machining rotors

[artificialist]

Originally Posted By: OneEyeJack
In the future brake rotors will probably be designed with built in hubs and wheel bearings installed to eliminate subtle problems that are hard for someone changing parts to figure out.


Certain versions of the Ford F-series trucks had rotors with bearings built in from 2004 to 2008. I am not sure about 2009 and up.

Those Rotor+Bearing combos cost about $200 each, making machining them worthwhile.

 

[Johnny2Bad]

I think it's OK to machine OEM rotors or OEM-quality replacements (ie the standard replacement Brembo rotors). Some vehicles are notorious for creating runout on rotors ... the 1973-86 GM/Chevy light duty trucks, for example, have front rotors that are notorious for rotor stress when dealing with water immersion, and that 1-time event will often put the rotors out of round.

Also, you can create stresses on rotors if you don't properly torque (and re-torque) wheels when servicing tires that will cause offset.

"Premium" rotors run the gamut ... some are just "toys for boys" and don't offer any performance advantage (and may "offer" performance disadvantages) while others are serious products that decrease stopping distances but more importantly also reduce unsprung weight, or in some cases do not increase unsprung weight while increasing diameter.

I would put it this way ... do you check the weight of the exact size tire you are considering when you shop for tires? Do you check the weight of the aftermarket wheels you are considering? A premium 1-piece rotor can take 4 pounds of unsprung weight from each corner; a 2-piece (rotor and hat) can shave 10 pounds. If handling is an issue with you, then there will definitely be a noticeable difference.

That is one example; there are also differences in cooling capacity with the design of vanes, etc and rotors are most certainly made from different iron alloys and like all metal, cost is affected as well as performance.

Most premium rotors are made in the USA, the UK, Australia, and some European countries.

I have a truck I would never consider doing a rotor upgrade "just because" and I have a car that does some track duty. The car weighs less than 2500 lbs, and I was able to shed 10 pounds per corner while at the same time increasing rotor diameter by 2" by changing rotors. The wheel, tire, lug nuts and valve stems weigh 33 lbs; upper and lower A-arms, ball joints, and other moving parts weigh 22 lbs. 10 pounds means a lot under those conditions.

I could shave another 4 pounds per corner by changing wheels, but since it also sees street duty there are strength considerations as well that have to be taken into account. The rotors however are stronger than OEM and again for strength are plain, not slotted or drilled (and are USA made start to finish)

You can definitely notice the change in unsprung weight and stopping distances are much improved as well (I stop 30 feet sooner at 100 kmH).

In other words, horses for courses.

 

[Johnny2Bad]

Just a followup to the above, although I said I would never consider premium rotors for my 1/2 ton, that doesn't mean I ignore braking performance.

With the truck, I retained the stock drum rears (drum brakes are very good at slowing a vehicle) and the stock front rotors (disks are very good at stopping a vehicle; and there is a difference between slowing and stopping).

I did however upgrade the front calipers to the 1-ton OEM variants which have a larger piston area and also use two pistons to clamp the rotor versus one pressing on one side of the rotor. Again, hard braking was improved over stock.

Just wanted to mention it since there is more than one way to skin a cat.

Premium rotors and kits to swap to 4-wheel disks are available for that truck but every application has it's own issues and solutions. The cost / benefit for premium rotors simply were not there for the truck. Lots of cash for not much improvement.

In fact the reduction in stopping distance reported by testers and forum posters was not as good as the caliper swap and much more expensive. Nor are you going to feel or see much handling improvement since unsprung weight on a truck is high and always will be high.

You have to look at the big picture.

 

[Johnny2Bad]

There is nothing *inherently* wrong with offshore manufacturing; we can use the People's Republic of China (PRC, as compared to Taiwan) as an example.

America of the early 20th century did not have a reputation for quality in every industry; some were good and some were just plain cheap. The reputation for quality did not happen until after WWII.

Japanese goods in the 50's and 60's were also much like modern China's. It took Japan 30 years to obtain a reputation for quality.

Things are much different today in America, in Japan, in Germany, but China will catch up. It's only a matter of how long.

A manufacturer needs to have people in the PRC that closely watch the factory and the management. If you don't have people there, your stuff will be going out the back door as copies and source material used in manufacturing will be poorly controlled. The components you use to make parts can be counterfeits if you do not take precautions.

You cannot simply contract with a Chinese manufacturer, stay in your office in Chicago, and expect things to go smoothly. In fact you can pretty much state without reservation that they will not go smoothly.

On the other hand if you manage your offshore part supply closely, quality can be excellent. That is why it's worthwhile to deal with known good brands even if the part originated offshore, because they have this figured out and implement the necessary controls.

There is some, but not much, difference in price between "mystery manufactured" parts and reputable brands that come from China. There is value in paying just a bit more which amounts to a premium for good management.

By way of example, Manley's lowest cost H-beam rods are made in the PRC and I doubt Manley would argue if you suggested these rods come from the same factory as numerous "eBay special" off-brand units.

But Manley finish-machines these rods in the USA; many of the "eBay specials" come to you as machined in the PRC. The difference? About $40 a set. Very much worth it. Plus Manley will know very quickly if there are problems with metallurgy or manufacturing because they work the part themselves.

You can shop eBay or you can shop NAPA, but you can't paint everything from China with the same brush.

In any case it may all be moot in a few years; China's industrial wages have increased tenfold since 2000 and are now roughly equivalent to Mexico. There is a lot of new manufacturing plants being constructed in Mexico today in preference to China; it's the "happening place" for companies seeking access to the US and Canadian markets right now in combination with low-cost manufacturing.

Mazda's first non-Japanese factory will open in Mexico soon; if you bought a deep freeze in the last 5 years it's almost certainly made in Mexico (90% market share).

It's predicted that Mexico will surpass China as America's #1 source of imports within 5 years.

Okay, I'll shut up now.