Over 1000Lb/Ft Tq And A Few Awd Questions

[carcrafter22]

I'm shooting for roughly 1000-1200ft/lbs tq out of my little 4 banger to go in my AWD classic truck (and yes it will happen trust me ) and I'm looking at rear axles and front diffs.

 

Currently I'm planning to use an escalade or SS front diff but have considered the 9.25 diff also for the front and I will most likely use a 9.5" GM axle I have laying around with 9" big bearing housing ends and custom axles.

 

These plans are still in the air but things will be happening fast once I get home at the end of this month so I am trying to work out the small things.

 

Do you think the nv149 will handle this much tq at low rpm from a small diesel engine with a quick spooing supercharger and large turbo combo?

 

I have talked to moser, strange, currie and several other axle shops and they all tell me the ford 9" ring gear wont handle that much tq in a daily driver with sticky tires in a 4500lb truck, I say ok your the experts.

 

I know the nv149 has a split of around 36%/64% depending on who you talk to so I wonder if a built 9" (ruffstuff housing, richmond gear, wavelock diff, 35 spline shafts, strange center section) would take only 64% of that I would imagine it would or am I missing something/ over thinking this?

 

I havent weighed the 9.5" yet but I'd imagine it will be heavier than even a well built aftermarket 9" (housing weighs about 35lbs more than a stock 9" housing alone)

 

Dont forget diesels make power differntly than gassers, I may have 800ft/lb at 2000rpm and 1100ft/lb at 5000rpm where as a gasser may make 1000ft/lb from 5500-6500rpm.

 

Just thought I'd get some opinions from AWD experts since I'm very new to it all.

[BlueAKSSS]

From what I've read the NV149 is a very strong AWD transfer case so I may very well be able to handle that kind of power.

 

......Now I'm getting curious what type of classic truck exactly are you building?

[f1ss]

I heard Hummer came out with a front locking diff a year or so ago, might want to check it out. I do not know if this helps as I am not familiar with high tq/hp applications like you are talking about. Good luck!

[04CHASE]

here in my take , no one has pushed the t case that far yet . some have broken them at less power though . not many but some have . they are stout , i have had not one issue with mine . i plan to take it near 1200 ft lbs this year . i am running the stock front and rear with some upgrades. i plan to blow them up before i replace.

 

the 9 inch in the rear will take the power pretty easily infact i would trust a built 10 bolt to handle it .

 

now the part that im not looking forward too is the front diff. there is some options but not tons. the 8.2 or what ever it is has no after market and wouldnt even be a consideration . now the 9.25 3/4 ton diff is an option and is what im looking into. i know arb has an air locker as well as eaton making an e locker . ( id go dual e locker's front and rear ) this setup would make for a badd drag setup . it will put all the stress on the parts as there will be no slipping so hook and go or hook and break . making something awd with these power levels requires seriously strong parts to handle time .

[carcrafter22]

Good info guys. I guess its a good and bad thing that diesels make the power they do on one hand all that tq will get a truck moving much better than a gas engine making the same power since it comes in much sooner and stays longer but it will test even the strongest of parts. I know for a fact the 9.25 will hold up just fine since I've seen duramax's making over 1700hp make passes with them I know of a couple guys makeing over 1000hp and over 2000tq with air lockers make several passes with no problems. I may wind up using it in the end.

 

 

I doubt you guys really want to see what this is going in but hey you asked for it.

 

Here is the truck 1967 F100 short bed, excuse the mess we were remodeling at the time and the ford wound up in the garage

 

 

Currently has a 2007 crown vic IFS, 1994 lincoln mark 8 IRS, boxed frame, rear fuel cell, custom dash, etc.

 

 

Here is the little 3.9L with the he341 and hx52 compound turbos running 80psi (not a typo - eighty psi) Just something I threw together in my shop.

 

 

 

Here is the new engine, same 3.9L isuzu diesel with a procharger D1SC and holset he351 both should push around 150lb/min of air and easily get me to some healthy numbers calculator says the combo should be good for mid 10's if the stars are aligned lol.

 

 

I dont see much point in hacking up this frame since its in great shape so I'm just going to use a chevy front clip and build my own frame from rectangular tube from the firewall back, redrill the front hubs for a 5X4.75 bolt pattern and have custom axles made for the rear since I have to shorten the housing anyway and use explorer discs on the back with chevy bolt pattern drilled into the rotors.

Edited September 9, 2010 by carcrafter22 (see edit history)

[carcrafter22]

Does anyone know what usually fails on the nv149? How about the viscous coupling? I know they fail with different height tires or if you run with only 1 driveshaft but how about power wise? How would one fail? do they slip, shear, blow up?

 

If all else fails I will just run a 9.25" diff with redrilled hubs up front and a standard 4x4 transfer case like a 261HD manual shift but I really dont care for shifters in the floor and would rather have AWD.

[rojo_143]

wow!!! that is gunna be a stout little setup!!

[dcairns]

Nice truck, even if it is a Ford I like old trucks from the 50's and 60's.

