Loss Of Brakes Offroad Downhill 4WD High

Hello,

I recently was coming back from a camp trip. Going downhill in the mountains. My 4WD was engaged, wet condition, and in regular drive. I did not disable any lsd or trac. Cut to the chase I loss all pressure to brakes. I had to feather between the e-brake and pedal. I never had this happen before. Brake are little over a year, fluid flush was done earlier this year, extended rear lines that have been on the truck for over 6 years and have been working good until this happen. The brakes are back to normal now, like it never happened. I have pressure a quarter of the way in now. The truck was running normal the whole time until about 2/3 of the way down the mountain is when I loss brakes.

Any thoughts would be great!

 

Did you ride the brakes for miles and miles and boil your brake fluid?

 

I think you are right, I was on that pedal the whole way down for a while. I was able to check everything yesterday and nothing was out of place.

 

wait, you were in 4LO and needed hard brakes? typically 4LO is a 1st and maybe a 2nd gear option, reason is for Engine braking and slow maintainable speed.
If you have DSC I would use that next time, its there for a reason.( offroad only)
I cant see you boiling off your brake fluid in 4LO unless you're driving at freeway speeds , which you should never do. Your Title says 4LOW, was down hill on a road or trail that was not graded? It sounds to me that you were possibly low on brake fluid to begin with.

I have thousands of miles offroad including crawling as well as towing an offroad trailer and I have never had an issue of brake loss while in 4LO.

 

Probably had brake fade due to overheating. Flush your brake fluid again. In the future manually select 1st gear in 4lo for downhill sections on the trail. DAC/DSC uses brakes, so it's just as prone to overheating.

 

Not if used correctly. Pulse rather than constant brake pressure coupled with 4LO and 1st gear.

 

Pulse is using the brakes, so it can still (theoretically) lead to overheating. 4LO and 1st gear though should do the trick, and the DAC/DSC and occasional brake use shouldn't really have an issue. I'm sure the problem was that he said he was in D still, and hadn't shifted down.

 

As I stated used correctly, you wouldn't uses DSC above 5MPH.

 

Yeah, gotta be careful with riding the brakes for so long. It reminds me of a time I was coming down our mountain and came across a long line of vehicles. Helicopter and emergency vehicles were around the corner. A Tacoma had lost it's brakes, blew past the guardrail, and down the road side. Kids were in the bed. Everyone got ejected and a few people died. Now, the mountain rangers check everyone's brake temps.

Happens to a lot of rental vehicles with drivers who don't know how to drive down prolonged downhill drives, which is why some rental companies restrict (try to) people from driving certain areas of our island.

 

I just did Pikes Peak recently where they have signs everywhere saying a few things:

1. Use Low gear or equivalent. Even in my rental Altima with a CVT, it had a "sport mode" that allows the revs to go up and consume some of your downhill momentum.

2. When braking, do it quick and hard and let off quickly. (I assume this is the same as pulsing as Socal said). This allows the brakes time to cool and recover between switchbacks.


Plus it's just fun to get to use low gear in a practical setting!

 

Sorry I was in H4

 

Brake fluid flush necessary?

 

From now on, instead of riding your brakes, shift the transmission down.

What speed were you trying to maintain downhill? like 5 or 10 mph, or were you on the freeway and trying to keep it to 55 or 60 for long periods of time?

 

I would. Cheap insurance.