Is this a similar root cause to the gx470 failure?
Mishap at Moab (1 Viewer)
- Thread starter bearskinrug
- Start date
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I’d say that was likely the same issue.
There are videos on GXOR (viewable w/o being on FB.
But word I'd read was...
"GXOR:
This is Ryan Babroff and the vehicle that had a failure yesterday was mine and I was the driver. DJ was with me in the car as a passenger as he has solid experience of this obstacle and was helping to lead me on the best and safest line possible. Now I don’t know who the spotter was who came down but what I do know is that it wasn’t just one thing that happened all at once that caused this accident. DJ was directing me and you can hear him in the video clearly giving me directions from inside the car right before it slipped into the crevice and started the chain of events. Once the vehicle slipped into the crevice we had only a moment to try and continue forward for those of you who actually know this location that is your only option. Just as that happened the vehicles front tires lifted off the rock and the vehicle suddenly stalled, I know for a fact it stalled at this point and it went dead silent gauges all dropped and the fall back started. I attempted to slam the brakes down with the pedal only going to the floor. I then pulled the emergency brake and that didn’t help. The next thought in my mind was steer and brace for an impact of some sort wether it was how we rolled backwaters down the chute or that we were going end over end flipping our way down. Anyone can speculate what happened but I know the facts, I was the driver. I can sit here till I’m blue in the face defending but my job at that point was to try whatever I could to ride it out. When the decent happened it only took 7-8 seconds from tire lift to impact which in the vehicle can feel like and eternity when in reality it’s only a moment. We are all extremely thankful every single person was able to walk away from an accident like this as some have suffered the same on this specific obstacle and didn’t have the same luck. Thank you for those who have the kind words."
Bummer.
My armchair quarterback (though I've done Hells Gate a few times):
Heavy vehicle and not a great spotter (should have been farther passenger). If you fall in that gap on the gate, it takes a lot of power and a lot grip to get out. Or a disregard for your body panels. We had that happen with a 200 a while back, he opted to winch up which was the right choice. He fell in the gap due to a bad spotter.
My armchair quarterback (though I've done Hells Gate a few times):
Heavy vehicle and not a great spotter (should have been farther passenger). If you fall in that gap on the gate, it takes a lot of power and a lot grip to get out. Or a disregard for your body panels. We had that happen with a 200 a while back, he opted to winch up which was the right choice. He fell in the gap due to a bad spotter.
REKCUT
SILVER Star
Yep, once you slip off the wall in that spot with our vehicles it’s time to pull out the winch.
Why is the gx470 stalling while going uphill? That has me concerned. If the gx470 doesn’t stall, he doesn’t roll backwards!
You can only winch if you can apply the brakes and stop.
You can only winch if you can apply the brakes and stop.
Agreed, my main concern is stall and subsequent loss of brakes. That is the main concern for me here. The point of electric assist doesn’t seem to apply in this situation which doesn’t make sense to me. I must be missing something.
MoJ
Moderator
I’m thinking the best chance of stopping in that situation is to immediately pull the e brake before the vehicle builds so much momentum. Don’t waste time with the pedal etc. I’m sure that’s easier said than done and certainly not meant as a criticism to the driver of the GX.
REKCUT
SILVER Star
Without know what caused it, from the moment it started rolling down hill I'd give the driver 10 for his efforts.
I saw two thing that might cause the problem here:
1. Engine stall after bouncing at medium RPM.
2. The electric brake booster stop giving asist.
What can cause the engine to stall?
What can cause the electric brake booster to fail?
All just speculation and i am just trying to build fault tree analysis.
There are a rash of videos like this the last few months and all is old vehicle with automatic transmission.
1. Engine stall after bouncing at medium RPM.
2. The electric brake booster stop giving asist.
What can cause the engine to stall?
- Torque converter lockup solenoid late reaction
- Gummed up solenoid
- Improper spring in valve body
- Overheated fluid
- Old fluid
- Losing electric power due to some loose connection
- Loose battery terminal
- Worn key switch
- A shor in the power circuit
- Fuel starvation?
What can cause the electric brake booster to fail?
- Lost power
- Bad motor
- Low fluid level and extreme angle cause it to suck air in
- Etc
There are a rash of videos like this the last few months and all is old vehicle with automatic transmission.
This is interesting because the brake master is not dependent on the engine running/vacuum. But yet when the engine stalls the brakes seem to fail....
This is concerning because my 100(4.7 same as the gx) has stalled at inopportune times while offroad.
This is concerning because my 100(4.7 same as the gx) has stalled at inopportune times while offroad.
- Thread starter
- #35
What were the circumstances around these stalls? There have been reports of stalls in steep climbs in v8 tundras as well.
i see a trend here....torque converters.
manual all the way (and lower gearing)
but for real, when your engine cuts off, there is USUALLY enough boost left for one good braking opportunity, before the boost is gone from the booster, and if you hold hard on the pedal, you'll usually stay put, or at least slow down. Here, it looks like they went quickly into reverse without slowing down a bit. I know its a very steep angle in the above situations, but they accelerate backwards very quickly.
manual all the way (and lower gearing)
but for real, when your engine cuts off, there is USUALLY enough boost left for one good braking opportunity, before the boost is gone from the booster, and if you hold hard on the pedal, you'll usually stay put, or at least slow down. Here, it looks like they went quickly into reverse without slowing down a bit. I know its a very steep angle in the above situations, but they accelerate backwards very quickly.
MoJ
Moderator
I’ve been wondering about the “one good braking opportunity”. Is that still true if the system is electric based rather than vacuum?
Brakes alone won't hold you on the gate. I had the driver of the GX in my truck all day last week and we talked. ATs will stall if you try to stop on that grade with just a brake pedal...it's just too much. Once you lose power, you lose brakes. RPMs and two foot braking are your friend. I drove the gate a few years ago in my GX. I know what happened. Lost RPMs, bad line, slipped, smacked the brakes, AT stalled the motor, and the roll back began. It is extremely hard to drive that obstacle and a panic moment like sliding off the line results in a brake smash and you easily forget the throttle. Both are needed to maintain the line. It wasn't a total failure of anything, just a bad sequence of events.
Is this AT stalling when braking at that grade and losing power and brakes specific to Toyota/Lexus or it also happens to Jeep’s, Mercedes, and Land Rovers?
I’m asking because the drivers reaction is similar to what I would do. I would try to go forward but when i lose momentum going uphill, my instinct is to press the brakes and hold in place.
I’m just saying not everyone is experienced enough to always know when and how to do two pedal driving.
I’m asking because the drivers reaction is similar to what I would do. I would try to go forward but when i lose momentum going uphill, my instinct is to press the brakes and hold in place.
I’m just saying not everyone is experienced enough to always know when and how to do two pedal driving.
