Rear Wheel Bearings
Someone wrote to ask -- I've been hearing some noise coming out of my rear passenger side wheel. It doesn't quite squeal but sort of a grinding noise and it doesn't sound like a brake problem.
Rob responded -- I can think of two possibilities here - 1. The wheel bearing is worn out; 2. The brake drum is not tight and is moving slightly causing the brake shoes to rub a little.
- Worn wheel bearing -- I don't know if your Bug has the IRS (double joint) axle, or the older swing axle (both types were used in various parts of the world in 1970, and I don't know what country you are in). With the car jacked up and in neutral, and the brake drum removed, you may be able to feel the axle turning smoothly or roughly and get an idea if the bearing is worn out. After removing the bearing cover plate (inside the brake assembly) you might also be able to see enough of the ball bearings themselves to see if they are shiny bright or pitted/cracked (on the swing axles models).
If your's has the IRS suspension, then changing the wheel bearing should be a fairly straight forward process. These bearings are sealed and use grease. You have to take care that when reassembling them that the wheel is correctly aligned (you can adjust the toe-in on the rear wheels of beetles), so take care when taking it apart and mark the hub assembly against the mounting plates so you can get it lined up properly afterwards.
If you have a swing axle, the bearings are harder to get out as you need an "inside" puller to grab the inside of the outer bearing race (after removing the cover plate inside the brake assembly of course). The only other way to get this off is to remove the whole axle and axle-tube from the car and tap the gearbox end of the axle so it pushes the bearing out of the outer end (using the axle itself to push the bearing out). The bearings are not really tight in the tube - just nothing to grab on to to help remove them. Once again, when taking the brake assembly off the spring plate - make sure you mark them so you can re-align them on re-assembly. There is a "v" notch in the top of the brake hub assembly to help you with this - just make a mark on the spring plate next to it.
These bearings use oil from the gearbox which sloshes up the axle tubes and sits behind the bearing. Low oil in the gearbox can therefore cause dry wheel bearings (the gearbox must be filled with 80w90 or 85w90 Hypoid Gear Oil until it runs out the filler plug in the left side of the gearbox).
If you do top up the gearbox oil, make sure the hypoid oil you use is GL4 standard, not the newer GL5 (look for the specifications on the pack). GL5 will cause corrosion of the bronze synchromesh rings inside the gearbox.
- Drum not tight -- If the axle nut is not done up hard (217 ft-lbs is correct) it can allow the whole brake drum to move a little on the axle and you will hear it rubbing on the brake shoes or the backing plate -- probably mostly in corners. So check that the axle nuts are tightened correctly. If you don't have a tool for it yet, you will need a 36mm socket (1-7/8" SAE will work too) and a 3/4" drive bar (the 1/2" bars will break too easily). It's useful to have a piece of steel tube about 4-feet long to put over the drive bar as a "cheater bar" to help get the force you need. (See our Rear Brake Drum Removal procedure for more information, including safety precautions).
Question continued -- As of late, I've been hearing something like a wobbling noise, as if a tire were unbalanced, at high speed (over 30mph).
Rob responded -- If the sound is coming from the same wheel, it could be the wheel moving because of either 1. or 2. above. If it's from another wheel, it could be 1. tyre out of balance, 2. tyre out or round, 3 rim out of round (damaged). I would try to fix the bearing/drum problem (if that's what it is) first and then see if the tyre noise disappears. If it doesn't - take the car to a tyre place and have the tyre and wheel checked out. You don't want to be driving a dangerous car for the sake of a few dollars. (See our procedure for resolving a Tire "Out-of-Round" problem.)
If the bearings fail and a wheel falls off, it will cost you a LOT more than getting it fixed before it breaks.
Question -- I'm replacing the rear wheel bearings on my '73 Super Bettle. I have everything apart except the transaxle side bearing. I was told I need to remove the circlip in order to remove the inner bearing. Your web article doesn't mention the circlip. Do I drive the bearing outward with a drift ( transaxle to wheel ) and don't bother with the circlip, or does it remove wheel to transaxle direction, and I need to remove the circlip? If I need to remove the circlip any tips? I tried briefly with a
cheap circlip removal tool with no luck.
Rob responded -- If I have this right, you are trying to renew the ball and roller bearings which make up the greased wheel bearings around the stub axle which goes through the brake assembly on IRS bugs (ball bearing on the transaxle side and roller bearing on the wheel side).
I'm working from two-year old memories here, but I THINK there is a small indent in the rim of the slot which holds the circlip in place. You need to move the clip around in it's slot so one end of it is across the indent, and then you can get a thin screw driver through the indent and UNDER the end of the clip, and gently pry that end up clear of the slot. While holding that end up clear of the slot you use a second thin screw driver to work around under the circlip lifting a little more and levering it slightly outwards so it's sitting partly on the rim of the slot, until you've worked about 1/2 way round an it's then possible to grab the "loose" end with some pliers and with a gently twist and pull (the twist is into the middle - trying to make the circlip smaller) it will pop free. Take is easy so you don't break the circlip.
* * * *