How many of you check TIR & DTV on new rotors?

[ordinarybloke]

There's so much auto-BS it's become the default. Fact is, unless they're a mile out you'll not notice. Of course someone will claim they're such an excellent driver or tech. they know in an instant - thus inferring you dear reader are the lesser. And so it goes.

You know what they say, When you can't beat them...

 

[wwillson]

There's so much auto-BS it's become the default. Fact is, unless they're a mile out you'll not notice. Of course someone will claim they're such an excellent driver or tech. they know in an instant - thus inferring you dear reader are the lesser. And so it goes.

You know what they say, When you can't beat them...

You say nobody could possibly notice run out and if they say they do they are full of it. Have you ever felt a pulsating brake and were curious enough to take the time to measure run-out? I have and it was there. I put data to a feeling and proved it was true. The rotor was not a "mile out of round". How does that make me full of it?

 

[The Critic]

You say nobody could possibly notice run out and if they say they do they are full of it. Have you ever felt a pulsating brake and were curious enough to take the time to measure run-out? I have and it was there. I put data to a feeling and proved it was true. The rotor was not a "mile out of round". How does that make me full of it?

To be clear - on sliding calipers, lateral runout does not cause pulsation by itself. The excessive lateral runout causes low spots to be worn on the rotor; this results in disc thickness variation. The excessive disc thickness variation is what causes the "pedal feedback" aka vibration.

 

[pdxglocker9mm]

I was gm mechanic for 8 years. Also sae certified. Brake pulsation was definitely a common concern. We had a on car brake lathe. But if you were replacing rotors due to being under minimum refinish thickness which is above the minimum stamped thickness. I would clock rotors and or used shims to get the runout as low as possible. I think in the long run it did help. Only takes a few minutes. I no longer wrench on cars for a living. I actually just bought my own HF clamping dial indicator setup this week. I need to do the brakes on my parents nissan rogue this weekend.

 

[Blueshound]

I was gm mechanic for 8 years. Also sae certified. .... I would clock rotors and or used shims to get the runout as low as possible. I think in the long run it did help. Only takes a few minutes. I no longer wrench on cars for a living. I actually just bought my own HF clamping dial indicator setup this week.

This is excellent mechanic process in my opinion. Thank you for the info.

 

[John105]

I don't--I guess a tool to do so is cheap? I also "assume" new is good and fine. So I'm replacing and not checking the old, if I "think" it's needed. Yes, I've done pads only more than I've done pads/rotors, except with BMW.

We all do things wrong for a long time on things. I used to bleed brakes by starting at the furthest from the master, usually rear right. One day I noticed (5 years ago) someone using a syringe taking fluid out first, then filling up with new. It dawned on me I was doing a 1/4 a**ed job! My first bleed was simply bleeding out dirty fluid, not clean! I'm the type who likes to share info. There are others here that do that. There are also others who seem to like to pour salt in wounds and always act like they know everything, never understood that mentality.

 

[D60]

For those who want to go down this rabbit hole, I wouldn't bother with Mitutoyo or Starrett. The first time you drop it on a concrete floor you'll be a sad panda. Inexpensive measuring tools are accurate enough and MUCH easier on the wallet.

As a machinist I've never checked runout on brakes unless there's a pedal pulsation. I've never had new brakes give me an issue in this regard (noise is a different story)