A mighty bang in the rear area of a series rover whilst driving, followed instantly by complete loss of drive is most likely a snapped rear half shaft. The half shafts transfer power from the differential to the hubs of the wheels by means of splines around each end (10 splines in general for most original rover axles). Almost certainly the break will be right next to the splined sleeve of the side gears in the differential, and probably on the short (right hand side) half shaft as it has less length to flex and absorb shock. The original series 2/a half shafts are infamous for breaking, due to the design and low number of the splines it is only a matter of time until shock or fatigue ends the adventure suddenly.
In this scenario there is a way to get home: if possible, remove the broken half shaft and the snapped off bit so it doesn’t cause differential trouble, and for on-road travel remove the good half shaft as well, bolt the drive flanges back on with the dust covers in place and drive home gently in 4wd high (with the red knob forward for high range and the yellow knob depressed for 4wd). This will act as a 2wd front wheel drive but should be done a little more slowly and gently so as not to over stress the front drive line, which was designed to work together with the rear rather than alone.
The procedure for half shaft removal is to slide off the dust cover from the centre of the wheel, undo the 6 bolts holding the flange to the hub, and slide out the half shaft and flange assembly, no jacking required and wheels stay mounted in place. The flange may need a bit of minimal prying around the edges to get started as the broken end may be twisted slightly in the diff sleeve. To remove only the half shaft and replace the flanges for front wheel driving it is better to detach the flange from the half shaft before unbolting the 6 flange bolts. This is accomplished by removing the cotter pin, then the large castellated nut, then unbolting the flange and separating the two, and finally remounting the flange and placing the dust cap back in place.
It may be possible to carefully fish the snapped-off end of the half shaft out with a strong magnet mounted securely on a rod, the main thing is not to push or drop it into the differential. If it is tightly jammed in place another method is to leave the magnet attached to it, then remove the other side half shaft and tap the broken bit out into the axle tube across the diff using a steel rod narrow enough to slide past the spindle which sits in the centre of the diff. A 1/2″ x 1/8″ or 3/16″ flat bar with the corners rounded off on one side might do it, ensure that the pressure is on the broken stub and not the spindle or gears before tapping carefully on the end with a hammer, shouldn’t take a huge amount of force to release. Clean and inspect both broken faces to see if there might be more pieces missing, large chunks of metal in the diff could mean trouble in the long run so draining and changing out the oil may be wise.
If possible replace the broken half shaft with an uprated version machined for better stress management. Also the paper gaskets on the flanges (and possibly the centre felt washer) will likely need replacing and a check of the oil level in the differential would be a final step in getting back on the road. Remember that anytime a half shaft is out the parking brake is not acting on the rear wheels, so engage 4wd and use wheel chocks. Thanks to 3 Brothers Classic Rovers for getting a replacement out to the island in less than 48 hours, back on the road!
the right hand side is usually the first to break due to the shorter length of shaft which has less stress resistance and shock absorbing abilitythe dust cover that slips over the flange and castellated shaft nut can be removed by gentle pryingremoving the dust cover reveals the castellated nut and cotter pin on the end of the half shaftafter removing the 6 bolts that hold the flange to the hubafter prying loose the flangesliding the half shaft out with flange still mounted to itthe broken end of the right hand half shaftdriveline torque before the break has twisted the splines diagonally, the lower cracks are in the usual break location, right at the stress pointlooking into the right hand side axle tube to see the snapped off bit of shaft still lodged inside the side gear of the differentialremoving the left hand side half shaft and flange as a unit, appears to be a 1970s or 80s replacement, from Australia and marked “DUFOR AS 569”looking into the left hand side axle tube to see the near side gear then the spindle (diagonal rod) crossing the centre of the differential and behind it the snapped off bit of shaft blocking the light from the other sidethe good and broken half shafts compared, the left hand seems to be a later replacement with a slightly different stress-relieving design at the shoulder, unlike the originalsforming a tool to press the broken bit out, because of the spindle there is a very narrow space to slide from the left side through the diff to reach the right hand side geara narrow round or flat bar would probably work, the shape in this case is flat inside and the outside at a radius similar to the half shafts, putting the most material possible through the openingsliding carefully around the spindle and tapping with a small hammer to loosen the broken bit on the opposite side, marking depths on the rod will help ensure no damage is done to the spindle or gearsmoving to the right side: a pickup magnet pulls the piece the rest of the way out, note that it has flipped while dragging through the axle tube, the magnet preferring the smooth face to the brokenlight is now visible right through the axle tube, the spindle visible crossing the centre of the diffa look at the break, stress risers at each spline propagating the cracksthe amount of twisting force becomes evident when the straight splines are put next to their counterparts, check for any large missing pieces that may require draining or disassembly of the diffoutside end cryptically marked “415”, is likely made from some sort of tool steel, possibly 4140/4340while the half shafts are off and the wheels chocked, the prop shaft can be rotated by hand to check if there are any issues inside the diff, feeling and listening for grinding or bindingto remove the half shaft from the drive flange it is best to undo the large castellated nut while the flange bolts are still in place (not shown) or put the shaft in a vise after the cotter pin is removed a wrench is used to loosen the castellated nutthe half shaft will then separate from the flangethe wheel bearings visible between the hub and axle tube nut, flanges must be remounted to keep dirt and water out of this areaflange remounted without the half shaft, rear wheel will now free wheel with no connection to the drive line, note felt washer visible at centrereplacing the dust cover keeps dirt and moisture out until the replacement half shaft arrivesless than 48 hours later a package arrived from 3 Brothers Classic Rovers with a replacement half shaft and some new paper gasketsoriginal shaft vs replacementback to the hub, first removing the dust cap and the 6 flange boltsremoving the old paper gasket and wiping the flange and hub surfaces cleaninstalling the felt washer, steel washer, and castellated nuta fresh split/cotter pin and the assembly is ready to install, a bit of oil on the splines before they go into the diffthe bolts hold the new paper gasket in place for installationtightening evenly in a star pattern, pulling the flange into placenew half shaft installed and ready for the dust coverreinstalling the left side dufor half shaft with the new paper gasket, first wiping both surfaces cleanpaper gasket in place on the flange before inserting boltsinterestingly, the two lower holes in the hub have been partially filled and then tapped to accept coarse thread bolts at some point in the past when the proper ones were unavailable, perhaps the original threads are still inside past the filled arealeft two are the replacements (not ideal for multiple reasons), right two are the original typealigning and tightening, for now the two odd bolts will stay, at some point they should probably be drilled and re tapped back to the proper threadall tightened up, will recheck the bolts after some milesif the dust cover is loose a slight tap right near the rim can increase the tension…now back on the road!
