Brake rotor turning

There was a thread recently about turning Rotor on a small lathe. I turn a set of front rotor from my 1990 Subaru before but didn't take a picture. Last wee I needed to turn the rear rotor. The Rear on this car is a rotor drum combination, not to be replaced for 35 dollars. I only turn the rotor one side at a time and reverse the unit, trued it and turn the other side on a Shoptask 4 in 1. Pictures here show the indicator.

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Reply to
Bill Cotton
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Tell us how they work.

Reply to
Charles A. Sherwood

Reply to
R. Wink

Uh huh! It takes almost no error to end up with lumpy brakes. If the disc does so much as flutter when it's running on the bearings, it will be noticeable when the car is driven, even if the faces are parallel to one another. Turning them in two setups is asking for problems. The very best scenario is to get them running true to the bearings, and cut both sides while set up. I'd be interested in hearing how they turned out, too.

Harold

Reply to
Harold & Susan Vordos

It is difficult to do in 2 setups, but certainly not impossible for an experienced machinist with half decent equipment. That said, a proper rotor lathe makes the job a lot easier

A very small amount of runout, as long as the surfaces are parallel, is not a serious issue, as the calipers are designed to "float" and this will absorb a couple thou of runout - but you want as little as is physically possible. Some cars are much more sensitive to runout than others, but all are more sensitive to vatiations in thickness.

Reply to
nospam.clare.nce

Yep. Exactly my point. Not sure what you might consider an experienced machinist, but I started working in the industry in '57, aero-space stuff. I ran my own commercial shop for years, sub-contracting primarily from the same industry, so I know the difference between a thou and a tenth, and I'm here to tell you that any deviation from "perfect" shows up in your pedal, much the same way extended use can, and usually does. Been there, done that. I had a thou or less runout when I turned the disks for a '77 TransAm, one side at a time, several years ago. I used a commercially rated engine lathe (Graziano). I ended up making a mandrel to do them over. One thing I discovered is that the floating caliper helps, but does not eliminate the lumpiness. It's ultra critical that the surfaces be parallel, and dead perpendicular is almost as important. The loaded caliper doesn't float as easily as you might imagine, what with the force of the braking being applied against the pins. You *can* feel the resistance in the pedal, which translates into lumpiness.

Harold

Reply to
Harold & Susan Vordos

What makes them squeal like banshees? I got a brake job at the dealer in town, and I swear I could drop all pedestrians to the ground to either side, covering their ears in agony, by playing the brakes. I never looked, but I'll bet the discs looked like an LP. I switched to another dealer and had them install new rotors with ceramic pads to end the horrendous noise.

Pete Keillor

Reply to
Peter T. Keillor III

||On Tue, 19 Oct 2004 01:56:10 -0700, "Harold & Susan Vordos" || wrote: || ||>

||>> >

||>> >

||>> >Uh huh! It takes almost no error to end up with lumpy brakes. If the ||>> >disc does so much as flutter when it's running on the bearings, it will ||>be ||>> >noticeable when the car is driven, even if the faces are parallel to one ||>> >another. Turning them in two setups is asking for problems. The ||>very ||>> >best scenario is to get them running true to the bearings, and cut both ||>> >sides while set up. I'd be interested in hearing how they turned out, ||>too. ||>> >

||>> >Harold ||>> >

||>> It is difficult to do in 2 setups, but certainly not impossible for an ||>> experienced machinist with half decent equipment. ||>> That said, a proper rotor lathe makes the job a lot easier ||>>

||>> A very small amount of runout, as long as the surfaces are parallel, ||>> is not a serious issue, as the calipers are designed to "float" and ||>> this will absorb a couple thou of runout - but you want as little as ||>> is physically possible. Some cars are much more sensitive to runout ||>> than others, but all are more sensitive to vatiations in thickness. ||>

||>Yep. Exactly my point. Not sure what you might consider an experienced ||>machinist, but I started working in the industry in '57, aero-space stuff. ||>I ran my own commercial shop for years, sub-contracting primarily from the ||>same industry, so I know the difference between a thou and a tenth, and I'm ||>here to tell you that any deviation from "perfect" shows up in your pedal, ||>much the same way extended use can, and usually does. Been there, done ||>that. I had a thou or less runout when I turned the disks for a '77 ||>TransAm, one side at a time, several years ago. I used a commercially rated ||>engine lathe (Graziano). I ended up making a mandrel to do them over. One ||>thing I discovered is that the floating caliper helps, but does not ||>eliminate the lumpiness. It's ultra critical that the surfaces be ||>parallel, and dead perpendicular is almost as important. The loaded caliper ||>doesn't float as easily as you might imagine, what with the force of the ||>braking being applied against the pins. You *can* feel the resistance in ||>the pedal, which translates into lumpiness. ||>

||>Harold ||>

||What makes them squeal like banshees? I got a brake job at the dealer ||in town, and I swear I could drop all pedestrians to the ground to ||either side, covering their ears in agony, by playing the brakes. I ||never looked, but I'll bet the discs looked like an LP. I switched to ||another dealer and had them install new rotors with ceramic pads to ||end the horrendous noise. || ||Pete Keillor

As the manufacturers have experimented with non-asbestos pad formulations, there have been some premium products on the market that have shown a tendency to squeal if the installation was anything less than perfect. Squealing almost never has anything to do with the way the rotor is turned. Compound and weight of the pads, along with the age of the clips and springs, and the amount of wear of the caliper contact surfaces all interact to produce squeal. Building a pad that lasts over 40K miles, has good grip, and doesn't squeal *ever* is almost a black art. Having said that, Wagner and Raybestos premium ceramic pads are as good as it gets currently. Texas Parts Guy

Reply to
Rex B

One problem is that rotors tend to get hard spots from the pads, and they're quite thin. It's easy to get lumpy spots (where the rotor material is locally harder then the rest) even with a super rigid setup.

