Outer Limits 4x4 Board

hi all,

i tried searching for this topic but nothing came up.

my question is:

What is the better gearbox to have for wheeling/crawling?

i have a 89wt sierra, i will be running toy locked diffs, 6.5gears 4afe 1.6 DOHC corolla motor with 35" BFG MT's.

i currently have a supra 5speed box that i am planning to use but have been toying with the idea of an auto. im just wondering which will be the better option.

the supra boxes are strong and fairly reliable.

the auto boxes come from an 84 ae71 corolla, im a bit worried about strength.

any opinions and advise would be great.

thanks

Pubic

For pretty much everything except sand, auto would be my pick. Allows you to concentrate so much more on wheel placement etc and you can load up the converter which can be an advantage.
Having said that, I prefer manual for onroad but for a dedicated offroader I would go the auto for sure. Look at all the top rockcrawling comp guys, autos everywhere.

Try this thread from general tech (early bit is better than the last few pages):

http://www.outerlimits4x4.com/ftopic114977.php

v840, why do you say you wouldn't pick an auto for sand work? Autos are particularly at home in sand in my opinion. Not having to change gears and have that 'lul' between them makes gliding over the soft sand allot easier, and less strenuous on ths car.

Personally I get no enjoyment out of autos and would never own one, but thats just a personal choice, I do respect their benefits.

Having had both in the same car - auto.

Auto everytime, everywhere (except on road)

I have near 130:1 crawl in my Sierra, and whilst it's good, it's still not as capable as an auto with less than 1/2 the gearing.

Steve.

ok sorry but im a little under educated on the whole gearing side of things.

how do i work out my gearing?

i have what i belive to be stock hilux diff ratios and will be running 6.5 crawler gears.

what else do i need to know to work out my ratio?

1st gear ratio.

Crawl ratio for a manual is:

First gearratio X transfer ratio X rear diff ratio

For an auto:

First gear ratio X transfer ratio X rear diff ratio X converter stall ratio

Converter stall ratio varies between something like 1.8:1 -trimatic) to 2.4:1 (AW-4)

for a manual, useful crawl ratios start at about 60:1. around 80:1 starts getting pretty sweet.

For an auto, 40:1 would be plenty.

Steve.

Highway-Star wrote:
v840, why do you say you wouldn't pick an auto for sand work?

I do actually agree that auto's are better in sand but a manual seems to suit my driving style alot better in sand than an auto. Its just a personal preference. I have friends who love their auto's on sand.

TBH I only have auto-on-sand experience driving my old GQ petrol on stockton. Compared to all my other manual 4wd's I felt it sucked. Changing up too early, and generally losing alot of momentum between shifts. Whether that was due to that particular auto or not I couldnt say. Im sure driving a heavy ass GQ didnt help either . Again, just relaying my experience.

That GQ was the only auto Ive owned and it pwned all others on rocks (where I do 99% of my off roading) and every other type of terrain.

just to let you all know. i have decided to go ahead with the 3sp auto corolla box.

im picking one up today. thanks for your input.

pubic

I have never understood the thery on why autos are better on sand.
I know i can change a manual substantually faster than an auto and i know exacty when i want/need to change

pubic wrote:ok sorry but im a little under educated on the whole gearing side of things.

how do i work out my gearing?

i have what i belive to be stock hilux diff ratios and will be running 6.5 crawler gears.

what else do i need to know to work out my ratio?

http://www.trailhed.com/calculator.html

3 speed autos....not so good....suzuki 4 speed electronics........bullet proof! the idea with autos in the sand is they will gradually turn the wheels with minimal wheel spin...the side effect is heat......not going back to a manual.....and will never touch a tri matic again.

Ispent a bucket load rebuiling and installing a A15 with 3 speed auto, short story it sucked went back to stock.
Even with 3.9 diffs 4.16 t/c and 32s road speed wasnt great, and front up to an obsticle and put your foot down and nothing would happen wentb through 2 boxes and had them checked by a auto mechanic and said there was nothing wrong with them. Also once Igot too much of an angle it would suck air and go into neutral not good halfway up an obsticle.
Yes I could have made a deeper pan but too why polish a turd?
Just my experience have seen 2 other zuks run this set up with success one was in tt.
Nik

make sure a cooler is on there too

just punched some numbers into the calculator...

the low gear of the box is approx 2.45 i couldnt fine the exact gearbox but all others around the same time were running prettymuch the same numbers


im going to run the 6.5 crawler gears

stock lux diffs correct me if im wrong 4.88

all this equals 77.71

but its an auto. im not sure of the converter ratio.

if i multiply the 77.71 by this it will only get bigger right? unles the con ratio is a decimal number i.e 0.xxx??

That's plenty of gearing. Even with 1.8 converter, you're at 138:1 which will be fine.

Just watch your road speed. with a direct 3rd gear and 4.88's, your going to be revving REALLY hard on the highway.

The Trimatic car I built recently runs 3.9 diffs, 6.5 transfer (RH S4) and spins 4K @ 100km/h, and that's with over 35" tyres.

PS not all stock Hilux diffs are 4.88.

Gen 2 Diesels ran 4.5
Gen 3 Diesels ran 4.3

I think only Gen 2 5 speed petrols are 4.88 stock, but I could be wrong.

Steve.

my diffs dropped from a 2lt (i think it was a 2lt or something small) petrol motor. around 83 model.

if im going to be wheeling at a decent distance from home i will be getting towed by my mates patrol (5lt holden motor).... then i will return the favour and pull him out of holes when wheeling

although 4k rpm sounds high, my diesel truck sits near 3k @120 kp/h

and corolla motors dont mind revving.

i will be sure to let everyone know how my build up goes any how.

Be careful with super low gearing in auto's, as you will wind up driving through your brakes. Not fun if you cant stall your motor up, of even stop, because your brakes wont hold it

Layto....

Be careful with super low gearing in auto's, as you will wind up driving through your brakes. Not fun if you cant stall your motor up, of even stop, because your brakes wont hold it

Layto....

good point. i guess there are two options... run taller crawler gears.. a bit cheaper than buying the lower gearing ones, or upgrade brakes.

probably a good idea to do both i suppose.

lay80n wrote:Be careful with super low gearing in auto's, as you will wind up driving through your brakes. Not fun if you cant stall your motor up, of even stop, because your brakes wont hold it

Layto....

What do you class as "super low" for this effect to happen ?

I'm running around 70:1 ( gearing not T/C ) and haven't experienced this - perhaps I've misunderstood what your suggesting ?

id say it would be different if you had decent brakes.

well the standard brakes as they are, are basic discs on front and drums on back...

i will up grade the rears to disc once i mount the diffs.

do slotted discs make muh of a difference off road?

pubic wrote:
do slotted discs make muh of a difference off road?

fawk yeh,
heaps of difference when i changed them on my GU.... cant comment on a zook but.
i can lock up all 4 35s with the GU fully loaded without any probs.. whereas before only one or two tires would lock up

if i locked up all 4 on my zook the thing would probably cartwheel!!!

might just look into getting the slotted front discs and some braided lines. i did a bit of a read up on it and found a pretty decent point that was " the rears dont do much of the braking work... the fronts do the majority of it all." this is true on the road in 2wd but what about when wheeling?

i would imagine that at slow speeds, on a relatively flat obstacle all 4 would share pretty evenly. on a steep descent the fronts would bare it all right?

upgrading the brakes on a sierra is so easy. the vented disc and calipers from a LWB vitara will bolt right on with only trimming of the stone guard.bleeding is a bit of a PITA but the extra stopping power is unmatched by any stock sierra. best $100 i spent on the brakes

built4thrashing wrote:upgrading the brakes on a sierra is so easy. the vented disc and calipers from a LWB vitara will bolt right on with only trimming of the stone guard.bleeding is a bit of a PITA but the extra stopping power is unmatched by any stock sierra. best $100 i spent on the brakes

I sell them 'cause I don't need them and then I go and buy a Sierra lucky I found another set

Slotted brakes aren't the be all and end all that some make them out to be. Yes, I run slotted rotors and braided lines too and they do improve certain facets of braking but don't go thinking that they will make your braking performance that much better or you may be dissapointed. In fact in some circumstances not having slotted rotors is better IMHO.

Pretty much at low speeds it's going to be pad area and line pressure.

I think the driving though the brakes thing is more based around V8's, low stall speed and lots of reduction.

Some of us in Vic have/do run quite low gearing with autos and it's not a big problem.

Steve.

Slotted, Ventilated, Cross drilled ???
Would these help me stop quicker?
http://kalecoauto.com/index.php?main_pa ... ducts_id=1