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Discussion Starter · #1 ·
Why does Ford prohibit the practice of turning disc brake rotors on a traditional (off-the-car) brake lathe? Factory svc manaul states rotors must be turned while installed on the car using special machine.
 

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Discussion Starter · #3 ·
I don't understand what you mean by "tomato y tomato". What does that have to do with the question I posted?
 

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I never turn mine, I replace rotors everytime I replace pads. When you turn them, it takes metal off, and they become easy to warp. Take them off the car to turn them, I never even heard of turing them on the car until today (gotta love those dealers). I'm very happy with the new Napa ultra-premium rotors, and ceramic hybrid pads I just put on the front. The orig brakes lasted beyond 110k, and still had over 50% left when I replaced them (due to warped rotors).
 

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Discussion Starter · #7 ·
The only other thing I can figure is that they save $$$ by using lesser surface lateral runout tolerances on the hubs and therefore can't get an absolutely trued rotor to runt true on their hub. Kinda like to old drum brake days of the 50's and 60's where you took the wheel/tire, hub & drum assy off the spindle and balanced it as an assembly on the "Bear" machines.

Now if I can just figure out how to get 2 screwdrivers in the slot on the rear drum brakes to back off the adjuster. They put the adjuster access slot right against the rear control arm knuckle. Been over an hour, can't get the lever pushed back away from the star wheel. Can't figure it out. Anybody got any photos of someone actually doing this?
 

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meaning, 6 one way half a dozen the other, etc etc. It REALLY does not make that much difference. I've done it both ways. Set-up usually takes twice the time with an on car lathe, therefore "most" techs opt not to do it, if the shop is equipped. Time is money, the faster you move the work out the more you make.
 

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Discussion Starter · #10 ·
Update on turning the rotors off the car---
  1. Had brake specialty place turn the front rotors off the car.
  2. Installed on of them on the car, torqued uniformely to 20 ft/lb, indexed the rotor to the hub with paint stick
  3. Set up my dial indicator about an inch from the outside dia of the roto.
  4. Turned the rotor an hub through 360 deg, found lateral runout low spot of 0.035". Marked this point on the rotor.
  5. Turned rotor one stud from base index, repeated the procedure, found same amount of runout at same mark on the rotor.
  6. Repeated 3 more times, same results. Hub face is not perfectly perpendicular to the axis.
  7. Raybestos sells a Ford Disc Brake rotor shim kit, BA-903-03. I purchased a pair. They are round shims which go between the rotor and hub. They are wider one side than the other by a few 1/10,000's" the items are about $18.00 ea.
  8. Installed the shim, reinstalled and torqued rotor to 20 ft/lb, ran it through again, is now within 0.015" lateral runnout. That's pretty doggone close!
  9. Test drove the car, brake pedal has absolutley no pulsing.
Some may ask why didn't I buy new rotors instead of turning these? They only needed to have a very shallow cut to clean them up. At $12.00 ea to turn them it was not economical to replace them as there is substantial amount of meat left before wear limit. If you were to buy new rotors, you would still have the hub squareness issue, unless you turned them on the car.

Based on the responses to various threads I have followed on this site I'm sure this post will draw a lot of criticism telling me how stupid I am for doing it this way, but this is my two-cents worth for anyone that is interested.
 

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Update on turning the rotors off the car---
  1. Had brake specialty place turn the front rotors off the car.
  2. Installed on of them on the car, torqued uniformely to 20 ft/lb, indexed the rotor to the hub with paint stick
  3. Set up my dial indicator about an inch from the outside dia of the roto.
  4. Turned the rotor an hub through 360 deg, found lateral runout low spot of 0.035". Marked this point on the rotor.
  5. Turned rotor one stud from base index, repeated the procedure, found same amount of runout at same mark on the rotor.
  6. Repeated 3 more times, same results. Hub face is not perfectly perpendicular to the axis.
  7. Raybestos sells a Ford Disc Brake rotor shim kit, BA-903-03. I purchased a pair. They are round shims which go between the rotor and hub. They are wider one side than the other by a few 1/10,000's" the items are about $18.00 ea.
  8. Installed the shim, reinstalled and torqued rotor to 20 ft/lb, ran it through again, is now within 0.015" lateral runnout. That's pretty doggone close!
  9. Test drove the car, brake pedal has absolutley no pulsing.
Some may ask why didn't I buy new rotors instead of turning these? They only needed to have a very shallow cut to clean them up. At $12.00 ea to turn them it was not economical to replace them as there is substantial amount of meat left before wear limit. If you were to buy new rotors, you would still have the hub squareness issue, unless you turned them on the car.

