Huge axle big block low gear confusion

[original balzer]

I wanted to post this in the lounge but figured it was too tech!

I been watching a lot of mud bog vids lately and come across a conundrum for my little brain.

So a lot of these built for mud trucks are runnin huge axles like all the way up to 5 ton. They also run some mean sounding big blocks. But it seams they are geared too low. I hear a big block reaching for 7000-8000 RPM and the tires seam to turn about 30MPH. Yet lets say a monster truck runs 5 ton axles but they are blistering fast! Do these huge axles have different gear ratios available or do the monster truck guys machine new gears or whats the deal here? I realize a monster truck is pushing upwards of 1400+ HP but I would imagine some of these swap guys have to be getting near 800+ HP.

Are the swap boys running a lot of HP low gears AND 4 low? I see a lot of videos that make me think "damn man shift that turd and spin those tires".

Anybody know what I'm talking about?

 

[imiceman44]

I wanted to post this in the lounge but figured it was too tech!

I been watching a lot of mud bog vids lately and come across a conundrum for my little brain.

So a lot of these built for mud trucks are runnin huge axles like all the way up to 5 ton. They also run some mean sounding big blocks. But it seams they are geared too low. I hear a big block reaching for 7000-8000 RPM and the tires seam to turn about 30MPH. Yet lets say a monster truck runs 5 ton axles but they are blistering fast! Do these huge axles have different gear ratios available or do the monster truck guys machine new gears or whats the deal here? I realize a monster truck is pushing upwards of 1400+ HP but I would imagine some of these swap guys have to be getting near 800+ HP.

Are the swap boys running a lot of HP low gears AND 4 low? I see a lot of videos that make me think "damn man shift that turd and spin those tires".

Anybody know what I'm talking about?

The swamp guys do run low gears and run in 4 low yes.
They do that to keep moving without making a big wave that could flood their engines.
As for the Monster trucks, most of these axles are fully custom, with custom gears and custom outers.
And to make things more confusing, they run huge tires that with the low speed of the axles still makes faster speeds on the ground.

 

[K5dreamer]

i think tire size and twice the hp is whats confusing you, the monster trucks also run planitary reduction gears in the hubs. so they are running lower gears than the diffs as well.

 

[original balzer]

1st I need to rephrase swap guys. I'm talking about the guys running in lake beds with huge tractor tires and thick deep mud.

Well I kinda get it. But take 2 engines one is 800HP around 8000-9000RMP the other is 1400HP at 8000-9000RPM put them both in trucks built exactly alike and the wheel speed should be the same, regardless of the HP.

This truck/thing show what im talking about right before he breaks it. The RPM is up there and the wheel speed still seams slow and the engine sounds pretty healthy (before it breaks lol)

http://www.youtube.com/watch?v=oOfx8K83Wbc&feature=related

I guess what I don't understand is the gearing in the main trans and transfer cases in the monster trucks (hell I don't even know what they have). A small difference there makes a big difference in wheel speed.

The reason I even bring this up is I have personally been in mud and 4 low, and basically stuck, then in a last effort switch to 4 high and pop right out cuz I can spin the tires fast enough to clean them out.

 

[K5dreamer]

truck A - 800hp, tractor tires
truck B - 1400hp, monster truck tires

Truck B has nearly twice the power, all else being equal it will accellerate faster, for something that large, accelleration will seem dramatic.

Truck B also has larger tires. for a similar gearing, the tire that has a larger radius, turning at the same speed, will have a higher effective wheel speed at its circumference.

 

[6.2Blazer]

Just don't confuse "mean sounding" with actually having high power numbers. I've spent a few holiday weekends at the big mud parks and have watched a lot of rigs. Maybe slap in a cam for a rowdy idle and a pair of 4" straight pipes and it "sounds" really mean, but doesn't actually run that good to turn over those tall heavy tires that fast.

For monster trucks, I'd be surprised if they were going over 20-30 mph most of the time. Plus they also are usually running 1,200+ horsepower engines with a much higher redline than the typical mud truck.

 

[Stomis]

If I remember correctly monster truck axles start life as school bus rears. They then add in custom shafts, custom planetary, outer knuckles, and hubs.

The core of it is a factory part though.

 

[original balzer]

LMFAO check this guy out in the flamed ford at 0.37 Bouncing the valves at 5-6kRPM and tires look to be turning at 5MPH.

http://www.youtube.com/watch?v=xQhs6iJvvFw&feature=related

My confusion, I really just had to actually thing about it for a minute.
1400HP= running like 2:1 transfer case and having power to hit 2nd and 3rd gear.
800HP= needing deeper gears like 4:1 in the transfer case so you can hit 2nd and 3rd gear effectivly cutting wheel speed in half.

As far as the tire size some of these guys are running 60+ inch tires pretty similar to a monster truck tire just a lot narrower. Monster truck tires start out as a 66" tall tractor tires only diff is they cut 100% of the tread off to lighten them and make them flex a lot more, then they cut an additional 5% to make new tread. To really describe the cutting Im talking about imagine running a tire until its completely slick bald then cutting new tread into whats left.

 

[original balzer]

If I remember correctly monster truck axles start life as school bus rears. They then add in custom shafts, custom planetary, outer knuckles, and hubs.

The core of it is a factory part though.

I thought they was 5 ton military truck axles... same thing? lol

We need to know the anatomy of a monster truck LMAO.
Some other things I wonder about is the super fast mud boggers and the super fast pulling trucks. Someone once told me the these use some sort of centrifical type of transmission "sorta" like a snowmobile. I dont know if thats true or not.

 

[shaun89]

my buddy has a ford with a decent big block,2.5 rocks on 63" tractor tires and he uses back to back 205s,he said that if he put it in high it will break shafts real easy,he broke 1 or two in low already. im not sure if someone mentioned this already,i read some of the posts. but i always thought the samething about lack of tire spin in those big trucks.