Brake pulsing - do you measure run out ?

[98v70dad]

I've been doing my own brake work for many years and was self taught which means I may not being doing it right. I've never bothered with measuring the run out on a new rotor. I just assumed that they would be adequate (wasn't thinking about stacked tolerances) and justified it by not having a run out gauge.

However, its not uncommon for me that brake pulsing starts about a year after changing a set of rotors. I've read that run out which exceeds the specifications can lead to pulsing.

So, I'm wondering if skipping that step is the source of the pulsing problem. What is your experience with that? Do you check run out or just put on the new rotors and hope (hoping is a low cost tool I have that often doesn't work)?

Also, since the rotors bolt onto hub instead of riding on lugs how do you bolt up a rotor to a Volvo to check the run out - it seems the wheel bolts will be too long? On a car with lugs people put on some conical washers and the lug nuts and torque.

[MrAl]

I've been doing my own brake work for many years and was self taught which means I may not being doing it right. I've never bothered with measuring the run out on a new rotor. I just assumed that they would be adequate (wasn't thinking about stacked tolerances) and justified it by not having a run out gauge.

However, its not uncommon for me that brake pulsing starts about a year after changing a set of rotors. I've read that run out which exceeds the specifications can lead to pulsing.

So, I'm wondering if skipping that step is the source of the pulsing problem. What is your experience with that? Do you check run out or just put on the new rotors and hope (hoping is a low cost tool I have that often doesn't work)?

Also, since the rotors bolt onto hub instead of riding on lugs how do you bolt up a rotor to a Volvo to check the run out - it seems the wheel bolts will be too long? On a car with lugs people put on some conical washers and the lug nuts and torque.

Hi,

That bolt up question is a good one. I was thinking maybe short pipes, but someone here probably has done it already and knows the best way to do it.

Why not check the run out if you can?

I do know now that if the break pads or rotors are not installed properly the rubbing will come back because the wear is more complicated than just plain friction...there is transfer of material back and forth going on so it has to be right. What could be wrong though someone else here might know better.

[98v70dad]

I have never measured run out because I don't have the necessary tool and I figured that the parts would be in tolerance. I never considered stacked tolerance and probably should have. I can't believe that so few have commented on this since it gets to the essence of DIY. If you DIY you can do it right and know that it as done right. Is measuring run out part of doing it right? Often what's written in books is theoretical and has no real connection to standard practice.

[MrAl]

Hi,

An old saying in the electronic world is:
"One measurement is worth a thousand expert opinions"
but i suppose this could apply to any discipline.

From what i understand now there could be runout that is not detected right away by vibration but later shows up as vibration because of the metal to pad interface action over time (weeks, months, etc.). That tells me that a check is in order.
Also from what i understand, an experienced tech can do the test in under five minutes with the tire removed. This tells me that a good tech would do it as part of the routine.

[j-dawg]

If you're worried about it, use your wheel bolts to center the rotor! Hang the rotor up on the hub, and install two bolts without the wheel. Tighten them down all the way, so the cones in the bolts are seated on the bolt holes in the rotor. This should center the rotor on the hub bolt pattern. Tighten the little rotor retention pin bolt. Your runout is now as low as the tolerances on your wheel hub, wheel bolts, and brake rotor.

I've never thought much about it. For a few months I had actually removed the pins altogether and noticed no problems during braking.

[98v70dad]

There are many websites that have videos of how to properly replace rotors. The one I watched the other night indicates that the source of brake pulsing is three things. 1) not checking run out and not correcting it if out of spec. 2) improper clean up of the wheel hub before installing the rotor. 3) improper lug torque. I have changed rotors on 4 cars and 3 of them started pulsing again within 18 months (my wife has a heavy foot when braking but it made me wonder if I am doing something to cause the problem). I never check the run out or clean up the wheel hub or use a torque wrench on the lugs. I figure that I cant tighten the bolts enough by hand to warp the rotor even if I don't check the torque.

