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-   -   Uneven rotors heating after calipers replacement (http://www.irv2.com/forums/f23/uneven-rotors-heating-after-calipers-replacement-459719.html)

mikleg74 09-02-2019 03:45 PM

Uneven rotors heating after calipers replacement
 
Hello everybody!

After replacement front calipers, pads and hoses, I still always have a higher temperature on my left front brake rotor. For example, if 3 other rotors have 300F, it has 390. I have an infrared thermometer and I live in the Seattle area which has a lot of hills. The hubs temperatures are the same on all four wheels, so it is not a bearing.
My question is why it happens? Any ideas?

Additional information:

Physically the rotor looks good, although it has a little vibration during braking, I suspect it is a little bit not even. But I don't feel any vibration during driving.
Why I replaced calipers and hoses:

At the end of my last trip, (300 miles mostly mountains) I had a temperature alarm from the left front wheel's TPMS.
It happened almost in the storage parking, so I decided to complete the trip.
After a stop, I noted the left hot wheel. The temperature of the brake rotor was 660F. The temperature of the hub was ok. (I have an infrared thermometer) I suspected the stuck caliper.


I tried to find any information about the same issue, but I was unsuccessful. :sad:

Redapple 09-02-2019 03:47 PM

Check the front inner and outer wheel bearings. Bearings that are going bad or that have gone bad will generate excess heat.

Good Luck

twinboat 09-02-2019 04:21 PM

The vibration during stopping is a sign of a bad rotor.
A warped rotor will cause some extra heat by rubbing against the pads, even with no brake application..

MoCoTom 09-02-2019 07:03 PM

Quote:

Originally Posted by twinboat (Post 4938681)
The vibration during stopping is a sign of a bad rotor.
A warped rotor will cause some extra heat by rubbing against the pads, even with no brake application..

:iagree:

TeJay 09-03-2019 07:06 AM

mikleg74,

What you experienced following a caliper and pad replacement is not uncommon. Why did it happen??

Some have mentioned the causes. I also like to further explain some of the whys so folks better understand the results. Sometimes saving some $$$$ on a repair drives why a person chooses a shop. That can bite you in the butt.

First of all you didn't tell us if the stock rotors were machined as part of the repair. Not everyone agrees with machining rotors but the industry has recommended for years trueing the rotors if pads are changed.

The two rotor surfaces need to be clean,flat and parallel for several reasons. The surface finish is very critical to proper breakin or burnishing of the new pads. If the surface is not parallel, flat or warped that will cause issues. Also the surface needs to have the ability to create friction so it can't/shouldn't be smooth. More importantly the rotors require about 200 moderate stops for proper break-in.

During this period of burnishing surface material from the pads are transferred to the rotor. This won't happen if the stock rotor is smooth, warped or not parallel. The end result will be poor stopping caused by a rotor surface that did not provide a 100% surface to surface contact. It's really that simple.

If your previous stopping had vibration the rotor(s) were warped. If the new rotor causes vibration when you apply the brakes then it too is warped.

You mentioned the vehicle still had vibration but not when you were just driving down the road. Since the rotor surfaces are not completely touching the pads you won't have vibration. It only occurs when the brakes are applied.

You paid for a less than average brake service. They did not machine the stock rotors to assure two clean, flat, parallel surfaces on each rotor. That saved you some $$$$ but since they didn't check the new rotors for warps in the end it will cost you more $$$$$.

As twinboat mentioned & MoCoTom agreed even a small amount of warping will allow the pads to touch the spinning rotor generating some heat and that's why they are running slightly hotter. Your brakes work because they create friction when you want to stop. They should not create friction when you are driving. An old rotor that was not machined or a new rotor that was warped right out of the box causes your heat.

Brakes are one area where I recommend to never cut corners. We never did a brake service unless we machined all old rotors and at least check the parallel of new rotors out of the box. Yes we often found rotors out of the box that were not true.

Those who don't agree with machining rotors remember the minimum thickness is always stamped on the rotor. The proper thickness is vital so the heat from braking can be absorbed and that requires a thick rotor. Cars and small trucks began not having rotors with much meat on them. We had to be careful when machining. They were smaller because the manufacturer made the rotors lighter to get better fuel mileage (CAFE standards).

I can understand why larger trucks might not need to be machined like the smaller vehicles because they probably had more metal on the rotors. That much I'll give you.

