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Machining brake rotors---salt belt rust

Modern living thru chemistry sounds like a better plan. But there's no denying the old guys cars and truck were rust free so I guess old motor oil does work as well.
We used to have an "old guy" that advertised "used oil undercoating".....the stuff he used was jet black, and he did my friends white dodge truck.
The "runoff" that leaked onto the outside body panels made a horrible mess, looked like tar.

His wife went ballistic, and refused to allow him to do the same to her car.

We doo have a few that use "clean/new oil" and then there is the new upstarts with FluidFilm.
 
I never turn rotors- I stopped.
I've always lived in salty MN except an 'All inclusive' Uncle Sam Vaca in Kosovo
I worked in an auto machine shop and did hundreds, there's a per se brake lathe in a shed, and the Clausing will obv do them.
I just stopped, metal on metal or clean. It works. Vehicle stops just as any other.
Every auto parts store displays 'Lightweight' rotors with massive fin holes vs their premium rotors. No body on this forum should have it explained that a new rotor which weighs several pounds (Not exaggerating) less than the old one you're replacing makes no sense.
But making not sense ever stopped anyone ...
IF you go way to thin, had this happen on a 1 ton where the shop used the wrong min thickness because of axle GW confusion, it will crack and make noise.
I did use the Clausing to turn down (Diameter) rotors to fit a smaller dia knuckle for a little car I used to drag race.
The factory manuals (printed by the people who engineer your car) DO NOT require turning a rotor if it's withing their spec.
'Spend money AND make your car worse.' No thanks.
 
Surprised no one has mentioned the newer portable machine which resurfaces the rotors in situ.

On-Car-Rotor-Resurfacing.jpg

jack vines
 
The last set of rotors I bought I miked them right out of the box and they were exactly at the minimum. No material to turn off.
I've often wondered if when they dump the scrap containers they pull and sort all the brake rotors, blast, turn, repackage, and load them back on the ship? Stupid Americans won't pay $20 to get their rotors turned, but will gladly pay $25 to buy them back :nutter:
 
I did sir.
I didn't mention painting the plastic inner fender liner.

You just did.

I said "underside".

Doo you understand the word "underside" ?

Maybe not.
Clearly I thought you meant something different that the actual underside of the car unrelated to the wheel wells."
Now I know that your statement that plastic inner fenders don't stop rust in other places is just the most Captain Obvious statement ever written. It added a lot to the conversation.
 
I guess "newer" is a relative term because I've seen more primitive "on car brake lathes" decades ago. There were several made for front wheel drive cars that used the car itself as the power source.
I worked for Bear Automotive back in 1984 and sold their small rotor grinder. It had two 4" grinding discs that could be adjusted for squeeze pressure. It bolted on a front wheel drive car via the caliper mount threads. Then you had the engine drive the axles. It left a nice swirl pattern on the rotor and threw a lot of sparks. It was very finicky to set up and adjust so never caught on.
 
I bought some 'OnTruck" brake drum lathes from Volvo ...unused ,and they sold them for scrap............IMHO ,reconditioning truck drums isnt viable ,because new one are so cheap ,and the axle seals have to be replaced anyway.............so the wheels have to come off.
 
Surprised no one has mentioned the newer portable machine which resurfaces the rotors in situ.

On-Car-Rotor-Resurfacing.jpg

jack vines
the large shops have them around here, but for the cost, its not worth turning a $70 rotor and charging $120/hr labor. Even my 3/4 ton rotors are only $150, and not worth turning due to rust makes you replace it long before the metal wears out. My last set delaminated the face in chunks and was NFG.
 
I bought some 'OnTruck" brake drum lathes from Volvo ...unused ,and they sold them for scrap............IMHO ,reconditioning truck drums isnt viable ,because new one are so cheap ,and the axle seals have to be replaced anyway.............so the wheels have to come off.
I've seen "on truck" disk brake lathes, but how the heck would you do a drum without flipping it and mounting it backwards?
 
But the brake shoes would still be in the way. Maybe if you removed drum, removed the shoes, re-install drum and turn, then remove drum again, install new shoes, re-install the drum, what a pia, and back.
I'm sure you could sneek a bar in there somewhere.
 
The way Volvo operated ,its quite possible the machines wouldnt work.......Im not up with new trucks,but back in the day Volvos had what they called Z cams ...still full air ,but a lot more expensive..................You d have to take off the wheels to replace the linings anyway......truck wheels are taken off in one piece...undo the axle nuts,slip the wheel,hub ,drum ,the lot off sideways on a trolley.,then replace the assy to turn the drums..............its only viable with Volvos because of the price of drums......$1000 against a Rockwell drum @$100...............a lot of Jap trucks have excessive brake drum prices ,too.
 
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If rotors are still thick enough and not grooved (especially if they are the original rotors), I use a 4.5 inch angle grinder with a 60 or 80 grit flap disk to knock off the built up rust on my sacrificial winter beater - holding the grinder in one hand and spinning the rotor on the car with the other. Fine enough of a grit that I am not changing the braking surface on the rotor to any significant amount.

My wife's '11 Fusion (w/stick) has 144K miles and I'm about to replace the original front pads, rotors still OK. Over the decades, I've learned to not even bother checking the brakes on her car for the first time until the car's mileage is past 100K miles.


If I'm not using top quality rotors and pads I don't replace rotors unless there was metal on metal and the rotor is destroyed. I leave the rotor mounted and use a 9" grinder with a 24 grit pad to blow the high spots off while turning the rotor by hand.

Friend that owns a big shop told me about this trick he uses when customers are too cheap to pay parts and labor for rotors and he doesn't want it coming back.
 
If rotors are still thick enough and not grooved (especially if they are the original rotors), I use a 4.5 inch angle grinder with a 60 or 80 grit flap disk to knock off the built up rust on my sacrificial winter beater - holding the grinder in one hand and spinning the rotor on the car with the other. Fine enough of a grit that I am not changing the braking surface on the rotor to any significant amount.

My wife's '11 Fusion (w/stick) has 144K miles and I'm about to replace the original front pads, rotors still OK. Over the decades, I've learned to not even bother checking the brakes on her car for the first time until the car's mileage is past 100K miles.

Aren't you a picky one! I consider grooves in the rotors a free upgrade! You just don't call them grooves- They're slotted!

Full disclosure, I was the primary retail distributor for a brand of drilled and slotted rotors for awhile. I sold tens of thousands of sets of them and never, ever had a problem besides a couple times shipping the wrong ones.

The engineer that worked for the manufacturer/wholesaler (machined in USA from asian blanks) told me the slots were the trick. You'd never get a squeal or a glazed rotor if they are slotted. Virtually eliminates all the problems associated with the imperfect nature of shadetree vehicle brake jobs.

In that sense, if I'm doing a thorough brake job I buy slotted rotors. They are dirt cheap if you know who sells the good ones. If I'm not doing a thorough brake job I use the 9" grinder with 24 grit method. I want the 24 grit to chew into the surface a little bit- That's your slots.
 








 
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