Turning brake discs/drums

I turned a pair of brake rotors off a Ford Mustang a few months ago. Car runs fine. I just chucked them in the 3-jaw with the jaws facing outwards, and tapped the rotor with a rubber mallet to make sure it sat flat before facing it off. I don't know what speed I used but I used a standard carbide bit and it worked fine.

Grant

Mike Slowey wrote:

They are pretty cheap now. With semi-metallic pads rotor life is not what it used to be. With drums, unless they're out of round or scored, cutting them is not really necessary.

I turned them on the car with a electric hand grinder.Works real nice in a pinch on a sunday night with know one to do them

That's terrifying. Please don't drive behind me.

I did the same for my Mazda pickup a couple times, using a large bullnose center in the tailstock. I finally replaced both front rotors a year or so ago when there wasnt enough meat left. $35 each at the AutoZone.

Gunner

"There is no difference between communism and socialism, except in the means of achieving the same ultimate end: communism proposes to enslave men by force, socialism - by vote. It is merely the difference between murder and suicide." - Ayn Rand, from "Foreign Policy Drains U.S. of Main Weapons"

I've done the same thing! Works pretty good. 20,000 miles later you would never know the disc was scored.

-- Gary Brady Austin, TX

On 20 Aug 2004 23:00:54 -0700, snipped-for-privacy@gmail.com (Justin) calmly ranted:

Especially with the "know one" driving that vehicle. Eek!

--- -If thy poster offends thee, *PLONK* it out.-

Why not? How many brake jobs are done by real machinists?

So how'd you do that? let the grinder spin the rotor fast, while it cut? I can see that that would work.

With new rotors and drums running about $25-35 for my vehicles, there really isn't a lot of desire on my part to do this. If you look at a brake lathe, both sides of rotors are faced simultaneously, you'd have a hard time setting this up on a general purpose lathe. If you change pads and shoes before the rivets start dragging, you can usually get by without any machining of the surfaces. I've done 4-5 changes of brake pads and shoes on a vehicle without doign anything to the drums or rotors and they still didn't have really deep grooving or ridges. The deal is that with modern vehicles, the iron surfaces really don't have a lot of meat on them to be turning the surface down all the time. Not like older cars where the drums were really thick and you could turn them 4-5 times before you needed new ones. If they're really grooved, just replace them.

Stan

I turn discs, but only for race car applications where I typically have to thin a disc down from what the standard application was. It's really typical to turn a disc down to .280", for example, for use on the rear of FFords. I run it at the speed recommended for cast iron and carbide, I do a finish cut at minimal depth and high FPS for finish, and I take a long time doing the setup to keep the surfaces parallel. Last time I was asked to do this I did the basic turning (cut them down on the OD of the disc) then sent to guy off to the local NAPA to have them turned down to proper thickness. He told me later that it took well over an hour of turning and cost less than $20 for the pair. I told him that I don't cut CI for less than $20 an hour, not even for myself!

Brian

I use a belt sander to break the glaze on my front rotors at each pad change. It also knocks off the small ridges. Just run the sander and the rotor will spin on its own, leaving a nice "ground" finish. I had to cut away some of the shielding on the inner side to reach with the sander.

Tony

Did you see the post that i use electric grinder and let it spin also

Which Mandrell, Louise or Barbara?

Now if I were turning a brake rotor, I'd use a mandrel that duplicates the factory wheel bearing outer race.

Gary

||On Fri, 20 Aug 2004 12:04:13 -0500, snipped-for-privacy@vanderbilt.edu (Mike Slowey) wrote: ||>If you need a mandrell, what do you use to mount the discs? || ||Which Mandrell, Louise or Barbara? || ||Now if I were turning a brake rotor, I'd use a mandrel that duplicates the ||factory wheel bearing outer race. || ||Gary

The way the AMMCO and other purpose-built machines do it is better. Leave the races in place, and center on them with a rounded cone.

Sorta like this /( )\ on both inner and outer

Barbara woulda been like this (*) (*) Texas Parts Guy

What do you do when the disc doesn't have bearing races (like virtually all of the discs I ever work with). Mine either mount to a bell with 6 or 8 bolts, or both to the back of the hub with four bolts. I chuck them up and indicate from a virgin factory surface. Is there a better way to do it?

Brian

Slowey)

||> ||On Fri, 20 Aug 2004 12:04:13 -0500, snipped-for-privacy@vanderbilt.edu (Mike ||Slowey) ||> wrote: ||> ||>If you need a mandrell, what do you use to mount the discs? ||> || ||> ||Which Mandrell, Louise or Barbara? ||> || ||> ||Now if I were turning a brake rotor, I'd use a mandrel that duplicates ||the ||> ||factory wheel bearing outer race. ||> || ||> ||Gary ||>

||> The way the AMMCO and other purpose-built machines do it is better. ||> Leave the races in place, and center on them with a rounded cone. ||>

||> Sorta like this /( )\ on both inner and outer ||>

||> Barbara woulda been like this (*) (*) ||> Texas Parts Guy || ||

Texas Parts Guy