We know the CAFE standards are still driving the need to lower some of the vehicle weight so hence the smaller or thinner rotors. The CAFE standards are not the same on the heavy truck fleets because there are not as many on the roads. However the old smooth surface is still present and will compromise the burnishing in period.

Reacher 09-03-2019 02:48 PM

Great post TeJay. After a brake service what would you recommend as a good break-in procedure for F-53 chassis?

TeJay 09-03-2019 03:10 PM

Thanks for the comment!

According to my information it takes about 200 moderate stops from say 40-45 MPH down to 25 or 30 then a 30 second run to cool them down then repeat 200 times.

They realize folks just won't do that but they emphasized that no panic stops should be performed as a way to speed up the break in period. Just normal driving within several weeks will accomplish the burnish or break in period.

If you want the full story just google "How to properly Burnish brake pads."

I didn't learn this in school or in any brake clinics. I watched a CD from NAPA that really covered a lot of good information that I've never even read in any tech manuals.

A fellow on a TT forum posted that he broke his shoes in by getting up to a good speed enough times to get the shoes to smoking and that did it. Yep he prematurely glazed the shoes or pads and ruined the brakes. Some folks just don't THINK!!

Reacher 09-03-2019 08:01 PM

Thanks. Lol yeah panic stops in MH! I try to avoid those. Meanwhile I'll hit the NAPA info as you suggested.

akeagle 09-03-2019 08:10 PM

I also agree that the likely problem is a warped rotor. Its usually a good idea to replace BOTH rotors on the same axel at the same time. The initial warping could have been caused by overheating on a long downhill application or a rapid cycle of repeated hard applications without enough cooling off time in between, and what happens to one rotor usually happens to the other. Look hard at the other rotor for even a little runout.

THenne1713 09-03-2019 10:25 PM

Great post, but one additional thought is replace the HOSES to front calipers (esp. if they were not replaced when calipers replaced); Arguments I have read have been 1) breakdown inside of hose, w/ age; 2) internal damage to hose from overheated caliper? 3) Believe I read one story where they said bits of rubber floating around in line was the CAUSE of brakes not releasing and often the cause of overheating?

Sweetbriar 09-04-2019 03:19 AM

Quote:

Originally Posted by THenne1713 (Post 4940682)
Great post, but one additional thought is replace the HOSES to front calipers (esp. if they were not replaced when calipers replaced); Arguments I have read have been 1) breakdown inside of hose, w/ age; 2) internal damage to hose from overheated caliper? 3) Believe I read one story where they said bits of rubber floating around in line was the CAUSE of brakes not releasing and often the cause of overheating?

I was thinking the same particularly for a 2002 model year chassis. Around $15 each for the fronts from Rock Auto.

txcpl 09-04-2019 05:26 AM

I will add this to what TeJay had to say.

Any time you disassemble the front wheel assembly for a brake job, that is the perfect time to clean and repack the front bearings, particularly if high temps have been noted. From your description, most likely your rotors are slightly warped, and they will not get any better. At least the temps are down, so the sticking caliper problem has been taken care of.

I learned a long time ago that if you take care of potential problems while you are in the area making repairs, you very seldom have to go back in at a later date.

Good luck and keep us posted.

akeagle 09-05-2019 08:45 AM

Quote:

Originally Posted by THenne1713 (Post 4940682)
Great post, but one additional thought is replace the HOSES to front calipers (esp. if they were not replaced when calipers replaced); Arguments I have read have been 1) breakdown inside of hose, w/ age; 2) internal damage to hose from overheated caliper? 3) Believe I read one story where they said bits of rubber floating around in line was the CAUSE of brakes not releasing and often the cause of overheating?


Finding debris in the brake hose is probably enough justification to flush the entire brake system and replace it with new fluid.

TeJay 09-05-2019 04:00 PM

akeagle,

Interesting that you'd mention brake fluid flushing. Over maybe the last 10 or so years it has become recommended that brake systems be completely flushed about every 2-3 or 3-4 years. I think every 4-5 years is a good interval.

I did ours this last spring which was at the end of 4 years. The fluid was discolored but not bad looking. There's a decent thread telling folks all about it.

In reality think about this. The brake fluid is the only liquid (except battery acid) used in all vehicles that does not circulate and has no filter on it. It is also corrosive to metals, paint and absorbs water easily. Why wouldn't we want to change it somewhat frequently??


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