Transfer Case Help

[rac74]

Hi,

New member here and I have a few non-explorer related questions. I'm building a car with AWD in mind. The Explorer BW 4404 and 4405 cases are what I'm looking at now.

I would go ahead and use the viscous drive 4404 but the 4405 has caught my eye. This is mainly due in part to quick reaction and 2wd when not in use. I'm after general problems associated with this case and if anyone has broken one from excess TQ input. Clutch life, over heating, electronic issues, etc...

I see a lot change to the 1354 for 4wd, but this isn't an issue.

Also, I did some browsing and didn't see any measurements for the input and the two output shaft diameters and spline count. If anyone has this information I'd greatly appreciate it.

Regards,
Joe

 

[cjeckert]

What kind of vehicle are you building? that probably would help making your decision.

 

[IZwack]

Hello fellow Marylander!!

What exactly do you mean by "quick reaction"?

I ask because, while it may be quicker for you to flip a switch to go from 2wd to 4wd, the reliability of the 4405 is nowhere near the reliability of the manual 1354.

 

[gijoecam]

The problem with trying to use a 44-05 in a build-up is that the system is electronically-controlled, so you'd have to transplant the control system into the vehicle as well, and that's no easy task. The system is controlled jointly by the Generic Electronic Module or GEM and the Torque On Demand Relay, and it's constantly monitoring the wheel speed data fed to it from the ABS control module. It would be a VERY complicated system to attempt to transplant into the build-up vehicle.

The AWD case is completely electronics-free. That would likely be a better choice for an on-road sports car. For off-road use, it's not the greatest choice since it's only a single-speed case.

-Joe

 

[rac74]

Car in mind is a Ford Focus ZX3 with a longitudinally mounted Duratec V6 and 5sp. 4wd is not of concern since it is a road car, strictly after AWD.

I'm not too worried with difficulty of installing the system, more the reliability of the case itself for on-road performance use.

By quick reaction I mean that the time it takes for the system to react to changes in driveshaft speed. Viscous couplings, from my readings, tend to not work well under heavy track abuse from overheating of the fluid. Because the fluid has mass, it does lag.

This system is similer to the case used by the Skyline, although actuated by a high pressure oil pump vs an electromagent (both use clutches). I like the idea of having 2wd when AWD is not needed.

I'm very open to suggestions as I want real world experiences on how well each system works and under what conditions.

 

[gijoecam]

Hmmm... Interesting... How the heck does that work? I mean, doesn't longitudinally mounting a FWD engine and trans give you a front and rear driveshaft right there? I guess I'm just confused with where the transfer case would mount with that setup...

The 44-05 won't be a good choice IMHO. It's not a true all wheel drive case. It's automatic 4 wheel drive... in order for the system to recognize that it needs to be engaged, the rear wheels have to be slipping anyways. The OEM system (utilizing the GEM, of course), also has an algorhythm built into it to use throttle position to preemptively engage the system by varying the duty cycle of the transfer case clutch. However, overall, I don't think it's going to give you the type of performance you want to see from it. You'd be better-off with a VC.

For torque rating numbers, I'd contact customer service at Borg-Warner. They should be able to get you pointed in the right direction.

 

[IZwack]

.. contact customer service at Borg-Warner. They should be able to get you pointed in the right direction.

x2 -- cauz from what I'm reading, you want an AWD transfer case with an option to disengage the front output -- and I"m not sure that exists in the Ford truck realm.

Quick question though (aka "hijack" ): Wouldnt the VC basically destroy itself after a while if the front output shaft was disabled and one were to floor the gas pedal a few times on dry pavement?

 

[rac74]

Hmmm... Interesting... How the heck does that work? I mean, doesn't longitudinally mounting a FWD engine and trans give you a front and rear driveshaft right there? I guess I'm just confused with where the transfer case would mount with that setup...

Using a MTX brings up an issue, gearing. You have the TQ/speed multiplication from the main and layshafts, then that of the final drive ratio. So I would need a set of LOW axle ratios to bring the wheel speed back which don't exist. Also, one shaft would now have the load of two wheels, I'm not too sure the old MTX would like that too much! An MTX is short, so the weight bias is towards the front. Using a RWD box slides some weight back as well.

I think I may go with a viscous coupling now. Doesn't sound like it would offer the characteristics I'm looking for (not quite like the ATTESA system electronically). Thanks for the help.

 

[CDW6212R]

I agree with most of what has been said. The 4WD units will all be either full time(not street), or the automatic clutch engaging front(TOD)(A4WD). The Navigator TC BW4406 is too big for you but it could survive easily. The BW4405 isn't really a high power unit, like it sounds as you may need.

The AWD BW4403 and BW4404 both have survived in high powered street Explorers, though that surely didn't include tire spinning track car kind of abuse. If you build the car for street use and don't have enough power to constantly spin tires, those AWD's may do fine.

The AWD fluid heats with rpm difference between front and back. Under normal conditions on the street that means no trouble. The two AWD's may be the only thing small enough to go in a small car. I would go looking at center diff's from an Audi, see if those are separate units. Good luck,

 

[cjeckert]

Just from my experience from auto racing (i do allot of DE and club races with my 87 924s porsche) the awd would need to be on all the time having the front engage and disengage suddenly would seriously unsettle a sports car going into a turn. I think a better option would be the viscus box or something with a split torque bias that is constant. The above is my observations while at track days at summit point with the Porsche club of Potomac and the Ferrari club of Washington .

