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Re: Shop says new drums and rotors are not turnable
[Re: moparx]
#2928423
05/30/21 09:59 AM
05/30/21 09:59 AM
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Joined: Jan 2003
Posts: 10,721
North Dakota
6PakBee
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 10,721
North Dakota
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i turn rotors and drums on the lathe. i get a much better finish than a brake lathe, and i can do the job when i feel like it because i have "extras" on the shelf. i turn them, put a thin layer of grease on the fresh surface, then put into a small garbage bag and on the shelf ready for the next time needed. that gives me something to do so i stay out of trouble.  What are you using for a mandrel?
"We live in a time when intelligent people are being silenced so that stupid people won't be offended".
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Re: Shop says new drums and rotors are not turnable
[Re: 6PakBee]
#2928425
05/30/21 10:02 AM
05/30/21 10:02 AM
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Joined: Jan 2003
Posts: 10,721
North Dakota
6PakBee
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 10,721
North Dakota
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i turn rotors and drums on the lathe. i get a much better finish than a brake lathe, and i can do the job when i feel like it because i have "extras" on the shelf. i turn them, put a thin layer of grease on the fresh surface, then put into a small garbage bag and on the shelf ready for the next time needed. that gives me something to do so i stay out of trouble. What are you using for a mandrel? For rotors, did you mount a brake lathe cutting head to the lathe toolpost?
"We live in a time when intelligent people are being silenced so that stupid people won't be offended".
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Re: Shop says new drums and rotors are not turnable
[Re: 6PakBee]
#2928504
05/30/21 02:00 PM
05/30/21 02:00 PM
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Joined: Sep 2003
Posts: 19,408
north of coder
moparx
"Butt Crack Bob"
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"Butt Crack Bob"
Joined: Sep 2003
Posts: 19,408
north of coder
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i whittled out a few different mandrels from chunks of 5" aluminum bar stock for late style, hubless rotors. for these, i duplicated the hub register outside diameter to locate the rotor, then use a piece of 5/8" [it might be 3/4"] round plate that just covers the bolt pattern of the rotor, retained with a 3/4" bolt to clamp the rotor to the mandrel. this setup somewhat duplicates the clamping forces the rotor sees on the vehicle. for the rotors with the cast hubs [like our classics], i use a couple of the cones from an old snap-on wheel balancer i picked up at carlisle many moons ago. this balancer uses a shaft resting on four sealed bearings to find the heavy spot on the tire/wheel combo. [it works pretty good !] anyway, i pick the cones that fit the bearing races, and use a 3/4" bolt to retain the assembly to a small face plate on the lathe. for cutting, i use 1" diameter boring bars [one right hand, one left hand] with replaceable carbide cutters [diamond shaped] on either the tool post or the tail stock post, depending on whether i'm cutting the front or rear of the rotor. this setup is very stout, and there is no deflection during the cutting process. for drums, i have similar mandrels to fit different drum register holes, and i use the same cutting tools as used with the rotors. the secret to my success is a very rigid clamping setup and short [just long enough to get the job done] large tooling. the lathe i use is not a crapsman "wobblechuck", so it's a tad more heavy duty than your best brake lathe.
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Re: Shop says new drums and rotors are not turnable
[Re: moparx]
#2928522
05/30/21 03:05 PM
05/30/21 03:05 PM
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Joined: Jan 2003
Posts: 43,555
Round Lake Beach, Illinoisy
Rhinodart
Rhinotruck
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Rhinotruck
Joined: Jan 2003
Posts: 43,555
Round Lake Beach, Illinoisy
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The Chrysler dealer where I bought my truck only uses new rotors, they will not just replace pads. I put pads on the rear rotors on my 2015 truck and I can tell it does not stop as well as original but it is good enough.
The funny thing about science is that if you change one miniscule parameter you change the entire outcome to the way you want it.
JB Rhinehart, Realist
A-Body's RULE!
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Re: Shop says new drums and rotors are not turnable
[Re: moparx]
#2928586
05/30/21 06:13 PM
05/30/21 06:13 PM
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Joined: Jan 2003
Posts: 10,721
North Dakota
6PakBee
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 10,721
North Dakota
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i whittled out a few different mandrels from chunks of 5" aluminum bar stock for late style, hubless rotors. for these, i duplicated the hub register outside diameter to locate the rotor, then use a piece of 5/8" [it might be 3/4"] round plate that just covers the bolt pattern of the rotor, retained with a 3/4" bolt to clamp the rotor to the mandrel. this setup somewhat duplicates the clamping forces the rotor sees on the vehicle. for the rotors with the cast hubs [like our classics], i use a couple of the cones from an old snap-on wheel balancer i picked up at carlisle many moons ago. this balancer uses a shaft resting on four sealed bearings to find the heavy spot on the tire/wheel combo. [it works pretty good !] anyway, i pick the cones that fit the bearing races, and use a 3/4" bolt to retain the assembly to a small face plate on the lathe. for cutting, i use 1" diameter boring bars [one right hand, one left hand] with replaceable carbide cutters [diamond shaped] on either the tool post or the tail stock post, depending on whether i'm cutting the front or rear of the rotor. this setup is very stout, and there is no deflection during the cutting process. for drums, i have similar mandrels to fit different drum register holes, and i use the same cutting tools as used with the rotors. the secret to my success is a very rigid clamping setup and short [just long enough to get the job done] large tooling. the lathe i use is not a crapsman "wobblechuck", so it's a tad more heavy duty than your best brake lathe. I have an Enco 12" X 36" metal lathe and have been wondering if I could cut drums/rotors with it. Thanks for the complete and detailed response. 
"We live in a time when intelligent people are being silenced so that stupid people won't be offended".
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Re: Shop says new drums and rotors are not turnable
[Re: feets]
#2928949
05/31/21 04:42 PM
05/31/21 04:42 PM
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Joined: Jan 2005
Posts: 12,419
Kalispell Mt.
HotRodDave
I Live Here
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I Live Here
Joined: Jan 2005
Posts: 12,419
Kalispell Mt.
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Some manufacturers like BMW and Merciless Bends have rotors that are surface hardened. If you turn there there's a good chance you'll cut off the hardened surface. That dramatically shortens the lift of the rotor. Funny you say they are hardened, they usually wear the rotor out as if it was made of playdough! Most of the time there is a huge ridge either side of where the pad rides because the pad eats right through the rotor long before it gets metal to metal.
I am not causing global warming, I am just trying to hold off a impending Ice Age!
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Re: Shop says new drums and rotors are not turnable
[Re: Kern Dog]
#2928959
05/31/21 05:03 PM
05/31/21 05:03 PM
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Joined: Feb 2003
Posts: 4,796
Castlegar, BC, Canada
That AMC Guy
master
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master
Joined: Feb 2003
Posts: 4,796
Castlegar, BC, Canada
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Hey....What was so wrong with the "Rambler Man" name? It was an inaccurate moniker. I rarely ramble and "man" is quite subjective these days.  That, and I do intend on starting up a small Youtube deal to document my adventures and I've decided on "That AMC Guy" to be my brand name. So, I've changed my name on most of the forums I frequent. If anybody remembers the comedian Glenn Foster, they'll get the reference. His website used to be "thatcanadianguy.com" because he and I were in the same boat; folks often can't remember what our name is.
Last edited by That AMC Guy; 05/31/21 05:03 PM.
Bloody Mary, Full of Vodka, Blessed art thou among cocktails....
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