REAR HUB TWIN BEARING CONVERSION

Please read these instructions, and understand them fully, before attempting this conversion. It is recommended that these units be installed by a person with the appropriate qualifications/experience.

• Raise the vehicle and support safely before working on the rear axle.
• Remove the road wheel and brake drum.
• Remove the axle (aka: half shaft), fold back the tab washer, undo the hub nuts (remember – LH side is LH thread) and then using a suitable puller, remove the old hubs.
• Carefully press out the wheel studs from the old hub and retain.
• Disconnect the brake fluid line at the wheel cylinder and plug the cylinder to prevent contamination from dirt etc. Plug the brake line to prevent excess fluid loss.
• Detach the hand brake rods and remove the brake shoes, springs, brake adjuster wedges and screws.
• Undo the brake backing plate retaining bolts and nuts and remove the backing plate.
• Remove and discard the slinger flange from the backing plate. It is easily removed from the rear with a cold chisel applied to the spot welds, or alternatively you can drill out the welds. Ensure the area the slinger is removed from is flat, smooth and free from burrs, bits of spot weld etc and thoroughly clean the backing plate.
• Carefully examine the axle housing. These are now up to 60+ years old and often have pitting, scoring etc. where the original bearing and oil seal have been running. The new hub will move the oil seal further inwards towards the backing plate flange, and it is critical that the new seal runs on a smooth, undamaged section of the shaft or it will almost certainly wear, leak oil and contaminate the brake shoes. It is STRONGLY recommended to fit the appropriate “Speedi Sleeve” to provide a new, smooth surface in this area to prevent this occurring. These are readily obtained at bearing supply stores; the one required has an ID of 1.75” and is 0.375” wide, its’ part/reference number for SKF is 99172. This is the ONLY size that will allow the inner bearing to locate correctly on the shaft, allowing the outer bearing to be pressed fully home against the shaft shoulder, whilst giving the new oil seal a new, smooth surface to run on. Press the sleeve fully home against the axle flange.
• The hubs come fully assembled and the bearings are tightly fitted, DO NOT ATTEMPT TO REMOVE THE BEARINGS OR THE OIL SEAL, or the seal will be damaged/distorted and will cause oil leaks.
• Press the wheel studs into the new hub. Ensure that the wheel nuts are not going to “bottom out “on the studs before the road wheel is fully tightened against the drum, measure, and modify the studs/nuts, as necessary. This is particularly important if wider wheels and/or spacers have been used on vehicles that are used in competition. Longer studs may be required to ensure solid contact.
• Install the modified backing plate and ensure that its 4 retaining bolts are fitted with the bolt head through the backing plate and new nyloc nuts at the back against the diff housing.
• Lightly lubricate the oil seal lip and fit the new hubs, taking care not to distort the rear oil seal or the outer bearing sealing ring. If the outer bearing is a loose fit on the axle shaft, apply some “Loctite 243” to ensure the race does not spin on the shaft. The hub is correctly fitted when the outer sealed bearing is hard up against the stepped shoulder of the axle housing, retained with a new hub nut and locking washer, and tightened fully, using the appropriate socket/tool. Bend over the lock tab to a flat on the hex nut. Remember to use a LEFT-HAND THREAD nut on the left-hand axle casing.
• Refit the axle over the wheel studs onto the hub using appropriate gasket/sealant and the new rubber “O” ring. Retain with the countersunk grub screw and ensure the axle is fully flush with the hub face.
• Refit the fluid lines, brake adjuster screws and wedges, hand brake levers and rods, brake shoes and springs. The brake shoe return springs may need to be re-positioned to avoid fouling on the hub, and this may require new holes to be drilled in the shoes. Ensure that the same spring spacing is retained. (Re-positioning the springs may not be necessary if the larger 8” brakes have been fitted from such vehicles as Morris Major, Austin Lancer, Wolseley 1500, Riley 1.5.) Refit the brake drums and retain with the two countersunk grub screws. Adjust the brakes and hand brake as required, and bleed the brakes.
• It is also advisable to check that the axle casing is not distorted or twisted out of alignment. This can happen if the vehicle has been involved in a heavy rear-end/side-on collision in the past. If the casing is not square to the hub, additional high stresses are placed on the axle, the new bearings and the differential side gears, leading to accelerated wear and potential failure of all these components.
• Check the differential/casing seal and pinion seal for oil leaks. The old oil should be drained, the casing thoroughly cleaned out, and re-filled with new gear oil; 85/95 – 145 grade is recommended. Inspect and clean the breather plug on the top of the axle casing. Ensure the oil used is compatible with any LSD that may be fitted. The differential itself also needs to be in good serviceable condition, worn gear teeth and bearings will shed fine metal particles into the oil, with corresponding reduction in service life to ANY new hub bearings fitted, single or double. A magnetic drain plug is highly recommended.
• Refit the road wheels ensuring the wheel nuts solidly secure the wheel.

These hubs are made here in Australia, to exacting tolerances, on the latest CAD/CNC equipment, from 1045 grade steel, NOT from some cheap, second rate source in Asia. The bearings and seals are maintenance free, giving many years of service PROVIDED that the hubs have been correctly installed, and sufficient correct grade gear oil is retained within the axle casing. Insufficient oil will quickly damage differential gears and lead to diff/hub bearing failure and this is particularly so if the vehicle is used in competition.

HOW TO ORDER

All orders are to be made through SPRITE PARTS, 2 Parklea Close, Dural, 2158. SPRITE PARTS can be contacted on 0414 789 263, or