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  • Brake Drum Lathes

    Seems as though every time I open a paper these days, or go online, I see an ad for a really cheap Van Norman, or Ammco, Brake Drum Lathe. (Sadly, I have yet to see an ad for an old SB). I'm wondering whether there is any use to which these can reasonably be put, other than the obvious. My experience with second hand tools has pretty much put me off somewhat goofy adaptations like the Multimachines. I can usually get the exact tool I want if I am just patient. Still I'm curious whether anyone with the adventurous spirit has done something noteworthy with these machines.
    Last edited by Blacksmith; 12-10-2007, 12:52 PM.

  • #2
    I'd like to find one by me just to turn drums and rotors ... not sure about other uses though

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    • #3
      Brake drum& rotor lathes do very nice work but are built for very specialized work. They would be difficult to convert to be an engine lathe (like to turn tapers, threads etc.) But someone with a great imagination might prove me wrong! JIM
      jim

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      • #4
        Originally posted by Fasttrack
        I'd like to find one by me just to turn drums and rotors ... not sure about other uses though
        Speaking of turning rotors: Yesterday I installed new brake pads front and rear on my Forester, which has 82,000 miles. I hate doing shoes, so I was glad this vehicle has discs in the rear. I'd heard the warning scratching of what I assumed was the wear-indicator spring, so knew it was time. I should have checked earlier! One of the rear inside pads had worn completely, down to a small patch of bare metal. I figured this must have put some grooving on the rotor, but it didn't feel like much, so I installed the new pads and called it a day. I didn't measure the runout, either -- in this rush of a Christmas season I just didn't want to know.

        I guess a brake shop would argue that the rotors needed to be turned. But I detect no problems at all with my newly installed pads.

        So, when do rotors really need to be turned?
        Last edited by aostling; 12-10-2007, 03:36 PM.
        Allan Ostling

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        • #5
          If you take it in, they will replace or cut the rotors when they put on new pads, usually. Otherwise, the rule of thumb is replace or cut (which ever is most economical) on the second set of pads and replace on the fourth set of pads.

          The way you should actually determine this is with a pair of calipers that have a point attachment for the jaws. You measure the depth of the grooves and subtract that from the total width. If this value is below a certain value (looked up in a service manual or book) then the rotor is trash. If its above the value then you can turn the rotor and not worry about the rotor becoming too thin and causing break fade.

          Same thing goes for "runout" which is usually just a variation in the thickness of the rotor. Shop practice around here is to measure the width at 6 locations on the rotor and compare them. If there is a variation above a certain value (again looked up in a book) then the rotor needs attention. It is either small enough to be taken out by turning the rotor, or sometimes you need a new rotor.

          If it has "run-out" in it, you will notice it right away when you mash the breaks. The pedal will pulsate. If there is no noticeable pulsation then i wouldn't worry about it. As far as grooves go, if they can be seen/felt with a fingernail, then they really should be cleaned up with a light cut. The break pad is fairly hard and grooves beyond a certain depth are essentially the same as drilling a hole in the rotor - it removes the effective braking surface area. That being said, realistically, you can get away with grooves as long as you are a conservative driver. NOT GOOD SHOP PRACTICE - but its ok if its your car

          The other thing you might want to do is scuff the pads - even after cutting, to get a good finish that will help the pads and discs last longer and work quieter we always scuffed the pads with a air drill and essentially a brillo pad. This works good for any squeaking too - sometimes oil or something gets on there and burns on to the rotor making a hard spot. Then it squeaks, but scuffing it makes it better!

          OK, and lastly, you bring up a good point about alot of the pads on the market now. Make sure you check your pads every so many miles because many of the pads do no have squealers on them. Some are designed so that as you wear out the pad you get into harder material that squeaks, but most will just wear normally until you get into the rivet or metal material!

          Here are the numbers:

          Grooves with a depth greater than 0.060 inch, pulsation from lateral runout of more than
          .003 inch, or a thickness variation in excess of 0.001 inch require the rotors to be cut. You will still need to check these against the minimum allowed thickness of the rotor to insure that you dont cut the rotor too thin.
          Last edited by Fasttrack; 12-10-2007, 03:48 PM.

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          • #6
            I have a complete Ammco 4000 brake lathe and most of the trimmings, and no, there's absolutely no easy way you could set it up to do anything but brake rotors, drums and flywheels.

            If you had something that was shaped about the same size and style as a rotor or drum, as in it had a 1" or larger center hole, the surface to be worked was no closer than 2" to the center, and so on, then it's possible.

            But the spindle moves back and forth, not the carriage, so there's no real "bed". There's no spindle thru-hole, the top spindle speed is still pretty low (I think around 400 rpm, but I'd have to check my manual for that) and there's a small plastic gear in there that's meant to shear if you get into a bind or the load is otherwise too high.

            Somebody perhaps incredibly enterprising could maybe retrofit it with a new bed somehow, replace the "bar" spindle with something you could screw a regular chuck onto, and whatever else it might need, but at that point it'd be just a headstock. You'd have been better off making one with some plain bearings.

            Doc.
            Doc's Machine. (Probably not what you expect.)

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            • #7
              Deleted due to redundant nature of post.
              Last edited by Carld; 12-10-2007, 08:31 PM.
              It's only ink and paper

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              • #8
                I have a Star drum/rotor/brake shoe sander that I got for doing a small job. He mostly just wanted to get rid of it because he got a new one.

                Here is what you will find if you try to have your rotors or drums turned.

                Store/shop, we can't turn them because they are under specs. But said I, they measure more than what is stamped on the rotor. They say, our book says they are undersize and the GOVERNMENT won't alllow them to be turned. Says I, all I want is to skim them. Say they, we can't do that, just buy these new ones we have here. Says I, I don't want new ones, just dust them off. Says they, NO CAN DO, buy new or put the old ones back on. Sometimes I did put them back on.

                After several attemps at different places over many years I gave up and bought new untill I got this rotor/drum turner. Piss on them jerks that only want to sell new parts.

                The problem is the min. thickness stamped on the rotor is not the min. thickness listed in their manuals. No amount of argueing will change their mind because they want to sell parts. The point is a rotor can be lightly machined once or twice if the surface is not gouged and the pads are changed before damage is done.

                You can turn a flywheel on them using the rotor turning feature. You can do other machining on them if you use your imagination.
                Last edited by Carld; 12-11-2007, 10:20 AM.
                It's only ink and paper

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                • #9
                  Yep - when i go to get a drum or rotor turned i take them to brake shops like meineke. It ends up costing about 40 bucks most of the time (a rip off if you ask me, but its the best i've found locally) but if your talking about big ol' truck rotors that is still cheaper than buying new. On the other hand, you can get rotors for civics for 12 bucks a pop. No exageration!

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                  • #10
                    Doubtless why they are popping up second hand everywhere, cheap parts.

                    On a sorta related sad point, I was looking over Craig's list and found a local add for a free 18" engine lathe! Contacted the guy and it had already been junked, nice looking lathe too.

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                    • #11
                      I had a local brake shop do just that to me- tell me the rotors were too thin to machine and best to put new ones on. They said that if they machined them, they probably wouldn't last another six months. I opted for the machining instead of the new chinese parts, and they reluctantly agreed to do it. I looked at the rotors- they were worn but not gouged, and there was lots of meat left on them. That's more than two years ago now, and no problems at all. Not a hint of squeal, and very even braking.

                      The chinese replacement products scare me. I would bet they are less uniform than the originals, and wear out quicker. I would also bet there is less thickness to the rotors than my supposedly worn out ones had. It would not surprise me either to find that the replacement parts like rotors are simply cleaned up and turned to look like new, and re-sold as new. It appears in many cases that a blind eye is turned allowing this type of thing to happen, and it's basically green-lighted by regulatory agencies or the government, so we're guinea pigs until a big stink is raised about something.

                      I was talking with a friend the other day about how much melamine per capita that we ingest. Chances are by the time you've swallowed a years worth of toothpaste, you've been poisoned by a small handful of it. Add it all up- might as well add in brake dust for all the time we spend in traffic- put in some powdered rubber as well, along with the usual additives, acids, and new-car smell. We live in a solvent based economy, and formaldehyde is coming at us from everywhere. How the heck are we still alive-

                      Anyway, I know nothing about brake drum lathes, but I've wondered about this alternate use thing more than a few times.
                      I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

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                      • #12
                        Disk brakes

                        I don't give a "rats" as regards my brakes being any less than as near as I can get them to be(ing) as reliable as I can possibly get them.

