Severe brake fade?

[Pskhaat]

On a trip yesterday we took a road from Prescott to Jerome, AZ. It's hilly and moderately steep. On the way down into Jerome from the hills I had severe brake fade in my Hundy. We were not loaded down.

When stopped I noticed the distinct hot brake smell off the rear passenger side. Pads/rotors in great shape as of earlier this year. Yeah, the 100 is heavy but I'm guessing I should not be experiencing this problem, these are not the Rockies, just moderate hills. What gets me is the I got the brake smell off of only ONE rear side, not both, and not in the front. Think I have a stuck caliper (she rolls just fine).

Other thing is that even if the back were performing poorly it seems as though the fronts should well have been providing more braking power! Could it be the electric power assist system too?

 

[WristPin]

you should down shift while descending hills.
to test for a collapsed brake hose, remove the suspect wheel, and crack the bleeder screw. it should drip at least one drop per second or better.
and if you have not flushed the fluid, now would be a good time.


i didnt fully understand this post.
this problem is with your hyundai, or your 100?

 

[CivicFerio]

Where you on the brakes hard during decent? There are 2 types of brake fade.

First is the brake pad fade which is when you exceeded the temperature range of the pads. The pedal will remain firm but braking force will be lessened. The pads will alsol start to crumble and wear rapidly. Pads whether street or race pads will sometimes fade when it's heated up severely for the first time; this is called a green pad in which the resins used to mold the pad are getting burned off. After the resins have burned off the pad shouldn’t fade anymore.

Second, is called the fluid fade where the temperatures in the caliper got high enough to boil the brake fluid. The brake pedal will start to get spongy and will eventually lose all braking capability if it's not allowed to cool down.

My only guess why you are burned the rear pads is that the EBD biased a lot of brake force to the rear during light braking. Thus, too much light braking might cause the rear to heat up more than the fronts.

 

[Pskhaat]

this problem is with your hyundai, or your 100?

100 == Hundy.

Given the proper speeds and conditions the tranny I keep in lower gears on descent. You said ``collapsed brake hose''...what about a kinked axle hard line? It's the only thing I can think of that I havn't yet checked prior to this weekend and getting the brakes off.

 

[Pskhaat]

Where you on the brakes hard during decent?

Absolutely, but no more than I have ever been on my 80 well exceeding GVWR on much steeper descents than this.

First is the brake pad fade which is when you exceeded the temperature range of the pads. The pedal will remain firm but braking force will be lessened.

Well, these are the symptoms it seems. Pedal is as normal but friction and force lacking.

EBD biased a lot of brake force to the rear during light braking. Thus, too much light braking might cause the rear to heat up more than the fronts.

Anything that would cause the EBD to do this that you can think of?

 

[cary]

Absolutely, but no more than I have ever been on my 80 well exceeding GVWR on much steeper descents than this.



Well, these are the symptoms it seems. Pedal is as normal but friction and force lacking.

Sounds like you outgassed the pads (overheated them). Have you been on the same road with the 80, as the 100 has better brakes which suggests a problem with yours.

 

[ShottsUZJ100]

these are not the Rockies, just moderate hills.

Coming down Mingus Mountain? Those ARE grades with many tight turns, one after the other that require braking then power, braking then power...speed limit 25MPH. I drive down stuff like that in 1st or 2nd and have OD off for the faster sections. 7700' at the top and 5500 at the bottom.

The 100's brakes are 2nd to none in the SUV world, though that mountain is a brake-eater. I know of 3 friends on Mt. Graham (the worst decent in AZ) who burned their brakes down to the metal...and two of them were cars. One was stupid enough to return to Phx using only the emergency brake. It's the constant sharp turns that wipe them out.

Save you vehicle's brakes. It's rare for me to ever use my brakes on the downhills. Gearing works the best. I'm not getting on ya, but unless you have something wrong you should never overtax those 100's brakes. 80 = yes 100 = nope.

 

[cruiser99]

I lost my brakes completely (pedal to the metal) a few weeks ago in the sierras. Had to stop and "water cool" them before they came back.
Truck was loaded for a long trip towing a trailer and...I was in a hurry.

I started working on the last weekend and ended up with 2 diffs on my bench. Go figure

 

[ShottsUZJ100]

I lost my brakes completely (pedal to the metal) a few weeks ago in the sierras. Had to stop and "water cool" them before they came back.
Truck was loaded for a long trip towing a trailer and...I was in a hurry.

I started working on the last weekend and ended up with 2 diffs on my bench. Go figure

What are you doing with your diffs Doron?

 

[cruiser99]

What are you doing with your diffs Doron?

I guess I am going to have to regear now

 

[ShottsUZJ100]

I guess I am going to have to regear now

You will be SO happy. You have that SUPER expo-rig. All is needs is gears!

 

[Pskhaat]

Sounds like you outgassed the pads (overheated them). Have you been on the same road with the 80, as the 100 has better brakes which suggests a problem with yours.

Well, I lived many years of my life in Colorado and have descended many steeper hills loaded way beyond GVWR in my 80. I have not taken my 80 on the same road, but do not feel that the grade warranted the brake fade.

I would chalk this up as anomoly, but what is funny to me is that the REAR appears to have faded, not the front, where I would expect the fronts to go well before the rears due to how much more braking comes from the front.

When I first bough my 100 last year, I had a flat tire and had to change it with the bottle jack that slipped on the axle and bent up the hard brake line slightly. I straightened the hard line but there is still a kink in it. When changing out a lug from said incident in the rear, the brake fluid drain valve had sufficient flow in my estimation. I wonder if possibly restricted flow (which I'm doubting, but...) to the left rear has caused a bias in force on the right rear from where the heat and smell were coming, and obviously was the source of the fade? Thoughts?

 

[ShottsUZJ100]

Well, I lived many years of my life in Colorado and have descended many steeper hills loaded way beyond GVWR in my 80. I have not taken my 80 on the same road, but do not feel that the grade warranted the brake fade.

I would chalk this up as anomoly, but what is funny to me is that the REAR appears to have faded, not the front, where I would expect the fronts to go well before the rears due to how much more braking comes from the front.

When I first bough my 100 last year, I had a flat tire and had to change it with the bottle jack that slipped on the axle and bent up the hard brake line slightly. I straightened the hard line but there is still a kink in it. When changing out a lug from said incident in the rear, the brake fluid drain valve had sufficient flow in my estimation. I wonder if possibly restricted flow (which I'm doubting, but...) to the left rear has caused a bias in force on the right rear from where the heat and smell were coming, and obviously was the source of the fade? Thoughts?

Yes....very wierd. This is a rare 100-series story. Something might not be 100%?

 

[LXPearl]

If you have a 2000+ the TRAC/VSC could be using the rear brakes on those winding curves in addition to your own braking. It sounds like you are well acustomed to mountain driving and use the lower gears and OD Off effectively - so that does not appear to be the problem.

I am concerned about the crimped metal brake line because that would affect the performance of the brake fluid under severe conditions - the restriction in the line itself would add to the friction experienced by the fluid and build up extra heat. Also, if there happened to be dirt in the line, the crimped area collect the "dirt" and cause restriction... and heat. Personally, I would replace that line to be certain that is not the cause.

The brakes in my 100s have always performed extremely well in the mountains, so I believe your experience is abnormal.

 

[Pskhaat]

Cool, I hear ya. I do have the hard line and will replace ASAP, the kink is small but no reason not to replace it, it isn't that expensive. I have a 1999 and no electric assist traction

 

[ShottsUZJ100]

If you have a 2000+ the TRAC/VSC could be using the rear brakes on those winding curves in addition to your own braking.

Not possible. If VSC would have kicked in he'd a known it due to the BEEP BEEP BEEP. TRAC will not operate in those conditions.

 

[cary]

Well, I lived many years of my life in Colorado and have descended many steeper hills loaded way beyond GVWR in my 80. I have not taken my 80 on the same road, but do not feel that the grade warranted the brake fade.

Keep in mind that the speed that you are using the brakes at will significantly affect fade. I can hard stop my 80 from 80mph with no fade several times in a row, but a slow steep decent at 15-20mph will heat them way up and outgass them. At the constant low speeds, there is a lack of airflow to cool (at least on the 80). Without you having gone down the same hill in your 80 or another vehicle it is hard to tell if it is a vehicle specific problem or a design issue.

Note, I would not rely on any brake line that has been kinked. It is a pain in the ass, but the line has to be replaced. While it may be flowing fluid, it is probably restricted, and more importantly, it has been significantly weakened. The bottom line is it represents a safety issue. You can deal if the engine stops running, but a potential brake failure is not to be triffled with.

 

[LXPearl]

Shotts - your description of 25 MPH max downhill - I agree, not the place for TRAC. VSC makes beeps, which leaves ABS - back to the brakes again. I do not like the compromised brake line - maybe we can get an update after Scott replaces it.

 

[ShottsUZJ100]

Shotts - your description of 25 MPH max downhill - I agree, not the place for TRAC. VSC makes beeps, which leaves ABS - back to the brakes again. I do not like the compromised brake line - maybe we can get an update after Scott replaces it.

Plus...TRAC cannot activate when at idle or off the gas. Ya..might have something not 100%?