PDA

View Full Version : Climbing steep hills


calbiker
09-15-2010, 03:50 AM
I've noticed it twice now that when my 3500 Sprinter based motor home starts up a steep hill (from a stand still) it takes what seems forever for the vehicle to start moving. My last episode was on a mountain pass in Crested Butte, Co. This dirt road was starting to deteriorate into a jeep road. In front of me was a large water bar which I didn't know if the vehicle could clear so I stopped (on a steep incline) to take a look. After trying to back up - which became impossible; I had no choice but to take on the hill and water bar. I believe the accelerator was floored but the rpm remained below 2000. After perhaps 3 seconds it decided to take off. My wife thought she saw the check engine light flash on, then off again. I made it safely over the water bar, but not without quite a bit of rock & roll. The Koni shocks nor stiffer rear sway bar could keep the stuff in the locked (upper) cabinets from falling to the floor.

Why doesn't the turbo turn on? A manual turbo switch would be great. Is it normal for a Sprinter to struggle as it starts up a steep incline? The vehicle is probably a few pounds over weight.

I wish I have a manual transmission.

After finding a place to turn around, I camped at a lower elevation. This view is overlooking a famous mountain bike trail (401 Trail) in Crested Butte. There were no stored error codes in the computer.

Cal

http://i429.photobucket.com/albums/qq12/Calbiker/Boondocking/P1070318.jpg

Altered Sprinter
09-15-2010, 04:30 AM
FAIR COMMENT:However please do not take my reply as a negative to wards your question and thoughts.
I would like to know what your rear axle ratio is.?
Ok! I'm on a steep mountain pass and stop! What was the angle on the pass incline 45 degree! I'll bet my Sprinter on it.
Condition of road surface loose under surfaces with a marbleized fine gravel with a hard packed under base mains surface or corrugated.
On selecting 1st gear not drive,and with light acceleration there is a monetary delay on rpm as to ASR and ABS inter-reacting as to each wheel finding the sweet spot to prevent wheel spin.
If you floor it and look at the rpm you will hit the red-line and the on your van sprinters RPM 's will automatically slow your engine down and end up in a brief monetary LHM
Lights will flash on a full digital dash.
Tires if standard hi-way don't work that well off road.especially on a RV in part you have the wrong rear suspension and final drive axles.the latter you can't avoid. Solution is this Tyre by Bridgestone as it's off road and works with rear dual setups.
Explorer select D94 load rated at 110 and 112 205 CLT or 205 R-16
Your traction will increase dramatically.
26210

On a recent mountain trip with extreme switch backs I swear my van was a 4x4 However the surface was compacted and damp.If in Summer I would never have negotiated the switch backs as they were at left to right angles hitting over 45 degree.Basically I would end up on a spin as to over reeving the engine which results in a shut down of power back to a lower rpm
Not much fun when the pure weight of your van starts sliding backwards under its own wright because of a marbleized road surface that offers no real stopping action.
26211
26212
Even the local goats have four wheel traction
:smilewink:
Richard

gottahavabenz
09-15-2010, 11:58 AM
Calbiker sorry I don't have much in the way of helping you but I wanted to comment on Crested Butte, I live in VT but work in Co. occasionally. While there we like to go 4 wheeling over the mountains and as it turns out we drove our rental hummer over a couple mountains doing a big loop and dropped right into Crested Butte I thought it was the most amazing little town I had ever seen with the Mt views and being so small and out of the way. I hope you enjoy your trip and be careful of the water bars, it turns out the hummers side impact air bags will go off if you corner down the mountain to quickly! :rad: That was seriously tough to explain to the wife! I tried to express to her what is 3200 amongst friends!

Eric Experience
09-15-2010, 12:49 PM
Cal.
Sounds like your rear wheels are spinning. Did you have have your Electronic stability control turned on or off? Fitting a heavy duty sway bar causes your vehicle to sway more on uneven surfaces. Also the sway bar prevents you having even pressure on the ground with your rear wheels. You get maximum traction without a sway bar. Eric.

teammontana
09-15-2010, 03:55 PM
The electronic traction control will retard the engine RPM when it senses wheel slippage. While great on the highway, I find it a nuisance driving slow on ice or steeper terrain, and have been stuck more than once due to the engine power decreasing trying to find a balance between traction and power, eventually causing the vehicle to stop. The lights you saw were the traction control telling you the wheels were slipping. There is a switch on the consol by the shifter to disable the traction control, but don't wait till you are stopped-sometimes the only way is with good old fashioned wheel spin to pull you through. Once you are stopped, most of the time you are stuck and will not get going again.

