Bottom line
We are glad your cruiser is ok. Oh and you too
We are glad your cruiser is ok. Oh and you too
Near accident: help understanding root cause
- Thread starter ravenholm
- Start date
This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.
Second that.
One thing that I learned from mountain biking a lot is always try to cross slick objects like roots (similar to RR tracks) at a perpendicular. If you have the chance of having a tire slide off, you should keep the possible slide time (along the object) as short as possible).
It also sounds like you 'cracked the whip' with your rig starting with the sharp turn away from the turn and then the correction into the turn. This can multiply the forces pushing the rear end drastically.
My next purchase for the 40 was going to be a set of 33x10.5 BFG MT's. I'm bummed to hear the not-so-good things about them in the rain, not like we get THAT much here in the central valley anyway, but still...
Maybe I'll stick with the AT's
Glad you and the cruiser are ok.
Hijack over.
Maybe I'll stick with the AT's
Glad you and the cruiser are ok.
Hijack over.
40Habits
Sure... why not
I have run lots of sets of BFG mud terrains on many different trucks. The new km2 is better then its predecessor. I would bet it was black ice. I have had that happen to me on a straight away and it was not because of tires.
I'm glad you're ok.
I had a similar thing happen a few years back... even without the tracks or rear locker. Driving down the road at +/- 30 mph on dry roads, started into a curve to the highway on ramp, saw the road was a wet and let off the gas... Next thing you know, I'm steering to correct as the truck is now perpendicular to the direction I was traveling.
Short wheel base + forward weight shift + engine braking + slick wet roads + sloped corner = spin out.
I'd air down quite a bit, more than you'd think, I ran 21 psi on my 33x12.50s Yokohamas for the life of the tire... They wore like they were over inflated. With my 33x10.50 BFG ATs I'm now running 25 psi to get away from a twitchy feeling ride and keep most of the tire width on the ground. Try drawing a chalk line across your tire and driving for a block... You might be surprised. At 30 psi, only 3-4" of the 9-10" were in contact with the road.
An open diff helps, mine is open and it is 20x more stable in the corners than our bigger SUV which has a limited slip in the rear... I often drive it in 4WD if the roads are wet... No more drifting around corners.
Try to take tracks at close to 90. If you can't, slow down even more.
I don't think MTs are the main problem. I've almost always had ATs and have encountered similar problems. I've heard Siping helps a lot.
I had a similar thing happen a few years back... even without the tracks or rear locker. Driving down the road at +/- 30 mph on dry roads, started into a curve to the highway on ramp, saw the road was a wet and let off the gas... Next thing you know, I'm steering to correct as the truck is now perpendicular to the direction I was traveling.
Short wheel base + forward weight shift + engine braking + slick wet roads + sloped corner = spin out.
I'd air down quite a bit, more than you'd think, I ran 21 psi on my 33x12.50s Yokohamas for the life of the tire... They wore like they were over inflated. With my 33x10.50 BFG ATs I'm now running 25 psi to get away from a twitchy feeling ride and keep most of the tire width on the ground. Try drawing a chalk line across your tire and driving for a block... You might be surprised. At 30 psi, only 3-4" of the 9-10" were in contact with the road.
An open diff helps, mine is open and it is 20x more stable in the corners than our bigger SUV which has a limited slip in the rear... I often drive it in 4WD if the roads are wet... No more drifting around corners.
Try to take tracks at close to 90. If you can't, slow down even more.
I don't think MTs are the main problem. I've almost always had ATs and have encountered similar problems. I've heard Siping helps a lot.
ravenholm
Father of Crows
- Thread starter
- #26
Thanks all. I'm glad my cruiser if OK too.
And me.
SO I have a very specific question for those of you who have, I think correctly, observed that engine-breaking is part of the problem....
In the same situation again, going down the hill, it the correct method to disengage the drive-train with the clutch so no sudden engine breaking occurs?
Or is the idea the "neutral throttle" technique: once a hazard is identified, slow down early, pick your approach, and stay even on the gas no matter what happens until you're through it?
I was running in 2wd at the time. This aspect just occurred to me (talk about "duh"). Would having it in 4H have helped since the front tires would be under traction and less likely to just follow the tracks?
And me.
SO I have a very specific question for those of you who have, I think correctly, observed that engine-breaking is part of the problem....
In the same situation again, going down the hill, it the correct method to disengage the drive-train with the clutch so no sudden engine breaking occurs?
Or is the idea the "neutral throttle" technique: once a hazard is identified, slow down early, pick your approach, and stay even on the gas no matter what happens until you're through it?
I was running in 2wd at the time. This aspect just occurred to me (talk about "duh"). Would having it in 4H have helped since the front tires would be under traction and less likely to just follow the tracks?
Last edited:
Without the locker, the answer would be, "yes-stay on the throttle (just enough to keep the weight from transferring = very light throttle." With the locker, I imagine you want to slow to a crawl and coast through the turn (I don't have a locker). Being in 4wd would not have prevented you from losing traction and, in fact, would probably have contributed to losing traction, but may have helped you recover after losing traction.
In the same situation again, going down the hill, it the correct method to disengage the drive-train with the clutch so no sudden engine breaking occurs?
The rear locker was your primary culprit in initiating your spin, coupled w/ an unweighted rear. When using a locker w/ both axle shafts coupled, you lose lateral resistance. The vehicle is fine in a straight line since there is no side-loading. In a turn, both tires are turning, some times binding due to different revolutions between the two tires. This initiates the slide, getting off the throttle and on the brakes exaccerbates the condition. An open diff would negate much of this issue, when within the performance parameters of the tires. With an open diff, the tires are allowed to roll at different revolution speeds, thus maintaining some degree of lateral resistance. When your rear begins to slide out, often times it can be 'caught' by pushing in the clutch, and thus dis-engaging the brake horsepower of the motor from the now free-spinning rear wheels. This will allow a greater degree of traction, allowing you to gather-up your rig, and keep it heading in the intended direction. When it's under control, re-engage the clutch, add throttle, and continue on your journey. Happy trails.
The rear locker was your primary culprit in initiating your spin, coupled w/ an unweighted rear. When using a locker w/ both axle shafts coupled, you lose lateral resistance. The vehicle is fine in a straight line since there is no side-loading. In a turn, both tires are turning, some times binding due to different revolutions between the two tires. This initiates the slide, getting off the throttle and on the brakes exaccerbates the condition. An open diff would negate much of this issue, when within the performance parameters of the tires. With an open diff, the tires are allowed to roll at different revolution speeds, thus maintaining some degree of lateral resistance. When your rear begins to slide out, often times it can be 'caught' by pushing in the clutch, and thus dis-engaging the brake horsepower of the motor from the now free-spinning rear wheels. This will allow a greater degree of traction, allowing you to gather-up your rig, and keep it heading in the intended direction. When it's under control, re-engage the clutch, add throttle, and continue on your journey. Happy trails.
More on the staying on the throttle (lightly) because it feels so counter-intuitive. Preventing the weight transfer keeps you in the game of trying to get out of a bad situation as it keeps the rear wheels in the game. Once you lose the rear wheels, things tend to happen quickly in a short-wheelbase vehicle that was not designed to handle well (like a Miata). Of course if you're coming into a corner way too fast, good technique is not going to overcome the laws of physics (don't ask me how I know 
).
).More useless trivia, weight transfer is important on a motorcycle because not only are you concerned about the rear tire, you are also concerned about the front one as well. If the front tire has too much load to deal with, it cannot do its job of steering, gets overloaded, and then washes out, which results in a lowside mishap :-o okay, I'll shut up now.
ravenholm
Father of Crows
- Thread starter
- #32
Taro,
Like most guys, I wanted a motorcycle too. We've had some really sad family tragedies involving motorcycles, so that's not really an option.
Fascinating vehicles, but essentially I traded any future requests for motorcycle privileges for support from my lovely
in getting a FJ40.
So, it's my four-wheel drive motorcycle.
And from what I've learned in this thread, requires close to the amount of attention and skill to safely drive.
Like most guys, I wanted a motorcycle too. We've had some really sad family tragedies involving motorcycles, so that's not really an option.
Fascinating vehicles, but essentially I traded any future requests for motorcycle privileges for support from my lovely
in getting a FJ40.So, it's my four-wheel drive motorcycle.
And from what I've learned in this thread, requires close to the amount of attention and skill to safely drive.
A very good thread and a great amount of knowledge. Here in the Pinas it rains all the time and I am running 33 x12.5 x 15 MT's mostly because roads here are like driving off road. Cement for awhile, then gravel then dirt then mud lol! I air mine down as well as others have suggested to put more rubber on the surface during rain and to help prevent skidding when barkes are applied. It works well here but again this is not Portland. And don't worry and the Duh comment. He always makes comments that are not what people like to hear like an expert in every field of life and especially 40's. I think he was locked in the closet a lot as a child but if we were all the same it would definately be a boring world. Very happy you are okay as well as your truck. There are 90 million people here and 180 million motorcycles and 70 million of them have a death wish. I have a big bike but it stays in the garage most of the time not because I don't trust myself it is because of the Kamikazi's around here lol! Wish more people thought about things like you do. 28 huh? Wish most 28 year old guys I know were thinkers like you, most I know could not pour water out of a boot without the directions on the heel!
Guy, I'm sorry to hear about the family tragedies with motorcycles and although I'm late to say it, I'm glad you and your cruiser are okay.
Having a lovely wife to support you through your lc addiction is a rare and precious thing indeed.
Modern vehicles have so many nannies in place that they really are much safer vehicles. That being said, it deprives most drivers of understanding vehicle dynamics. My biggest adjustment to driving my 40 was the brakes. Before I started driving my 40 as a daily driver, I was what you might call an aggressive driver. But the first time I locked up the brakes on the interstate when traffic suddenly came to a halt was an eye opener to say the least :O
I remember reading an article once comparing an old mustang to its competitors at the time. The author noted that when all of the other cars had stopped from a certain speed, the mustang was still going 35 mph! The lc's stopping ability is worse Lcs definitely take commitment, but it's fun to always be learning. When my new body gets swapped, I'm hoping to get to learn about various off-road and winching techniques!
Speaking of which, when considering a roll cage, my recommendation is to have the roll cage "tied" or connected to the frame. This is much safer than roll cages that are merely attached to the body. In my case, my roll cage was practically the only thing holding the body together and so if I did roll, the only thing the cage would have done would have been to leave an imprint of where it crushed my skull. Also, I've read that the stock roll bar is relatively weak and shouldn't be depended upon. I've read others say that it does well enough and is better than nothing. My roll cage that was already installed when I bought my 40 is a front section welded on to the stock roll bar. Before I knew any better, this is what I was looking for because I like the look of this setup and I wanted to keep the jump seats.
Your choice in roll cage may force you to get rid of the jump seats, which are considered unsafe anyway. This may lead to the purchase of a bench seat, preferably one with head rests that folds and tumbles … it’s maddening how one thing leads to another … but I really like the jump seats … can you tell I’m neurotic?
While I’m babbling … the reason why being in 4wd may have resulted in a loss of traction is that on a part-time 4wd system like we have, the transfer case locks the front and rear driveshafts together and sends an equal amount of torque to the front and rear axles forcing them to spin at the same speed. This doesn’t cause a problem when going straight with all four tires travelling at the same speed. But when the tires begin to rotate at different speeds, which is what happens when going through a tight turn, the system depends on wheel slip to deal with the difference in speed between the front and rear axles, which is what you don’t want to happen in the scenario that you experienced. Btw, this is why we shouldn’t use 4wd on dry, high-traction surfaces—the tires can’t slip, which causes binding, which may lead to something breaking. Awd systems have differentials that allow for differences in speed. But like I said, being in 4wd could have helped you recover once the traction was lost. Can you tell I’ve had many Monster energy drinks today? I’ll try to stop babbling now.
Having a lovely wife to support you through your lc addiction is a rare and precious thing indeed.
Modern vehicles have so many nannies in place that they really are much safer vehicles. That being said, it deprives most drivers of understanding vehicle dynamics. My biggest adjustment to driving my 40 was the brakes. Before I started driving my 40 as a daily driver, I was what you might call an aggressive driver. But the first time I locked up the brakes on the interstate when traffic suddenly came to a halt was an eye opener to say the least :O
I remember reading an article once comparing an old mustang to its competitors at the time. The author noted that when all of the other cars had stopped from a certain speed, the mustang was still going 35 mph! The lc's stopping ability is worse
Lcs definitely take commitment, but it's fun to always be learning. When my new body gets swapped, I'm hoping to get to learn about various off-road and winching techniques!Speaking of which, when considering a roll cage, my recommendation is to have the roll cage "tied" or connected to the frame. This is much safer than roll cages that are merely attached to the body. In my case, my roll cage was practically the only thing holding the body together and so if I did roll, the only thing the cage would have done would have been to leave an imprint of where it crushed my skull. Also, I've read that the stock roll bar is relatively weak and shouldn't be depended upon. I've read others say that it does well enough and is better than nothing. My roll cage that was already installed when I bought my 40 is a front section welded on to the stock roll bar. Before I knew any better, this is what I was looking for because I like the look of this setup and I wanted to keep the jump seats.
Your choice in roll cage may force you to get rid of the jump seats, which are considered unsafe anyway. This may lead to the purchase of a bench seat, preferably one with head rests that folds and tumbles … it’s maddening how one thing leads to another … but I really like the jump seats … can you tell I’m neurotic?
While I’m babbling … the reason why being in 4wd may have resulted in a loss of traction is that on a part-time 4wd system like we have, the transfer case locks the front and rear driveshafts together and sends an equal amount of torque to the front and rear axles forcing them to spin at the same speed. This doesn’t cause a problem when going straight with all four tires travelling at the same speed. But when the tires begin to rotate at different speeds, which is what happens when going through a tight turn, the system depends on wheel slip to deal with the difference in speed between the front and rear axles, which is what you don’t want to happen in the scenario that you experienced. Btw, this is why we shouldn’t use 4wd on dry, high-traction surfaces—the tires can’t slip, which causes binding, which may lead to something breaking. Awd systems have differentials that allow for differences in speed. But like I said, being in 4wd could have helped you recover once the traction was lost. Can you tell I’ve had many Monster energy drinks today? I’ll try to stop babbling now.
coleman2347
Ole Jarhead
Glad ur ok
Just a thought on the tires, when I was in the states and could get them I use to run Mich.LTX's, I found them to be great in the rain, snow and any other condition except four wheeling in very rocky conditions (thin sidewalls). A little costly but worth it.
