One of the persistent problems of the Metro, since we picked it up, is a pulsation in the brake pedal and braking force. I suspected the front rotors but a quick check for warping came up clear. I didn’t bother checking the drums in the back - I simply ended up with a set of new drums after noticing how cheap they were and needing to add a few dollars to an online parts order to get free shipping. On they go!
The rear of the car goes up on the jack, and the rear wheels come off. To free the drums we need to remove the little dust caps covering the axle nut. A sharp wood chisel works well to push the cap free.
We are then presented with the staked nut, which is a nut with a special sleeve attached that is dented inwards to help hold things in place.
This one has been a bit mangled. A bit of prying with a flat blade screwdriver gets enough of the metal out of the way that it can be turned off with a 23mm socket. Engage the handbrake to keep the drum from turning.
With the nut off, the drum should come straight off the spindle. Sometimes it needs a little coaxing (by foul language and/or use of a BFH), but these ones came off drama-free. That is, after I remembered to disengage the handbrake.
There are some important items that are attached to the drum - namely the wheel studs and the wheel bearings. The new drums don’t come with these attached, so we need to remove them from the old drums. Let’s start with the studs.
But first, a quick note about the order of things. Perhaps you’re someone who likes to do every stage completely before moving on to the next. You would prefer to knock out all the wheel studs before reattaching any of them. By doing so you are losing a fully-assembled example to compare with while you assemble the parts. If you instead do one side at a time, you never have to rack your brain as to the order of parts or how they need to go together - you can simply look at the assembled side for a perfect example.
Wheel studs come out with that BFH we spoke about earlier. For the uninitiated, a BFH is a BIG FUCKING HAMMER. Just pounding on the studs is likely to mess them up, however, so we can protect them by threading on a lug nut. Only the open type, not the acorn-type, is useful here. It’s worth buying one when you buy drums if your car only has acorn nuts.
A few good whacks should free the stud from the drum. Once all four are out, we can reattach them to the new drum. This is again done with the lug nut by tightening it up until the stud is fully seated.
With the studs in place, on to the bearings. Many front-wheel-drive cars with drums brakes share this design with two bearings per side. There is a bearing on the outside, a spacer in the middle, and another bearing on the inside. Ideally, you would just install new bearings. These ones had no signs of play and seemed good, and I’m cheap, so I’ll reuse them.
Without a proper press, the only way to get the old bearings out is to smack them out with that BFH. Do be gentle, and try not to bang on the inner part of the bearing if at all possible - bearings like these aren’t designed to take banging, axial loads, and their lifespan will be reduced by violence! I like to use a soft brass drift to drive them out - steel drifts will dent the also-steel bearing races.
When removing or installing bearings with a hammer and drift, it’s best to circle around the bearing while hammering as gently as possible, rather than concentrating all your force on one particular quadrant of the bearing.
Pictured: brass drift, outer bearing, spacer (on top of) inner bearing.
Greasy! Make sure you keep the bearings out of the dirt, or you’ll have to give them a thorough cleaning.
I added a little extra fresh grease and set to reinstalling the bearings into the new drum.
The inner bearing sits flush with the drum surface, and a block of wood works well to drive it in. Kind of like in the following picture (outer bearing pictured):
Speaking of the outer bearing, ensure the spacer is correctly oriented before driving it in! I somehow got it backwards and had to redo one drum. The narrow tapered side should face OUT.
The inner bearing sits down in the drum instead of flush, so you’ll have to use a narrow piece of wood or a drift to get it all the way seated. Drive the bearing in until it bottoms out. It should be fairly obvious when it’s not going in any farther.
Alright! The new drum has been outfitted with studs and bearings, but it’s not done quite yet. Most new brake parts are coated with oil at the factory to prevent rust. Oil and brakes do not mix, so the braking surfaces need to be cleaned up with brake cleaner. On the drums, that’s just the inner circumference. The rest can stay oiled for rust protection.
The drums can now be reinstalled on the car. Ideally, you will have brand new stake nuts. I did not, so I used a little trick to extend their life a little. Swap the left side nut to the right and vice versa. This way, once they are tightened up, there should be an unstaked portion of the nut at the stake point. 129 ft/lbs with the torque wrench produces this:
And then it’s ready to be staked with a cold chisel and hammer. Ding!
Install the dust cap, then the wheel, repeat on the other side, and you’re done! No more brake pulsation!
Cost:
$40 - two Geo Metro brake drums (autopartsway)
Incidental supplies:
A dab o’ grease
brake cleaner
The rear of the car goes up on the jack, and the rear wheels come off. To free the drums we need to remove the little dust caps covering the axle nut. A sharp wood chisel works well to push the cap free.
We are then presented with the staked nut, which is a nut with a special sleeve attached that is dented inwards to help hold things in place.
This one has been a bit mangled. A bit of prying with a flat blade screwdriver gets enough of the metal out of the way that it can be turned off with a 23mm socket. Engage the handbrake to keep the drum from turning.
With the nut off, the drum should come straight off the spindle. Sometimes it needs a little coaxing (by foul language and/or use of a BFH), but these ones came off drama-free. That is, after I remembered to disengage the handbrake.
There are some important items that are attached to the drum - namely the wheel studs and the wheel bearings. The new drums don’t come with these attached, so we need to remove them from the old drums. Let’s start with the studs.
But first, a quick note about the order of things. Perhaps you’re someone who likes to do every stage completely before moving on to the next. You would prefer to knock out all the wheel studs before reattaching any of them. By doing so you are losing a fully-assembled example to compare with while you assemble the parts. If you instead do one side at a time, you never have to rack your brain as to the order of parts or how they need to go together - you can simply look at the assembled side for a perfect example.
Wheel studs come out with that BFH we spoke about earlier. For the uninitiated, a BFH is a BIG FUCKING HAMMER. Just pounding on the studs is likely to mess them up, however, so we can protect them by threading on a lug nut. Only the open type, not the acorn-type, is useful here. It’s worth buying one when you buy drums if your car only has acorn nuts.
A few good whacks should free the stud from the drum. Once all four are out, we can reattach them to the new drum. This is again done with the lug nut by tightening it up until the stud is fully seated.
With the studs in place, on to the bearings. Many front-wheel-drive cars with drums brakes share this design with two bearings per side. There is a bearing on the outside, a spacer in the middle, and another bearing on the inside. Ideally, you would just install new bearings. These ones had no signs of play and seemed good, and I’m cheap, so I’ll reuse them.
Without a proper press, the only way to get the old bearings out is to smack them out with that BFH. Do be gentle, and try not to bang on the inner part of the bearing if at all possible - bearings like these aren’t designed to take banging, axial loads, and their lifespan will be reduced by violence! I like to use a soft brass drift to drive them out - steel drifts will dent the also-steel bearing races.
When removing or installing bearings with a hammer and drift, it’s best to circle around the bearing while hammering as gently as possible, rather than concentrating all your force on one particular quadrant of the bearing.
Pictured: brass drift, outer bearing, spacer (on top of) inner bearing.
Greasy! Make sure you keep the bearings out of the dirt, or you’ll have to give them a thorough cleaning.
I added a little extra fresh grease and set to reinstalling the bearings into the new drum.
The inner bearing sits flush with the drum surface, and a block of wood works well to drive it in. Kind of like in the following picture (outer bearing pictured):
Speaking of the outer bearing, ensure the spacer is correctly oriented before driving it in! I somehow got it backwards and had to redo one drum. The narrow tapered side should face OUT.
The inner bearing sits down in the drum instead of flush, so you’ll have to use a narrow piece of wood or a drift to get it all the way seated. Drive the bearing in until it bottoms out. It should be fairly obvious when it’s not going in any farther.
Alright! The new drum has been outfitted with studs and bearings, but it’s not done quite yet. Most new brake parts are coated with oil at the factory to prevent rust. Oil and brakes do not mix, so the braking surfaces need to be cleaned up with brake cleaner. On the drums, that’s just the inner circumference. The rest can stay oiled for rust protection.
The drums can now be reinstalled on the car. Ideally, you will have brand new stake nuts. I did not, so I used a little trick to extend their life a little. Swap the left side nut to the right and vice versa. This way, once they are tightened up, there should be an unstaked portion of the nut at the stake point. 129 ft/lbs with the torque wrench produces this:
And then it’s ready to be staked with a cold chisel and hammer. Ding!
Install the dust cap, then the wheel, repeat on the other side, and you’re done! No more brake pulsation!
Cost:
$40 - two Geo Metro brake drums (autopartsway)
Incidental supplies:
A dab o’ grease
brake cleaner
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