listen next to the car as you switch between driving and reverse with the engine running. This is to confirm the noise is coming from under the body and front or rear of the car. If the ping is heard during this process it’s time to have a closer look.
Next, raise the car and stabilize with the appropriate jack stands on a flat concrete surface. With engine stopped, engage neutral and maneuver yourself under the vehicle. Now rotate the prop shaft(s) back and forth, quickly. On most cars these days there are one, two, or even more universal joints connecting the gearbox to the differential(s), although this will depend on the particular configuration of your car. For example, front wheel drive like most Volvo 850's found in the USA, all wheel drive, and rear wheel drive.
Watch and listen for tell tale signs of rust, wear, looseness, or noise at the universal joint(s) as you rotate the prop shaft(s). If any ping noise or looseness is apparent then it’s time to repair and replace. If you have two or more joints, the likelihood is that they are all close to replacement time, so it would be prudent to change them, too. However, sometimes the wear is very subtle and not noticeable with this technique, in which case further exploration of the problem will be needed.
In any case, the procedure for repair is not too difficult and I would rate this as about a two or three out of ten, on a difficulty scale. The most common tools needed will be, sockets, and spanners, for removal of the prop shaft, bench press, and/or a good vice for pressing out the universal joints. A gearbox oil plug that fits in the gearbox housing to prevent oil spillage and dirt entering the gearbox is highly recommended, as well as a torque wrench. Some paint or marker to ensure reassembly of prop shafts in exactly the same position will also be useful. Correctly reassembling is essential to maintain the correct balance of the shaft.
Some additional points to consider:
- Some vehicles have multiple piece prop-shafts or multiple prop-shafts. This can increase the difficulty of the repair.
- Some prop-shafts have universal joints that are machined in and cannot be replaced without highly specialized equipment, or perhaps even needing entire prop-shaft replacement.
- Be careful while handling and working on the prop shaft, as it is weighted for precise balance.
- Ensure you support the machined end of the prop-shaft when sliding from the rear of the gearbox, so that it doesn't drop and hit the ground.
- Ensure all four of your vehicle’s wheels are chocked securely.
- Changing your universal joints at this time could save big dollars later, such as, vibration problems and possible total transmission/differential failure.
I have heard that people have up-ended cars on failure of universal joints, however I have never seen this. So, it would be interesting to hear any stories about a catastrophic failure from a broken universal joint.
About The Author: Alan Power
Alan Power, is a father, grandfather, husband, and a DIY enthusiast. He lives down-under in Western Australia and he enjoys spending time with his family and working in his home workshop. Not to mention enjoying maintaining and driving his classic cars.
