(no subject)
Apr. 15th, 2018 08:56 amYesterday, man.
My ISP had some sort of hardware catastrophe so I had no wired internet all day, which was okay, because I had too much to do anyway.
When I was driving home Thursday my car started making Really Terrible noises. It's been making nasty grindy noises during braking for a while, and I couldn't figure out what the problem was. I took off every wheel, checked the brake pads from the top to make sure they were still adequate, checked the rotor front faces for obvious scoring, with no success. But the noises it was making Thursday meant it was time to increase my efforts. I took![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png)
threemeninaboat's terrifying car to Japanese class, came home, put my car up on jackstands, and proceeded to try to completely disassemble the front braking system into its individual components and inspect every component for cracks, burrs, debris, or whatever.
It didn't actually take that long to find the problem. The front right disc brake backside (which is really difficult to see) was horribly scored. The brake pad that pushes against it had sufficient thickness, but the pad lining had failed somehow and come loose from the backing, so it was all crunched up and there was a bunch of gravely debris in the space where it had failed and provided a recess for junk to accumulate.
Because I'd previously thought I might have a damaged rotor, I had a brand new rotor sitting around, so I figured this wasn't going to be a big problem.
To get the rotor off, you remove the caliper, which encloses part of the rotor, and then the caliper mounting bracket, which also encloses part of the rotor. Caliper came right off. The upper bracket bolt came out with a LOT of work. But I could not shift the lower bolt. I put a breaker bar on there and squat-lifted hard enough to start lifting the front of the car up a little, which was not approved of by Department Of Lumbar Resources, so I had the clever(ish...) idea of putting the breaker bar on the hydraulic floor jack. Ha HA! I can apply four tons (3.6 tonnes) of lifting force to that!
Of course the bolt just broke off, because it REALLY WAS STUCK.
So now I have a whole new problem. To get the disc off, the bracket has to come off because it encloses the disc. But the bracket has a broken-off bolt so it can't side sideways to clear the disc.
ARRRGH.
Well, Subaru, bless them, put two threaded holes in the disc. The rotor is only held to the hub by the lug nuts clamping the wheel against it, but in case it gets stuck (rusted) in place, you can screw a couple of bolts into those holes and extract it that way. Which, thankfully, is in line with the broken-off bolt: if I screw-extract the disc, it'll also pull the bracket off by pulling the shaft of the broken bolt out the wrong side of the hub.
Of course the extractor is approximately the only size bolt I don't have in stock (8mm fine pitch) but I had to go to the auto store anyway to get new pads, and they have a big bucket o' bolts.
Sooooo the stupid disc came off and the stupid bracket came off and now I have to remove a broken-off bolt stub. I sprayed it with penetrating oil, whacked it with a hammer, heated it up with a plumbing torch, stuck it in the freezer, whacked on it some more, and finally ended up very carefully centering it in the milling machine and drilling out the center of the bolt so there was only a 0.5mm thick cylinder of it left and then crumpling that with pliers and pulling it out.
And now I need a replacement bolt.
The hardware store had a bolt, in a lower strength grade (this is the mounting bolt for the front brake caliper: arguably the most important bolt on the whole car) and almost 2cm longer, so I had to put it in the lathe, center-drill it, cut off the excess while supported with a dead center, chamfer the end so it'd thread, cut off the support nubbin, put it under a microscope and pick out the little bit of debris from turning it that had folded down in the thread valley, and finally reassemble everything. (To do: get the correct bolt in the correct grade.)
In conclusion, car repair is a land of many contrasts.
But since the internet was still dead, I fired up the 3d printer and printed out an adapter so I can stick one of my antique dial indicators on the toolpost of my lathe and measure (and align) stuff I'm turning to 0.00005 inches, yes that's 1.5 microns. Nothing exceeds like excess.
My ISP had some sort of hardware catastrophe so I had no wired internet all day, which was okay, because I had too much to do anyway.
When I was driving home Thursday my car started making Really Terrible noises. It's been making nasty grindy noises during braking for a while, and I couldn't figure out what the problem was. I took off every wheel, checked the brake pads from the top to make sure they were still adequate, checked the rotor front faces for obvious scoring, with no success. But the noises it was making Thursday meant it was time to increase my efforts. I took
threemeninaboat's terrifying car to Japanese class, came home, put my car up on jackstands, and proceeded to try to completely disassemble the front braking system into its individual components and inspect every component for cracks, burrs, debris, or whatever.It didn't actually take that long to find the problem. The front right disc brake backside (which is really difficult to see) was horribly scored. The brake pad that pushes against it had sufficient thickness, but the pad lining had failed somehow and come loose from the backing, so it was all crunched up and there was a bunch of gravely debris in the space where it had failed and provided a recess for junk to accumulate.
Because I'd previously thought I might have a damaged rotor, I had a brand new rotor sitting around, so I figured this wasn't going to be a big problem.
To get the rotor off, you remove the caliper, which encloses part of the rotor, and then the caliper mounting bracket, which also encloses part of the rotor. Caliper came right off. The upper bracket bolt came out with a LOT of work. But I could not shift the lower bolt. I put a breaker bar on there and squat-lifted hard enough to start lifting the front of the car up a little, which was not approved of by Department Of Lumbar Resources, so I had the clever(ish...) idea of putting the breaker bar on the hydraulic floor jack. Ha HA! I can apply four tons (3.6 tonnes) of lifting force to that!
Of course the bolt just broke off, because it REALLY WAS STUCK.
So now I have a whole new problem. To get the disc off, the bracket has to come off because it encloses the disc. But the bracket has a broken-off bolt so it can't side sideways to clear the disc.
ARRRGH.
Well, Subaru, bless them, put two threaded holes in the disc. The rotor is only held to the hub by the lug nuts clamping the wheel against it, but in case it gets stuck (rusted) in place, you can screw a couple of bolts into those holes and extract it that way. Which, thankfully, is in line with the broken-off bolt: if I screw-extract the disc, it'll also pull the bracket off by pulling the shaft of the broken bolt out the wrong side of the hub.
Of course the extractor is approximately the only size bolt I don't have in stock (8mm fine pitch) but I had to go to the auto store anyway to get new pads, and they have a big bucket o' bolts.
Sooooo the stupid disc came off and the stupid bracket came off and now I have to remove a broken-off bolt stub. I sprayed it with penetrating oil, whacked it with a hammer, heated it up with a plumbing torch, stuck it in the freezer, whacked on it some more, and finally ended up very carefully centering it in the milling machine and drilling out the center of the bolt so there was only a 0.5mm thick cylinder of it left and then crumpling that with pliers and pulling it out.
And now I need a replacement bolt.
The hardware store had a bolt, in a lower strength grade (this is the mounting bolt for the front brake caliper: arguably the most important bolt on the whole car) and almost 2cm longer, so I had to put it in the lathe, center-drill it, cut off the excess while supported with a dead center, chamfer the end so it'd thread, cut off the support nubbin, put it under a microscope and pick out the little bit of debris from turning it that had folded down in the thread valley, and finally reassemble everything. (To do: get the correct bolt in the correct grade.)
In conclusion, car repair is a land of many contrasts.
But since the internet was still dead, I fired up the 3d printer and printed out an adapter so I can stick one of my antique dial indicators on the toolpost of my lathe and measure (and align) stuff I'm turning to 0.00005 inches, yes that's 1.5 microns. Nothing exceeds like excess.
