NV149 or NV120 AWD TC??? Go Fast???

[InDaShop]

Does anyone here know anything about the New Venture 149 or 120 single speed all-wheel drive transfer cases? The 149 comes in Silverado SS's, and the 120 comes in the Trailblazer SS?

This is what about them
http://www.wtfba.org/temp/NVG-149.pdf

Wondering about putting a Klune in between one and the transmission so that you'd have a low side for getting through the rocks and a variable bias for hauling ass on the flatstuff.

I know Atlas's are not living long glorious lives in Ultra4 cars, thats IFS or straight axle. Alot to be said about deceleration of the driveline when the front end lands before the rearend several thousand times in the course of a desert race. I'm wondering if one of these would be robust enough to survive, and then use the Klune for a lowside to just "get through the rock trails". Know what I mean?






Application....ah you dont really want to know at this point.

 

[kid rok]

Why can't you just run the fast stuff in 2wd then shift into 4wd when you get to the rocks?

 

[BamaTJ]

I thought most of the atlas issues were due to rear engine cars or running the 4sp case and have it in low the whole race?

 

[Bones]

Anyone know what desert guys run? Obviously that will be out of anyone's budgets, but is it an AWD that splits power like this?

 

[BamaTJ]

Most of them are 2wd, so they run nothing. I know a few people have run 4wd trophy trucks in the past, but most went away from it. Shannon used an Atlas in his recent Class 1 build.

 

[InDaShop]

With the front weight bias our cars have they get ass happy when in 2wd.
Matt you are mostly right, but there are now a handful of front engine cars that have split cases as well. ala Healy in the SS300 this year.

What I'm wondering if you can accomplish a clutch type bias for the frontend to suck up hits and not smash the atlas to ****. For rocks we dont want any slip at all right? Slip equals not getting up a climb hence why we use lockers and drive flanges. But with everything locked in when you do take these repetitive hits for 100's of miles something has to let loose. And so far it looks like its tearing up Atlas's.

When these AWD's slip they create a lot of heat, but shoot if you run a big cooler and fan like you've got on your trans and engine oil you should be able to negate the heat right?

I'm just brain storming solutions.

 

[Juan_Hong_Loe]

When these AWD's slip they create a lot of heat, but shoot if you run a big cooler and fan like you've got on your trans and engine oil you should be able to negate the heat right?

I'm just brain storming solutions.

Where are they slipping?

 

[BamaTJ]

I guess a lot of it depends on use. For the full on desert races sounds like an Atlas would be a weak link, but 4wd is also nice to have in some spots. For KOH I really think you will be in a disadvantage in the rocks without a proper tcase. Guess it depends on which style of racing interests you most, and then weighing the pros and cons. I heard they were re-designing the 4sp box to live for long miles in ultra 4 racing. Maybe they will do the same with the 2spd box also?

 

[InDaShop]

Where are they slipping?

They have a Viscous Coupling where they split the torque between the front and rear wheels.

Whenever there is a speed difference between the front and rear wheels, the
inner and outer plates of the viscous coupling spin relative to each other and the silicone fluid provides resistance. The
resistance was tuned to be high enough to bias power quickly to the wheels with traction, and low enough to prevent
binding in a tight turn on dry surfaces.

During normal operation, 100 percent torque is delivered to the input shaft (1) from the transmission. The torque is split
to 62 percent to the rear output shaft (2) and 38 percent to the front output shaft (3), by the planetary differential.
Because there is not a loss in traction or slip in the front or rear wheels, the viscous coupling is locked in place and
there is no "shear" mode or "hump" mode involved.
-When traction is lost at the front wheels, the viscous coupling works in conjunction with the differential to bias the
torque more to the rear wheels. The rear torque goes higher than the 62 percent, and up to 100 percent torque to the rear
output shaft (2). The torque at the front output shaft (3) is lowered from the 38 percent, to as low as 0 percent torque.
-When traction is lost at the rear wheels, the torque is biased to the front wheels. The torque to the front output shaft (3)
goes higher from the 38 percent, up to 100 percent torque. The torque at the rear output shaft (2) is lowered from the
62 percent, to as low as 0 percent torque.

 

[Juan_Hong_Loe]

Yeah I read that on the site but it's new to me. Haven't ever read about these cases. So I guess it's like a limited slip diff, once one side slips it engages the other. The fluid then is something like the additive for limited slip diffs? Seems like a lot of parts to fail. But then again so are the atlas cases. What do you do?

 

[InDaShop]

What do you do?

exactly! I dont know. Just trying to explore options. Seems like if you had the ability to LockUp the T-case and hit lowside on a Klune infront of the T-Case. You'd have something that wouldnt take the beating by being full engaged on every hit. But that you could then LockUp and take the slip out for climbs.

Obviously not a trail rig, but a race car that can "get through" rock trails, but excel and not fail in the open stretchs

 

[Juan_Hong_Loe]

Not sure how well it would work though. Reading the information in that service stuff I'm wondering too how much heat would be generated. It says to not let it slip for a long period of time due to damaging the clutch pack. I dont think it would help if you have a cooler put in line there either because unlike an automatic transmission its designed to slip (if any of that makes sense).

 

[InDaShop]

If the Herbst Bros. couldnt make a 4wd Trophy Truck work with a Viscous Couple T-case and all their money. I highly doubt I could pull it off using stock GM parts. And that TT wasnt used to go rock trails every now and then on a race course either.

I think the current best bet, is to stay Atlas with the long tailshaft and just know after every Endurance race you need to rebuild it. To keep the lash in check, and keep the slop out of it that ends up in binding and causing case failure, or gear failure.

Now....anyone know if you can take a long tailshaft for an Atlas and also fit it to the front output as well? So you get that other set of bearings to support a bit better?

 

[BamaTJ]

I think that is the best bet Wyatt, seems like more money and time to experiment with something else. I think the 4sp, once they redesign it, is the hot ticket for this because of the versatility it offers.

 

[Ni4x4]

http://www.pirate4x4.com/forum/showthread.php?t=829346&page=29
What about putting somthing like this behind a klune?

Post 702 in that page shows a chain case from formula offroad buggy that is one speed (1:1) chain case based off of an NP 241.

the chain may take up some of that initial impact from tearing through the whoops in the desert and still have definate 4wd in the rocks without the slipping from a viscous coupler.

they hold up to the 1000+ HP formula buggy's tearing up and over the sandy hills and across water to land at 180 MPH wheel speeds, and the 241's hold up with doublers in jeep trail trucks that take some decent beatings.

Sam

 

[InDaShop]

thats an idea I hadnt heard of. Now I got some monday research material setup!!!