 

[gijoecam]

x2 -- cauz from what I'm reading, you want an AWD transfer case with an option to disengage the front output -- and I"m not sure that exists in the Ford truck realm.

It does... sort-of... The Freestyle/TaurusX uses an electronically controlled VC in the transaxle to control the rear wheel engagement. Here's the info from the service manual:

Power Transfer Unit (PTU) Printable View (150 KB)

Torque from the engine goes through the transaxle to the power transfer unit (PTU). Torque is transferred from the driveshaft to the rear axle, which drives the rear halfshafts.
The vehicle is equipped with an intelligent all wheel drive (AWD) system that is always active and requires no driver input. The AWD system combines transparent all-surface operation, and is capable of handling all road conditions, including street and highway driving as well as winter driving. The AWD system continuously monitors vehicle conditions and automatically adjusts the torque distribution between the front and rear wheels. During normal operation, most of the torque is sent to the front wheels. If wheel slip between the front and rear wheels is detected, or if the vehicle is under heavy acceleration (HIGH THROTTLE position), the AWD system increases torque to the rear wheels to prevent or control wheel slip.
Serviceable components of the PTU are limited to the output shaft seal and flange, intermediate shaft seal and deflector and the input shaft seal. If any of the internal geared components, bearings or shafts are worn or damaged, a new PTU must be installed. The PTU is sealed from the transaxle and has its own oil sump

And the only other info I could find:

Principles of Operation
Differential Electronic Module (DEM) and Active On-Demand Coupling
The main role of the active on-demand coupling and the differential electronic module (DEM) is to regulate the all wheel drive (AWD) function by distributing torque between the front and rear axles. The system consists of a coupling that combines mechanical, hydraulic and electronic sections. The coupling unit is attached to the rear axle, between the differential gear and the driveshaft. The mechanical and hydraulic sections are driven by the driveshaft. Active on-demand coupling (AOC) has the following characteristics:

• Permanent AWD with electronic control of torque transfer front to rear
• 4X4 control module integrated into the DEM
• Similar to four wheel drive (4WD) operation
• No driveline wind-up during slow speed maneuvers or parking

The system is not sensitive to size differences between the 4 road tires (when driving with a spare wheel, for example). The system is not sensitive to being towed with one axle raised.

That appears to be the best of both worlds... A true VC with full electronic control... Not sure how the heck it works though... I tried contacting a couple guys I know in design, but they work in body engineering, not powertraind development. The folks a BW might be able to shed some more light on it.

My guess is that it uses a fluid pump to engage the VC, and electronic controls that regulate the fluid fllow and, therefore, the strength of the coupling... But that's just a guess.

Not sure if you could retrofit it into a Contour's transaxle though...

-Joe

 

[rac74]

Just from my experience from auto racing (i do allot of DE and club races with my 87 924s porsche) the awd would need to be on all the time having the front engage and disengage suddenly would seriously unsettle a sports car going into a turn. I think a better option would be the viscus box or something with a split torque bias that is constant.

Thats what I'm thinking. The GEM doesn't seem to have a gyro like on the Nissan ATTESA system, nor half the other sensors, to sense the car going into the turn and deliver TQ instantaneously before turn in.

I took the recommendation and looked at the Audi units with the Torsen diffs. which is what I'd really like. The older models have a 50/50 constant bias until binding occurs and TQ is transfered. The newer cars have the T-3 with an asymmetrical bias (40/60) but I can forget them (too new). The Toyota 4runner does have a T-3 that is affordable though so I'm going to look into compatability. Getting the right/workable shaft diameters/splines is a real pain.

I can't use the MTX longitudunally because of over gearing. I can mount this motor transversely with Jaguar X-type running gear but I wouldn't have much room to work on it. After dealing with a Contour engine bay, I'll never go back to transversely mounted engines.

 

[CDW6212R]

What is in the Jaguar X-types? I'd love to do something with AWD and a 69 fastback someday.

 

[rac74]

What is in the Jaguar X-types? I'd love to do something with AWD and a 69 fastback someday.

Ford 3L Duratec V6 with Jaguar designed heads (DAMB valve gear, narrower included valve angle resulting in a shollwer pent-roof chamber). I'm going to be using the Lincoln LS (non VCT) which is the same as the Jag engine minus the VCT. Of these, the LS was the only one with longitudinally mounted running gear and was n ot offered with AWD.

 

[CDW6212R]

I meant about the trans and center differential. Is any of it usable for high power, say over 500hp? The Lincoln V8's are good choices, a DOHC Cobra engine would be ideal.

 

[rac74]

The MTX75 has had ~400ft-lbs through it (550BHP+) and has seen 8,000 RPM. Front diff. is glass though so these were with Quaife/Torsen ATB diffs. No one has used the AWD running gear so capability is unknown. Quaife gearsets are avaiable but are very expensive.

 

[cjeckert]

I recall seeing a Audi quattro about 1990s vintage running 560hp wheel hp at the track and it was pretty impressive humbled some 06 911rs'. That erra i believe its right after they went from longitudinal to transverse however. My dad has the Audi tt with the quatro system and its pretty capable, certainly not for serious condition by on road and during auto cross its a blast. But having a 2wd go to 4wd while in a turn (at the edge of grip) would spell disaster because you would instantly under steer.