[detjoe]

the chain stretches...then the shafts wobble a egg into your transfercase...like Chase said not many have broken b/c of HP/TQ most are flukes or just radix beating on them.

[BlueAKSSS]

That's a pretty cool project! Definitely not something you see everyday!

[carcrafter22]

Thanks guys I like to make unusual projects. I guess I'll try and put it to the test.

[misterp]

GM rated the NVG-149 at 1900 ft-lbs. However in real life the failures seen are bushings and bearings going out prematurely, and even in bone-stock trim the service manual says to replace the transfer case chain at 60,000-miles (not a lot of people know that) so chain stretch is a serious concern. I have wondered if anyone makes a hardened or beefier chain... Viscous coupling, I have no idea what its specs are, but in theory as long as there is equal/balanced power front-to-rear then the viscous coupling will never be 'activated' and won't burn itself up.

 

LOVE your project - very different and pretty radical too.

 

Mr. P.

[Bear]

I don't know if this information will influence your decision to use the NVG-149, and I'm not trying to discourage your use of it, but I figured if you knew GM's description of it's capabilities and function it would give you more of an idea has to how it may work for you. That and it never hurts to have information out there for all the other members that already have one in there pride and joy and don't exactly understand the inner workings of it.

 

From GM:

 

The NVG-149 has a rated 2203 ft/lbs Maximum Torque Capacity in an approx. vehicle weight of 6800 lbs.

 

The viscous coupling can transfer up to 300 lb-ft of torque during a standard loss of traction and up to 600 lb-ft at the extreme – far more than a driver should ever need – to ensure its responsiveness to any operating situation.

 

The RPO NP3 is a single speed, single mode transfer case. The mode is full-time all wheel drive. It has a planetary differential gear set that splits the torque, normally 38 percent to the front wheels and 62 percent to the rear wheels.

 

The NVG-149 utilizes magnesium housings. Proper fasteners, brackets, and fill/drain plugs must be used to prevent galvanic corrosion. The planetary differential uses the carrier as the input. The annulus gear connects to the rear output shaft and rear wheels. The sun gear connects to the front output shaft and front wheels through the chain and sprockets. The viscous coupling consists of a sealed housing filled with a high viscosity silicone fluid and thin steel plates alternately splined to the inner and outer drum. The inner drum is connected to the input shaft, and the outer drum to the sun gear. 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. This is the most common way the viscous coupling is activated, the shear mode. If the speed difference is high, the coupling can lock or hump. This "hump" occurs when the heat generated, expands the fluid inside the housing, changing the fluid dynamics between the plates. This results in pressure between the plates, forcing them into contact with each other, similar to a clutch pack. In the hump mode, the coupling can bias torque 100% to one axle, if required. Situations requiring this are extreme such as backing up a steep gravel grade or climbing over off-road obstacles. The viscous coupling is not serviceable; it must be replaced if defective. This is because each viscous coupling is calibrated for optimum vehicle performance for both the shear and hump modes. If the viscous coupling is in the "hump" mode too long, severe damage will occur. To prevent damage to the viscous coupling, DO NOT:

 

Tow with only two wheels down

Drive without one propshaft

Drive with a "donut" spare tire for an extended period of time

 

Power Flow - No Wheels Slip

 

During normal operation, 100% torque is delivered to the input shaft from the transmission. The torque is split to 62% to the rear output shaft and 38% to the front output shaft, 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.

 

Power Flow - Front Wheels Slip

 

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%, and up to 100% torque to the rear output shaft. The torque at the front output shaft is lowered from the 38%, to as low as 0% torque.

Power Flow - Rear Wheels Slip

When traction is lost at the rear wheels, the torque is biased to the front wheels. The torque to the front output shaft goes higher from the 38%, up to 100% torque. The torque at the rear output shaft is lowered from the 62%, to as low as 0% torque.

 

Customers may have concern that the transfer case is not operating properly because one set of tires spun for a brief period. It is normal for one set of tires to spin until the viscous coupling engages.

 

Turning off the traction control switch, if equipped, enhances the function of the viscous coupling. The viscous coupling, as described above, engages by heat. Allowing one set of tires to spin or slip for a brief period will generate heat in the viscous coupling. The engine speed should be kept at a constant speed during the brief spin of the tires. Pulsating the engine speed or hard acceleration will not allow the viscous coupling to operate properly.

 

© Copyright General Motors Corporation. All Rights Reserved.

 

Document ID # 873908

2003 Chevrolet/Geo Chevy K Silverado - 4WD

[04CHASE]

good read i didnt know alot of that .

 

now i can actually make sense of when people ask why my fronts spin some times and the rears dont .

 

so much power it doesent know which tire to fry !!

[Bear]

good read i didnt know alot of that .

 

now i can actually make sense of when people ask why my fronts spin some times and the rears dont .

 

so much power it doesent know which tire to fry !!

 

Chase, I’m glad you picked up on that and got something from it. A lot of people will see that much writing and blow it off, but understanding how these cases function can be enlightening, as I don’t know how many times I’ve seen where people have been concerned that something was actually wrong with their transfer-case due to brief wheel spin from one axle.