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Johann
Veteran
Date registered: May 2006
Location: Centurion, South Africa
Vehicle(s): 1999 LWB 290GDT 1981 SWB 240GD+ Cabrio 2015 G63
Posts: 259
| Some scary offroading
It feels worse that what it looks like 
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 P1000771.jpg (269KB - 12 downloads)
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amzimmy
Elite Veteran
Date registered: Apr 2006
Location: South Africa/Italy
Vehicle(s): GD300 1981, Alfa GT 3,2 V6, Alfa Brera Q4 3,2 V6.
Posts: 850
| RE: Some scary offroading
Eishhhhhhh!  ................that's quite steep...........couldn't you find a flatter spot?
The "one" hiding behind the tree ....... is that "Pretty Michelle"? .......was she toooo scared to drive with you?  .......You should invest in some good threads ....... maybe with "slicks" works better........well done Johann!  you can trust a "G"!  hey!!
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Johann
Veteran
Date registered: May 2006
Location: Centurion, South Africa
Vehicle(s): 1999 LWB 290GDT 1981 SWB 240GD+ Cabrio 2015 G63
Posts: 259
| RE: Some scary offroading
Hi amzimmy
"Pretty Michelle" was taking the pictures behind me. She is the clever one in the family. She said there is no way in hell she is driving down there.
What didn't help was the video footage that was shown the night before of accidents that happened down there. Pickups falling and rolling all over the place.
The G was solid as a rock but even with the rough surface for traction she was sliding at some places. |
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Bier
Regular
Date registered: Apr 2006
Location: Pretoria, South Africa
Vehicle(s): 1999 290GDT W461
Posts: 86
| RE: Some scary offroading
Wow!
Sorry I missed the event. Any other SA G club members who also attempted/made it?
Danie
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Johann
Veteran
Date registered: May 2006
Location: Centurion, South Africa
Vehicle(s): 1999 LWB 290GDT 1981 SWB 240GD+ Cabrio 2015 G63
Posts: 259
| RE: Some scary offroading
Hi Danie
Yip. There was 6 of us. When are you getting your G?
Edited by Johann 5/26/2006 8:17 AM
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MarcO
Elite Veteran
Date registered: Apr 2006
Location: Irvington, NY
Vehicle(s): G 500 SWB, Volvo XC90 V8
Posts: 835
| Re: Some scary offroading
You are a very brave man. This looks way too scary for me. Amazing. Thanks for sharing. |
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Thai
Date registered: Dec 1899
Location:
Vehicle(s):
| Re: Some scary offroading
You must have good strong brakes!:D
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Braingears
Expert
Date registered: Apr 2006
Location: St Petersburg, FL
Vehicle(s): G320 & ML320
Posts: 1450
| Re: Some scary offroading
I'm guessing that you would NOT use diff locks on something like that. That would possibly cause you to break your wheels free in order to rotate at the same speed as the others... right? |
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Johann
Veteran
Date registered: May 2006
Location: Centurion, South Africa
Vehicle(s): 1999 LWB 290GDT 1981 SWB 240GD+ Cabrio 2015 G63
Posts: 259
| RE: Some scary offroading
Good question. I'm not sure. I have only used my back diff lock to ensure I do not loose traction.
One of the older G's brakes released when he was close to the bottom! It seems like when the brakes get too hot they release!
I have a video of us going down. As soon as I figure out how to create mpegs from the dvd vob I'll post it.
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KERR
Date registered: Dec 1899
Location:
Vehicle(s):
| Re: Some scary offroading
wow.. now that's a steep hill |
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FoxBaker
Date registered: Dec 1899
Location:
Vehicle(s):
| RE: Some scary offroading
steep ? watch the trees - land of extra gravity - but anyway - nice shots
fb  |
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AlanMcR
Expert
Date registered: Apr 2006
Location: US, CA, Los Altos
Vehicle(s): G300DT E300DT 230SL
Posts: 3500
| RE: Some scary offroading
Johann - 5/26/2006 12:02 PM
Good question. I'm not sure. I have only used my back diff lock to ensure I do not loose traction.
One of the older G's brakes released when he was close to the bottom! It seems like when the brakes get too hot they release!
I have a video of us going down. As soon as I figure out how to create mpegs from the dvd vob I'll post it.
My take would be no difflocks. Slight changes in slope against the tires will change the wheel to wheel speed.
This isn't a slippery situation you want each tire to get optimal grip no mater what speed it is going.
The brakes probably released due to all the fluid sloshing to the front of the brake reservoir. If you then let up (even slightly) on the brake and then reapply you get air in the lines. This would probably self bleed once the truck is level again. |
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Braingears
Expert
Date registered: Apr 2006
Location: St Petersburg, FL
Vehicle(s): G320 & ML320
Posts: 1450
| RE: Some scary offroading
AlanMcR - 5/26/2006 5:02 PM The brakes probably released due to all the fluid sloshing to the front of the brake reservoir. If you then let up (even slightly) on the brake and then reapply you get air in the lines. This would probably self bleed once the truck is level again. I have never seen any brakes that "self-bleed". I know that our differential locks can self bleed, but not our brakes... |
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ehdenoffroad
Date registered: Dec 1899
Location:
Vehicle(s):
| Re: Some scary offroading
Can u try this up-hill please :D |
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AlanMcR
Expert
Date registered: Apr 2006
Location: US, CA, Los Altos
Vehicle(s): G300DT E300DT 230SL
Posts: 3500
| RE: Some scary offroading
Braingears - 5/26/2006 2:09 PM
AlanMcR - 5/26/2006 5:02 PM The brakes probably released due to all the fluid sloshing to the front of the brake reservoir. If you then let up (even slightly) on the brake and then reapply you get air in the lines. This would probably self bleed once the truck is level again. I have never seen any brakes that "self-bleed". I know that our differential locks can self bleed, but not our brakes...
The usual case for air in the lines is that leaks or pad wear cause a flow of fluid down through the system sucking in some from an empty reservoir. The fluid doesn't return since the pads won't un-wear and the leak won't un-leak.
In this bizarre corner case some air is allowed in at the top of the system simply due to stomping on the pedal with an empty reservoir. Unlike the usual air in the lines case, the fluid will return when the pads push back. He's not likely to fully remove his foot from the brake until the truck is back somewhat level. At that point the feed holes from the reservoir to the master cylinder are covered again. Any remaining bubbles in the master cylinder will slowly make a one-way trip up through the reservoir. A self bleed. It only works when the bubbles have not made it past the master cylinder. Note: this might not work when backing down a hill. In that case the bubbles would get pressed into the lines right away due to the geometry of the master cylinder. |
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Johann
Veteran
Date registered: May 2006
Location: Centurion, South Africa
Vehicle(s): 1999 LWB 290GDT 1981 SWB 240GD+ Cabrio 2015 G63
Posts: 259
| RE: Some scary offroading
One of the guys with us has actually done this up-hill. He said going down is much worse!
Next time before the end of this year I'll do it up-hill. Will post some pics when I do.
Aha! Just found out the guy who's brakes released had these new self cleaning type brake disks. Seems these buggers couldn't handle the strain.
Edited by Johann 5/27/2006 3:01 PM
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Powerbrake%20All%20Terrain%20Gwagen%201.jpg (28KB - 12 downloads)
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G4Garret
Veteran
Date registered: Apr 2006
Location: Oak Ridge - Knoxville - Windrock Tennessee
Vehicle(s): 2000 G500, U1100, SLK350, LR 101, WC-63 6x6
Posts: 243
| Re: Some scary offroading
I find it very hard to believe that there would be any overheating of brakes on this slope. The speed's had to be very very slow, with corrospondingly low heat dissipation. I'm with Alan, I'd say fluid displacement to the front of the resevoir causing loss of brakes. It happens in all kinds of vehicles when the slope is this incredibly steep. And recover is pretty quick, once things are level again and the air has a chance to bubbple back up and out the resevoir.
Remember the video I posted of the truck crashing down the hill at Moab? That's what happened to them.
Garret
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Johann
Veteran
Date registered: May 2006
Location: Centurion, South Africa
Vehicle(s): 1999 LWB 290GDT 1981 SWB 240GD+ Cabrio 2015 G63
Posts: 259
| RE: Some scary offroading
Thanks Garret.
If that is true I won't be doing this again! Ignorance is bliss.
Although there is a theory that the grooves on the above disk does not allow the brake pad to make contact everywhere due to the grooves and with this extreme angle caused slippage and once you start running on this angle there is no stoppping!
What does Gratz say? Is there an angle limitation for the brakes to work effective? My G comes with a brake booster which I assume helps preventing this?
Is it only the 460 series that will have this problem?
Thanks
Johann
Edited by Johann 5/29/2006 3:40 AM
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G4Garret
Veteran
Date registered: Apr 2006
Location: Oak Ridge - Knoxville - Windrock Tennessee
Vehicle(s): 2000 G500, U1100, SLK350, LR 101, WC-63 6x6
Posts: 243
| RE: Some scary offroading
I forgot to say, those are really good pics! Great job Johann!
On the braking problem, I really don't have experience on the 460, so I really can't comment specifically on how it's brake system handles such steep descents. There are many variables, including master cylinder design, resevoir design, how full it is. It is far more likely to have the problem on drum brakes too. I have heard that the problem is worse on the older american-style integrated cast cylinder/resevoir types. Also, I believe the problem is worse on dual-circuit systems as opposed to the old and otherwise unsafe single hydraulic systems. FWIW, the old cheap looking tall "tea tin" reservoirs on older SI and II Land Rovers tend to never loose brakes on very steep inclines, although the motors won't run for long becuase of the affect upon the carberettor fuel bowl. I always make a point of keeping my resevoir up to the max reccommended level, just in case it might make a difference. Something I don't know is if ABS helps this out. I've never noticed it happening on an ABS equipped vehicle
Just for fun, here's the Moab video again:
Brake Failure at Moab.
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Johann
Veteran
Date registered: May 2006
Location: Centurion, South Africa
Vehicle(s): 1999 LWB 290GDT 1981 SWB 240GD+ Cabrio 2015 G63
Posts: 259
| RE: Some scary offroading
Thanks for sharing the video. I have seen this on Reality TV. It was a lady driver if I remember correctly. They took her there again but this time in a new Jeep. And she went down again without any problems. Now that takes b#lls after such a crash.
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