I began to think that one or all of the steps I'm not doing may be the source of my problem. That said, if you go to a place and have them do the work I really doubt any of these steps are followed. Cleaning up the wheel hub takes 5- to 10 minutes per wheel and checking the run out and correcting it probably adds another 10 minutes. They use air tools so I also doubt that the torque applied is correct, although it may be uniform. So I have reason to wonder what other DIY'rs do.

If you watch the video that FCP has about how to change your rotors, they do a perfunctory effort at cleaning the hub with a wire brush nocking the rust loose but leaving it mostly on the hub while putting on the new rotor. They don't check run out or even mention it. The video ends before the bolts would be torqued and they don't say anything about that either if IZ remember right.

Using the wheel bolts to center the rotor might work ... I don't know. I'd use them all though. Putting in just 2 and torqueing to spec is likely to warp the rotor which is what I'm trying to avoid. They may be too long and I won't find out until the car is up off the ground and the wheels are off and I can't get to the store to try something else.

I'm about to rebuild my brakes ... total overhaul ... and I don't want to waste my time and a lot of my money by doing it wrong. Based on my experience and peer results I think I may be doing it wrong. That's why I asked about it.

[scot850]

To be honest, I think you are over thinking all this, but then I can be equally anal about problems, but once into them, they tend to be less of an issue, it is just having the confidence to tackle the issue.

I have fitted many rotors, and have only had issues twice. On a recent thread I mentioned I had a set of aftermarket rotors on a 98 V70XC I fitted and they were bad out of the box. I had waited too long to get around to fitting them, that I couldn't return them under warranty. A local shop machined them for me and they were good after that.

On our 06 XC70 we went through 3 set of Volvo Rotors and a re-grind within 15,000km! All were fitted by the dealer, so maybe they had a bad batch?

I usually find the issues are more often than not caused by failing calipers (sticking pistons), poor maintenance (pads sticking due to rust), lack of lube on the sliders, etc.

The key I find is ensuring the seating face of the hub is cleaned of any rust prior to fitting.

Another issue I have found in areas were a lot of salt is used is of liquid salt getting between the rotor back and the hub and then rust causing the rotor seat to not sit flat.

You can check the rotors fairly easily as you are suggesting, but using duct-tape, a lead pencil/marker pen and something to mount them onto. Put the tip up against the edge of the rotor and spin. This will leave a mark if you have high points. Nice to have a dial gauge, but for something that is not used often it is a nice to have.

Neil.

[98v70dad]

[quote="scot850"]To be honest, I think you are over thinking all this, but then I can be equally anal about problems, but once into them, they tend to be less of an issue, it is just having the confidence to tackle the issue. /quote]

Well, I appreciate your input but in this case I don't agree. I've replaced rotors about 4 times on three different cars ('94 Ford Crown Vic - success, '049 Hyundai sonata -fail, '04 Honda Odyssey twice - fail). 3 of the 4 times I've done this maintenance the rotors end up pulsing again in about 18 months. I buy high quality parts so cheap parts isn't that causing my problem. I take everything off, clean the parts thoroughly (including the pins), lubricate everything that needs lube with high temp brake lube, etc. A 25% success rate doesn't impress me. I concluded that I must be doing something wrong and went to the trouble of learning something more about it, identified a few steps I've never done and wrote this thread with a few questions. Almost every response I've gotten is in essence don't worry about it, you're over thinking it which isn't really helpful.

[scot850]

Ok. I can see with the new info why you are so concerned with the luck you have had on this subject.

As I said, our 06 XC70 had 3!! sets of OE brake rotors installed by a certified dealer mechanic and they had issues.

Did you see the part where I said that I have found moisture getting between the rotor and the hub causing it to swell? What mileages are these vehicles doing and as you point out your wife may be a heavy brake user. Does your wife or any other drivers tend to ride the brakes? These issues in themselves can overheat rotors and cause warping.

On the cars where warping is an issue, are any of them still having these issues? If they are, it may be worth looking at the moisture on the mating faces, and clean and re-fit to see if the issue goes away.

