I have a C4 auto transmission, dana 20 t-case, and 5.13 gears in my Bronco. I've been thinking of adding some sort of crawler box like KluneV's Marin Crawler that will give me another 4.7 reduction. How will this difference be noticed with an automatic? I've never driven an automatic that has a crawl ratio in the 100s. Is this a worthwhile thing to do? It's a lot of $$$ if it's not going to be a huge difference.

Thanks,
Steve

dont forget u gotta be able to stop the thing, too low qith an auto and it might creep through teh brakes! jiMMy

Yeah, even with the stock tranny/t-case, my Toy will creep on 4Lo if I'm not concentrating...

Ramstein has setup a nice auto, with a crawler. He has tweeked the converter for a different stall, and claims that it will mimic a stick when crawling. Get a hold of him, or hope he wanders by this thread.
Or, any of the ARCA guys could help.

my current low is 29.5:1 if i'm figuring right (2.46 for the tranny, 2.34 for the D20, and 5.13 in the diff). If I added the 4.7 crawler i'd be at 138.8:1. I've got Dana 60s with discs front and rear, seems to stop the 38.5s fine now, i wouldn't expect that to be too much of a problem. Maybe with a crawl in the 200s it would be.

-Steve

Grady also does some trick slush box magic on the Jackyl.
He was explaining the manual valve body, and other trick swag he does, but I probably had a blank stare of confusion as its all just FM(fuckin Magic) to me. I am very curiouse about how it would feel to drive an auto in serious rock crawler. Im looking forward to hearing Kelly's opinion of it, after she competes in the Jackyl at the Womens event in JV next weekend. I think Im gonna beg for some more wheel time in someones slush box equipt rockcrawler really soon.
I am so used to my manual tranny, that the little bit of time I have spent driving an auto in a 100:1 rock crawler just seems, foriegn. I would like to drive an entire trail, so I could get used to it, and make a real evaluation. My manual tranny(130:1 1st gear) in 3rd gear low,with the low end torque I get from the 5.0 HO basicly acts like an auto, I can lug it down to 500 rpm without stalling, but then launch it to 15mph or so in an instant at 4500rpms.

I don't see a reason for such a drastic jump, I mean are you so unhappy now that you need 4.7 times lower gears :eek: best advive is try it and see if you like it. Personally that is way to drastic of a change and I would be looking at the 2.7:1 low or looking at a np-203 reduction for 2:1

Originally posted by NE-RokToy
I don't see a reason for such a drastic jump, I mean are you so unhappy now that you need 4.7 times lower gears :eek: best advive is try it and see if you like it. Personally that is way to drastic of a change and I would be looking at the 2.7:1 low or looking at a np-203 reduction for 2:1

The main reason I could see with going to a 4.7 (or whatever), is because you already have a 2.5(plus or minus, depending on which D20) so to install a 2. 7 gives you no more versatility. If you go with the 4.7, you can run in 1:1 high range of your T case and have the 4.7. Or run 1:1 in your reducer and run 2.46 out of your T case. And in the rare situation that you really need 300:1, it is there as an option.
It doesnt make sense to have two reduction cases in your set up, that close to each other, if more options are available.

how about this i am planning running 4:10 gears in my 60 and 14 bolt. i will be running a c-6 with a 205. well i have all the parts, and i would save alot of money not lowering the axle gears to 5:13. would this hurt me much, do you think i coul be able to run it with these gears until i save up enough for the 203/205 kit?
i have a big blockso im not to woried about the torque and i can run it at low rpms
what do you think
pat

I've got a C 6 (2.46 1st) and had a t'case with 4.3 reduction.
Hated it. Too low. Sold the t'case and got one with 3.0 reduction.

H8monday said it perfectly. I would want the 4.7 because it gives me a new middle range plus and really low range. It allows for so many more combinations. Anyway this is all thought for a project way in the future. I definitely need to find someone with a 140:1 auto somewhere around here so i can see what it's like.

Thanks,
Steve

Here's my set-up I'll have after the axle swap. :D

AW-4 and 4.56 gears

12.77 to 1, 7.07 to 1, 4.56 to 1 and 3.15 to 1

Klune V 2.7 to 1 engaged

34.47 to 1, 19.08 to 1, 12.31 to 1 and 8.50 to 1

Atlas II 3.8 to 1 engaged

48.52 to 1, 26.86 to 1, 17.33 to 1 and 11.96 to 1

Atlas II & Klune V engaged

131.00 to 1, 72.52 to 1, 46.79 to 1 and 32.28 to 1

NOTE: None of the above ratios takes torque converter multiplication into account. I'm not sure it matters with 130 to1 gearing???

