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My Crawl Ratio
- Thread starter skidpan
- Start date
GEORGIA GABE
1/2 ton status
use grimms ratio calcutator. it will give you alot more info and take the guesswork out of it
gabe
http://www.dfw-tx4wd.org/Tech-Dept/Tech-Dept/gears.html
gabe
http://www.dfw-tx4wd.org/Tech-Dept/Tech-Dept/gears.html
zero cool
1/2 ton status
GEORGIA GABE said:use grimms ratio calcutator. it will give you alot more info and take the guesswork out of it
gabe
http://www.dfw-tx4wd.org/Tech-Dept/Tech-Dept/gears.html
That's the outdated version. It was supposed to be gone but they had a failure and the hosting company reloaded it from backup. The admin can't get in right now to take it back down since the hosting company is rebuilding the back end. That page will be coming down again by this weekend some time.
I already posted the link to the new version a couple posts back:
http://coloradok5.com/forums/showpost.php?p=1530329&postcount=20
The new and improved version is at http://www.grimmjeeper.com/gears.html
Hopefully, the admin at the dfw-tx4wd site will put in a forwarding page but I'm not going to hold my breath.
Update your links and pass along the new address to everyone so they can see the new and improved site. And if you find anything wrong, let me know and I'll get it fixed.
Chevy305 said:
Sorry I got my T-Case ratio wrong, the NP208 should have a 2.61:1 LO
so,
6.55 x 2.61 x 4.10 = 70.019155
I think that is better
skidpan said:
same as I except my hawgs measure 38.8
I have not found a need for anything lower.. yes we do have some rocks around here... but to go .69 mph through mud would get ya stuck in a hurry
depends on what you want to do with your truck..... I am thinking a NV4500 or nv5600 would be nice one day... keep my same gears and throw that overdrive in there...
Some of us have to drive our rig to the trails, beat it up and drive it home... cant afford a tow rig and trailer... so overdrive would be nice to make the gas go a tad farther.....
skidpan said:
Just to add another opinion on your question about a 59:1 C/R - It is a fairly good number for most trails but not for truly low speed crawling. If you are after more power through gear than it is fairly good in most applications but if you are after slower tire speed than it is a little on the high side.
I have a 63:1 C/R on my tow rig and it does well enough on the mild off-road use that it see's but I wish I had slower speed at times . The motor does not need any help as far as extra gear for power but the slower wheel speed would be nice at times.
My Blazer has a C/R of 241:1 with 36" tall tires so I can limit how much tire speed is needed and have enough grunt at idle.
I think of gearing as a tool to make use of the power band of the motor and a way to control actual wheel speed.
HTH's Tom
I like that calculator. Thats the way it should be measured, as it includes tire diameter. 31's to 38's make a huge difference, with all other parts remaining the same. I don't see what good a C/R does without including tire diameter.
btw, a torque convertor does not play a role as a ratio in a crawl ratio. It is a touque multiplier and its whole job in life is to transfer torque to the transmission and allow slippage so the engine can idle without stalling. Torque convertors operate at 85%+or- efficency when crusing down the highway so they never have 100% engagement to the tranny(unless lockup styles). The flash speed of the convertor is nothing more than the fins in the tranny locking up and engaging after rpms have increased, very similar to using a clutch reving it a little, let it slip little, then dumping it.
my crawl ratio is crap 2.48 x 2.01 x 4.10= 20.48:1 and i have a auto and it doesnt give me any more gear ratio.
my crawl ratio is crap 2.48 x 2.01 x 4.10= 20.48:1 and i have a auto and it doesnt give me any more gear ratio.
marv_springer
1/2 ton status
onetonbb74 said:
Then your starting off in 3rd or something...
I've seen the argument a thousand times about how much/little of an advantage the TC provides... but nobody can deny that it does provide some advantage when crawling. Now it is true that the "multiplication effect" of it goes away quickly as you increase rpm - but it does provide more tire speed control at idle than a stick-rig of same Crawl Ratio.
Marv
pauly383
Daddy383
Your right , otherwise lots of rigs with autos , highway gears and taller tires wouldn't be able to crawl out of the driveway .
i guess i agree it helps a little but so little id rather have a stick. It would make my 165hp 350 come alive instead of being boring with crappy automatic gears.
marv_springer said:Then your starting off in 3rd or something...
I've seen the argument a thousand times about how much/little of an advantage the TC provides... but nobody can deny that it does provide some advantage when crawling. Now it is true that the "multiplication effect" of it goes away quickly as you increase rpm - but it does provide more tire speed control at idle than a stick-rig of same Crawl Ratio.
Marv
Very well said !
Tom