Root Cause= WTF
Just a thought on the tires, when I was in the states and could get them I use to run Mich.LTX's, I found them to be great in the rain, snow and any other condition except four wheeling in very rocky conditions (thin sidewalls). A little costly but worth it.
Root Cause= WTF
watch where your driving and know what your driving.......
maybe you shouldnt be in a 40 "nervous nellie"
Portland has a great bus system too.
maybe you shouldnt be in a 40 "nervous nellie"
Portland has a great bus system too.
ravenholm
Father of Crows
- Thread starter
- #37
Taro,
For roll cage, a frame mounted aftermarket full deal is what I'm looking at (made by metal tech, nice and local).
The stock rollbar is a joke, and my body is so rusted that the skull print is all it would be worth. Well said.
I've driven a lot of big trucks. Not semi's, but delivery / box trucks 20-24 feet with heavy cargo.
The stopping distance there as taught me to leave lots of room. HOWEVER, I have never spent much time with something that doesn't have ABS, but I know the basic idea behind how not to lock them up. And mostly it comes down to predictive driving, as others have pointed out. If your inside your safe stopping distance in any vehicle, yer options are limited to figuring out how to best mitigate the coming impact. Knowing what the rig is gonna do before it does it is the best technique. Unfortunately, only time and study creates that...
RoboosFJ40 : yeah, I learned a pile from everybody's help in this thread. I'm happy to hear that other people may be benefiting from my error as well.
Alaska60:
Good advice regarding knowing what your driving and where you're driving. Portland does have a good bus system, but they don't use FJ40s for public transit vehicles, so it's only so much fun....
Knowing what your driving -according to your advice- requires *learning* what is different about a particular vehicle, which is why I"m asking for advice. And good advice I seem to have gotten in spades...
So, here's to learning new skills.
For roll cage, a frame mounted aftermarket full deal is what I'm looking at (made by metal tech, nice and local).
The stock rollbar is a joke, and my body is so rusted that the skull print is all it would be worth. Well said.
I've driven a lot of big trucks. Not semi's, but delivery / box trucks 20-24 feet with heavy cargo.
The stopping distance there as taught me to leave lots of room. HOWEVER, I have never spent much time with something that doesn't have ABS, but I know the basic idea behind how not to lock them up. And mostly it comes down to predictive driving, as others have pointed out. If your inside your safe stopping distance in any vehicle, yer options are limited to figuring out how to best mitigate the coming impact. Knowing what the rig is gonna do before it does it is the best technique. Unfortunately, only time and study creates that...
RoboosFJ40 : yeah, I learned a pile from everybody's help in this thread. I'm happy to hear that other people may be benefiting from my error as well.
Alaska60:
Good advice regarding knowing what your driving and where you're driving. Portland does have a good bus system, but they don't use FJ40s for public transit vehicles, so it's only so much fun....
Knowing what your driving -according to your advice- requires *learning* what is different about a particular vehicle, which is why I"m asking for advice. And good advice I seem to have gotten in spades...
So, here's to learning new skills.
I see a couple on here has never made any mistakes in driving or otherwise. Hmmmm? Born with a steering wheel in each hand and a gear shift between their leggs I suppose. Some people's children omg! I have made a 1000 mistakes and lived through many and not too proud to admit it. But that is just me. A mistake in judgement, driving, finances or anything can be a learning experience and if you live through it, don't make the same mistake twice.
I Had just about the same thing happen to me 18 years ago, when I was lived in Sacramento, CA the only diff was I was in an 81 Mustang.
Rain and a road with RR tracks in it do not mix. Now in Calif they have to place some kind enhaced tracktion surface on both sides and in between the tracks.
I would call the RR company, City, County, or state and let them know what happend because I bet you are not the only one this happend to at that location.
Rain and a road with RR tracks in it do not mix. Now in Calif they have to place some kind enhaced tracktion surface on both sides and in between the tracks.
I would call the RR company, City, County, or state and let them know what happend because I bet you are not the only one this happend to at that location.
Root Cause
you asked for the root cause? I say it was speed. All of those things mentioned in the posts above were contributors...... Slow it down, and the spin will not happen.
Your note was a good reminder to all of us that we need to take extra precautions with our toys.
you asked for the root cause? I say it was speed. All of those things mentioned in the posts above were contributors...... Slow it down, and the spin will not happen.
Your note was a good reminder to all of us that we need to take extra precautions with our toys.
