A LowMax Question

[Greg72]

I wanna do it too, cause with the 42's installed, I drop under 100:1 now.

Hope they make a kit for the drivers drop soon.

???? Huh?

Tire diameter has nothing to do with crawl ratio. What is this 100:1 calculation you are referring to??

 

[Hossbaby50]

Sumner Machine I believe is the guy on Pirate that was part of WMS. I believe he is not making them anymore though.

Harley

 

[tarussell]

Sumner Machine I believe is the guy on Pirate that was part of WMS. I believe he is not making them anymore though.

Harley

If it helps anyone the guy I delt with at WMS ( when they were a business ) was named Casey . Very helpful dude ! I don't know if he is the same guy Ya'll are talking about ???

Tom

 

[vtblazer]

???? Huh?

Tire diameter has nothing to do with crawl ratio. What is this 100:1 calculation you are referring to??

Okay, I stated it incorrectly, maybe.

According to what you wrote somewhere lately, the "perfect" final ratio should match the circumferance of the tires being run.

Mine doesn't any more, the 42's are about 120"s around.
My numbers with the th-400/203-205/5:13's come out to about 101 or close to it.

Of course tire size effect's final ratio's, how could it not?

 

[Greg72]

Okay, I stated it incorrectly, maybe.

According to what you wrote somewhere lately, the "perfect" final ratio should match the circumferance of the tires being run.

Mine doesn't any more, the 42's are about 120"s around.
My numbers with the th-400/203-205/5:13's come out to about 101 or close to it.

Of course tire size effect's final ratio's, how could it not?

OK, I see what you're getting at now.

The formula for crawl ratio REALLY doesn't include a value for the tire diameter (I swear! ), which is why the ratio by itself doesn't tell the whole story.

In general, a larger number is better than a smaller number...and most conventional methods for increasing the crawl ratio won't ever get you to a number that is "too large" for the tire size, so most people ignore it as a factor.


Oh, and by the way for the other poster talking about WMS (Wagoner Machine) the guy I dealt with there was Casey Groth....very nice guy. I suspect that if you can locate him you might be able to still figure out how to get a 3:1 gearset for a 203.

 

[vtblazer]

OK, I see what you're getting at now.

The formula for crawl ratio REALLY doesn't include a value for the tire diameter (I swear! ), which is why the ratio by itself doesn't tell the whole story.

In general, a larger number is better than a smaller number...and most conventional methods for increasing the crawl ratio won't ever get you to a number that is "too large" for the tire size, so most people ignore it as a factor.

Not the crawl ratio by the numbers (I understand that one) but does impact the final 'tire to ground' ratio...right?

 

[Greg72]

Not the crawl ratio by the numbers (I understand that one) but does impact the final 'tire to ground' ratio...right?

Absolutely!

Your travel speed across the ground will be different at 100:1 with a 35" tire (slower) than with a 44" tire (faster).

The thinking man (which we know you are) will consider both the crawl ratio and the tire circumference as determining factors for how the truck will perform offroad.

I've got some calcs somewhere that show the feet/minute that various setups would travel at 650RPM (idle basically). Consider that 1MPH is equal to about 88 feet/minute of travel speed, and these types of crawl ratios put the truck down at around 60 feet/minute.

 

[fourwheelerjeff]

Your travel speed across the ground will be different at 100:1 with a 35" tire (slower) than with a 44" tire (faster).

isn't that backwards??

 

[Greg72]

isn't that backwards??

No.



A single rotation of the engine (through the gearbox and axles) will require more distance across the ground for a larger diameter tire, since it's circumference is larger (in this example, 138 inches for a 44" tire vs. 109 inches for a 35" tire)

If you are talking about a fixed engine RPM in both cases, then the time (remember, the M in RPM is "Minutes") is constant....so the larger tire must move across the ground faster in to complete one revolution in the same amount of time.

 

[fourwheelerjeff]

maybe i am looking at it wrong; with a 35 inch tire you are going 2.6 mph at 2500 rpm; with a 44 you are going 3.3 mph; with a 100:1 crawl.

damn, once i did the numbers, i understand

 

[gmc4cw]

so what you guys are saying is that my 700R4/241-4.56 axles aren't enough to go wheeling with my 44's and I should stop. Thats a shame because I really like wheeling and the truck seems to perform OK, but if you guys don't think its enough gear I guess I'll build a ricer.

