Brake Temperature Question

[Stumper]

I didn’t want to add this to my post of rear brakes grabbing so starting a new thread. This is a bit nit-picky but I would like to try understanding what I am seeing. Since trouble shooting the battle of my rear brakes heating up I bought an IR thermometer… while I believe my rear brake drag issue has been resolved I now have the IR gun and……while my rear drums were running over twice the temps of the fronts before when I had the problem, after i replaced the drums I am now seeing where the fronts may run around 110 after a drive, while the rears run 130 or so with the left rear tending to be about 10 degrees more than the right rear. One would think that with the majority of the braking taking place with the fronts, that they would run warmer ?
My thoughts so far are 1) the rear shoes are new while the fronts have a few hundred miles on them and maybe not broken in yet? 2) the front drums are old Mopar drums while the rear are new ACDelco (which are noticeable thinner on the braking surface) 3) i run 215-70x15 up front and 245-60s on rear and also the rear May pick up heat from the rear differential.

i would be interested in any thoughts as to why my rear drums are running warmer than fronts??

 

[1STMP]

It could be that the fronts recieve more
clean (cooler) air. Shelby Mustangs
compensated for this by installing
air scoops that channeled cooler air
to the rear brakes. You're correct in
your assumption that the rear diff
will elevate (and maintain) higher
temps, but I wouldn't worry too
much about a 20 degree difference.

 

[Stumper]

It could be that the fronts recieve more
clean (cooler) air. Shelby Mustangs
compensated for this by installing
air scoops that channeled cooler air
to the rear brakes. You're correct in
your assumption that the rear diff
will elevate (and maintain) higher
temps, but I wouldn't worry too
much about a 20 degree difference.

Thanks for replying to this. I understand the difference is negligible in the scheme of things but I’m curious what would cause the rear to run warmer. It may just be a combination of fatter tires, rear differential and new shoes I guess. I just never gave it a thought before.

 

[1STMP]

Thanks for replying to this. I understand the difference is negligible in the scheme of things but I’m curious what would cause the rear to run warmer. It may just be a combination of fatter tires, rear differential and new shoes I guess. I just never gave it a thought before.

You're welcome.
Your high range temps in a diff will
be from 180-200 deg. Hot enough
to touch for just a couple of seconds.
I have a Jeep, and have recorded
temps of the front and rear diffs after
giving her some strenuous exercise,
(in 4-low pulling a steep grade)
after a gear change, to make sure I
was running the correct gear oil. They
both measured 183 deg. with ambient
air being 93 deg.
The 20 difference you're seeing is the
added heat from the diff.

 

[Stumper]

You're welcome.
Your high range temps in a diff will
be from 180-200 deg. Hot enough
to touch for just a couple of seconds.
I have a Jeep, and have recorded
temps of the front and rear diffs after
giving her some strenuous exercise,
(in 4-low pulling a steep grade)
after a gear change, to make sure I
was running the correct gear oil. They
both measured 183 deg. with ambient
air being 93 deg.
The 20 difference you're seeing is the
added heat from the diff.

That may well be the most significant factor. I’m just surprised that the fronts getting much more use, do not offset the differential heat. Now that I’ve got this temp gun to play with I’ll try getting more measurements.

 

[Dananator]

I didn’t want to add this to my post of rear brakes grabbing so starting a new thread. This is a bit nit-picky but I would like to try understanding what I am seeing. Since trouble shooting the battle of my rear brakes heating up I bought an IR thermometer… while I believe my rear brake drag issue has been resolved I now have the IR gun and……while my rear drums were running over twice the temps of the fronts before when I had the problem, after i replaced the drums I am now seeing where the fronts may run around 110 after a drive, while the rears run 130 or so with the left rear tending to be about 10 degrees more than the right rear. One would think that with the majority of the braking taking place with the fronts, that they would run warmer ?
My thoughts so far are 1) the rear shoes are new while the fronts have a few hundred miles on them and maybe not broken in yet? 2) the front drums are old Mopar drums while the rear are new ACDelco (which are noticeable thinner on the braking surface) 3) i run 215-70x15 up front and 245-60s on rear and also the rear May pick up heat from the rear differential.

i would be interested in any thoughts as to why my rear drums are running warmer than fronts??

Adjusted too tight. Back the off 3 clicks.