My wheel shakes when i brake hard and some metioned acouple days ago that my rotors are warp and i looked it up and im pretty sure thats the problem. does anybody have a write up on how to shave them the proper way. Seeing as i have never done this befor. Should i upgrade or just fix them?
kotten148
well, you would not do that yourself.. they have machines for that. Take it is a parts store and they will resurface them for you if they can be.
yea I meant vato zone.. but if you have a shop you should be able to do it yourself.
There is someone there that does this job normally? You just plug a couple of numbers into the computer on the machine and it does it for you in half hour or so.
There is someone there that does this job normally? You just plug a couple of numbers into the computer on the machine and it does it for you in half hour or so.
If you do not know how to use a brake lathe, i would recommend against machining your own rotors at least before you have some practice on others. It is VERY easy to mess something up. You have to have everything set up perfectly or else that imperfection will get transferred to your rotor.
You said you have access to a shop, so if you know how to use lots of shop tools (you HAVE to know how to do measurements down to .001") and such and still want to try, here is how.
>>>>WEAR SAFETY GLASSES AT ALL TIMES AND WEAR A PROTECTIVE MASK WHENEVER THE MACHINE IS ON<<<<
Lift up the vehicle, take of the wheel, and spray everything down with brake cleaner. Torque the lug nuts to 100 ft/lb using conical washers between the lug nuts and the rotor. Mount a dial indicator somewhere in the wheel well so it can reach the rotor. Set it up so the rod on the indicator is pushed down, but not too far, so it has play room. Spin the rotor to find the high and low spots. Find either the highest or lowest spot and zero the dial indicator, and then find out how much lateral run out the rotor has. I forgot the maximum allowed lateral run out, but i will check it tomorrow. Most manufacturers recommendations are between .002" and .008".
Measure the thickness of the rotor using a rotor micrometer, if available, or a micrometer. If you can see any deep groves, measure in there. If you cant, measure in 6-10 different spots all over the rotor. Find the biggest thickness variation. Again, i forgot the specifications but i will look them up tomorrow.
Now, if the lateral run out or thickness variation does not exceed specifications, and you cant physically feel ridges, DO NOT machine those rotors. Those rotors are good and you will only be making them worse by cutting them. Tires may also be a cause of vibration when braking if they have different patterns on them or are worn down differently. Otherwise, continue.
Now you have to check the run out of the spindle on the brake lathe. Mount a dial indicator somewhere so it can reach about halfway on the spindle and check for run out and check for excessive run out. Now mount the rotor using the the cones and adapters as recommended by the lathe and tighten the spindle nut. DO NOT DROP THE ROTOR ONTO THE SPINDLE. Mount a dampener on the rotor. Not using a dampener could cause the rotor to "sing" as its being cut, and the lathe will cut lots of ridges from the vibrations into it that may be very hard if not impossible to get out, wasting the rotor.
Now position the bits close to the surface all the way inside the rotor. Make sure the lathe is in neutral. You will be using only the N and the R, which stand for neutral and rotor. If you set it to D, for drum, one of those bits is going to go right into your rotor and ruin it. Some lathes may be different so make sure first. Turn on the lathe and move the bits in until they barely scratch the surface of the rotor. Turn off the lathe and back of the bits. Loosen the spindle nut and rotate the rotor 180 degrees without turning the spindle. Tighten it back up and do another scratch like you just did but right next to it, not over it. The two scratches should be side by side. If they are not side by side, something is not mounted correctly.
Once it is set up correctly you can begin the cut. Try to find the lowest spot on each side of the rotor and move the bit into it until it touches. Note the measurement and zero out the control knob if it can be, if not youll just have to remember where youre starting at. Do it for each side individually as each side may have a different low point. How much you want to cut depends on how bad the rotors are and how much you can cut from them. Just make sure not to go past the recommended machine to specifications, which is usually .03" bigger than the minimum thickness (again ill check tomorrow). You also want to cut both sides as evenly as possible. You can cut a little more on one side than the other if one is messed up more, just dont cut.02" from one and .1" from the other. Also, dont cut only side at a time. Even if it one side doesnt need to be cut anymore but the other does still, cut .002" from the side that doesnt need it. Pressure from only one bit will cut it unevenly. Any less than .002" and the bit will not cut properly and will just slide instead.