I haven't had a chance to wheel hard since the Atlas/Klune was installed. It will idle over a 2' rock in compound low no problem though.... Kinda like an stick. :p

Being able to stop is a problem. The new axles will be 4 wheel disc so hopefully that will be enough otherwise I'll probably remove the gates in the shifter between first and neutral so it's easier to get into neutral to stop when needed.

At least I should have a gear for almost every situation. :smokin:

Originally posted by JR
I've got a C 6 (2.46 1st) and had a t'case with 4.3 reduction.
Hated it. Too low. Sold the t'case and got one with 3.0 reduction.

jr, what is the final drive gear with your portal axles? i know you have two reductions with the portals but what does the two together equal to? i am just curious because alot of the portal have really low gearing this on top of a 4.3 would definatly be bad. i just want to know because you are scaring me!!! i just ordered an atlas 3.8 to go behind my th400. i chose the 3.8 because of the auto but i actually considered the 3.0. i run 4.56's in the pigs. i just hope i won't be in your shoes and regret the 3.8!!!

I'm at 60:1 with an automatic and feel that the best thing I could do would be to go manual valve body with diesel torque convertor at 800rpm but even with my 1000 that I currently have you better have good, very good brakes if you go above 100:1...just can't see much of a use for that low...but hey the slower you go the easier it gets...

Originally posted by high5


jr, what is the final drive gear with your portal axles? i know you have two reductions with the portals but what does the two together equal to? i am just curious because alot of the portal have really low gearing this on top of a 4.3 would definatly be bad. i just want to know because you are scaring me!!! i just ordered an atlas 3.8 to go behind my th400. i chose the 3.8 because of the auto but i actually considered the 3.0. i run 4.56's in the pigs. i just hope i won't be in your shoes and regret the 3.8!!!

the final is about 5 and a quarter total.It's not that low with 42s.
For me, 1st gear was useless sence it would shift to 2nd before you could get your hand back from the shifter, and it's too jerky when the gas is used.
I wanted more momentum.
Without an overdrive, I got tired of shifting to high just to cover a hundred yards in a reasonable time.
I kept the stock T'case ratios in my cherokee with an auto and love it.
Hope this is some help.

In the Slinky, I run the TH350, dual toy cases w/4.7:1 gear in the second case and it works so awesome. So much better than I ever thought it could. I used to run stick for years, but decided to try the auto. What a difference it made for me. That puts me at roughly 111:1 mechanically, or 222:1 theoretical after you incorporate the auto torque convertor slip reduction.

I actually cruise around in 3rd gear most the time (its a sometimes manual valve body. Don't ask because I don't know why it is sometimes a manual and sometimes acts like a regualr automatic). 3rd covers most of my good trail crawling. When I want to go slow, I slide it into first. When I want to stop, it will actually stop in gear, but if it doesn't I just hit neutral. Super simple and gets the job done.

I was fearful before I did it, but I like it so much better than my old manual. Its really preference of course.

-Sam

My setup is sweet

I have one of those adjustable stall converters (200-6500rpm) and I have a long black lever that allows me to select different ratios (4 of them) I can get up to 6.5:1 Reduction for real slow stuff ...and when I have to stop I have this special pedal I push and it disconnects the motor somehow. It's all very trick.

Originally posted by dirtrod
My setup is sweet

I have one of those adjustable stall converters (200-6500rpm) and I have a long black lever that allows me to select different ratios (4 of them) I can get up to 6.5:1 Reduction for real slow stuff ...and when I have to stop I have this special pedal I push and it disconnects the motor somehow. It's all very trick.

bahahahahahah well said.

and Steve. you dont even have the truck yet so why dont you get out and WHEEL IT before you start thinking about big $$$ mods. i know you have a wad of cash in your pocket from selling your overpriced 90, but why dont you sit on it for a while. find out what you do and do not like about this bronco that you bought before you worry yourself with mods for it. it sounds bad ass already. :flipoff2:

i agree, drive the rig a while before you make any changes

as far as the auto, i cant top the 4 ratio with the magic pedal
but with mine i put it in neutral, stops everytime
hydroboost brakes
i would love to have a klune V, just to have options

I run an auto with dual 2.28:1 Toy cases. I really like it. Having only a 1:1 and 4.7:1 would be too big a jump I think. Nice to have middle low for the milder stuff.

With a stick you can start out rolling in any gear. With an auto, you always start in first so banging thru the gears to get to a higher gear with a super low t-case ratio would not be a lot of fun.

But....does a manual valve body let you start out in any gear?

Jay

yes this is all thought for a while in the future. however my last truck was auto so i already know that i would like some lower gearing. I don't have the money, time or tools to do it right now...it will probably be a summer project. I'm just trying to hear people's opinions on a very low geared auto seeing as i've never had the chance to really put one through it's paces.

-Steve

Ok it seems the auto is not the best because you cant use your engine as a brake.
What if you had an auto with a lock-up torque converter so whine you went down hill you locked up the torque converter and had it in 1st. I have seen kits you can buy that enable you to keep the converter locked.

yes with a manual valve body, you start in the gear you have it
it in

Ok it seems the auto is not the best because you cant use your engine as a brake.

Not true. With low enough gearing, it does actaully slow the truck down. If you gear it down, you have the slow gearing for crawling and the slow down ability for coming down off of things.

-Sam

Don't sweat it so much. I had a sweet auto in my Scout with dual cases. I put in a full manual valve body and an 800 rpm stall converter and it would idle up any hill same as a stick-with at least two advantages. You converter already provides as much as 3 times gear reduction (so you already have a crawler box), second and most noticeable, is when the stick-boys gotta jump for the clutch and brake pedals, back off the throttle on an auto or apply a small amount of brake pressure, and you can hold a truck in any wheels up position. Be sure to minimise unnecessary clearances between pickup and pan and it WILL engage upside down. The auto will also allow engine braking just fine with enough gearing, just be warned that do so for a length of time can blow seals or crack servos. I had custom milled billet titanium(a little overkill, yes), servos in mine. The manual valve body also increases line pressure on the bands so everything wins here. Do it, you'll love it.

When you are calculating auto crawl ratios you shouldn't multiply by 2 theoretically the crawl ratio including the torque converter is infinite you can go as slow as you want in any gear, but in reality that doesn't work because you generate so much heat from the torque converter slipping that there is no way you could keep it cool. In fact to keep an auto running cool you can't have very much slip at all, but if you have an 800 rpm stall converter and you are driving on the trail at close to 800 rpm then there is essentially no slip going on at all. Above 1000 or 1200 RPM that auto would act just like as stick almost no slipping going on at all. The place that the 2 comes from is the Torque multiplication. In a well designed torque converter in the rpm range where it is slipping it can multiply torque a little bit but not very efficiently the torque multiplication can range from about 2 to one to about 2.6 to one. But for that 2 to one torque multiplication there is a more than 2 to one speed reduction. The extra energy goes to heating the transmission fluid. so basically you can use the infinite crawl ratio of the automatic in short bursts maybe 10 minuites at at time but not all day long. But that is OK because even at 25 to 1 you can run most of most trails above the stall speed of a stock converter. It is for that slowest most technical stuff that you would need to let the torque converter slip. With lower gears on that slow technical stuff you gain the ability to run the engine above the stall speed so that the torque converter doesn't slip. this is helpfull for smothly climbing ledges and such, because in the lower RPM's where the converter is slipping when your tires are trying to climb something you need to give it more gass to maintain the same speed. This is hard to do smoothly which is the main reason most people want extra low gears with their auto. A lower stall speed would help too, but if you get the stalll speed to close to idle then the vehicle tries to pull forward to much even when you don't give it any gas. If you have a high enough stall (like stock) and aren't afraid to spin a few more RPM's than the manual guys when crawling then you can make an auto work great. and you have the advantage of being able to stop and start with just one pedal per foot the smoothness that this adds is great in tippy crawling at the limit situations. If you don't have low enough gears to smoothly transition from level ground to climbing a ledge just by keeping the RPM above the stall speed, you can cheat and use the gas and brake together. By riding the brake to keep the engine loaded you can climb and drop off stuff at a fairly constant speed even below the converters stall speed, but by doing this you loose a lot of the benefit of the auto being easier on driveline parts, and you make a lot of heat in the trans really fast. I switched to an auto 7 years ago, but I still don't have low enough gearing. The only reason I would go back is if I wheeled where there were a lot of deep water crossings water in an auto makes for a bad day.

so, gordon, what would you say the ideal gearing for the auto would be? I already have 2 dana 20s that I could run together. Or i could opt for having one 2.x case and one 4.x. Keep in mind i'm running 38.5" tires and 5.13 in the diffs.

