Rotors (replace or not)

[bobjffry]

I get some vibration when I apply brakes so I recently took the '66 to a shop for them to test drive. They suggested I replace the pads and rotors considering the "obvious uneven wear of the rotors." I always thought you had to take the rotors off and measure them to determine if they need to be replaced or not. Is that really something that can be determined from how the car feels while driving? I'm about to convert to the dual master cylinder and don't have a problem replacing the rotors, but I don't have money to throw away if replacement isn't needed.

[ReijerLincoln]

I do know that if the car - and particularly the steering wheel - shudders during braking, the front rotors are warped and need to turned. If there's not enough meat on them to have them turned, they need to be replaced.

If the shop said nothing about turning the rotors and did not even measure their width, I'd find another shop.

[TonyC]

Dittos to Reijer's assessment. If they didn't physically measure the thickness of the rotors, don't use that shop. Take them off, take them to your nearest parts store, have the rotors measured and turned--but if they say the rotors are too thin to turn, then that is your cue to get new ones.

I too have that recurring problem with Frankenstein. Even after turning, they eventually warp again, causing a Richter-measurable shudder. But I'm still not sure if I should go for fresh ones; could be that the bearings and respective cups inside the hub are mismatched and contributing to that warping. But the roll is normal, no noise or vibrations when rolling, so I don't know. Something I need to find out when I go back to do surgery on him.

---Tony

[bobjffry]

FYI, I relocated to southern Cali so I'm enjoying her a lot more now. Top pretty much stays down, but I occasionally let it up to give her exercise and it gets a little chili at night.

[brendanw]

It's a little long-winded, but I put up a REALLY detailed post on rebuilding the front brakes on my '68, including the thickness measurement of the rotors relative to the original Lincoln specs. It's not a straightforward measurement, but can be done by a good shop with pretty basic shop tools. Get a cup of coffee to sip on and read on!

viewtopic.php?f=4&t=38743&p=280425&hilit=68+brake+rotor#p280425

[TonyC]

Hi, all,

Bumping this thread because it seemed the most relevant in my topic search. A couple days ago I searched the Forum for anyone's experience with transferring hubs to new rotors; a few folks mentioned wanting to try it but no follow-ups with actual experience. As of yesterday, I can say now that I have that experience and can provide a guidance...as well as some hard lessons learned, being that it was not all good.

My guess was right about the lug studs being the main parts holding the hub and rotor together as one piece. I was able to un-stake them by first screwing the lug nuts onto the studs, flush with the stud tips, then using a thick driver bar and a heavy hammer to push them out (see first visual aid below). Once the studs were out, I saw that the hub was still jammed into the rotor; decades of use did that, and it almost looked like they were in fact one piece. But I knew that couldn't be the case, so I used another handy cobbled-up driver tool, placing the unit face-down on a large bench-vise opened up just past the hub diameter, then was able to knock the hub free with about four good whacks (see second visual aid below). Another thing I was right about was that the inner wheel bearing and grease seal do not have to come out, at least not with the handy-dandy driver tool I found in the auto center's machine shop. The smaller outer bearing does have to come out once the hub is unbolted from the spindle, but not the larger inner one, nor the grease seal. Once done, I placed the hub onto the new rotor (third visual aid below), hand pressed the studs into the back of the unit feeling for stake grooves to line the studs into, and proceeded to stake them down...

...and that was when my problems really began. I made the mistake of trying to use the flat sides of the lug nuts to torque the studs back into place. The first hub-rotor job wasn't so bad, but the second taught me a valuable lesson which I'm passing on at this point: NEVER use the lug nuts to press the studs back into place! It sounds like a good theory, but in practice it cannot be done. The torque limits of the studs and nuts are well below the amount of force needed to drive the studs fully into place, meaning you risk stripping the threads of the studs and nuts. I stripped four lug nuts and a stud on the second rotor-hub job doing that, before finally realizing it was a bad idea. To finish the job in the little time I had left, I finally flipped the unit face-down on the bench-vise and used the driver rod and heavy hammer to sink the studs the rest of the way. There was a hydraulic press there, but I was reluctant to try using that without staff supervision. I then had to cannibalize nuts from the other wheels just to be able to secure four nuts on the one, until I could buy new lug nuts. Luckily, O'Reilly had them in stock (for the record, the stock dimensions for the studs and nuts are 1/2" x 20-pitch). This morning I went back to finish the repairs to the botches I did; I was lucky enough to repair the stud threads with a dye and one of the nuts with a tap, again thanks to the auto-center's machine shop. Although I do feel like they have been compromised, they held up to the 92 foot-pounds of torque I always apply to the wheels without spinning (i.e., stripping again). Another bad thing that happened was that, due to issues with the nuts and studs but still trying to get me out the door yesterday, one of the staff suggested leaving off the wheel covers until I could get replacement nuts, so I did. When I got home I discovered that the grease cap on the right wheel spun off somewhere between the shop and home, lost forever. I got a new one at O'Reilly, but the real kicker is that I've lost a radio-static collector spring, which fits inside the grease cap and contacts the center of the spindle. Now I need to source another one, somewhere, from someone. Anyone have a spare...?

The take-away from this, to share with everyone here, is not to try this yourself at home, unless you have a machine shop at home to include either a press or some heavy driver tools and a lot of arm muscles. It's a workout. Or farm out the rotor transfer to a shop, which is probably the better idea.

The job is done now, and I think it will be some time before I get used to the total absence of vibration when I press the brake pedal.

---Tony