Differential Repair
Also called differential noise
The differential lets the driven wheels turn at different speeds through a corner. It contains gears and bearings running in their own oil, and it wears when the oil is old, low or contaminated. Symptoms are a whine that changes with road speed, clunking when taking up drive, and oil leaking from the pinion or side seals. Repair means replacing worn bearings and seals and resetting the gear mesh. It will not cure noise coming from a wheel bearing or a tyre.
Signs you need this
- A whine or howl that rises with road speed, not engine speed
- Clunking when taking up drive or changing between forward and reverse
- Oil leaking from the rear of the gearbox or the axle casing
- A rumbling that changes when cornering left versus right
- Vibration that appears only under power
Not all of these have to be present, and one of them on its own can mean something else entirely. That is what the diagnosis is for.
What the job includes
- Road test to separate differential noise from wheel bearings and tyres
- Oil drained and inspected for metal content and smell
- Inspection of crown wheel and pinion tooth pattern and backlash
- Replacement of worn bearings, pinion and side seals
- Backlash and pinion preload set to specification on reassembly
- Refill with correct specification oil and a road test to confirm
How we do it
Confirm the noise source
A road test on and off power, and left and right turns, separates differential noise from wheel bearing and tyre noise.
Inspect the oil
The oil is drained and checked for metal, which indicates whether bearings or gear faces are breaking down.
Open and measure
Backlash, preload and the tooth contact pattern are measured, since these determine whether gears can be reused.
Replace and set
Worn bearings and seals are replaced, and backlash and preload are set to specification with shims.
Refill and road test
Correct oil is filled to level and a road test at the speed the noise occurred confirms the repair.
How we work
The same on every job, which is why we can write it down.
Diagnosis before quote
We find the fault first. A price given over the phone for a noise nobody has heard is a guess.
The price is agreed first
You approve the work and the cost before a spanner is picked up. Extra work means another call.
Parts you can check
We tell you whether a part is genuine, OEM, aftermarket or used, and what each one costs.
Old parts returned
Ask and we will hand back whatever we replaced. It is the simplest proof that the job was done.
Book differential repair
Fill this in and a person will call you back to confirm the time and the price. Only your name and one way to reach you are required.
You send this
Takes a minute. No payment, no obligation.
We call you
To confirm the car, the time and the location.
Tell us the car and the symptom
We will arrange a mechanic at your location, or a slot at the nearest workshop. No payment until the price is agreed.