Clicking Joint and a 90 km/h Shake: Two Complaints, One Cheap Request
A front-wheel-drive sedan, 78,000 km, comes in with two complaints: a rhythmic tak-tak-tak from the front right when turning left at walking speed, and a steering-wheel shake at 70–90 km/h. Tyre pressures are 32 and 33 psi. The front right outer CV boot is split and grease has been thrown onto the inner fender. On road test the clicking appears only in left turns and disappears when driving straight. With the wheel raised there is no bearing play and no roughness. The front right tyre shows scalloped wear on the inner shoulder; the other three tyres are even. Wheel alignment reads front toe +0.45° against a specification of +0.10° ± 0.10°, camber left −0.3° and right −1.1° against −0.5° ± 0.5°. Rim runout on the right front is 0.4 mm. The customer asks for 'just a wheel balancing' because it is cheaper.
1. Explain how you separate the two complaints, and name the most likely cause of each with the evidence you would quote.
Read the worked answer
Complaint 1 - clicking. The clicking appears only in left turns, at low speed, and disappears when straight. When the car turns left, weight transfers to the right and the right outer CV joint is the one under load and at a sharper angle. So the noise points to the right outer joint, and the split boot with thrown grease confirms it: the boot failed, grit and water entered, and the cage and balls are worn. The absence of bearing play and roughness on the raised wheel supports this and argues against a wheel bearing.
Complaint 2 - shake at 70–90 km/h. This is a wheel-speed-related vibration, not a joint noise that appears on turns. The evidence is the scalloped inner shoulder on the right front tyre, which points to a camber or toe problem rather than simple imbalance, and the alignment readings: toe +0.45° is 0.35° outside the ±0.10° band, and right camber −1.1° is outside −0.5° ± 0.5°. Rim runout at 0.4 mm is not the leading suspect but should be checked against the wheel specification.
Conclusion. These are two separate faults. Doing one repair will leave the other complaint alive.
2. Give the repair order you would follow and justify the sequence, including what you would tell the customer about the 'just balance it' request.
Read the worked answer
Sequence:
- Replace the right outer CV joint and boot, or the complete shaft if the joint is badly worn; clean the thrown grease from the inner fender and check the inner joint and the other boot at the same time.
- Inspect the right front strut, knuckle and lower arm for impact damage, because camber at −1.1° is outside spec and usually means a bent component rather than a wear item. Replace before aligning.
- Balance both front wheels and check rim and tyre runout on a balancer; the scalloped tyre may need replacement, since a worn tyre will not balance properly and will keep the shake.
- Set alignment only after the suspension parts are final, then road-test.
Why this order: aligning a car with a bent strut wastes the alignment and the customer's money, and balancing a worn tyre does the same. Alignment after suspension work is the only way the numbers hold.
Telling the customer: 'just balancing' would mask the vibration at best and leave a clicking joint that can fail completely and strand the car. Say that plainly, with the price of each stage, and let the customer decide the order. If they still decline the joint, record the advice on the job card and note the safety risk - a seized or broken CV joint can stop the vehicle.
3. If only one repair could be approved this month, which would you recommend and what would you write on the job card?
Read the worked answer
Recommend the CV joint. A worn outer joint can fail suddenly, and a broken shaft or seized joint can leave the car immobile or damage the transmission casing. The vibration is uncomfortable and accelerates tyre wear, but it is far less likely to cause a breakdown in the next few weeks.
However, the two are not equal in cost of delay. Leaving the shake and the scalloped tyre will destroy a tyre, and a badly worn tyre is its own safety issue. So the honest recommendation is: joint now, and if the shake is severe, at least balance and swap the worn tyre to the rear or replace it, with alignment as soon as funds allow.
On the job card, write: the measured click condition, the split boot and thrown grease, the alignment readings with specification, the camber finding and the suspected bent strut, the tyre condition, what was recommended, what the customer approved, what was declined, and a line stating that the customer was advised of the safety implications of delaying the CV joint repair. Add the date, time and the name of the person who gave the instruction. That record protects both the customer and the workshop if the joint fails later.