Gears

[tonto]

[quote author=Broncobowsher link=board=5;threadid=10419;start=15#75963 date=1035314214]<br>NP435 1st gear 6.69, not 4.78 (is the close ratio box?)<br>C4 multiply in about another 2 for the torque convertor. you just don't get it in compression braking.<br><br>Anything beats the stock 2.99 first.<br>[/quote]<br>Your right, I was using info from the E.B.R. Super Sight, that’s funny I should’ve caught it because I had one in my E.B. for a while before I got tired of a manual and went to an AOD.

 

[c2computer]

How about those Tera Low gears or Chuck's RockEater gears? According to my calculations, I would get a crawl ratio of 42.44 with the 3.55 gears and 54.51 with the 4.56 gears and the Rockeater gears. To me this sounds good because I get the driveability on the street and highway and I get the low crawling on the rocks.<br><br>But, would this be too low to be driving around in all the time in 4 low?

 

[randall]

Im not posotive but i think you may be able to use stock low range still. Stock three speeds arnt a very good tranny though, second gear tends to fail in them, randy at driven told me that and then i blew up two of them. I would either go to an np435 or an automatic, C4 would be the cheapest to swap in. Probly 4.56s too, that would work ok with 35s and good with 33s.

 

[c2computer]

Yeah I was thinking of keeping my C4 ( I just rebuilt it), put 4.56 in the diffs, the Rock Eaters in the Trans case (4.86) and that would give me the ratios above. Does anyone run these Rock Eaters? I would sure love to see them in action before I paid for them. But it sure seams easy, no major mods, no cutting, no driveshafts to change (I just got new ones), etc. Seems like a good idea... decisions, decisions. At least I am not married so I am the only one who sees the check.

 

[Lttrbox]

Does anyone run these Rock Eaters?

<br><br>I thought about this too, but I have other things going so opted to go for the Atlas for the extra<br>few bucks. I get to replace a tired old rear drive shaft so why not go where I would like, especially<br>since Im going to go with a bigger lift. If I remember the numbers correctly once Im done, including<br>the auto torque multiplier (4.11*4.33*2.8*2=rear*t-case*AOD*TC) give me 100:1.<br>Did I do that right?? ?:?

 

[tonto]

You might already know this, the Dana-20 gear swap and of course you should want to do the output upgrade also, combined will be about as much $$ as an Atlas II and if you do the mods to the Dana-20 the lower gears will be putting more stress on the drive line so it would be a good idea to at least upgrade your rear drive shaft to 1330 C.V. & u-joints to handle the additional stress’s or ideally 1350’s so there again eventually you will have to deal with driveshaft mods anyway.<br>Something else to consider is if you haven’t already twin sticked your t-case the Atlas comes twin sticked in the price.<br>Sounds like your set on keeping your C4, if not B.C. Bronco’s manual 5 speed with the O.D. mated to the Dana-20 might be another option. Good Luck, Francois.<br>

 

[c2computer]

What do you mean by 1330? Is that some kind of strength of the drive shafts? They were custom made for my truck with off roading in mind but not sure how strong they are. I guess with the atlas I would need stronge shafts and of course new ones/shortened/lengthened. I would like to keep the C4, I don't want a manual and I just rebuilt it.<br><br>I like to cruise and I off road a lot but I am not Mr. Serious off roader. I just want a safe rig that can go a lot of places without having to hammer it to get up the trail...

 

[c2computer]

Thanks for all the help, I think I decided to do 4.56 in the diffs, keep the C4, test it out and see. Then put the rock eater gears in and go with this. I am not enterning a rock crawling competition and I rarely go over obstacle more than 5 mph (that is what lockers are for) so I think stress will be fine. Thanks for the help.

 

[thumper]

I am running 4:56 gears and Bogger 35x16x15's and have no problem on the freeway or in the rocks. I can motor to Moab on the freeway and then climb like a billy goat on the rock. I also have a detroit locker in the rear 9" and a quik lok in the D44 up front. Good all around combo for me so far!!<br>

 

[c2computer]

Thumper,<br><br>So you don't have any low gears in the transfer case? I think I may be ok too after I put 4.56 in but not sure until I try it. Thanks for the info.