When to replace drums and rotors?

[JessicaJeeper08]

How do I know when it is time to replace the rotors and drums? Is there a way to convert the rear to rotors instead of drums? As far as I know they are factory ones as I’ve never replaced them. I’m not having any issues as far as I know.

I need to replace my brake pads soon but I didn’t know if I should just get all new parts when doing so since I’m at 140K? Also, how often should I replace the rear brake shoes?

Thank you for any advice.

 

[Gilaguy23]

In a nut shell, rears last far longer than fronts. When to replace either? Are there grooves in the rotors? do the drums have gouges in them from dirt and debris getting in between the linings and drums? I change out pads at around 3mils leat, some pads have wear indicators that screech when the pads are worn down to a minimum. Rotors and drums and drums can be serviced to a point but then its time for new ones. There are kits to do a disc conversion in the rears, its all about what you want/need. I will add in todays world there is way to much JUNK for parts. Servicing OEM parts is a good idea or just buy quality parts preferably of the non China type.

 

[macleanflood]

Also a good time to do the pads if you have a leaking axle seal. Pads don't work good when soaked in oil.

Rust is another deciding factor.

And sometimes you need to manually turn the adjuster to get things dialed in. Always a good place to start if your parking brake isn't grabbing like it should.

-Mac

 

[KennethS]

Rotors and drums have specified dimensions, so in the absence of any scrapes, gouges, or other visible damage, you would need to measure the rotor thickness and drum inside diameter with micrometer / calipers to determine if they are worn to the point of needing to be replaced. My TJ has just over 150K on it and the original rotors and drums are still in spec.

 

[tnjeepguy]

Is there a way to convert the rear to rotors instead of drums?

Yes, lots of info on here to tell you how. Junkyard parts one cheaper way. Keep in mind you have to also change the mount plate on the axles (means new bearings etc) if you do and also all say it does not really help much in braking, only helps in brake maintenance ??

Front pads, turn wheel and use flashlight to look and see how much pad is left. Rears, have to take off the wheel and drum to see how much pad is left.

https://wranglertjforum.com/threads/how-do-i-know-if-i-need-to-replace-brake-rotors-or-drums.36044/
https://wranglertjforum.com/threads...signs-that-i-may-need-a-brake-overhaul.78256/

 

[Strizzo]

There are minimum specs for rotor thickness, and diameter on the drums. often the spec is also cast into the rotor or drum.

It is also pretty common now for aftermarket rotors to be just barely bigger than spec out of the box, so you basically get one set of pads out of a set of rotors. YMMV.

 

[joniki]

I have never, ever had a rotor turned that didn;t warp soon after.

 

[macleanflood]

Not to hijack this thread...but last time I checked my rear brakes I have two completely different drums. One looked original Mopar. They also weighed different amounts. I've contemplated replacing them with a matched set. I've got pictures around here somewhere.

-Mac

 

[BlueC]

How do I know when it is time to replace the rotors and drums?

When there is obvious damage and/or they are at their measured min thickness (rotor) or max diameter (drum). Those are stamped on the rotor and drum.

 

[Zorba]

Not to hijack this thread...but last time I checked my rear brakes I have two completely different drums. One looked original Mopar. They also weighed different amounts. I've contemplated replacing them with a matched set. I've got pictures around here somewhere.

-Mac

Why would it matter?

 

[macleanflood]

Why would it matter?

I dunno, physics, maybe? Technically speaking the shafts are already different lengths...and therefore different weights...

I suppose somewhere in the tenths or thousands of some equation less rotating mass on each wheel is a good thing.

-Mac

 

[KennethS]

I have never, ever had a rotor turned that didn;t warp soon after.

This happens with OEM and inexpensive aftermarket rotors made to OEM specs. The OEM rotors are thin to reduce weight and manufacturing costs, and turning them removes the surface hardening and they warp easily. Next time you’re at the auto parts store, have them pull one of the cheap rotors and one of the premium rotors. You will immediately feel the difference in weight, and looking at them you will see the metal on the premium rotor is thicker (the center gap is narrower because of this). The premium rotors can be turned without fear of warping.

 

[Zorba]

I dunno, physics, maybe? Technically speaking the shafts are already different lengths...and therefore different weights...

I suppose somewhere in the tenths or thousands of some equation less rotating mass on each wheel is a good thing.

-Mac

I was just wondering since I recently replaced my rear drums with a mismatched set. *shrug*

 

[BlueC]

Why would it matter?

It shouldn't as long as everything is within spec and logical reason. If one weighs 5 lbs and the other 50 lbs, then I'd be concerned. I think it would be very unlikely to find a perfectly matched set off the production line too, and ultimately some factory produced vehicles will wind up with a mixed set of min and max tolerance parts.