A universal joint, or u-joint, is a cross-shaped casting with short, even-length arms and cups with needle bearings fitted onto the ends of each arm. It is packed with heavy grease for lubrication and often has a grease fitting to allow regular servicing. The bearing cups press into machined holes in the driveshaft and component flanges and are usually held in place by clips.
The job of a universal joint is to help transfer power from the engine to the wheels. The most common application is on a rear-wheel drive vehicle, which uses a driveshaft to connect the transmission to the differential. The heights and angles of both vary from vehicle to vehicle and, again, on how much weight is being carried and how much power is being applied. Because of the varying angles, a rigid connection between the two isn’t practical, and a u-joint is used to provide flexibility.
On a simple one-piece driveshaft, there is a u-joint at the front where it connects to the transmission, and a u-joint at the back where it connects to the differential. On a two-piece driveshaft, another u-joint is added in the middle, along with a carrier bearing that holds the centre of the driveshaft steady in the vehicle frame.
Other applications are on a four-wheel-drive vehicle, which has a second driveshaft using u-joints to transfer power from a transfer case to the front differential. Replacement is basically the same in either case; the driveshaft is removed from the vehicle, the holding clips are removed from the u-joint, and the u-joint cups are knocked out of the flanges they are pressed into. Installation is a little tricky, having a particular order in which it needs to be done, and some care is required that the needle bearings stay in place during assembly. But it’s usually quick to work, and not difficult for a mechanic who has done a few and understands the procedure.
Cost of U-Joint Replacement
On average, it costs about £110 to replace a universal joint on most vehicles. The labour is roughly the same on most, and parts don’t vary a great deal between different vehicles.
For some specific examples using £70 (workshop) to £100 (factory) an hour as a labour rate:
- On a 2000 Ford F150, the labour time to replace a rear u-joint is about an hour, which includes removing the driveshaft, replacing the u-joint, and re-installing the driveshaft. A new factory u-joint costs about £25. A heavy duty (solid core) OEM u-joint costs about £35. An aftermarket u-joint costs about £15. So, the range of costs starts from around £95 to £105, depending on the parts used. Other trucks, domestic and imported, are essentially equivalent. In the Ford example above, with four-wheel drive, the front driveshaft would follow the same labour costs and parts options if it needed a u-joint replacement. An option that can be taken once the driveshaft is out is to replace all the u-joints rather than just the failed one. The labour time to replace another u-joint on a driveshaft that’s already out on the workbench is.3 of an hour. So, to do the second u-joint on a driveshaft adds around £40 to £60 to the job, again depending on the parts used. On a two-piece driveshaft, there is an additional centre u-joint, which would cost an additional £40 to £60 to replace as well.
- On a 2000 Jeep Cherokee with a 4.0-litre engine and four-wheel drive, replacing a rear u-joint with factory parts would cost around £100 to £120. There is, however, a difference in the front driveshaft in that it uses a double cardan joint at the transfer case. This is a special u-joint assembly that employs two u-joints in a carrier with a stabilising device between them, essentially for strength and smooth power transmission. If a u-joint in a double cardan assembly needs replacement, then both joints are replaced, and the procedure is a little different and more time-consuming, taking a little over an hour. So, to replace u-joints in the double cardan joint in the front driveshaft, the estimate would be 1.6 hours of labour plus about £50 for a pair of universal joints. The total cost would then come to around £120. There is also a conventional u-joint at the front side of the front driveshaft, which would add about £40 to replace, if desired.
- On a 2004 Ram 2500 four-wheel drive truck, the front and rear driveshaft u-joints are all conventional and conform to the first estimate mentioned above. However, this truck also uses u-joints at the front wheels to transmit power to the hubs. These are usually called front-drive axle u-joints. If a front drive axle u-joint needs replacing, the labour is 2.3 hours, involving removing the front brakes and front hub to pull the axle and allow the u-joint to be replaced on the bench. A factory u-joint costs about £35, and an aftermarket u-joint costs about £15, making the job about £200 using factory parts or about £176 using aftermarket parts.
PRO TIP – Most factory-installed u-joints don’t come with grease fittings any longer, but replacement u-joints almost always do. As the ability to maintain the grease in the u-joint is the main factor in its longevity, it is worth making sure that the replacement u-joint has a grease fitting.
Signs That a Universal Joint Needs Replacement
As the main job of a u-joint is to allow the smooth transfer of power, one of the main signs that one needs to be replaced is if there is roughness or oscillation felt under load. Another sign is if there is a clunk when starting out or when going from forward motion to reverse.
In practice, a vehicle is jacked up on lifts, and its u-joints are inspected visually first. They will seldom wear out if their lubricating grease is in good shape, and if the grease has exhausted, they will often rust. This tends to shed a fine orange powder, so if there is a fine orange powder spreading out from the cup of a u-joint, the odds are high that it needs replaced. They can also be checked for end-play or looseness at each cup of each u-joint, either manually or with a pry bar.
If the u-joints have grease fittings, they should be serviced with each oil change. It’s less common nowadays, so it’s best to ask for it to be done or checked on.
Roughness or shaking when accelerating. In worse cases, there is a clunk when going from forward to reverse.
On most vehicles, it takes about an hour – a little over a half-hour to remove and reinstall the driveshaft, and about a quarter of an hour to replace a u-joint.