 

[resurrected_jimmy]

so what you guys are saying is that my 700R4/241-4.56 axles aren't enough to go wheeling with my 44's and I should stop. Thats a shame because I really like wheeling and the truck seems to perform OK, but if you guys don't think its enough gear I guess I'll build a ricer.

How do you fit a 241 in a ricer

 

[fourwheelerjeff]

shoot no, this is like armchair quarterback the day after the game.

my calculations show that you have a 37.95 crawl ratio, not taking into account the torque converter.

obviously you have a set up that is working very well for you, and you are having lots of fun. i envy you. by comparision, i am only going to have a crawl ratio of 26.54 in my m1009 once i am done, while my dedicated crawler will have 87.2, not taking into account the converter in either rig.

 

[Greg72]

so what you guys are saying is that my 700R4/241-4.56 axles aren't enough to go wheeling with my 44's and I should stop. Thats a shame because I really like wheeling and the truck seems to perform OK, but if you guys don't think its enough gear I guess I'll build a ricer.

I don't think anyone was even talking to you...

Your 76:1 Crawl is certainly respectable, better than my 40:1 for sure!


However, once you decide to spend the money required for deeper gearing (Doubler, Atlas, etc) it DOES make sense to understand what you're doing and to be able to calculate what you're actually going to get for those thousands of extra dollars.

 

[vtblazer]

so what you guys are saying is that my 700R4/241-4.56 axles aren't enough to go wheeling with my 44's and I should stop. Thats a shame because I really like wheeling and the truck seems to perform OK, but if you guys don't think its enough gear I guess I'll build a ricer.

Yeah good idea, we could use it as an obstacle.

Your truck performs OK because you DO, have low enough gearing.

 

[gmc4cw]

I don't think anyone was even talking to you...

Your 76:1 Crawl is certainly respectable, better than my 40:1 for sure!


However, once you decide to spend the money required for deeper gearing (Doubler, Atlas, etc) it DOES make sense to understand what you're doing and to be able to calculate what you're actually going to get for those thousands of extra dollars.

40:1 that sucks. what combo is that 350/208-2.72 gears??? or maybe 350/205-3.73 gears. either setup sucks.

I plan on better gears for the diffs. they are just really expensive. I have always liked the Klune-V. seems like a good deal for the price and its really compact and light, unlike a 203 rangebox.

since I have 4.56 gears now, is it worth the effort to swap carriers in the 14 bolt and go with a 5.38 gear over a 5.13 gear?

 

[Greg72]

TH350/NP205 & 4.10s... yep, a dead-sexy 40:1 crawl!

Conceptually, it sounds like you understand the problem.... you're at 76:1 now, and 5.13s will only get you to 85:1 and 5.38s only do slightly better at 90:1.

Either way it's about $1000 for the gears and getting them professionally set-up. Is such a small change worth $1000? Probably not.....considering that you're on 44s, where you'd be better off with something in the 140:1 range.

 

[gmc4cw]

TH350/NP205 & 4.10s... yep, a dead-sexy 40:1 crawl!

Conceptually, it sounds like you understand the problem.... you're at 76:1 now, and 5.13s will only get you to 85:1 and 5.38s only do slightly better at 90:1.

Either way it's about $1000 for the gears and getting them professionally set-up. Is such a small change worth $1000? Probably not.....considering that you're on 44s, where you'd be better off with something in the 140:1 range.

I completely understand. at first I was just joking about getting a ricer. I will eventually regear, but like you said its alot of money. I'm hoping that I can sell the 4.56 gear sets and get at least half the cost of a new set. I have sold a lot of 44 gear sets and gotten half or better of what new ones cost.

I'll quit muddying up Julians thread now.

 

[resurrected_jimmy]

TH350/NP205 & 4.10s... yep, a dead-sexy 40:1 crawl!

With the motors you run you don't need gears

 

[FOR MUD]

I'll quit muddying up Julians thread now.

My question was answered, now I'm sitting back quietly watching and learning. Lots of good info here.