Wow, never seen so many roller thrust washers in use for one application. They are a stout low friction method of keeping clearances accurate. Just amazed how well they all looked given the amount of saturated heat they must endure. And then, the darned transmission is filled with plastic washers! It's almost like two different engineering teams designed this unit with very different philosophy's ! :-)
As usual, great job and use of accessories. Learned what that funky looking thing in one of my Grandad's tool bins is actually for !! Lathe dog...huh..never knew. :-) Thanks for showing the technique used and its potential drawbacks. I know you hate having to do things twice, but I think it's a great lesson learned (for us).
Now for the fun stuff. I've read all the comments here about machining the hub, rotor and the potential 'dangers' it may cause on the axle. There are indeed some potential dangers if the application is misguided. But in this case, none exist. I'm not a machinist, I'm a mechanic and have raced all forms of motorsports for over three decades. Fixed more than a few race cars and street rods in my lifetime.
What I would suggest are the following 'fun' parts for a machinist to consider as an exercise. When indicating a brake rotor for squaring it relative to registering it to an axle hub is to mic it to the inside face of the rotor hub, not the inside diameter of the bore itself. Once that's 'straight' on the lathe, then mic the ID of the rotor flange to center it. This ensures that the rotor is square to the axle hub flange and that any additional machining op is 'square'. Then if machining of the front of the rotor flange is required for any reason, it will be parallel to the inside wall. If the inside wall of the flange is excessively warped, it should either be returned to the manufacturer or machined flat and square to the axle. For the use intended, It's not critical. For a race car doing 150+ mph, it's where we get stupid picky.
The actual brake rotor faces with runout of a thousand is within tolerance for most general uses. But if it was for a big track (mile or longer) stock car, we'd never want more than 50 thousandth. Ductile iron and nodular iron expands roughly 6-7% per 200 F degrees. Stainless steel approximately 9%. I would be surprised if the axle hub gets over 200 F. In short track stock cars the highest recorded temperature I've seen is 250 F on the hat wall and 195 F at the axle flange, but that's with custom two piece units where the brake rotor is bolted to the hat. (steel). The heat transfer is not as much as some think it is. Somebody please tell me a mud truck where it is going 150 mph in 4 feet of mud, cuz that would be something worth watching! Baja trucks don't even know what brakes are :-)
The machining steps Adam shows are safe and not going to impact performance of the rotor and axle hub. If the rotor inside ID was cut more than .250, then it would be getting near maximum safe limits. The hub flange cuts are safe as well. Brake rotors with in-cast flanges (hat) are modified for use in stock car (Street Stock, Limited Late, Late Model) all over North America with no issues. The high heat is relatively contained to the brake rotor face surfaces and first inch of the brake rotor 'hat" near the rotors brake surface. There is not sufficient heat transfer to the hub that would over stress the axle hub assembly. The brake calipers see more heat then the hubs or brake rotor hats do.
And because this is for off-road truck use, there are no safety or engineering concerns that I see in any shape or form. I would have actually increased the clearance between the O.D. hub flange and brake rotor from 5 thousands to 15 thousands for ease of maintenance. Steel, ductile and nodular iron loves to rust and can be a pain in the ass. I would have machined the extra from the outside flange for the clearance required for the rotor. These rotor surfaces will be lucky if they get to 500 - 700 F. Premium steel brake rotors used in racing exceed 1,000 F, which you'll never see in a mud truck on the street or off road.
As for centering the rotor to register the wheel, in racing we never register using the center hub flange. The wheel studs and wheel nuts are centric. Wheel rims are either round to their stud centers or they aren't. If you wheel center on the axle center, it could tear the studs apart if the stud holes not centered properly or worse, bent from a racing incident. It's why all wheels are champfered (okay, conical) using champfered lugs. The only cars that axle center are Formula 1, GTP, GT1. And they do not do it for wheel balance or specific method of centricity. They do it for speed - ONE nut to re and re the tire (or tyre as they say in England) In all my years in stock car racing (including Michigan International Speedway), I've never had a wheel come apart or vibrate because of lack of axle center, which are stud centric. Wheel adapters made by Coleman, Lefthander, etc., are not hub centered engineered, they are stud centric designed. (i.e. 5 on 5 adapter to Wide 5). Yes, they are CNC machined using center as the reference point for the adapter studs. But the wheel itself is centered on the studs, which are centered on the...
Again, if the rim bends during a racing incident, the flange wall can bend and still hold the wheel onto the hub. If it was hub centered, it would probably fly apart due to imbalance. The number one reason wheel studs fail is fatigue from idiots using impact guns, not centricity.
last segment where he puts an small champfer on the axle hub is a wise move. Between the brake rotor surface and the hub face is called the rotor "hat". The hat can build up heat that when cooled allows corrosion to build quickly. If no space exists, it will be like crazy glue trying to get the rotor later. ugh, been there too many times.
I do have one ask of Adam in the future. Please (ohh please for us mechanics...), when machining parts that still have wheel bearings installed (such as the one's shown, which are press fit), ... PLEASE cover them up with a plastic bag. We don't know if a small bit of metal shavings or chips have accidentally contaminated the bearing grease. Even if they are going to be taken off, cleaned and inspected, sometimes metal chips just have a habit of getting stuck in the roller bearing races and no matter how much compressed air you use, won't come out and we don't see it or know. :-)
Great video and thanks again for posting it. Oh one day, big shop, Monarch lathe, 4 jaw chuck... damn! Maybe I should just move next door to Adam's place!
Fatigue failure over time is avoided and compensated for by overdesign of the bolts in terms of shear strength and yield stress for lateral forces.
The modification as done by Adam is a common one in America when retrofitting disk brakes to replace rear drum brakes - and, from this engineer's point of view, was done quite safely for the intended use on a Jeep vehicle.
There might be different standards involved if this was for a vehicle that had to pass the TUeV standards for the Autobahn - and, most definitely different design standards for a Formula One or Indy type race car.
Look elsewhere for validation of your version of reality - part of engineering is knowing which standards apply to which uses.
Also, your comments about "American crap" are not winning you any points here.
The axles and brake disks are for use on a Jeep - probably a Wrangler - being modified for use in mud crawling, and the original design was not compromised, despite your personal dislike for the design.
The axle as modified is safe for use on highways in the United States and Canada.
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