setting up an auto for rock crawling

[zukijames]

hey guys im gona be getting a 4.3 v6 with th350 and dual yotas

ive never wheeled a auto.. but ive noticed alot of people with autos that dont really launch that great.. what can you do to get more launch right of the bat.. shift kit.. differnt torque converter? or should i just put it in and try it lol
ive searched alittle but not really found to much some people say stock torch converter others say high stall some say shift kits some say no

any opinions or links appreciated

 

[utah340six]

why do you want it to launch?

u rockcrawling or racing?

 

[mesha]

He probably wants to "launch" for the situations where a little bump is required. I know with my auto I have to have a lot of space or the auto will not get me enough momentum sometimes.

 

[mesha]

To answer to question, I have a 4.3 vortec and a 4l60e in my buggy with a stock converter. I would like a little more launch. I decided to put in some lower axle gears for now and will mess with the torque converter later if that doesn't help. I don't have dual cases in this one though so you will have way more options for gearing then I do.

 

[fj40fax]

add another TC or a 4:1 TC and you should get plenty o' launch

 

[Lifelong Jeeper]

what about giving it some rpm's while in nuetral and shift it in.

 

[mbryson]

what about giving it some rpm's while in nuetral and shift it in.

You'll dump your trans. You'll just need to adjust your driving style a little. You'll need to give your self a little room on an obstacle to do a bump. I'd keep all the stock stuff.

 

[Kiel]

I would do a higher stall, then a manual valve body. Mine TC is about 2600 rpm, then I have a manual valve body. Mine seems to launch just fine

 

[broncomitch]

trans brake baby! jk,but would work...just dont hold it in or your trans will get hot.

I love my trans, when i need a bump i just back up a little bit and push on the skinny pedal.
also you will find with swapping in a v6 you will have more power, so ya wont need to rev the nut's off it to move.

 

[outlaw_offroad]

Power brake it. Hold the brake with the left foot throttle with the right. Also, bumping seems to work best for me with a little less tire pressure. I run about 7 to 12 psi offroad (no beadlocks).

 

[zukijames]

launch

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i think i will just try it stock for now and see what happens.. then 4.7s in the back case then if still not enough i will mess with it

 

[Lifelong Jeeper]

You'll dump your trans. You'll just need to adjust your driving style a little. You'll need to give your self a little room on an obstacle to do a bump. I'd keep all the stock stuff.

That's what I wondered. I've never run an auto off road. I can see that you'd dump your trans if you're reving high rpm's, but I wasn't sure about 1500-1800 range. Then again, with low gearing, that is still a significant slam.

 

[Tacoma]

Engaging any kind of transmission at rpm is hard on parts. Some can take it better than others, but it's hard regardless. Foot brake the trans, and go cat go.

After missing reverse backing down a very long hillclimb attempt out here I don't ever want a manual for any serious trails ever again.

 

[zukijames]

really ? to me getting an auto into reverse seems harder than just stabbing the clutch in a manual and rolling back .. im pretty nervous about this new set up .. 3 times the power and an auto instead of a stick .. it might take me awhile to learn how to drive again.

 

[Tacoma]

On a really steep hill, you can ease off the gas and use the trans as kind of a brake, rolling backwards in drive. In my case, I was almost to the top of a loooooong hill in Tooele County, and had to back down-- missed reverse, and spent about 800' sliding backwards on the brakes, trying to steer with a locked set of front wheels. NOT FUN.

Autos are great on the trail. You can handle it.

 

[dabears]

I just got a converter with a little higher stall, and I think it helps with the bumps alot better.

 

[utah340six]

i like the auto better than the standard not as hard on parts.
with auto u use torch and can go up stuff with out slaming the clutch.

 

[Tranny Frank]

Converter stall

Things to consider with converter stall, the higher the stall more heat build up in the trans, additional cooler is advisable with a higher stall converter,

The factory reason for different stall in a converter is what the eng is set up for torque range, engines that develop torque at low RPM require a lower stall.

For longevity reasons No more than 2,000 stall, the weak point in the Turbo 350 is the low one way roller clutch while a basic Turbo 350 can handle up to 500 hp, stalling up to 3000 and launching is going to hammer this roller clutch, the aftermarket does make a way to reinforce this but it is more for where this component splines into the case, where it is a very common wear point in this tranny.

One thing that you can do with the Turbo 350 to beef it up is have the forward piston machined down so that you can add another friction and steel, gaining that much more holding power,, eliminate the cushion spring in the 1/2 accumulator, and a good idea for wheeling manual first at any speed, with various shift kits,

aside from that get a turbo 400 if you really need to get serious, but I am not positive but I have heard that the Turbo 400 robs power from the eng the way the power flow goes thru the tranny, and drag racer guys dont like them for this reason, and actually the tranny of choice for a lot of them is a two speed power glide with the gears from a 6 banger eng, and its a preety tough trans, this may be an option to consider if you want some thing to wind up and launch, they seem to be able to make adapters to fit all sorts of stuff together, I do not know if they make a adapter for a 2 speed power glide, to bolt a T/C onto,

just some thoughts,

 

[zukijames]

thanks for all the input guys! set up should be here in a week or so ..l give me a year to get it put in

 

[jpndave]

There is a lot of info in this thread that will make the transmission shops very happy when the trans breaks instantly. Some sound advice here too. I build autos (not sure how many to date but more than 100). The Low roller clutch in the 350 is easily upgraded if you know what you are doing. The extra clutches are a good idea and standard procedure on my builds as is the hardened race on intermediate. Better quality clutches and a shift kit (set up properly not "slam bang") help a lot too. As to the converter, you don't want a super high stall race unit but you do want one that is sized properly for the engine/gearing/vehicle/application. All this factors in to the stall and the same converter will stall differently in different vehicles depending on weight, gearing and power.