A car whose rear wheels will not turn is one of the few faults that cannot be driven to the garage and cannot be guessed at. It has a short list of possible causes, and getting to the right one quickly is what separates a rebuild from a bill for parts that were never the problem. This is how the job went on a Jaguar in the St Helens workshop, photographed on the ramp.
What it came in with
It did not move. The rear wheels would not turn, not stiff, not noisy, locked, so the car came to us on the recovery truck rather than under its own power. On a rear-wheel-drive Jaguar that narrows things down to the back axle straight away, but it does not tell you which part of it, and the parts range from a seized caliper that costs an afternoon to a differential that costs a great deal more. So the first job is not to reach for a parts catalogue. It is to find out which one you are dealing with.
Ruling out the cheap answers first
Three things lock rear wheels on a car like this, and two of them are cheap. With the car on the ramp and the wheels off the ground, each rear wheel is turned by hand with the handbrake off.
- A seized brake. A stuck caliper piston or a corroded slider clamps the pad on the disc, and on cars with an electronic parking brake a failed motor does the same. It locks one wheel, and freeing the caliper frees the wheel. Both rear brakes on this car released properly.
- A collapsed wheel bearing. A bearing that has broken up will jam a hub, again on one side, usually after weeks of rumbling that got louder through bends. The hubs turned freely once the driveshafts were out, so the bearings were not the lock.
- The driveline. With both wheels locked together and the brakes cleared, the lock is behind the hubs: driveshaft, differential or propshaft. The quick test is at the front of the diff, where the propshaft bolts on.
The propshaft joint at the rear differential flange. With the wheels off the ground this should turn by hand. On this car it would not move, which put the fault inside the diff.What was found: a seized differential
The propshaft would not turn the diff, and the diff would not turn the wheels. A differential seizes for one reason underneath all the others: metal that should be running on a film of oil ends up running on metal. Sometimes the oil has leaked away through a tired pinion seal over months. Sometimes a bearing has broken up and its debris has jammed the gears. Either way the crown wheel, pinion and carrier bearings run hot, pick up and lock. Once it is that far gone there is no adjusting it back into life; the unit has to come out and come apart.
That is what happened here. The rear axle was stripped: driveshafts out of the hubs, hub carriers off, the differential out of the subframe and onto the bench.
Rear hub carrier with the driveshaft removed. The open bore in the centre is where the hub bearing sits; the driveshaft splines into it from the diff side.
The same carrier from below, next to the air suspension strut. The strut bellows are checked for splits while everything is apart.The rebuild, and why the hub was done at the same time
The differential was rebuilt rather than swapped for a used unit. Stripped, cleaned out, the damaged bearings and seals replaced, the gear set checked for pitting, then the pinion preload and crown-wheel backlash set up again on the bench before it went back into the subframe with fresh oil of the grade Jaguar specifies. A used diff of unknown history would have been cheaper on the day and a gamble on the rest of the year.
The rear hub was rebuilt in the same visit for a simple reason: getting to the differential means pulling the driveshaft out of the hub carrier, and once the carrier is off, most of the labour to replace the hub bearing has already been spent. Doing it then costs the bearing. Doing it in six months costs the bearing plus the strip-down all over again. That is the question we ask on every car repair at Boundary Road: what else is worth doing while it is apart, and what can honestly wait.
Rear suspension and hub stripped for the rebuild.
The rear subframe with the driveshaft out and the differential housing below it, ready to come out.Why Jaguar diffs get to this point. Jaguar owner forums and independent Jaguar specialists report the same pattern on the XF, XJ and S-Type: a whine from the back between roughly 45 and 70 mph that appears on the throttle and goes quiet on the overrun, often with a pinion seal that has been weeping for a while. The early XF up to 2009 is known for its factory-fill differential oil breaking down and wearing the pinion. A weeping seal that is topped up and ignored is how a whine turns into the car in these photos.
How it left
It arrived on a truck and left on its own wheels. Rebuilt differential, rebuilt rear hub, road tested, and back to the customer driving perfectly, with 12 months’ warranty on the parts. The price was agreed before the strip-down started, not after it finished, and the customer knew at each stage what had been found and what it changed.
If the back of your car is whining, or has stopped turning
A whine that changes with speed and throttle is the diff asking for attention while it is still a bearing-and-seal job. Locked wheels are the end of that road. Either way, do not have it driven to us. We recovered in cars that cannot move: send the registration on WhatsApp or call 01744 808586, tell us what it is doing, and we will say whether it is safe to move or needs bringing in on a truck. Our Jaguar specialist page covers the faults we see most on these cars, and diagnostics explains how a noise is traced before any part is ordered.
Rear-end noise, or a wheel that will not turn? Send us a message.
Tell us what the car is doing and we will tell you what it points to before you book. Independent Jaguar specialists on Boundary Road, St Helens.
Frequently asked questions
One of three things: a seized brake, a collapsed wheel bearing or a locked differential. A brake or a bearing locks one wheel; a diff usually locks both. Do not try to drive or tow it on its wheels, because dragging a locked axle wrecks whatever is still good. Call 01744 808586, tell us which wheels are stuck, and we will arrange recovery and check the cheap causes first on the ramp, the way we did on the Jaguar in this job.
By ruling the brakes and bearings out first rather than guessing. With the car on the ramp the handbrake was released and each rear wheel turned by hand: the calipers freed, so the brakes were not holding it. The propshaft was then turned at the differential flange and would not move, which puts the lock inside the diff. That order matters, because it is the difference between a brake repair and a rebuild. Our diagnostics page explains the approach.
Almost always because it has run low on oil or the oil has broken down, so the bearings and gear teeth run hot and start to pick up on each other. A failed pinion or carrier bearing can also collapse and jam the gears, and a weeping pinion seal will empty the diff over months without any warning light. On this Jaguar the unit had seized solid, which is why the rear axle was stripped rather than treated as a bearing job. Our Jaguar specialist page covers the Jaguar faults we see most.
Often it can be rebuilt, which is what was done here: the unit is stripped, the damaged bearings and seals replaced, any pitted gears dealt with, the housing cleaned out and the preload and backlash set up again before it goes back in with fresh oil. A replacement unit is the answer when the casing is cracked or the crown wheel is beyond saving. We tell you which it is before any car repair starts and price it up front. Call 01744 808586 if yours is making a noise.
Because getting to the differential means pulling the driveshaft out of the rear hub, and once the hub is apart most of the labour to replace the bearing has already been spent. A hub bearing that is even slightly tired is done then rather than a few months later on a second visit with a second bill. That is the thinking behind every car repair at Boundary Road: what else is worth doing while it is apart, and what can honestly wait.
Only as far as the garage, and only while it is a faint whine with no other symptoms. Once it is clunking or dragging, stop: a diff that seizes on the move can lock a rear wheel, which is a control problem at any speed, and driving on it turns a rebuild into a replacement. Ring 01744 808586 first and describe the noise. If we think it needs recovery we will say so rather than have you risk it. Our gearbox and driveline repairs page covers propshaft and driveshaft faults too.
A wheel bearing hum usually changes when you load the car through a bend, getting louder turning one way and quieter the other, and it stays roughly the same whether you are on or off the throttle. A differential whine changes with throttle: louder on drive, different on overrun, often with a clunk on take-up. We confirm it on the ramp by turning the wheels and the propshaft by hand and listening with the car unloaded, which is part of our diagnostics work before any part is ordered.
Mostly what is found inside once it is stripped: a bearing kit and seals is one job, pitted gears or a damaged crown wheel is another, and a cracked casing means a replacement unit. Labour depends on the car, because on some the diff comes out with the subframe and on others it drops on its own. You get the figure before we start, not after we finish, and it can be spread with Payment Assist over 3, 4 or 6 months at 0% interest. Call 01744 808586 for a price on your car.
Usually two to three working days including the strip, the parts and the rebuild, longer if a part has to be ordered for an older or rarer model. We tell you the expected time when we book it in and update you if anything changes once it is apart. If the car cannot move, recovery is arranged first so it is here when the parts are; ask on 01744 808586 and we will sort both in one call.
Yes, and the wrong grade is one of the reasons diffs fail early. Most rear axles take a hypoid gear oil of a specific viscosity, and limited-slip differentials need an oil with a friction modifier or they chatter and wear. We fill to the manufacturer specification on every rebuild and on every service where the diff oil is due. If you are not sure when yours was last changed, ask when you book.
A noise on its own is not an MOT failure, because the tester does not drive the car under load, but the things that come with a failing diff often are: an oil leak dripping onto the road, a worn propshaft joint with play in it, or a hub bearing with movement at the wheel. If your MOT is due and the back end is noisy, have it looked at first so the test does not turn into a fail and a retest.
12 months on parts, on this job and on every car repair at Boundary Road. The rebuild is checked on a road test before the car goes back, and if anything on the job is not right in that time you bring it back to us, not to a dealer. Book by phone on 01744 808586, on WhatsApp with your registration, or online, and ask for the workshop if you want to talk it through first.