I'm looking for ideas on how to better get up piles of loose rock and gravel. I understand light weight, a long wheelbase and a lot of inertia could work but I'm just trying to stay safe on the trail, not win a competition.
My trail vehicle is over 4000 lbs, has a 100 inch wheelbase, about 11" of suspension travel, detroits with a crawl ratio of about 42:1 on a V8 with an AT, and KM2's at about 15psi. I'm losing traction on loose rock hills and steep dirt banks, digging in with all four instead of moving up and forward.
How can I get more traction? Is there anything that's going to make a big difference besides some 49" paddles or a bulldozer? It's not practical for me to shed 1000 pounds, but for a given weight, what else can make a significant difference in traction?
Traction bar(s), slightly stiffer rear suspension, more aggressive tires, more wheel speed. It really all depends on why it's spinning. Is it just due to the material you are climbing? If is it like pea gravel, you need a more aggressive tire and more wheel speed.
Try hammering it in 4HI? It sounds like it's almost like pea gravel and if it is you are not going to crawl up it, that's for sure.
is it a loss of traction pure and simple or is it because the suspension is unloading. if the latter, a suck down winch would help a great deal. if due to the material like posted above, then nothing will probably help but sheer horsepower.
It's the material. It's not pea gravel, but like loose river rock with some gravel, very deep. I can't always hit it. Some of the hills are 1000 feet high. Inertia just gets me to the place where when I fail, I can't even hold the position. It may be that it can't practically be done, but there is a vehicle path on some of the hills I've failed. Maybe it takes a purpose built hillclimber or a bulldozer, I don't know.
Besides the river rock, I've failed on dirt ledges. The rear wheels could push the front over the top but they couldn't climb the face and the front's with little weight on them couldn't pull up either. The wheelbase was at 30 degrees from horizontal but the rear wheels were clawing at a compacted dirt face more like 50 degrees. I'd rather not "hit it" in these kinds of situations.
Obviously I have limited offroad driving experience and I'm still learning the limits of my vehicle's capabilities. I bought it and installed the lockers and junk this summer. I don't need to surmount the obstacles that I've had trouble with, but I know when rain and snow hits, the traction limits are going to come down to routes I drive routinely. I'm looking for ideas to up those limits.
The vehicle is coil spring so I don't think I can use traction bars. I've looked at the swampers but I think the difference to the BFG muds for a given size is minimal and there's some considerable trade-offs as well. Maybe if I could go up 10" in diameter it would make a bigger difference but that's not going to happen.
After I get so far, the tires just churn down into this stuff. This picture is only half way up the hill.
It's a full-bodied trail pig so I can lose some weight but like I wrote, I can't take off 1000 pounds without fundamentally changing the vehicle's purpose. It's not my street car but it is highway legal and all-weather capable, carries four people and a dog plus camp gear. I need all that. Getting up the hill is nice too.
He says detroits in the op, I assume front and rear.
Wider tires and lighter rig are always helpful for this kind of stuff, but outside of that, play with your driving style to see what methods get you farther.
My method for a hill like you posted would be to roll in at the bottom of the hill, not crazy fast and spinning tires, but to have momentum. The farther you get up the hill steadily increase throttle as you feel the tires begin to slip a little, DON'T stab it, the key is you want to maintain as much momentum as you can. If you really begin to lose traction begin cutting the wheel back and forth, sometimes it will help find the extra bite you need.
If you're really as new at this as you sound, I recommend this dvd, everything I've seen about it seems to say it is worth it for beginners and novice wheelers : http://www.pirate4x4.com/forum/showthread.php?t=777184
If your drivetrains stout, weight helps alot with loose terrain. My heavy ass Cummins with A/T tires out climbs built rigs on non technical stuff like that. The more weight you put on those rocks, the more traction those rocks have to the ground.
If he's running radials that may not really work for him. I was originally running Maxxis bighorns on my beadlocks and could only drop to about 13psi before I was riding on the sidewall. I'm running bias TSL's now and keep them at 10PSI, but could drop to probably 8 or so if I wanted without the squatting as much as the bighorns did.
I appreciate the ideas. I can't easily switch to beadlocks on the Land Rover axles. Most people wanting to run 37's and beadlocks ditch the Rovers. I do have upgraded carriers (detroits) and upgraded ring and pinions (more durable not just the ratio) and upgraded driveshafts. I can upgrade the axles and cv's if I break the ones I have, but it will never be built to dump boatloads of torque into huge meats if I don't swap. That would be cool, but it would cost more than what I have into whole vehicle.
Besides the radials at 15psi, I can run 33 or 34" bias at a lower pressure but still without beadlocks. I'm guessing I could run some swampers at 7 psi on the stock rims. I could clear 35's but Land Rover people tell me the axles are sketchy at that point.
Do what you have/want to, but I will tell you that traction in loose stuff requires an aired down tire to increase the footprint/contact patch....as well as not "dig" in but "float" on top.
Have you tried locking your center differential? When you hill climb with that thing the front is getting light and that cener diff is sending power to the wheel spin.You know what I mean? You have Detroits front and rear?But you combat the open diff in the center.
My disco is a '00. Before I could lock the centere diff my pig(they're more like 5500lbs) could'nt do any hill climbs. Now I barely do hill climbs! Wish I had Detroits.
When I had my stock '98 Wrangler I had trouble on the loos inclines. It did great climbing up rocks though. I had 31" tires with street tread. My tires sucked in the loose stuff. I had a crawl ratio of 32:1 with 3.07:1 gears. My gearing sucked. I had open differenchials.
To have been more capable I would have needed larger tires with more aggressive tread. The lugs would have to have been spaced further apart to move more dirt and sand. My tire pressure could have been lower. I needed lower gears. There is no replacement for locked differenchials.
You say you load the vehicle with camping gear. Make sure to load the vehicle with as much weight towards the front. Whether this involves putting toolboxes in the front passenger footwell or seat (if possible), or as simple as positioning the heavier items as far forward in the boot as possible. Right up against the back of the rear seats.
My trail vehicle is over 4000 lbs, has a 100 inch wheelbase, about 11" of suspension travel, detroits with a crawl ratio of about 42:1 on a V8 with an AT, and KM2's at about 15psi.
What Lukethedork is referring to is a "center" diff...not the one in the axle. Full time 4wd vehicles like the Rover and my 100 series Landcruiser have a differential in the middle of the truck by the transfer case. This allows the front and rear axles to spin at different speed to give a more pleasant road feel. The OP has locked the axles, but Luke was seeing if he had locked the center diff as well.
Not quite the same thing, but we have some giant sand, chat, and pea gravel hills that I've played on a lot over the years. If you're spinning your tires hard all the way up, start to lift off the throttle just a hair as you near the crest. You'll be amazed at the sudden traction you gain for a few feet. If you dig holes, go ahead & dig 'em good. Then, you can back (SLOWLY) up onto the "lip" of the hole, and get another short run at it. Repeat as needed.
Yes, I locked the center differential. I realize that's a no-brainer when you have the linkage, but that some years the factory omitted it and it could be overlooked by someone who didn't have the option without retrofitting it.
I found my tire guage was off by about 5 psi so I had at least 20 psi in the radial tires. I could have gone lower.
My next jobs are a roll cage (hiring it out), and tires.
I do realize weight loss is important (as I'm adding more, I know) but I don't think it can happen in a significant way unless I start taking doors and roof off. The vehicle is usually not loaded with any more than the recovery bag, and all my people and dog are skinny. The five of us combined are 373 lbs.
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