                        If they can be machined the mechanic that services my car does it. If they can't be machined - he replaces them. My car is an oldish Ford that has quite a reputation for distorting disks (front mainly). There is not a lot of "meat" on them even when new (from Ford).

                        Add wear and distortion and there can be quite a lot of metal to be removed.

                        I will not gamble with the safety part of the car - at all. If it needs doing - I have it done - and have it done right.

                        Its not a matter of whether I can afford to do it right, but a matter of whether I can afford not to.

                        I refuse to even be seen to be gambling with my own or my wife's life - and by extension with the life or well-being of any other innocent/third party.

                        If those disks were "over-machined" and were found to even be defective let alone the cause in an accident that required the Police (or the Coroner!!) to attend, then my Mechanic and I would have some very serious questions and some very annoyed people to deal with.

                        I am NOT suggesting that anyone or everyone else should do the same - its their right to do as they will - and I respect and support that right.

                        I just want my safety systems to be at least 100% when they are needed in case "someone else" systems (or themselves) are NOT up to the job when needed.

                        My steering, brakes and tyres have got me out of some potentially nasty situations on a number of occasions - lessons well and truly learned!!

                        Comment


                        • #13
                          Yep i agree oldtiffe, i think the issue here is whether or not the mechanic knows what hes doing. GM actually released a service bulletien stating that the drums and rotors SHOULD NOT be cut every time pads/shoes are replaced - only when needed. When you cut rotors or drums you then have to properly burnish them after the pads are installed. Most brake shops will not do this but they will cut the rotors and this leads to excessive wear and heat build up.

                          Comment


                          • #14
                            Originally posted by oldtiffie
                            My steering, brakes and tyres have got me out of some potentially nasty situations on a number of occasions - lessons well and truly learned!!
                            Steering, brakes, and tyres have got me into some potentially nasty situations on a number of occasions. The steering arm on my 1936 Singer snapped, three times. This gets your attention very fast.

                            Then there was the time when I had perfectly good brakes, but couldn't reach the brake pedal to apply them. This was coming down a hill into Livingston, New Zealand. The car was right-hand drive, of course. I didn't know it when I got into the car, but my right boot laces were untied. I'd shut the drivers door on the laces. When I went to apply the brakes the trapped laces went taut, and I was momentarily out of control. Thinking fast again, I opened the door and freed the laces, and averted disaster.
                            Allan Ostling

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                            • #15
                              Mincer-effect

                              Originally posted by Fasttrack
                              Yep i agree oldtiffe, i think the issue here is whether or not the mechanic knows what hes doing. GM actually released a service bulletien stating that the drums and rotors SHOULD NOT be cut every time pads/shoes are replaced - only when needed. When you cut rotors or drums you then have to properly burnish them after the pads are installed. Most brake shops will not do this but they will cut the rotors and this leads to excessive wear and heat build up.
                              Thanks Fasttrack.

                              Good post.

                              And very relevant to a lot of other issues on posts on this BBS/Forum.

                              The effect you describe is similar to a "(spiral) mincer effect" where a spiral (the non-burnished drum/disk) passes over the ("fixed") pad and "shaves" the pad (off) until the drum or disk is smooth. Causes a loss of more pad than the time "saved" by NOT (pre-fitting) "burnishing" - as you describe.

                              My mechanic told me that this can often be the cause of "very short life" of some pads. He is super careful and reports everything he sees and does - in writing - and discusses it before and after the work is done.

                              The people here who have the most successful tyre business and another that does radiators etc. are all much the same. Auto-electrician is very good too.

                              I put my car into my local Panel Shop every 2 years to have what-ever needs doing done. I am always staggered at what he sees and points out and discusses the "pros and cons" of. I just can't see it for looking but it is all too obvious when he points it out.

                              This might all seem like BS but my car is nearly 20 years old and in very good condition. I don't have to borrow or use my own capital to regularly buy a new(er) car nor do I have the high depreciation and insurance costs nor having to fight a Car Dealer through the warranty period (if new) or find out previous faults the hard way if i buy one just out of warranty either.

                              I must say that with all of the work that has been done on car that it seems that if I did it all at once it would seem that I could have taken the Ford emblem off the hood and replaced the whole bloody car!!.

                              I regard myself as being very fortunate in that regard.

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