NBB
09-15-2010, 04:12 PM
Low RPM's, a small motor and what appears to be a ****-ton of weight over a dual wheel rear axle. Unless it was over a bunch of really loose gravel, I'm thinking that thing wasn't slipping at all.

The computer might have been effecting things in some way, but not sure anyone can say for sure how.

The obvious, though, is that this is a really tiny engine/driveline to be dragging such a load over 4x4 jeep roads. If one thing isn't snapping, something else will. These are 0-60 in 5 minutes vehicles designed for the highway.


EDIT: "What was the angle on the pass incline 45 degree! I'll bet my Sprinter on it."

32 degrees is about the angle of Colorado's steepest in bounds double-black diamond ski runs. 45 and you are front pointing with 2 axes. 20% grade, the steepest of paved mountain roads in the US, are around 11 degrees. 7%, the steepest of highway passes, are around 4 degrees.

sailquik
09-15-2010, 04:24 PM
Cal,
Good suggestions here!
For sure disable the ASR Traction Control.... before you try to move the vehicle.
What I did not see in the othe replys is "how" the traction control ensures that any rear wheel slippage
gets stopped so it matches the rotation rate of the front tires.
The "how" is that the ASR Traction control applies the big disc brake on the rear wheel that's slipping. If this causes the
other rear wheel to slip, then the ASR applies that brake also. Soon, the ASR will have locked up both rear disc brakes,
and you go nowhere. This often results in the engine/trans going into low power limp home mode (LHM).
So, when getting your Sprinter underway from a stop, on a hill, in the snow or any other low traction situation,
MANUALLY shift your transmission to 1st gear (do not use D fro drive).
Disengage the traction control (ASR) with the middle swith (Marked ASR) at the top of the console.
The little achtung ! triangle in the top of the speedometer will light up telling you the ASR is off.
Add power very slowly to minimize rear wheel slip (or you could spin the tire the big anti-say bar is doing
it's best to lift off the road) and you will have done everything possible to get your van going.
Sometimes it's better to check the terrain behind the vehicle (on a hill) and see if you can find a more level
place to get started forward, by letting the vehicle roll back and using the steering to get the rear wheels on
most level best traction terrain available.
In your case it sounds like you didn't disengage the ASR, tried to get going in D (drive), and could not "back up".
So what exactly is a "water bar"?
Roger

calbiker
09-15-2010, 06:26 PM
Thanks for the replies and suggestions. The ASR was active and looks like that was the cause of the very slow start up the hill. The rpm's weren't higher because more were not needed. I believe I manually put it in 1st gear before starting up. I hope I don't get into that situation again (probably will), but now I know better and need to turn off the ASR.

A water bar is like a speed bump, placed on steep (long) hills to divert water off the road. The up hill side of the bump has a trough so water gets funneled to the falling side of the hill. The wheels hit the bar at an angle so one wheel at a time travels over the bar causing a rock & roll of the chassis. The chassis natural rocking frequency is 1 hertz. That means if the interval of the 2 front tires and 2 rear tires hitting the bar are about 1 second apart then the rocking gets amplified. Not good!

I believe the axle ratio is 3.72:1

Cal

chris118
09-15-2010, 07:04 PM
just hold the asr switch down the entire time. I wish there was a way to just switch it off completely.
its during those time you really would like to have both hands on the wheel.

It is pretty annoying, especially when you are going up hill or driving through loose sand.
but the rest of the van is awesome so...

as for the rocking, my short wheel based low roof sprinter with koni's and a sway bar upgrade still rocks like a boat in choppy seas when off road.
not surprising you rig rocks around.

david_42
09-15-2010, 08:51 PM
My ASB stays off until I stop/start the engine. I don't have to hold the switch down and I disable it every single time I climb my driveway.

mendonsy
09-15-2010, 09:21 PM
I read somewhere that once you turn the ASR off it will stay off until you reach 30 mph or stop the engine.:hmmm: