it kills the neutral safety switch that is activated when you press the clutch to the floor so you dont fly forward and stall out by accident...so it allows you to start without pushing the clutch in

 

The clutch start cancel switch is a nice feature, but you can also heel-toe or, like somebody mentioned above, use the parking brake as a hill holder. I would rather wear out the parking brake (I'm sure the wear is minimal when this technique is used properly) than tax the starter unnecessarily.

 

I dunno...the parking brake isn't gonna hold that well. It's on a drum brake and isn't very strong. I would rather not break the cable trying to pull it really tight to hold the truck on a steep hill.

 

abced

 

don't slip the clutch unless absolutely necessary off-road. i like to put it in 4L, 1st gear and put it to the floor. with the amount of trees around here, you'll become a technical driver in a hurry

although i'm going to start saving for a crawl box eventually, makes things that much easier.

 

That's for sure! For rock crawling, I would much rather have an auto. With a manual, we bounce and bang our way through the rocks and the guys with autos seem to just slowly keep advancing. It takes more driver skill to get a manual through Now I'm starting trouble!!!

I thought if you touched the brake with an auto, it is like putting the clutch in on a manual and effectly takes it out of gear? Maybe that is only in high range. I have never had an auto 4x4 so set me straight.

 

Not entirely...it takes a different skill to drive a manual correctly, but not nessesarily better...An auto with a crawler, IIRC from other threads, cannot be stopped with the brakes in double low.

A manual is more entertaining to watch, i've got one and folks laugh at me all the time, but its fun, and i enjoy it. Since you already have a locker, i would suggest you get a crawler if you plan on doing more diffficult wheeling. For myself, i need the locker first, as a crawler would be somewhat silly since all i could do is spin my wheels very slowly.

 

Is that because the torque generated by the low gearing of the crawler exceeds the frictional force of the brakes or are you saying that applying the brakes doesn't disengage the crawler with an auto?

Same here, a crawler is definately on my long term plans/wish list!

 

yeah. just some quick math

i'm going to make some assumption here, fill in the real values for your engine and gears, but it won't make a big difference in the end:

100ft-lbs of torque from the engine
the torque converter can multiply the torque by about 2 if it's unlocked
the first gear on an auto is about 3:1
the first low range is 2.2:1
the second low range is 4.7:1
the gears are 5.29:1

(100*2*3*2.2*4.7*5.29)/4 = 8,200 ft-lbs of torque per wheel

now, how much force can the brakes apply?

60-0mph stopping is probably somewhere around 150ft which will take about 3.5 seconds
with gear and driver the truck is probalby around 4,000lbs
assuming a constant deceleration over that time, the brakes are required to dissipate 39,000W or 520HP of power while applying 3200lbs of force to the ground.

so if it requires about 3200lbs of force at the ground, assuming 31" tires. that means the brakes need to apply 8200 ft-lbs of total torque to stop the truck, which means that each wheel only supplys approximately 1/4 of that or 2100 ft-lbs

so in summary, engine with auto in 1st gear and double crawler can apply 8200ft-lbs of torque per wheel. the strongest the brakes can be is 2100ft-lbs of torque per wheel. you'll never be able to stop it in gear.

mike ( )

 

Cool, physics that you can use in a real life situation!

I had to think about the auto trans a bit more and of course, you can do a brake stand with an auto so it's always trying to move the vehicle forward even when you have the brakes on. I was thinking depressing the brake pedal disengaged the torque converter in an auto or something like that but it can't be.

I know when you are slowing to a stop in our Honda Odyssey minivan the trans automatically drops down to low gear which can catch you off guard sometimes as it lunges you forward in the seat.

 

Crawler, 3.4 and auto with 5.29 diff gear and an auto, I can stop fine. Standing on the gas like that does nothing but rev the engine.

Most comp rigs are auto's.

Best advice, as I said, the clutch is in or out.

 

I stand corrected, just thought i'd read that somewhere, must've been something else.

 

Do what I did and you'll never have to worry about a clutch, go here.

 

As others have said, for manual, crawler gear is your friend.

 

I've been offroading a couple of times and have experience with both manual and auto transmissions and can say that the only time I can see an auto benefit is that you can concentrate a little more on throttle and steering since you won't have to worry about spinning your tires when you go from a dead stop. A little experience in knowing when your auto is going to shift goes a long way, though. The hard shifts when you're in 4L can catch you off gaurd sometimes. My auto tranny has grown on me since I got my new truck but I always enjoy a manual.

Edit: I seem to remember that my dad's '05 tacoma (5spd auto) does do a little downshifting but my '02 (4spd auto) just leaves it in a powerless gear until I come to a complete stop or hit the gas.