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.
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.
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