The 'cut both sides at once' approach helps a lot because the rotor has a tough time springing away from one tool when there's another one right behind the other side.

This being said, I've never been able to cut stainless brake rotors on my motorcycles. They have to be sent to a specialty house that blanchard grinds them. Then you get a nice finish.

Jim

Reply to
jim rozen

After living with squealing brakes on my Volvo, I finally got some good advice. It was suggested that the noise was caused by the back of the brake pad vibrating against the caliper. I applied some copper based anti-seize compound to the back of the pads and noise was gone. I suspect that a brake pad compound that resisted vibration would accomplish the same thing. The anti-seize trick lasts for about a year then needs to be reapplied.

Dean Horstman

Reply to
Dean

Work great! If you look at the top picture

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you will see an indicaton that is graduated in .001 on an inch. The space between the graduations is .062 of an inch So when the needle move the width of the stamped line, the trueness is less that .0001 of an inch. I don't remember where I aquired this indicator. I have a Ames tenth indicator and a dial tenth indicators but I love using this one. I spent 35 years in the trade, 10 as a Gagemaker for an Army Arsenal making acceptance gages to send to vendor. then a tool and die maker a, repair machinist and an 15 as a supervisor. Making work parellel depends on the measuring equipment at your disposal. I have use scrapers, laping plates copper sulpfate, pussian blue, over my career to get work flat, after being machined. At times, in my career I was expected take the worst machines for my work and tighten gibs, scrape ways and adjust tail stock as I went along to get the machine better. As a retire person with plenty of time on my hands, A sharp carbide cutter, the carrage lock is tighten after each infeed and the cross slide gib lock snug so that feeding is like turning a class 3B nut. This drum/rotor was a piece of cake.

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Reply to
Bill Cotton

Work great!

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All very cool, Bill. I can't help but think that the problem I had when I turned the rotors for the TransAm was that I had no method to get the disk perpendicular until I made the arbor. Can't recall exactly how I went about it the first time, but I, too, used an indicator. The major problem was not having access to the back side bearing surface, as I recall. At any rate, the second setup worked well and the brakes turned out fine, just as yours did.

Congratulations on a job well done!

Harold

Reply to
Harold & Susan Vordos

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Bill Cotton, the original poster, *is* an experienced machinist, now retired. He had to do the brake the way he did, because he does not have room for a serious sized lathe, and wound up with a Shoptask, which he has been making do an excellent job. He is a machinist who knows how to work around the limitations of a machine.

Enjoy, DoN.

Reply to
DoN. Nichols

"DoN. Nichols" wrote in message news:cl4mqq$go1$ snipped-for-privacy@fuego.d-and-d.com...

Thanks DoN; In response to need for an arbor to machine brake rotor, it depends on how the rotor in mounted on the vehicle. If the rotor and bearing housing is one unit, then you may need to mount the bearing housing on an adapter. With a large enough lathe, you can clamp on the od the rotor using reversed jaws, so that there is a solid jaw behind the rotor, get a place undamaged to indicate side number one. Machine it, turn the rotor around, and place the rotor flush against the same jaws mount a indicator on the cross side. indicate each section between the jaws, back the cross side to clear the jaw and repeat. You may find that the chucking produce a true surface. All of the brake rotor that I have had is separated from the bearings. The one on the front of my Subaru are a disc with a machined hole that clears the bearing housing and the area above and below the bolt circle is machine paralleled. Using the outside jaws of my three jaw chuck give support at the bolt circle and holds the rotor parallel. The indicating is a check. A light tap here and there true the rotor. The rear rotor are combine drum/rotor for the parking brakes. The rotor is offset but setting it up was the same as the front, except I couldn't get the chuck key in and used a short piece of key stock. As Don mention, space is the reason for the three in one. The one thing I miss is a quick change gear box. I have more room now that in 1998 when the ShopTask was delivered and the prices are tempting to get a lathe with a gear box. Changing threads number and speeds is a chore now. but with lots of time I keep doing it. snipped-for-privacy@billcotton.com

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N40° 3.744' W75° 6.180'

Reply to
Bill Cotton

You can buy an arbor and the fittings for it from Ammco, and use it in your engine lathe.

Personally, I bought a used Ammco lathe to do the occasional rotor or flywheel. Also good for things like polishing wheels.

Texas Parts Guy

Reply to
Rex B

Thanks for the explanation, Bill. My exposure to disk brakes has been somewhat limited, so I had no idea that there were models that could be easily set up. . In both cases where I have been involved with them, the bearing assembly has been an integral part so setting them up on a conventional lathe is difficult.

Harold

Reply to
Harold & Susan Vordos

I've given that idea a little thought, but as I've grown older I have moved farther and farther away from working on cars. To be brutally honest, I hate it, but being retired, and living on a fixed income, I find I can save a ton of money doing my own work, so I do. My need for disk turning is so limited that I now just take them to a shop and try to get instant service so I don't have to drive the 50 mile round trip twice. Last time I did it, I wanted to step in and do the work myself after watching the young lad struggle with it. Maybe that's all the encouragement I need to buy my own machine!

Harold

Reply to
Harold & Susan Vordos

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