tyau

iTrader: (1)

What do many of you guys have for rotor runout?

Nissan suggests that a maximum runout of 0.0028" is tolerable. Many brake manufacturers round that off and say 0.003" is fine. The FSM doesn't specify the amount of tolerable runout for the hub. Many sites seem to imply that runout under 0.004" is fine for the hub.

I have an M45 and I have just removed the rotors for turning at a local garage. One of the hubs has a runout of 0.0025". I am not sure if the rotor is true, but the best rotor runout I could get is 0.005". This was much better than the 0.01" I had previously before resurfacing. But 0.0049" is still a little over the 0.0028" that is tolerable according to Nissan. I tried cleaning the problematic hub with sandpaper and wire brush. That reduced runout very slightly. I am suspecting that the rotor was not machined truly by the shop, thereby causing some runout. Is this possible?

I don't plan on buying new rotors or having these rotors resurfaced again. Buying new hub is definitely not an option because I just spent 40min cleaning it and the bearing is in tip top shape. I only drive the M45 four months a year during Spring. The rotors will last for years even if I leave the runout out of whack considering I will probably only put 3000 miles on it in 2011. But now that the car is uninsured, I would like to work on it to get as little runout as possible.

I plan on rotating the rotors between left and right and see if I can get a slightly lower reading. What do you guys think I should do? Do you guys think that a 0.0049" runout is acceptable?

I am sure that dealers wouldn't even bother checking for runout when you go in to have your rotors and pads replaced. With so many dealers offering "brake deals", the chance of them performing a runout test is even slimmer. Imagine an average person wanting to get his front brakes replaced, but then told that his hubs need replacement for another $500. Imagine his reaction. Although Nissan recommends resurfacing rotors using an on-car lathe, not many dealers have this equipment. Most still use bench lathes.

terrasmak

iTrader: (8)

Just buy a rotor, they can be had for under $40 each

cubs4worldseris

iTrader: (6)

Yep, just get new rotors. You can get quality rotors for cheap.

tyau

iTrader: (1)

I guess I will eventually. For now I just want to get runout to minimum by indexing the rotors because the rotors were just machined. Need to save money for the Z!!!

I am suspecting the runout is caused by the ancient lathe the shop used, or that the rotors were actually warped and resurfacing only reduced the unevenness.



Update: I just remember one thing. The problematic rotor before it was machined had a bird stuck into the vane area.The dead bird blocked airflow and caused overheating and actual warpage to the rotor. This suddenly came to my mind, because it happened more than 2 years ago. Again, I only put about 16,000 miles onto my M45 during my ownership.

I don't seem to have any vibration issue with 0.005" of runout on one rotor. I will just use the rotor until it goes bad. It probably won't go bad until another 6000-9000 miles. lol

solidsnake

iTrader: (14)

links to good stock rotors?

tyau

iTrader: (1)

I no longer buy stock rotors. Nissan contracts different Japanese factories to produce their rotors. From my experience, their quality is subpar to Centric Premium, about what you'd get from Centric Regular Grade parts. I am not sure what the rules are regarding posting non-sponsor links, so PM me for sites I personally go to.

I use EBC on the Z. They are CHEAP and made in England. Best quality coating I have ever seen for brakes under $100 each, and they weigh more than OEM, made with high Graphite metal. I personally find them to be of better quality than Brembo branded rotors. The Lotus enthusiasts mostly use EBC for their cost effectiveness.

The rotor noted in my original post is NOT of EBC. It is OEM rotor, manufacturered in Japan by Kiriu. Very expensive, susceptible to runout and "warping" under stress quite easily.

Chris_B

I don't like seeing any more than .002" runout, with less than .001" being ideal (and very hard to achieve!). I definitely start to feel .003" at the steering wheel, so that's where I get my targets.

Here is a great technical article from DBA, one of the best in the business, regarding measuring runout:

https://promo-manager.server-secure....sletter-11.pdf

Chris

tyau

iTrader: (1)

DBA's maximum tolerance for rotor runout is 0.001. That is achievable and I've done it in the past by rigorous cleaning or by pure fluke.

I will try cleaning the rotor and the hub even more to reduce the 0.005" I have. There is still a very very fine layer of rust that makes the difference of 0.001". 0.003" is my goal. After all, the rotor is old, so perfect trueness is out of the question.

I am going to get a hub cleaner attachment to clean the hub and around the lug area. I hope this makes the 0.001-0.002" difference I am looking for.

Chris_B

Right. Just remember that .001" at the hub translates to nearly .003" at the outer diameter of the rotor -- IF the rotor is a perfect .000" on its own. To get to less than .001" at the rotor OD, indexing (and maybe a little luck!) is usually required.

tyau

iTrader: (1)

Yeah, my hubs still rusty. I was unable to clean them with sandpaper and a wire brush. I am having my fingers crossed that the 0.0049" of runout I am getting is from rust on both the rotor and the hub. The average thickness of hair is about 0.004". If the hub is not clean, that could cause runout. The rust could be the cause of this runout, I hope.

I just bought a 3M hub cleaner... hope it works!