Thanks,
Steve

Sweet jesus! I totally agree but man oh mighty. Did that take you a week to prepare that speech? :flipoff2: :D

I have a 94 YJ with 4.0/999/300 (4:1 Gears) and 38"sx's with 4:56 gears in the axles. I love that combo and my only complaint is that is does like to creep in gear. I will be installing the adjustable idle kit to lower the rpm's and rear disk brakes. A manual valve body would be great also. My setup now is 2.74x4.0x4.56= 50:1

I have plenty of compression braking, can stop in the worst positions and start off again without the lurch that you get from the manual trannys. I have wheeled 3 other rigs for a long time with sticks and this is my first auto. I wont go back.


Originally posted by Gordon
When you are calculating auto crawl ratios you shouldn't multiply by 2 theoretically the crawl ratio including the torque converter is infinite you can go as slow as you want in any gear, but in reality that doesn't work because you generate so much heat from the torque converter slipping that there is no way you could keep it cool. In fact to keep an auto running cool you can't have very much slip at all, but if you have an 800 rpm stall converter and you are driving on the trail at close to 800 rpm then there is essentially no slip going on at all. Above 1000 or 1200 RPM that auto would act just like as stick almost no slipping going on at all. The place that the 2 comes from is the Torque multiplication. In a well designed torque converter in the rpm range where it is slipping it can multiply torque a little bit but not very efficiently the torque multiplication can range from about 2 to one to about 2.6 to one. But for that 2 to one torque multiplication there is a more than 2 to one speed reduction. The extra energy goes to heating the transmission fluid. so basically you can use the infinite crawl ratio of the automatic in short bursts maybe 10 minuites at at time but not all day long. But that is OK because even at 25 to 1 you can run most of most trails above the stall speed of a stock converter. It is for that slowest most technical stuff that you would need to let the torque converter slip. With lower gears on that slow technical stuff you gain the ability to run the engine above the stall speed so that the torque converter doesn't slip. this is helpfull for smothly climbing ledges and such, because in the lower RPM's where the converter is slipping when your tires are trying to climb something you need to give it more gass to maintain the same speed. This is hard to do smoothly which is the main reason most people want extra low gears with their auto. A lower stall speed would help too, but if you get the stalll speed to close to idle then the vehicle tries to pull forward to much even when you don't give it any gas. If you have a high enough stall (like stock) and aren't afraid to spin a few more RPM's than the manual guys when crawling then you can make an auto work great. and you have the advantage of being able to stop and start with just one pedal per foot the smoothness that this adds is great in tippy crawling at the limit situations. If you don't have low enough gears to smoothly transition from level ground to climbing a ledge just by keeping the RPM above the stall speed, you can cheat and use the gas and brake together. By riding the brake to keep the engine loaded you can climb and drop off stuff at a fairly constant speed even below the converters stall speed, but by doing this you loose a lot of the benefit of the auto being easier on driveline parts, and you make a lot of heat in the trans really fast. I switched to an auto 7 years ago, but I still don't have low enough gearing. The only reason I would go back is if I wheeled where there were a lot of deep water crossings water in an auto makes for a bad day.

The engine compression braking is a moot point IMHO. I run 5.38's w/37's in my XJ. Using my gears going down the steep hills isn't a problem, I hate using brakes. That being said, I can't wait to get my Klune so I can have all those choices of gearing. The heat buildup isn't an issue either IMHO. You aren't making the tranny slip the entire trail, and if you have a good aux. cooler you shouldn't have any prob's. Install a tranny temp gauge if it concerns you that much. Just some meaningless ramblings.

Easy

Originally posted by offroadr35
so, gordon, what would you say the ideal gearing for the auto would be? I already have 2 dana 20s that I could run together. Or i could opt for having one 2.x case and one 4.x. Keep in mind i'm running 38.5" tires and 5.13 in the diffs.