What mileages are you getting out of the rotors before problems occur?

There was another recent thread about wheel tightening. Again, I am not sure how tightening the wheel bolts is an issue as you are (or should be) bolting 2 flat surfaces together. Provided you are tightening in the proper sequence (in a star pattern) then you should not be causing issues with the lug nuts causing an issue.

Some models of cars can be hard on rotors. Growing up in Europe, in the 70's Fords were known to be hard on front rotors. Without breaking them in, you could have them warp in weeks. Personally I reckoned Ford brakes were crap in those years. Into the80's it was Volkswagen's turn with the Golf/Jetta/Rabbit. The front brakes were no only rubbish, but again warped readily. We had an 01 Honda Oddity van, and the brakes were warped after about 25,000km and had to be replaced. By comparison, our Suburban still had the same rotors at 140,000km, with a regrind at about 80,000km when purchased to remove deep rust on the faces.

Have you checked on the vehicles mentioned to find out if they are more prone to these issues than other cars? Do the vehicles get driven through deep water at all? Do you wash the cars when the brakes are still hot?

I appreciate it is confidence sapping when you see this issue. Personally, I don't think the issue is something you are doing. If so I'd expect a much shorter timeline before issues happen. Have you checked with the manufacturer of the brake parts if they have a breaking in process they recommend?

Final thing. On all our vehicles, I have to change the wheels from winter to summer rims for 4 vehicles, and in the 15 years I have been in Canada I have only had the rotor issues as mentioned previously.

My process for wheel tightening is:

1) Fit the wheel and put the lug bolt/nut on the highest point in/on first, and only tightening it enough to hold the rim in place (hand-tight).
2) Install (for a 5 stud configuration) the next nut/bolt 2 holes away, hand tighten again to just 'nipped-up' as per the first, and then continue in this manner until all 5 are installed.
3) You have a couple of choices, you could tighten the bolts in the star pattern (i.e. every second bolt in turn until all are tight). Some like to find a mid-point torque, and then the full value.
4) Drop the wheel onto the ground and then torque to the correct value.
5) Check the bolt/nut torques again in a 100 miles or less to ensure they are tight.

I use a little copper grease/anti-seize on the threads by the way.

So to sum, up, if you are really cleaning the mating faces, de-greasing the rotors before fitting, and doing a running in process if called for, then you my friend are doing the job right. Issues starting 18 months or so after you installed the part is not your install process.

Final point. Do you use the cars a lot, or occasionally only? If only occasionally you may be getting rust build up on the faces of the rotors, and it tends to be worse on the rear face.

Neil.

[MrAl]

To be honest, I think you are over thinking all this, but then I can be equally anal about problems, but once into them, they tend to be less of an issue, it is just having the confidence to tackle the issue. /quote]

Well, I appreciate your input but in this case I don't agree. I've replaced rotors about 4 times on three different cars ('94 Ford Crown Vic - success, '049 Hyundai sonata -fail, '04 Honda Odyssey twice - fail). 3 of the 4 times I've done this maintenance the rotors end up pulsing again in about 18 months. I buy high quality parts so cheap parts isn't that causing my problem. I take everything off, clean the parts thoroughly (including the pins), lubricate everything that needs lube with high temp brake lube, etc. A 25% success rate doesn't impress me. I concluded that I must be doing something wrong and went to the trouble of learning something more about it, identified a few steps I've never done and wrote this thread with a few questions. Almost every response I've gotten is in essence don't worry about it, you're over thinking it which isn't really helpful.

Hi,

In my posts i take just the opposite stance on this: go the distance and check the dang things
If you can afford to do the whole brake job i would think you could afford the test equipment. Why not give it a shot?
At least this way if it STILL doesnt improve the situation you'll know it is something else, but if you dont do it you'll forever wonder. I just cant help thinking how good it would feel to find a problem during the test, fix it, and then years later feel like you've finally cracked the problem when you realize it still works great!

Good luck with it