Place the bits all the way in (towards the center of the rotor) and turn on the lathe. Move the bits to your zero measurement and move them in however much you are going to cut and start the lathe by setting it to R (rotor). The lathe will now start cutting on its own, but DO NOT walk away and just let it cut on its own. If something happens (dampener snaps or something comes loose for whatever reason) you want to stop the lathe asap to save your rotor.
You should notice the color or the rotor changed. If there is any variation in color, additional cuts are required. The darker spots are spots that were too low for the lathe to cut. Repeat the steps to cut the rotor, again making sure not to cut too far.
Once the rotor is properly cut, with lathe still turning apply 150-grit aluminum-oxide sandpaper to the rotor with even pressure for 60 seconds to both sides. Use break cleaner to clean the rotors and you can now re install them on the vehicle.
Hope this helps you out and good luck!
You said you have access to a shop, so if you know how to use lots of shop tools (you HAVE to know how to do measurements down to .001") and such and still want to try, here is how.
>>>>WEAR SAFETY GLASSES AT ALL TIMES AND WEAR A PROTECTIVE MASK WHENEVER THE MACHINE IS ON<<<<
Lift up the vehicle, take of the wheel, and spray everything down with brake cleaner. Torque the lug nuts to 100 ft/lb using conical washers between the lug nuts and the rotor. Mount a dial indicator somewhere in the wheel well so it can reach the rotor. Set it up so the rod on the indicator is pushed down, but not too far, so it has play room. Spin the rotor to find the high and low spots. Find either the highest or lowest spot and zero the dial indicator, and then find out how much lateral run out the rotor has. I forgot the maximum allowed lateral run out, but i will check it tomorrow. Most manufacturers recommendations are between .002" and .008".
Measure the thickness of the rotor using a rotor micrometer, if available, or a micrometer. If you can see any deep groves, measure in there. If you cant, measure in 6-10 different spots all over the rotor. Find the biggest thickness variation. Again, i forgot the specifications but i will look them up tomorrow.
Now, if the lateral run out or thickness variation does not exceed specifications, and you cant physically feel ridges, DO NOT machine those rotors. Those rotors are good and you will only be making them worse by cutting them. Tires may also be a cause of vibration when braking if they have different patterns on them or are worn down differently. Otherwise, continue.
Now you have to check the run out of the spindle on the brake lathe. Mount a dial indicator somewhere so it can reach about halfway on the spindle and check for run out and check for excessive run out. Now mount the rotor using the the cones and adapters as recommended by the lathe and tighten the spindle nut. DO NOT DROP THE ROTOR ONTO THE SPINDLE. Mount a dampener on the rotor. Not using a dampener could cause the rotor to "sing" as its being cut, and the lathe will cut lots of ridges from the vibrations into it that may be very hard if not impossible to get out, wasting the rotor.
Now position the bits close to the surface all the way inside the rotor. Make sure the lathe is in neutral. You will be using only the N and the R, which stand for neutral and rotor. If you set it to D, for drum, one of those bits is going to go right into your rotor and ruin it. Some lathes may be different so make sure first. Turn on the lathe and move the bits in until they barely scratch the surface of the rotor. Turn off the lathe and back of the bits. Loosen the spindle nut and rotate the rotor 180 degrees without turning the spindle. Tighten it back up and do another scratch like you just did but right next to it, not over it. The two scratches should be side by side. If they are not side by side, something is not mounted correctly.
Once it is set up correctly you can begin the cut. Try to find the lowest spot on each side of the rotor and move the bit into it until it touches. Note the measurement and zero out the control knob if it can be, if not youll just have to remember where youre starting at. Do it for each side individually as each side may have a different low point. How much you want to cut depends on how bad the rotors are and how much you can cut from them. Just make sure not to go past the recommended machine to specifications, which is usually .03" bigger than the minimum thickness (again ill check tomorrow). You also want to cut both sides as evenly as possible. You can cut a little more on one side than the other if one is messed up more, just dont cut.02" from one and .1" from the other. Also, dont cut only side at a time. Even if it one side doesnt need to be cut anymore but the other does still, cut .002" from the side that doesnt need it. Pressure from only one bit will cut it unevenly. Any less than .002" and the bit will not cut properly and will just slide instead.
Place the bits all the way in (towards the center of the rotor) and turn on the lathe. Move the bits to your zero measurement and move them in however much you are going to cut and start the lathe by setting it to R (rotor). The lathe will now start cutting on its own, but DO NOT walk away and just let it cut on its own. If something happens (dampener snaps or something comes loose for whatever reason) you want to stop the lathe asap to save your rotor.
You should notice the color or the rotor changed. If there is any variation in color, additional cuts are required. The darker spots are spots that were too low for the lathe to cut. Repeat the steps to cut the rotor, again making sure not to cut too far.
Once the rotor is properly cut, with lathe still turning apply 150-grit aluminum-oxide sandpaper to the rotor with even pressure for 60 seconds to both sides. Use break cleaner to clean the rotors and you can now re install them on the vehicle.
Hope this helps you out and good luck!
If theres an on the car lathe available at the shop you can use that too. Its a lot move accurate since it spins on the axle that the rotor spins on during normal use anyway. The setup is similar to above except the lathe mounts to the caliper mounts and another machine spins the rotor, just make sure its lined up right down the center of the rotor. Youll have to look up the lathes manual to set it up right if you use one of these and you dont have to do a scratch cut.
Oh and the specs:
The minimum thickness is the point where they cant be used at all or you risk having the piston going out too far. The machine to thickness is the minimum thickness that the rotors can be machined to and still have room to wear from normal use.
Minimum front disc thickness - 1.11" / 28.4 mm
Minimum rear disc thickness - .68" / 17.4 mm
Minimum front machine-to thickness - 1.14" / 29 mm
Minimum rear machine-to thickness - .71" / 18 mm
Brake caliper bolts torque spec - 89 lb-in / 10 Nm
Also check the brake pad variation - maximum .079" / 2.0 mm from pad to pad. That could cause uneven wear and warp the rotor again.
You may also want to throw some silicone brake grease on the pins since youre already there just to avoid any problems later so they dont get stuck.
Oh and the specs:
The minimum thickness is the point where they cant be used at all or you risk having the piston going out too far. The machine to thickness is the minimum thickness that the rotors can be machined to and still have room to wear from normal use.
Minimum front disc thickness - 1.11" / 28.4 mm
Minimum rear disc thickness - .68" / 17.4 mm
Minimum front machine-to thickness - 1.14" / 29 mm
Minimum rear machine-to thickness - .71" / 18 mm
Brake caliper bolts torque spec - 89 lb-in / 10 Nm
Also check the brake pad variation - maximum .079" / 2.0 mm from pad to pad. That could cause uneven wear and warp the rotor again.
You may also want to throw some silicone brake grease on the pins since youre already there just to avoid any problems later so they dont get stuck.
I agree with him. If you don't know how to machine a rotor, even if you have access to the machine, don't do it. Just let someone who knows how do it.
hmusn, I have never in my life seen a brake lathe that works that way. Even when I was in school (and schools tend to have the fanciest, way-expensive equiptment that you'll never see in the field) brake lathes were all manual. I used an on-car lathe once that was somewhat automatic once it was set up, but it was a PITA to set up and it didn't work worth a ****.
hmusn, I have never in my life seen a brake lathe that works that way. Even when I was in school (and schools tend to have the fanciest, way-expensive equiptment that you'll never see in the field) brake lathes were all manual. I used an on-car lathe once that was somewhat automatic once it was set up, but it was a PITA to set up and it didn't work worth a ****.
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