Thanks,
Steve

That cold duck setup (2 dana 20's) seems towork good and be geared very good in my opinion. the 4.3 atlas seems to work really well too. I think Brian Wickert had exactly your setup with a 4.3 atlas and says sometimes it would be nice to be a little lower.

Originally posted by EasyXJ
The engine compression braking is a moot point IMHO. I run 5.38's w/37's in my XJ. Using my gears going down the steep hills isn't a problem, I hate using brakes. That being said, I can't wait to get my Klune so I can have all those choices of gearing. The heat buildup isn't an issue either IMHO. You aren't making the tranny slip the entire trail, and if you have a good aux. cooler you shouldn't have any prob's. Install a tranny temp gauge if it concerns you that much. Just some meaningless ramblings.

Easy

my tranny never gets hot on a trail but it does get hot screwing around on rock piles for more than 30 or 40 minuites at a time. I have 2 big coolers one from a moving truck and one that is the biggest one B&M makes. But that was kind of my point you have an infinite crawl ratio available but you can't use it for the whole trail because of heat. Put your XJ in high range and you can still go just as slow but your trans will get hot even on the easy trails.

My setup= 727 auto, Klune 4:1, NP 205, 5:13's. = 98.5:1
This works great. As others have said a big concern is stoping. Coming to a complete stop in low gear will take awesome brakes. Otherwise just stop in neutral. Compression braking is not a issue. Drives downhill just like a stick only no clutch pedal.
Try it youl like it. I'm thinking of gearing mine down even more.:)

A semi-boring question but I think important to understanding the torque converter. When the truck is in gear at a stop (waiting for the guys with manual trannys in front of you :D ) the engine is, obviously, still spinning. Spinning under the stall speed too. This means then that the torque converter has one end spinning, and the other end stopped? So you're generating heat here right? As bad as say doing constant crawling under the stall speed?

What is a standard factory stall speed? And if you know it, a tacoma with a v6?

Originally posted by Gordon
When you are calculating auto crawl ratios you shouldn't multiply by 2 theoretically the crawl ratio including the torque converter is infinite you can go as slow as you want in any gear, but in reality that doesn't work because you generate so much heat from the torque converter slipping that there is no way you could keep it cool. In fact to keep an auto running cool you can't have very much slip at all, but if you have an 800 rpm stall converter and you are driving on the trail at close to 800 rpm then there is essentially no slip going on at all. Above 1000 or 1200 RPM that auto would act just like as stick almost no slipping going on at all. The place that the 2 comes from is the Torque multiplication. In a well designed torque converter in the rpm range where it is slipping it can multiply torque a little bit but not very efficiently the torque multiplication can range from about 2 to one to about 2.6 to one. But for that 2 to one torque multiplication there is a more than 2 to one speed reduction. The extra energy goes to heating the transmission fluid. so basically you can use the infinite crawl ratio of the automatic in short bursts maybe 10 minuites at at time but not all day long. But that is OK because even at 25 to 1 you can run most of most trails above the stall speed of a stock converter. It is for that slowest most technical stuff that you would need to let the torque converter slip. With lower gears on that slow technical stuff you gain the ability to run the engine above the stall speed so that the torque converter doesn't slip. this is helpfull for smothly climbing ledges and such, because in the lower RPM's where the converter is slipping when your tires are trying to climb something you need to give it more gass to maintain the same speed. This is hard to do smoothly which is the main reason most people want extra low gears with their auto. A lower stall speed would help too, but if you get the stalll speed to close to idle then the vehicle tries to pull forward to much even when you don't give it any gas. If you have a high enough stall (like stock) and aren't afraid to spin a few more RPM's than the manual guys when crawling then you can make an auto work great. and you have the advantage of being able to stop and start with just one pedal per foot the smoothness that this adds is great in tippy crawling at the limit situations. If you don't have low enough gears to smoothly transition from level ground to climbing a ledge just by keeping the RPM above the stall speed, you can cheat and use the gas and brake together. By riding the brake to keep the engine loaded you can climb and drop off stuff at a fairly constant speed even below the converters stall speed, but by doing this you loose a lot of the benefit of the auto being easier on driveline parts, and you make a lot of heat in the trans really fast. I switched to an auto 7 years ago, but I still don't have low enough gearing. The only reason I would go back is if I wheeled where there were a lot of deep water crossings water in an auto makes for a bad day.

... :zzz: