Thanks to everyone for the Temp Device info. Looks like the Raytek Autopro
is the one to go with right now.
Paul, you mentioned that there will always be differences in tyre/brake
temps (I assume that means from side to side). So, in a correctly working
system, how much variance would one normally expect to see? Unless you know
what “normal” is, diagnozing the problem is somewhat difficult.
Skip the Radio Shack one and go for the Raytek Autopro, it is pretty much
the
standard for auto diagnostics. It’s range is -25 to 1000 F, has dual
lasers
to stabilize the distance, a magnetic base and fast response time. It is
very
useful at diagnosing brake problems, like dragging calipers, you will
always
find differences in brake temperatures and tire temperatures. Shop around,
it
has many high end features and can be found for around $130.
Paul, you mentioned that there will always be differences in tyre/brake
temps (I assume that means from side to side). So, in a correctly working
system, how much variance would one normally expect to see? Unless you know
what “normal” is, diagnozing the problem is somewhat difficult.
Hello Les,
You will find normal is all over the place, depending on how you drive, it is
a game of consistency and comparison. A dragging brake will cause at least a
30F degree difference. The heat will also spread around quite a distance to
the caliper, hub and wheel. I have measured a 100F difference on a dragging
brake with no perceptible difference from the driver’s seat in normal driving. A
dragging caliper can boil the fluid while cruising without informing the
occupants until the pedal goes to the floor. Every application will be different,
you need to establish some baselines. The recommended procedure is; drive
the car at a steady 50 mph, stop without heavy braking and measure the caliper,
disc and hub temperatures. Then make 5 stops from 30 mph with heavy braking
and repeat the measurements. Side to side should be within 10F if you make
good readings. There should also be around a 50F differential between the front
and rear brakes. Tires should be within 20F across the tread unless you use a
lot of negative camber and then the inside will read higher.
Once you get the device you will find many other uses, finding a spark plug
that is misfiring on a V-8 takes about 30 sec. and you won’t burn your fingers.
You will find normal is all over the place, depending on how you drive, it
is
a game of consistency and comparison. A dragging brake will cause at least
a
30F degree difference. The heat will also spread around quite a distance to
the caliper, hub and wheel. I have measured a 100F difference on a dragging
brake with no perceptible difference from the driver’s seat in normal
driving. A
dragging caliper can boil the fluid while cruising without informing the
occupants until the pedal goes to the floor. Every application will be
different,
you need to establish some baselines. The recommended procedure is; drive
the car at a steady 50 mph, stop without heavy braking and measure the
caliper,
disc and hub temperatures. Then make 5 stops from 30 mph with heavy
braking
and repeat the measurements. Side to side should be within 10F if you make
good readings. There should also be around a 50F differential between the
front
and rear brakes. Tires should be within 20F across the tread unless you
use a
lot of negative camber and then the inside will read higher.
Once you get the device you will find many other uses, finding a spark plug
that is misfiring on a V-8 takes about 30 sec. and you won’t burn your
fingers.