Completely Overheated my Brakes!!!!

cary

 
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Hi All,

So the wife and I decided to take the family to Yosemite on Sunday, and spend the night in Sonora, go back Monday and come home. We live in the SF Bay Area and took 120 up through the north entrance. On Highway 120 in Mocasin, there is a bypass called Old Priest Grade, that is 2 miles long, and eliminates about 7 miles of constant switchbacks. The tradeoff is that it is a mid 20% grade, with some sections approaching 30%. (note I was incorrect, it is 15% with slopes of up to 20%).

We climbed it in 1st to second gear (wouldn't maintain second at 25mph, so would shift back to first, accelerate, go to second, slow down, repeat). The good news, it was 95f out, had the a/c blasting, and the truck didn't overheat and the A/C didn't go off. I did get a bit of pinging right at the end of the climb on 89 octane.

Sunday night about 10:30, I come down the grade, second gear, on an off the brakes, no problem. That was until I hit the bottom and tried to stop. Complete and utter brake fade. It wasn't the fluid boiling over, wasn't air (running ATE Super Blue), a nice firm pedal with very little effect as the pads were gassing. (Note, I have never faded brakes this bad, even at the racetrack).

So I did what any normal human being would do. There was no cross traffic so I got of the brakes, ran the stop (Like I could stop anyways) and accelerated onto hwy 120. My wife freeked a bit and said pull over. I pulled over and there was smoke pouring out of the wheelwells. I told her we needed to keep moving to keep from warping the rotors and they would cool off in a couple of minutes (we were at a flat section of road).

The result when I got to sonora was limited to nicely blued rotors. I filled up with 91 octane that night, and the next day climbed the grade in 95F weather with no ping. Came down it last night in 1st, 25-30 mph, engine braking between 3000-3500rpm, very little brake usage and no problems.

So I was thinking, why the horrible fade. All components in the brakes are stock, truck was not heavily loaded, (wife (no she is not fat), me, 18 month old, 100 pound dog and our stuff). I think it is a combo of the following:

1) Low speed at 25mph didn't provide much rotor cooling.
2) I have the OME low lift and never adjusted the LPSV. Although my lift is small, I think it is enought that it pushed the system over.

Anyone's thoughts? I think it is time to go to 100 series pads and adjust that LPSV.

Cary

P.S. Obligatory Picture.
IMG_2979.jpg
 
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treerootCO

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My tahoe was never set up right from the beginning. I have brake fade eveywhere I go. I can drive to work and only hit the brakes on the off-ramp and the next stop is almost nothing, no brakes, and they smell hot. I adjusted everything, no drag, replaced the fluid with dot3 syn, and swapped the front rotors for slotted Brembos. Nothing hlelped and I wish I wouldn't have spent the money on the Brembos. They are blue with hairline cracks all over them. They are also blue from the heat.
 

Biff

 
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Wow!! thats scary, my wife would have killed me if I had her in that situation. On another note I have the 100 pads on mine and brand new OEM rotors. A few weeks ago on a trail ride with heavy brake usage on my part I notice at the end of the ride my brakes were extra mushy, I attributed the mushy feelin to my all day heavy usage. Once I reached the freeway I was okay. So I don't know if 100 pads would have made a diffrence in you situation.
 
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Did that in my Heep once. However my rear drums were completely out of adjustment and therefore contributing 0 to the braking forces. I had also been driving rather spiritedly(new word?) and using the hell out of the brakes. Scared myself half to death though when I was coming up on a 15mph corner, hit the brakes, and all I got was smoke out of the front wheelwells.

I've also experienced significant brake fade on my Cruiser and on our Yukon in Washington DC beltway traffic(typically acclerate to 45 just to brake to 0, then back to 45, and repeat). I thought the 100-series pads would help eliminate this, but they don't seem to have affected it at all.

Ary
 

AMMO

 
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Biff said:
Wow!! thats scary, my wife would have killed me if I had her in that situation. On another note I have the 100 pads on mine and brand new OEM rotors. A few weeks ago on a trail ride with heavy brake usage on my part I notice at the end of the ride my brakes were extra mushy, I attributed the mushy feelin to my all day heavy usage. Once I reached the freeway I was okay. So I don't know if 100 pads would have made a diffrence in you situation.
Victor,

The fade you had was mostly caused by all the dust from the trail.... Once back on the road, one hit of the brakes cleaned them off and you were good to go, no more dusty brakes.

-Matt
 

Biff

 
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AMMO said:
Victor,

The fade you had was mostly caused by all the dust from the trail.... Once back on the road, one hit of the brakes cleaned them off and you were good to go, no more dusty brakes.

-Matt

:doh: that makes more sense than overheating.
 

cary

 
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In searching through past threads, I noticed that the Hawk HPS pads are mentioned several times, but nobody has actually admited using them. Has anyone tried the Hawk or Performance Friction Pads? How did you like them?
 
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Cary:

Lifting your rig without adjusting the LPSV is a big no-no in my opinion. I think that even with a "small" lift, the braking power will be shifted significantly to the front. You might have gone down that mountain with front brakes only. Get the proper guages and take the measurements. I'd be interested to know just how out of spec a small lift can make the brakes.

Eric
 

MaddBaggins

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You got me cary, I use the Hawks and have had very good luck so far. I don't tow anything, but I do wheel alot and climb the local paved mountain roads a bit. i have had no problems with hard braking either. Hawk HPS pads and OEM rotors=very good for my applications. :cheers:
 
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cary said:
In searching through past threads, I noticed that the Hawk HPS pads are mentioned several times, but nobody has actually admited using them. Has anyone tried the Hawk or Performance Friction Pads? How did you like them?

I've used the HPS the last 2 times on my civic front brakes...love them...don't have to hit the pedal that much and they stop on a dime...but not sure how good they would be on a LC..only complaint about the HPS is alot of brake dust ...
 

MaddBaggins

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I hadn't noticed any excessive dust, but I have black steel rims and my LC is always dirty anyway.
Also, I have about 10k on my current set and they have quite a bit of life left, without chewing up my rotors. I felt an obvious improvement in stopping power after installing them.
 

e9999

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interesting story! scary!

but 30%? that would be a skier/fisherman 30%? Most folks looking at a 30% grade would say that it is practically vertical...
 

hoser

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While braking and going down a 30% grade, I could conceivably see the weight transfer causing the rear to lift 2-4 inches. Perhaps one of the faults of a LSPV system.
 

cary

 
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30% as in road grades. I cycle quite a bit and am pretty good at figuring grades as I can really tell on the bike. It is steeper in many sections than Ebbetts pass on Hwy 4 which is 24% at the steep part. Also, there is a local hill I ride that hits 26% and it is steeper in parts than that. See below as I have posted a quote from another biker saying it is 1500 feet in 2 miles (I confirmed from other places 1575 feet in 2 miles). I think his math is off on the grade.

I actually stopped by and talked to my mechanic at lunch today. He knows the climb and his thought was they shouldn't have heated up like that on that hill. I mentioned that LPSV to him and his comment was even with the rear brakes pinched off, the fronts shouldn't have overheated. His suggestion was to double check the rotors to make sure they are OEM as he has seen aftermarket rotors do some really weird things. I mentioned the hawk pads to him and he suggested trying the Peformance Friction offerings or Porterfield saying in his experience the hawk pads are often to agressive for daily drivers.

Here a couple of links on the road:

http://www.pashnit.com/roads/cal/OldPriestGrade.htm

http://republican.assembly.ca.gov/members/index.asp?Dist=25&Lang=1&Body=PressReleases&RefID=1424

and a couple of comments by other bike riders in reference to steep climbs

"Mind you, neither of these comes anywhere near "toughest climbs in the
U.S." status, and neither do most of the climbs people are mentioning
here. If you want *tough* climbs, consider the eastern sides of Sonora
Pass, Ebbetts Pass, and Monitor Pass in the Sierra Nevada, in decreasing
order of difficulty. I've done Monitor and most of Ebbetts but will
probably never attempt Sonora. And then there's Old Priest Grade on the
west slope of the Sierra, going up to Big Oak Flat, which I *know* I'll
never try."

"Actually, Old Priest Grade is 1500 ft. in 2 miles for an average grade
of 14+%. There are a couple of steep sections bordering on 20% right
at the top just to make sure you get the full effect. What a groaner!"


"A followup on a few California climbs.
Old Priest Grade: you might be interested knowing that there was an
all-junior stage race (Gold Nugget SR) that used OPG for a time trial for
all but the youngest juniors! I have the times for it somewhere. Some
riders brought walking shoes or special TT bikes, that rather than being
aero were essentially mountain bikes with super-low gears."
 

cary

 
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After going back and checking the math, it looks like my internal calculator is off, it is 15% with sections in the 20% range.
 

hoser

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Just to clarify, 30% grade means a 30ft rise/fall over 100 feet. A 100% grade is a 45 degree angle.
 
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There's a guy on 80sCOOL that's reported a few times that he's very happy with the 100-series Axxis Ultimates (kevlar and porcelein, IIRC).
 

e9999

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my mistake, sorry. I read % and was thinking degrees. 30% grade is about 16 degrees I think. And 20% is 11 degrees or so.
 
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dfmorse said:
Cary; first thing I did to my 94-FZJ80 was put DBA rotors on and fj100 pads in front. I have had to same problem u have had. Stopping the beast is good. ...
Did the DBA's and 100 pads help?
 
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