Method: Front wheel bearing replacement. Sept 29, 2016 10:54:52 GMT
Post by Penguin45 on Sept 29, 2016 10:54:52 GMT
ADO17 Wheel Bearing Replacement.
This is a reasonably involved job requiring some order and method to do correctly. It took me about three hours from start to finish and has restored silent running to the Red Dog.
Insert ½” block of wood between the top suspension arm and the lower bump stop. Ensure handbrake is applied, and first gear selected. Chocking the rear wheels is good garage practice. Crack the wheel nuts. Raise car with a jack and support it with an axle stand on the front chassis member. Remove wheel.
You can now access the swivel hub assembly. Undo the two small dust cover bolts, then the two bolts for the brake calliper. I used a stout cable tie to hang it out of the way without stressing the flexi hose.
Remove the drive shaft nut split pin, nut, washer and taper cone.
Pull off the driving flange and brake disc and separate them. The manual illustrates the most fantastical pulling machine to draw it off. Personally I have found that several light taps with a copper faced mallet is all that’s ever required to free it.
Undo the last dust cover screw and set it to one side.
You now have the bare swivel hub. Release the track rod end ball joint and the two hub ball joints. I have used the scissor tool as it’s less likely to damage the rubber dust boots.
Draw the axle/hub assembly towards you slightly and gently knock the shaft back through the hub. When released, you will find that the inboard bearing has stayed at the bottom of the shaft. It is a push fit and will slide off easily using a gear puller, or with some light levering behind. Bear in mind that the surface immediately behind the bearing is the running surface for the seal, so be careful!
Bearings and seals.
Lever out the oil seals at each end of the housing, then remove the outboard bearing and race. Knock out the inner races from the hub, using a drift and hammer. Work the races down evenly by tapping all around the perimeter of the exposed edge. Big blows are not required! A steady amount of force will keep it running out true. If you have (or have access to) an hydraulic press that’s an even better option, although make sure that the mandrels will drive on the edges of the new race when fitting and not on the running surfaces. Marks equal noise…..
Clean the hub, drive shaft and driving flange thoroughly, removing all traces of old grease and dirt.
Drive home the new races into the swivel hub. Proceed in a similar fashion to above – nice and steady. The race will give a nice “clack” noise as it bottoms into place. Note that the bearings are matched to each race – don’t mix them up.
Pack the new bearings with LM grease. This is not a smear of grease around the outside; this is working grease into the rollers through the ends of the bearing until it squeezes out and will take you a little while. Push the in-board bearing down the drive shaft and slide on the distance tube. A smear of grease will hold it on the shaft.
Next, fit the in-board seal to the hub. A large socket is the ideal tool to push it home with. Fit the out-board bearing into the hub, followed by the out-board seal. Note that bearing won’t fit through the seal. Pack the gap between the bearing and the seal with grease.
This is where things need to be done correctly if you wish a decent service life from the new bearings. Push the hub back onto the drive shaft, being careful not to snag the new oil seals. Locate the top and bottom ball joints and secure. Use the axle nut and big washer to ensure the hub is fully home on the shaft. Do not tighten it! Before refitting the brake disc and driving flange, the latter needs to be checked for wear across the inboard surface. It’s a critical component and wear on that surface will prevent the bearings from being tightened fully. The picture shows a straight edge across the rear face. Feeler gauges can be inserted to measure any wear. In this instance the surface was perfect.
Third picture shows a flange with a groove worn into the face. Depth gauge indicates the wear at .012". It is worth noting that a small amount of wear could be taken up by using shims from the ball joints as they are exactly the right bore. The face could also be machined flat, but bear in mind that the driving flange will be shallower as a result, so shimming will be almost inevitable.
So, bolt the disc to the flange and fit to the splines on the drive shaft. Fit the thick washer and the nut and tighten up to 150ft/lb. You will need to fit the wheel and drop the car down for this process. Lift the car again and give the wheel a few spins. Down again, nut off, split cone into place, thick washer and tighten the nut to 150ft/lb. Check where the alignment is for the hole for the split pin and tighten the nut just enough to line up the next hole.
Raise the car and remove the wheel. You will need a dial gauge on a magnetic base if you are going to do this properly. If you haven’t got one, they are available for £20 - £25 from a myriad of eBay sellers and are perfectly adequate for these two tasks.
End float. To check the end float on the bearings, mount the dial gauge onto a solid fixed base and adjust so that the needle is resting against the face of the driving flange. Pull the flange towards you and note the reading on the dial. Acceptable limits are 0 - .004” (0.10mm) of movement. Be very wary if the reading is actually zero. If the bearings have been over tightened, the reading will show as zero, but the bearings will be being crushed and a short service life will follow. For the record, the bearings shown in this article registered 0.11mm. As mentioned above, some excess end float can be shimmed out using ball joint shims, although major discrepancies will need further investigation. In the absence of a dial gauge, the wheel can be refitted and used as a lever. You should be able to detect fractional play, but obviously with no degree of accuracy.
Run out. As above, but align the needle to run against the outer part of the brake disc face. Revolve the hub and note the variation. .008” (0.2mm) is the maximum acceptable. I refitted the hub in several different locations on the splines to try and get a best reading, but mine read 0.41mm. In this instance it may be down to the occasion when the brakes seized on and everything got very hot indeed. Certainly nothing can be felt back through the brake pedal.
If everything is satisfactory, fit the split pin; refit the brake calliper and dust cover, the wheel and trim and go for a drive.
Patience is a major part of this particular job, especially the checking at the end. The Haynes manual notes that short bearing life can be expected if the measurements taken during reassembly are not satisfactory.
My thanks to David for extra input, thoughts and suggestions in the preparation of this article.