Recommendations for front brake rotors

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Recommendations for front brake rotors

June 15, 2019, 08:47:15 pm

I am about ready to have the brakes on my 2005 midbath checked out. Although I have attempted to use the "Tow/Haul" feature when going downhill, as well as, being as lightfooted as possible on the brakes, it appears my rotors need machining. I have had to do this a few times now. Is there a more heavy duty rotor I could request to be used on this rig?

Re: Recommendations for front brake rotors

Reply #1 – June 15, 2019, 09:53:31 pm

"... it appears my rotors need machining. I have had to do this a few times now."

Are you saying that you have had to machine the rotors "a few times" since 2005?

My '04 has had the rotors turned once in 15 years and just two weeks ago they were replaced. Seems to me the frequency of yours is a bit too often!

Re: Recommendations for front brake rotors

Reply #2 – June 15, 2019, 10:45:14 pm

Isn’t there a limitation on how much you can shave the rotors?

Re: Recommendations for front brake rotors

Reply #3 – June 15, 2019, 11:46:23 pm

"...how much you can shave the rotors? "

Can't quote the specs but, yes, you reach a certain point and the rotors must be replaced.

Re: Recommendations for front brake rotors

Reply #4 – June 16, 2019, 03:50:25 am

It's been my experience that once a rotor warps, it will continue to do the same until replaced. Factory rotors never seem to last as long as a high quality aftermarket rotor. I stopped machining most rotors a long time ago, preferring to install premium grade rotors that are less prone to warping.

A 115,000 miles, the rotors on our 2003 have been replaced twice, both sets developing warping and when measured, the rotors have been near the point of maximum wear, when legally, they cannot be reused, much less machined.
The legal minimum thickness is cast into each rotor so there can be no confusion as to what the specification is.
Pulling a 4000-lb Jeep for a 100,000+ miles, over most of the West's high passes, has worn the brakes .

Presently, our LD is wearing Bendix Fleet Metlok SDR5071rotors along with set of Powerstop calipers and Napa HD Fleet pads.
Amazon.com: Bendix Fleet Metlok SDR5071 Front Severe Duty Rotor: Automotive

If you can wait, Powerstop makes a complete HD kit, when I trying to order, it was back ordered, with a five week wait.
Amazon.com: Power Stop KC5084-36 Z36 Extreme Performance Truck And Tow...
I have used Powerstop kits on my Jeeps for years with good results

Larry

As an Amazon Associate Lazy Daze Owners' Group earns from qualifying purchases.

Re: Recommendations for front brake rotors

Reply #5 – June 16, 2019, 09:42:47 am

I guess we have been very LUCKY, 55,000 on our 31 foot LD pulling a 4,000 lb Jeep, still have original pads-rotors with plenty
of wear left. Our travels have been all over U.S., Canada to include Alaska. Looking forward to another 50,000 front brake frre
or replacement.

Bob

Re: Recommendations for front brake rotors

Reply #6 – June 16, 2019, 09:55:36 am

Realistically, it is impossible to warp a rotor under any driving conditions. If you don't believe me talk to a metallurgist, I have.

Now there may be some lateral runout but with modern manufacturing a machining methods this is rare. If you do install new rotors and have pedal pulsation your lateral runout can usually be traced to contamination between the hub and rotor, uneven wheel stud torque, etc.

So, if rotors don't warp and you have no lateral runout due to improperly installing the rotors, what is the problem?

The problem is uneven application of brake pad material on the surface of the rotor. Yes, when you apply your brakes a very thin layer of your brake pad material applies itself to the surface of your rotor in a uniform manner. If it is not applied uniformly you end up with a rotor with variations in friction which is felt as a pulsing pedal and incorrectly diagnosed as a warped rotor.

How can brake pad material become unevenly applied to rotors? The most common method occurs at a stop after heavy brake use. The rotors are very hot from heavy use and then the vehicle comes to a stop. The rotors cool unevenly since the surface area covered by the pad can not transfer the heat as quickly as the exposed areas. And if the rotor is hot enough the pad continues to transfer material to the rotor surface. We are talking microns of metallurgical changes taking place.

My recommendation is that once you receive new rotors and pads your bed them in per the manufactures suggestion - do not stop your vehicle until the rotors have cooled to a normal temperature. If you have just come down a hill and your brakes are very hot the absolute worst thing you can do is to come to a complete stop. Keep rolling, even just 1-2 MPH.

Re: Recommendations for front brake rotors

Reply #7 – June 16, 2019, 10:32:36 am

"...very LUCKY, 55,000 on our 31 foot LD..."

No big shakes on my '04 30' at 55K! Around the 90K point start keeping a close watch!

Re: Recommendations for front brake rotors

Reply #8 – June 16, 2019, 02:35:19 pm

Quote from: Renegade242 - June 16, 2019, 09:55:36 am

Realistically, it is impossible to warp a rotor under any driving conditions. If you don't believe me talk to a metallurgist I have.

Now there may be some lateral runout but with modern manufacturing a machining methods this is rare. If you do install new rotors and have pedal pulsation your lateral runout can usually be traced to contamination between the hub and rotor, uneven wheel stud torque, etc.

So, if rotors don't warp and you have no lateral runout due to improperly installing the rotors, what is the problem?
The problem is uneven application of brake pad material on the surface of the rotor. Yes, when you apply your brakes a very thin layer of your brake pad material applies itself to the surface of your rotor in a uniform manner. If it is not applied uniformly you end up with a rotor with variations in friction which is felt as a pulsing pedal and incorrectly diagnosed as a warped rotor.
My recommendation is that once you receive new rotors and pads your bed them in per the manufactures suggestion -

I'm not a metallurgist but I have talked with many automotive expects and engineers, taken classes and read hundreds of technical and teaching manuals pertaining to the automotive and mechanical fields, it's what I did when employed and still do in retirement .
Well, I guess my dial indicators are wrong indicating excessive lateral runout and the many rotors I have personally machined only appeared to cut unevenly at first.
Maybe it was all an illusion.
Some rotors have visible spotting and only need a slight amount machined off, mostly removing the thin, uneven layer of brake material.
One problem with turning worn rotors is more material is removed, reducing the mass needed to dissipate the heat generated by braking and ending up with a rotor that is closer to being worn out and more likely to warp.

I quite aware of how to properly install brakes, the torquing the lug nuts and other hardware and the right way to bed in new brake pads, laying down the critical thin layer of pad material evenly across the rotors. Done it a few times.
Most aftermarket performance brake pads come with detailed instructions on the bedding process, the process varies between manufacturers . Different pad materials evidently require their own procedures and I follow the manufacturer's recommendations as much as possible. It can be difficult to lightly use an RV brakes for the first 500 -1000 miles, especially when towing.

To check the rotors are cleanly mounted and properly torqued, I check each newly installed rotor for runout with a dial indicator, sometimes rotating the position of a rotor if the hub and/or rotor has a slight amount of runout. Tolerance differences can be used to stack the differences to get to the minimal runout.
002" or less of lateral runout is what I look for.

I never keep my foot on the pedal when the brakes are very hot, it's good way to deposit a small amount of material and can cause vibrations. I will used the parking brake occasionally, when stopped on a slope, to keep from rolling.
After 175,000 miles of LD ownership, you get a lot of practice driving.

Both sets of the LD's front rotors developed a pulsing brake pedal as they approached the point where they were legally worn out, with enough material worn away to need replacement . The rear brakes have never done so and still have the original rotors, while the pads and calipers have been replaced. The rear rotors will probably need replacement in the next 15,000 miles, due to wear.
Running 50-60,000 miles between front brake jobs doesn't seem excessive considering we are pushing 18,000-lbs up and down the road.
2008+ LDs have bigger brakes and may go farther between brake jobs. The pre-2008 LDs used the same front brake pads and rotor diameter as the E350 and E250s, the E450s may be undersized considering how more weight they deal with.

Driving in the West is a different animal than the East, everywhere we seem to go is either up or down, the engine and brakes get a tougher work out here.
I can show you grades where downshifting as low as first gear, along with heavy brake usage, are necessary to get to the bottom of the grade safely. Even though the Jeep has its own tow brake, much of the load is still transferred to the LD.
The brakes can get very hot.

Larry

Re: Recommendations for front brake rotors

Reply #9 – June 16, 2019, 02:50:13 pm

"I can show you grades where downshifting as low as first gear, along with heavy brake usage, are necessary to get to the bottom of the grade safely."

Last Thursday, returning from June Lake, Tioga Pass was still closed. I instead came home by way of Sonora Pass (Hwy 108).

During the westbound transit of that pass I encountered several Class C motorhomes headed east, all of which were rental units. Sonora Pass is noted for it's 25% grades and it's 10mph switchbacks. I'd bet my last dollar those drivers did not know the road or the situation they were facing.

Re: Recommendations for front brake rotors

Reply #10 – June 16, 2019, 03:09:38 pm

Last Thursday, returning from June Lake, Tioga Pass was still closed. I instead came home by way of Sonora Pass (Hwy 108).
During the westbound transit of that pass I encountered several Class C motorhomes headed east, all of which were rental units. Sonora Pass is noted for it's 25% grades and it's 10mph switchbacks. I'd bet my last dollar those drivers did not know the road or the situation they were facing.

[/quote]

That is hairy drive for an RV. We meet a pickup and travel trailer coming down the east side several years ago and I have never smelled hotter brakes . I would imagine there have been many serious crashes with folks who do not understand downshifting and have lost their brakes.

Larry

Re: Recommendations for front brake rotors

Reply #11 – June 16, 2019, 04:03:07 pm

I've driven 108 (Sonora Pass) a couple times in a pickup, and while a small RV, e.g., some pickup/camper outfits, class "B" rigs, should be able to navigate the road if the drivers have good mountain driving skills, 108 is not a road for a wide body RV, when towing anything, or any large, wide vehicle.

The notorious 26% grade is very short, and if that were the only constraint to driving 108, it would be do-able for large vehicles. But, much of the road is also very narrow, very curvy (often blind curves with long drops-offs) and has several stretches of 10-15% down (or up) grades; ; meeting another vehicle on this road - a much bigger danger than the grades and curves, IMO - can end in a very unpleasant and "impassable" scenario! Every once in a while, some disbeliever in a large vehicle, including a big rig (!), will try to drive the road, too often with predictable results.

Often I'll post a "YMMV" tag; not on this.

Re: Recommendations for front brake rotors

Reply #12 – June 16, 2019, 04:13:14 pm

Sonora Pass primer:

https://m.youtube.com/watch?v=LrFf3e815Ls

Re: Recommendations for front brake rotors

Reply #13 – June 16, 2019, 07:03:27 pm

"Sonora Pass primer:"

So what was the point? At 34:+ minutes of video that Imbecile Twit missed 95% of what is to be seen! If they would have slowed down a bit the ride would have been far more pleasurable.

At time 10:30 they blew past Chipmunk Flat, a very decent boon docking location.

At time 11:28 they flew past the gravesite of the Pioneer who gave name to the creek, Dead Man Creek. Also in that vicinity they missed out on seeing the remains of the old Wagon Road along the hillside.

At 15:20 they roared past two of my favorite hidy-holes, one is used as a storage area by the Hwy Dept to store gravel, etc. Both very secluded and private.

At 18:00 the Summit and the Pacific Crest Trail crossing were totally ignored.

At 26:10 they never took note of the Leavitt Lake Road and the old mining tipple located there.

Apparently they were not interested in the Pickle Meadow Pack Station at 34:00.

And why did the video end there, far short of the end of the road?

Re: Recommendations for front brake rotors

Reply #14 – June 16, 2019, 09:37:37 pm

"We me[e]t a pickup and travel trailer coming down the east side several years ago and I have never smelled hotter brakes."

I once seen a short bed semi, jackknifed around one of those hairpins. It took the CHP and a huge wrecker to finally get him out.

Re: Recommendations for front brake rotors

Reply #15 – June 16, 2019, 10:25:12 pm

My dad took us and a camping trailer East to West in a Chrysler New Yorker in 60 or 61 and I learned the smell of burning brakes.
I think I'd wait till Tioga opened.

Re: Recommendations for front brake rotors

Reply #16 – June 17, 2019, 03:51:18 am

Beautiful picture of the front rotor Larry. Did you change the inner and outer wheel bearings? Have you changed the rubber hoses yet? How do you feel about slotted and cross drilled rotors? RonB

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