Per the 1970 FSM the minimum front brake rotor thickness is 1.230 inches. What is the thickness of a brand new rotor?
When a rotor is turned, how many thousandths of an inch is removed?
I have an opportunity to acquire some used rotors at a boneyard and they measure above the minimum thickness, and would likely get them turned to clean them up, but I am wondering what the starting point thickness of a new rotor would be.
Hello Nicholas,
Are the boneyard rotors from a '70 Cadillac? How were the rotors measured? Were they measured in multiple spots on the rotor?
I don't own a '70 so i cannot tell you what the thickness was when new. In the case of drums, there may be a few ten thousandths available for machining. If the shop manual indicates a minimum thickness of 1.230, then it is not unreasonable to expect a new thickness of 1.250 giving .020 for machining.
How much material is removed is a function of the condition of the rotor. Many used rotors will have some warpage, so it is unlikely that a consistent, uniform depth of cut will true the rotor. Usually, a warped rotor will require a deep cut.
Respectfully submitted,
Christopher Winter
I know that whenever I change pads, I have to back the piston(s) ALL the way in or the caliper will not go over the rotor.
Take a caliper off, put New pads in it and back the piston all the way in. Measure the distance between pads and subtract .010 or. That will be close to a new rotor's thickness.
Watch O'Reilly autoparts... they had new rotors for sale last year, for like 2 days before they sold out. That's when
I got mine. Pads are everywhere. If you need new rotors I know John Abend hogged a bunch from O'Reilly during that
sale, find him on Facebook "The 1965-1970 Cadillac Collective".
\m/
Laurie
Thanks for the replies, the boneyard rotors, if I spend the time to wrench them off of the verhicles that they are on, would be off of two different 1969 deville convertibles. I measured them in two different spots, they are 1.236 thick, so if they were to get turned perhaps would end up being under the 1.230 minimum.
If I go the new rotor route, do they include the inner and outer bearing cups? (the picture on the Oreilly site looks like they do), and can and/or should I use my existing inner and outer wheel bearings?
Quote from: colorado4x4 on September 27, 2019, 08:45:52 AM
Thanks for the replies, the boneyard rotors, if I spend the time to wrench them off of the verhicles that they are on, would be off of two different 1969 deville convertibles. I measured them in two different spots, they are 1.236 thick, so if they were to get turned perhaps would end up being under the 1.230 minimum.
If I go the new rotor route, do they include the inner and outer bearing cups? (the picture on the Oreilly site looks like they do), and can and/or should I use my existing inner and outer wheel bearings?
Change the bearings, they usually come with the rotors.
Quote from: colorado4x4 on September 27, 2019, 08:45:52 AM
If I go the new rotor route, do they include the inner and outer bearing cups? (the picture on the Oreilly site looks like they do), and can and/or should I use my existing inner and outer wheel bearings?
New Rotors come fitted with bearing cups, but you have to purchase the cones separately.
If your own bearings are known to be good, then simply remove them, with the cups, and put them into the new rotors.
One thing to be very careful of is not to purchase new rotors that are made in China. I would prefer to use old US made ones, machined, than new Chinese, and that includes the bearings as well.
Bruce. >:D
Quote from: The Tassie Devil(le) on September 27, 2019, 08:41:04 PM
New Rotors come fitted with bearing cups, but you have to purchase the cones separately.
If your own bearings are known to be good, then simply remove them, with the cups, and put them into the new rotors.
One thing to be very careful of is not to purchase new rotors that are made in China. I would prefer to use old US made ones, machined, than new Chinese, and that includes the bearings as well.
Bruce. >:D
EVERYTHING IS MADE IN CHINA BRUCEThe 2019 Cadillac rotors are made in China.
So were my new ones for The Ark, and the bearings. Michael didn't grumble when he inspected them
before he installed them. "They're fine", etc.
I just had him put the cheapest pads and rotors on my SUV, $100 for the pair at Rock Auto.
Made In China. They're fine.
Quote from: Cape Cod Fleetwood on September 27, 2019, 01:32:59 PM
Change the bearings, they usually come with the rotors.
DO NOT use the cheap a$$ bearings that come with the rotors. get a set of Timken bearings from RockAuto or somewhere.
Get the Ceramic pads. The pads for RWD Full size are the SAME from 1968 through 1996. Look it up on RockAuto if you don't believe me.
Bone yards can be a good source of usable rotors especially here in the desert southwest. Warpage is a problem independent of the amount of stock remaining to effect a proper resurfacing. I use a Van Norman brake lathe for rotor resurfacing. It is a true machine tool that is very different than the units used at auto parts stores. After mounting the rotor on the machine spindle, the rotor is turned slowly against an index pointer affixed to a dial gauge and run on both sides of the rotor. A rough indication of warpage is then readable on both sides of the rotor. I always listen to the machine as the initial cuts are made. The sound of the cutter against the rotor is indicative of the degree of any warpage. With this machine it is possible to remove different amounts from each side of a rotor to obtain a satisfactory usable rotor that otherwise might be discarded. The caliper piston can accommodate the slight difference in side to side rotor thickness.
There is a thread here somewhere that shows you how to use 1972-76 rotors on a 1968-71 Full size RWD (all except Seville).
I also have one NIB 1968-71 rotor if anyone is interested.
G'day Mike,
Thanks for bringing that up. It was myself that did the conversion, and wrote it up on the Modified Chapter.
http://www.modifiedcadillac.org/articles/onepiecediscswap/onepiecediscswap.html
Bruce. >:D
PS. Not sure why it comes up in blue, which makes it very hard to read. See if the attachment makes it easier to read.
Quote from: The Tassie Devil(le) on September 28, 2019, 08:49:58 PM
G'day Mike,
Thanks for bringing that up. It was myself that did the conversion, and wrote it up on the Modified Chapter.
http://www.modifiedcadillac.org/articles/onepiecediscswap/onepiecediscswap.html
Bruce. >:D
PS. Not sure why it comes up in blue, which makes it very hard to read. See if the attachment makes it easier to read.
I did the same thing. 1972-76 rotors are half the cost of 1968-71 and the inner bearings and seals cost the same, and if I do come across a 1968-71 rotor it will fit right in (with the correct inner bearing and seal). I went 1 step further and put the 1970 one piece steering knuckle on the car as well.