Based on the responses to various threads I have followed on this site I'm sure this post will draw a lot of criticism telling me how stupid I am for doing it this way, but this is my two-cents worth for anyone that is interested.

Back in the mid to late 1990's Ford was matching mounting the rotors to the hubs on Tbird/Cougar and Mustangs. One of the front hubs studs tips was painted to reflect the high point and one of the rotors bolt holes was also painted to reflect the low point, and the guy on the assembly line would match them up to reduce lateral runout of the rotor. This was done to reduce Ford Brake Warranty costs. I do not know if this was ever done on the Taurus/Sable vehicle lines at the assembly line.

I personally did this on a 96 Ford Windstar I owned. I did not know about the Ford rotor shim kit, this is new to me.

Ford also in the mid 1990's bought and gave all their dealers Torque sticks so that the lug nuts were not overtorqued by the lug nut air guns, which were notorious at overtorquing the lug nuts past the 85-105 ft. lbs. torque specification thereby distorting the rotors and contributing to brake roughness.
 

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I suppose it's all about economics. There's no money in turning rotors. Similarly there's no gain using rebuild kits when re-manufactured stuff is the rule.
 

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I hope that guy above who achieved .015" runout after shimming lost a zero and meant .0015" because .015" is HORRIBLE if that is the right #. Ford doesn't recommend turning rotors off the car because 99% of shops do not keep their lathes maintained to the point that they will produce sufficient surface roughness, runout, and parallelism. I usually throw out rotors but recently I had a local shop that seemed to know what they are doing turn a set of Taurus rotors and I indicated them off the car when I got them back, and they had 0.006" runout. I threw them out and had wasted $35 to get them turned, and then I had to buy new rotors anyway. The Centric Premium rotors were like $40 each and measured 0.0015-0.002" runout off the car. Also a lathe turned finish is horrible compared to a ground finish that a new rotor will come with, which means you get much worse pad contact and will have local hot spots for many miles until your pads finally fully bed in.
 

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I'm sure that it's a machine designed to increase productivity. Turning a rotor on the vehicle may have it's advantages, but after 30+ years in the automotive world.. I think that it may be more of a sales gimmick that a tool that is used to give us a better end result.
 

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I don't understan truning roters. The cost for new ones on a Taurus has always been very reasonable. Its good money spent. I recomend buying the best break parts you can and never look back. The last thing you want it to have issues when you have to stop hard. Buy good breaks buy good tires and take some comfort you have done what you can to help the situation.

-Bryan
 

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Update on turning the rotors off the car---
  1. Had brake specialty place turn the front rotors off the car.
  2. Installed on of them on the car, torqued uniformely to 20 ft/lb, indexed the rotor to the hub with paint stick
  3. Set up my dial indicator about an inch from the outside dia of the roto.
  4. Turned the rotor an hub through 360 deg, found lateral runout low spot of 0.035". Marked this point on the rotor.
  5. Turned rotor one stud from base index, repeated the procedure, found same amount of runout at same mark on the rotor.
  6. Repeated 3 more times, same results. Hub face is not perfectly perpendicular to the axis.
  7. Raybestos sells a Ford Disc Brake rotor shim kit, BA-903-03. I purchased a pair. They are round shims which go between the rotor and hub. They are wider one side than the other by a few 1/10,000's" the items are about $18.00 ea.
  8. Installed the shim, reinstalled and torqued rotor to 20 ft/lb, ran it through again, is now within 0.015" lateral runnout. That's pretty doggone close!
  9. Test drove the car, brake pedal has absolutley no pulsing.
Some may ask why didn't I buy new rotors instead of turning these? They only needed to have a very shallow cut to clean them up. At $12.00 ea to turn them it was not economical to replace them as there is substantial amount of meat left before wear limit. If you were to buy new rotors, you would still have the hub squareness issue, unless you turned them on the car.

Based on the responses to various threads I have followed on this site I'm sure this post will draw a lot of criticism telling me how stupid I am for doing it this way, but this is my two-cents worth for anyone that is interested.
At $12 per for turning and $18 per for shims, that's $30 per, or the cost of a good OEM grade rotor....
(no pedal pulsing here either)
 
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