what options do we have for a low crawl ratio? Im going to start my sm420 swap but i think its only going to give me 70:1 or something. The mini truck guys are runnin 180:1 and stuff...........


Dan

http://www.pirate4x4.com/forum/showthread.php?s=&threadid=2187&highlight=aa+rockbox

the 420 unit should be ready pretty quick...$1100

I called on it last week and they said they are still 6-8 weeks from shipping the first run. I called a few weeks before that and they gave me the same time frame. They said they are waiting on tooling. They will however take your money if you want to place an order now, I declined.

I used to have a bookmark of a company that sold something else called the Rock Box. It was specifically used to mate a SM465 to a Land Cruiser t-case. It also had a selectable feature that let you choose between 53:1 and 109:1 ratios. I think it was produced by either Over the Hill 4x4 or Up and Over Innovations. Like I said, I can't find it anymore, and both of those web sites don't show it as part of product lines.
Is the Roc Box that AA producing the same thing as this, just being marketed by them and not the original company? Or is this something completely different. It sounds like the same thing. Anyway, that original Rock Box sounded like a sweet setup.

The rock box is just an NP203 gear reduction box with a factory GM SM465<->NP203 adapter on one side and an AA adapter on the other. Came up on the LCML about two years ago.

Cheaper to get an SM465-specific NP203 yourself and connect it to to an SM465 and your LC tcase, if you have the driveline room.

I did it, but under an FJ55. I like it a lot. With a 4spd tcase and 4.11 diffs I've got 105:1 low. It's not for daily drivers, tho. All that rotating gear mass wastes energy and makes for more lash and slower acceleration.

Morgan

Thats kind of an issue to for me, or at least in the future. Having te crappy luck I do, AA came out with the RocBox like the day after my SM420 swap...
I still have to lock the cruzah and regear, looking at 4:88's. I guess the only way to go lower is swap out the t-case...seeing $$$ flying out the window in future...
The 420 is low with the 35s but lower is better ( for crawl ratios, not vechile height)

Joseph A.

The link Bennet posted is to the AA crawler box. A bit different than the rock box. It is made to mate to a cruiser 4spd or 3spd tranny and t/c. It is 5" long. It will mate to any tranny that is setup to run a cruiser 3 or 4 spd tcase. You can also get it setup for a 4spd cruiser tranny to 3 spc cruiser tcase.

Rumor has it that AA is not even *close* to that 6-8 delivery date that has become their standard answer. I got it from a good source that it's more like 4-6 months at the rate they're going....

No one has addressed the real issue here. 70:1 in a Cruiser with a 350 or a 2F is like having 200:1 behind a Toyota 4cyl!

22R's are awesome but they put out ZERO power!

Do your SM420 swap and as long as you stay 36" tires and below you WILL be happy.

Go any bigger and look into spending some $$$$.

I have to agree with Nolen here, the 70:1 crawl ratio works awsome in a cruiser. I ran that exact setup for years behind my six cylinder with up to 39" tires. The only time I wanted to be a little lower was when I got bigger than 35's. I'd say put the 420 in and run, you can't go wrong.

Ill be runnin stock 2F ,420, extremebends plate, 3spd case, 4:11s at the diffs and 36" swampers.

Hopfully it should go ok

Dan

I have to agree with wayne.. I wheeled my buddy's SAS '87, and he had a marlin dual case w/ about a 100:1 crawl in it, but in order to get over some big obstacles, he HAD to use that gearing as his engine had to turn 2000 rpm so it wouldn't stall climbing the big stuff.

My FJ, with only a 305 hooked to a 465/205/stock gears never has to turn more than 1300rpm to get over anything...

You'll LOVE that granny low.

Originally posted by wngrog
No one has addressed the real issue here. 70:1 in a Cruiser with a 350 or a 2F is like having 200:1 behind a Toyota 4cyl!

22R's are awesome but they put out ZERO power!

Do your SM420 swap and as long as you stay 36" tires and below you WILL be happy.

Go any bigger and look into spending some $$$$.

Smack!!!....(hitting the nail on the head)....;)

Ok I have a stupid question, But why is it that all the jeep guys are going lower say like 140:1 vers the cruiser guys are saying 80:1 is fine?

In my CJ I run an sm420, 4.56s, d300 and I am right in the 80 something : 1 range. I also run a 360 v8 for a motor. I feel its low, but not low enough, I have wheeled with people that are up above 100:1 and it was alot smoother.

Just from a different side of the coin is all..

I plan on going an sm420 in the cruiser, But I am also thinking a klune or Atlas long term with a vortec 350 to push it over that 100:1 mark.

I dont plan on running tires bigger then 35s.

my crawl ratio sucks, but i have never had a proble getting over anything. i can spin 4 38.5x14.5 sxs if it is steep enough. i have a stock 3f[with 181k on it], a440 auto[i think] and a stock t case with 5.29s. i have had it dog down a couple of times but still made the climb. but i had it flat on the floor and the rig weighs about 6k loaded for the trail. the auto is very forgiving but some times the numbers are not that impressive. you don't need 200 to 1 except to brag about, unless you have about 25 fpt at the crank. just my 2 cents mike

Originally posted by WheelingPiazza
Ok I have a stupid question, But why is it that all the jeep guys are going lower say like 140:1 vers the cruiser guys are saying 80:1 is fine?

It all depends on what type of terrain you wheel on. If I wheeled 100% boulders and slickrock I would say go as low as possible, but around here you need some wheelspeed for the loose rocks and dirt climbs.

It all depends on preference and feel.

See I guess thats my point, It all depends on what you wheel on.

For me Rubi, Fordice, ETc Mainly rocks, Some snow, ETC

I am not into mud and doute I would get out to the east cost for some wheeling anytime soon.

For me the lower the better, and yes I think 200:! is over kill, I think the sweet spot is anything over 110:1

Not hard to accomplish in this day and age.