Stak/Atlas

[COBlu77]

Bigger $$ than that Just how often will you NEED 10.34?

I have yet found a need...I do have a auto;D

Cary

I took the cheap and easy way out for now with an NP205, but when I talked to AA and others with auto trannys, I was told that anything lower than 3.8:1would be an issue. Normal brakes would not be able to hold it from creeping and you'd have to shift it into neutral. AA said I'd be happiest over all with 3.0:1 and a 4R70W, unless I was doing extreme rock crawling. Miley pulled his brake pads off trying to hold back his Cummin's powered Bronco in low range with his 3.8:1 Atlas and hydroboosted brakes.

 

[av8rds]

I agree, I cant stop it with non-power disk/disk but I'm ok with shifting it into neutral to stop.

I personally love the control of the 150ish:1 low. I'll use the toyota guys with their 250ish:1 ratio as my example. Now I know they do that to offset for the lack of power but thier control in high traction situations is awesome. I agree that its not something to be used everywhere or maybe not even every trip but that control and the superslow speed picking my way through a rock field will be awesome.

Anyway, its all about 'your' personal preference. I wanted the 2.7 for the beach and for the trail sections between the harder-core sections. The 3.8 was for the real crawling. And the 10:1 was just a bonus, a bonus that I personally expect to use.

 

[av8rds]

does anyone know if AA ever made the electric shifter available for the 4sp planetary? I think the cable shifter is obnoxious and would love to switch if the price was right...

 

[chuck]

I didnt have to buy new adapters from the tranny like I would have had to if I went stak.[/QUOTE]
What adapter would you need?

 

[chuck]

I agree, I cant stop it with non-power disk/disk but I'm ok with shifting it into neutral to stop.

I personally love the control of the 150ish:1 low. I'll use the toyota guys with their 250ish:1 ratio as my example. Now I know they do that to offset for the lack of power but thier control in high traction situations is awesome. I agree that its not something to be used everywhere or maybe not even every trip but that control and the superslow speed picking my way through a rock field will be awesome.

Anyway, its all about 'your' personal preference. I wanted the 2.7 for the beach and for the trail sections between the harder-core sections. The 3.8 was for the real crawling. And the 10:1 was just a bonus, a bonus that I personally expect to use.

With my gears and the 10.1 atlas I would have a 263.44 to 1 low. I get bored waiting for the 120 to 1 I have now. I think the 263 to 1 would be useless other than bragging rights If you have the idle speed down below the torgue convertor you shouldn't have a problem stopping with whatever gears you have.

 

[av8rds]

I didnt have to buy new adapters from the tranny like I would have had to if I went stak.

What adapter would you need?

I already had a AA 700r4 conversion output shaft in my 4L60e mating to the Dana 20. Stak didnt produce anything that would mate. That was last year, things may have changed since then.

 

[av8rds]

With my gears and the 10.1 atlas I would have a 263.44 to 1 low. I get bored waiting for the 120 to 1 I have now. I think the 263 to 1 would be useless other than bragging rights If you have the idle speed down below the torgue convertor you shouldn't have a problem stopping with whatever gears you have.

Right now I'm at about 150:1 and its actually not as slow as I expected which is ok because I think its very usable now. Like I said before I really wanted the 2.7, 3.8 and this is just an unexpected nice bonus that I feel I can use the 10:1.

I'm not sure about your feeling that you would be able to stop the truck in low/low. Even at idle some of the TQ is getting through to the tires, just not enough to move the vehicle. Now take that idle TQ which for me is just under 400lb-ft and multiply it by 150 plus what ever the TQ converter is multiplying it by at that point. I'm not sure how you COULD stop it. Even at idle in low/low there is a large amount of TQ available to move the truck and if I cant apply at least that much pressure on the brakes then its going to move. no?

Again this is not for everyone or everywhere but I like it.

 

[NeverSatisfied]

Right now I'm at about 150:1 and its actually not as slow as I expected which is ok because I think its very usable now. Like I said before I really wanted the 2.7, 3.8 and this is just an unexpected nice bonus that I feel I can use the 10:1.

I'm not sure about your feeling that you would be able to stop the truck in low/low. Even at idle some of the TQ is getting through to the tires, just not enough to move the vehicle. Now take that idle TQ which for me is just under 400lb-ft and multiply it by 150 plus what ever the TQ converter is multiplying it by at that point. I'm not sure how you COULD stop it. Even at idle in low/low there is a large amount of TQ available to move the truck and if I cant apply at least that much pressure on the brakes then its going to move. no?

Again this is not for everyone or everywhere but I like it.

This is where I'm curious. My project should be on all fours in the next couple weeks to test out. I'm hoping with a chubby truck H-boost, chevy 1/2 ton front brakes and stock 76 drums, I'll be able to keep it from creeping forward at idle in at least 3.8:1 if not 10:1

 

[av8rds]

I'm hoping with a chubby truck H-boost, chevy 1/2 ton front brakes and stock 76 drums, I'll be able to keep it from creeping forward at idle in at least 3.8:1 if not 10:1

I can hold it in 3.8 no problems.

 

[tasker]

is that ratio or beers?

 

[av8rds]

Oh I was working on the 10:1 saturday!

 

[tasker]

is that ratio or beers?

 

[chuck]

If you have the right TC you should be able to stop it. ie If you idle at 700 and you have a stall speed of 900 you will not be able to stop it with the low gears at idle. I don't think your IDLE TQ is anywhere near 400 ft lbs but even if it was and you have a 2000 stall speed you should be able to stop it at the 700 idle. I am not saying you need a 2k stall speed to stop low gears but I am saying that a higher stall speed TC will allow you to stop even with low gears. Maybe a 1200 stall speed? Maybe some of the auto guys can tell us which TC to use?

 

[av8rds]

I dont have the dyno run here but the TQ was in the high 300's just off idle(13-1500 I think, hell it was at 450 by 2000rpm but it is also all done at 4500rpms, it was built for TQ and thats what I got) so your probably right its probably in the low to mid 300's at idle and my TQ converter is 1800rpm with 2.0(if I remember right) TQ mulitplication.

I had a 2300 rpm convertor when I re-did my engine at the suggestion of the convertor company(it was 'custom' built for my application by some shop big in the pro-mod world) and my engine builder as well. I hated it, so I sent it back and that it changed to closer to stock. If I had to do it again I might go a 1500 or so. And not to try to argue with you but with so much engine TQ so low it is my opinion damn near perfect.

 

[chuck]

I look at these exchanges as good info for you, me and everyone that reads the posts. I agree that low end torque is a good thing. I don't know your build but most dynos (at least the ones I have seen) are more like the dyno chart on my site. We were looking to prove my header design. The HP and torque are low at low RPM's. The chart shows 70ish HP at 1500 RPMs. The test did not start at idle but 1500. The tests were done on a stock 351 so it is not a big HP engine. I would like to see your dyno and engine info. Most likely the dyno shop will still have your chart. I would like a high torque engine at 700 RPM's and up.

 

[av8rds]

I'll have to look again for the engine info I think it was on an old computer and maybe lost. Trying to get it again from the builder may require a note from God. He's impossibly slow but I would like to have again too.

I have the dyno chart around some where I'll scan it and send it to you. I was originally disappointed I only got 380HP and that it was 'done' at 4500rpms but for what we do it worked out perfect. If I remember right it had 450lb-ft from 2000rpm up peaking at 505 and dropping back down to 450 at 4500rpm. It had a pretty damn flat 'curve'.

Just so there is some stak/atlas talk in my post...did anyone ever see if AA had a price on the electric planetary shifter? thanks