Anyone ever take a temp reading of the rotors? Today after a 60 mile run home. 95% freeway running 70 to 75 mph in 99 to 100 degree air temps, I would say under normal braking,nothing real agressive.I shot my rotors with an infared temp gun through the slots of my wheels and the hottest place I could find was right at the base of the hub and the rotor.Front left was reading 238 degrees. Front right was 248 degrees. Why I check the rotors, the other day I had pulled the wheels off and had put my hand on the hub end cap and I thought that it was pretty warm.So Im wondering if I may have a wheel bearing issue?? They all seem to spinn fine with no noises?? Anybody got ang thoughts?
Thanks Tom 82 300D 110k original miles

Here's one thought. Use grease that is intended for disk brakes. I think the dealer sells some.

I don't think I've seen any readings much higher than 160 degrees, but I've never been very precise when shooting them.

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238 degrees F, if correct, would indicate some severe braking just prior to the test. Furthermore, the disc would be the hottest area........much hotter than the hub.

The fact that the hub is the hottest..........and with those temperatures.........tells me the bearings are under preload. It's a common problem for anyone who doesn't have a dial indicator. Most of the people on the forum cannot set them properly and they generate significant heat when preloaded.

I'd pull the hubs and repack them..........and set the preload properly.........so that you have some bearing clearance.

True. And I'm sure that any of them are fine, as long as you remove every trace of old grease.

But you should also do this when using the factory grease, in case a prior owner did the above.

Brian,
Well, correct as the temp gun is??? But I think your confiming my thoughts about the bearings running the temp up. On the disk I was getting cooler temps, like 140 to 160 if I remember right. I wasnt paying real close attention out there because I was thinking of the bearings.
I too may be one of the forum members that cant set them properly.I may have gotten them too tight when I replaced pads and rotors.?? Maybe I need to recheck them. Do you have to have a "dial Indicaor" to do this?? Thanks Tom

Brian, what is the "proper" way to set the wheel berrings? I just grease them up, slap them in, reef down on the nut, spin the rotor a few times, then back it off a little.

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I preload mine by running the bolt up until the hub is difficult to turn, then back off 1/3 turn, whack spindle end with a hammer, and the hubs are then easy to spin. This id according to Haynes, if you do not have a dial indicator, like me!

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90 Dodge D250 5.9 Cummins/5 speed. 400K

I used a dial indicator but I am not sure you determine how much pressure to apply?

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This is how I do mine. except the whack with a hammer. I didnt do that part, but they spun freely.

Just got in from the same run today. I only ran 65mph and the temps today are 146 and136. I dont know. If I get time tomorrow I may pull the bearing double check them and repack. ??? I'll let you know what happens. Tom 82 300D

Just do not whack it so hard that you damage the spindle. I use a 3lb sledge and swing lightly, like a pendulum on an old wind up clock and hit square on the spindle.

__________________
RRGrassi


70's Southern Pacific #5608 Fairmont A-4 MOW car

13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete.

91 W124 300D Turbo replaced, Pressure W/G actuator installed. 210K

90 Dodge D250 5.9 Cummins/5 speed. 400K

No, I agree withyou. I just have never thought of that before. I didnt think you were whacking it to damge it.Makes sence to me to set the bearing. Tom

The problem with this approach is that you might end up with a preload. Backing it off "a little" is meaningless. The bearing must have some axial play. M/B specifies .0005" which you cannot feel. Better to have .002" which you can feel rather than -.002" which will overheat the bearing the more you drive it.

This procedure is completely random. Whether you get a preload or a slight clearance is strictly a matter of luck.