Brake rotor runout- Rookie needs advice

[Gary R.]

Re: Brake rotor runout- Rookie needs advice

I wouldn't use individual cutout shims. For one thing, you no longer have the full surface contact of the rotor to the face of the hub. You compromise the strength and heat transfer.

Secondly, you would have a very difficult time establishing the correct gradual transition from the thickest shim to no shim. If your thickest shim is .006 and the thinnest spot is no shim, what should the shims between the two be so that you establish the correct transition and don't distort the rotor when you tighten it?

The tapered shims provide full surface contact and there is no concern about transition, it is established in the taper.

Steve

Hi Steve,
Well I will have to disagree with your statements. If someone follows my procedure, as simple as it is, there is not going to be any compromise the strength, heat transfer, or warpage. I have done this literally hundreds of times and with the rotor bolted on it will be stronger then just lug nuts alone. I have them on street cars, road racers, and drag cars no issues at all. Now if someone varies from that procedures then yes you are correct who knows what the run out will be.

Considering what I have encountered with previous mechanics work on arms and rotors = burrs, dings and other surface imperfections, a 002-005" SS shim on one stud is not going to cause a problem. My own 72 has 1000's of miles on it without a change in run out, the last I checked and the rotor is secure. 002- 005 is critical in many applications in the automotive and machine world but not as much in this application. I have never seen a rotor hat distort from a thin shim. I have seen mechanics wreck rotors turning them though.

This is something just about any guy can do at home, once they understand the principle and source shim stock. The NAPA type full and partial shims may have a good place in other applications and some may work with these but the cost just isn't justified in my opinion.

I have also setup spindles and hubs in a lathe to kiss cut and found even those will have rotor run out since they were not a matched assembly. I have bolted rotors on spindles and faced them as one to -0- run out but I like to have access to the parking brake so that is why I bolt them on. I removed them and bolted them back on and the runout opened up to 002"- still fine. Under 003" runout will work great on any 65-82 vette that has good calipers, pads, and hoses.

I have gone over this for years and many have been able to do this at home and enjoy solid brakes. I have also encountered those that will tell me it won't work, just as I have been told a tuned posi without springs won't work yet they sure seem to in all the units I built over the years. I can only offer my experiences and leave the final decision to the owners on what they want to do but my brakes work great. Based on feedback from guys over the years they also have great brakes and positraction.

This is about all the time I will expend on this subject, those that would like more info or help know how to contact me. Now I'm back to tuning a posi without springs!

[Steve G.]

Re: Brake rotor runout- Rookie needs advice

Hi Steve,
Well I will have to disagree with your statements. If someone follows my procedure, as simple as it is, there is not going to be any compromise the strength, heat transfer, or warpage. I have done this literally hundreds of times and with the rotor bolted on it will be stronger then just lug nuts alone. I have them on street cars, road racers, and drag cars no issues at all. Now if someone varies from that procedures then yes you are correct who knows what the run out will be.

Considering what I have encountered with previous mechanics work on arms and rotors = burrs, dings and other surface imperfections, a 002-005" SS shim on one stud is not going to cause a problem. My own 72 has 1000's of miles on it without a change in run out, the last I checked and the rotor is secure. 002- 005 is critical in many applications in the automotive and machine world but not as much in this application. I have never seen a rotor hat distort from a thin shim. I have seen mechanics wreck rotors turning them though.

This is something just about any guy can do at home, once they understand the principle and source shim stock. The NAPA type full and partial shims may have a good place in other applications and some may work with these but the cost just isn't justified in my opinion.

I have also setup spindles and hubs in a lathe to kiss cut and found even those will have rotor run out since they were not a matched assembly. I have bolted rotors on spindles and faced them as one to -0- run out but I like to have access to the parking brake so that is why I bolt them on. I removed them and bolted them back on and the runout opened up to 002"- still fine. Under 003" runout will work great on any 65-82 vette that has good calipers, pads, and hoses.

I have gone over this for years and many have been able to do this at home and enjoy solid brakes. I have also encountered those that will tell me it won't work, just as I have been told a tuned posi without springs won't work yet they sure seem to in all the units I built over the years. I can only offer my experiences and leave the final decision to the owners on what they want to do but my brakes work great. Based on feedback from guys over the years they also have great brakes and positraction.

This is about all the time I will expend on this subject, those that would like more info or help know how to contact me. Now I'm back to tuning a posi without springs!

Hey Gary,

Each to his own. I told the op what I wouldn't do and why I wouldn't do it. There's no need for you and I to debate or discuss it further. I prefer to have my rotors contact the hub on the full face, just like the factory designed them and according to what makes the most sense to me.

I admit that as journeyman in the trade for almost 40 years I am inclined to take few chances and rely on the expertise of the teams of engineers that designed this stuff when it comes to areas of safety like this. This is a litigious world we live in.


Steve

[Gary R.]

Re: Brake rotor runout- Rookie needs advice

Steve,
I agree I have no time or desire to debate this. Opinions were expressed on both sides to help others do as they will. I tend to follow the designs of those guys from 40-60 years ago as well, in most cases. Some of those ideas didn't always work out so well though, maybe a discussion for another day and time.

What I will do whenever I get some time is make a cut away of an old spindle and rotor to show they are flat and tight when shimmed correctly, but don't when I'll have time to do it. I am working on some other cut aways to bring to Carlisle next month. Safety is paramount, I never play the scale with it. Maybe the guys who are welding the teeth in steering boxes or flipping the worm nut upside down -then selling them to vendors and customers should take note. The rebuilder in TX who sold a guy a rebuilt diff with a 2" cracked posi is another one. See you started me rambling! Gotta go, back to the 72 posi!

[Don H.]

Re: Brake rotor runout- Rookie needs advice

this seems like a good place to leave it since all had their say.