Jeep transfer case swap - preliminary fe data

[AdrianD]

Originally Posted by cRiPpLe_rOoStEr

Seems like the decoupling only works with the engine on. Well, I never held my breath for those "automatic 4WD" systems, unless they had a proper center differential which IIRC some SUVs from the '90s didn't resort to and relied mostly on sensors input to engage and disengage the front drive. And once the clutches wear out, it may become worse to drive on pavement.




That sounds good.

There's no electric involvement in the center differential. It's a set of clutches with a gerotor pump. When there is a speed difference between the front and rear output shafts, the gerotor spins to pressurize the clutch pack.

There's no preload on the clutch pack when it's new, but I suspect incorrect fluid usage or water contamination makes the clutch pack drag. I've seen an identical transfer case with even more resistance than mine.

Same system was in the front and rear axles (now replaced with air-locking differentials).

Pressure is regulated by a simple metal tab over the pressure relief orifice. Subsequent version used a solenoid to control pressure in both front and rear clutch packs and could act almost like lockers if the solenoids held pressure high and long enough.

It's a good system for mild off-roading but it requires wheel speed difference to work and it still allows for slip between sides. I couldn't have made it up that obstacle in the video I posted with the standard traction system.

Another bonus with the transfer case swap is that fluid changes (every 20k miles) cost $8 instead of $30. No need for special fluid.

[cRiPpLe_rOoStEr]

I'm more used to Ford's Control Trac II and other similar viscous-coupling systems. Well, considering clutch problems due to the usage of an unsuitable oil may plague even a cheap 125cc motorcycle, it wouldn't surprise me if this was the reason for the damage to your previous transfer case.

[AdrianD]

Pump to pump results are in!

27.705 MPG (8.49 l/100km) over 265 miles (427km) of national roads. Including some roads with construction work and a trip in town with mild traffic. All driving done with A/C on.
Trip computer showed 34.59 MPG, which is in-tune with the differences I've noticed in the past.

Previous results in similar conditions:
25.59 MPG (9.19 l/100km) over 318 miles (512 km)

All aero mods were in place in both situations.

I've never had such a low fuel consumption on national roads. Not even on the old Jeep. This is a personal record for me and it looks like the transfer case used up an extra 0.7 l/100km. Factoring in around 15.000km per year, that's 105 liters of fuel saved every year.

What would be the next mod without making my car look weird and maintain the current ride height?
A rear spoiler to improve the airflow at the rear of the car? The rear window gets dirty instantly in bad weather, so I assume some gains could be had there.

[aardvarcus]

https://ecomodder.com/forum/showthre...tml#post599010

I am very happy with my rear kamm back spoiler on my 99 4runner. If this motif does not pass your looks criteria, You could make something of this basic shape out of steel or aluminum integrated into a rear swing out style carrier with tire bumper carrier.

[AdrianD]

It's pretty big
I was thinking about starting with a first generation Porsche Cayenne spoiler as they are cheap and good base to start modifying to fit instead of building from scratch.

I think a good side picture of the car and an overlay of the optimum aero shape would help with ideas and show improvement points.

[cRiPpLe_rOoStEr]

Originally Posted by AdrianD

I was thinking about starting with a first generation Porsche Cayenne spoiler as they are cheap and good base to start modifying to fit instead of building from scratch.

The first thing that came across my mind is the spoiler of the Opel Corsa B GSi, which was also a quite common aftermarket feature for other versions of the Corsa back in the day.

[AdrianD]

Found one locally and I'll ask for measurements. Eye-balling it, it might fit nicely and remain as a permanent addition but I need to figure out a good way to test if it makes any improvement.

[cRiPpLe_rOoStEr]

Originally Posted by AdrianD

Found one locally and I'll ask for measurements. Eye-balling it, it might fit nicely and remain as a permanent addition but I need to figure out a good way to test if it makes any improvement.

You say the one out of a Corsa or out of a Cayenne? I'm sure both might need some adjustments anyway.

[AdrianD]

Corsa. You're right, both would need modifications and the Corsa one would have to become a 3-piece, as the side plates would mount to the D-pillar instead of on the hatch, like on the Corsa.

[cRiPpLe_rOoStEr]

Originally Posted by AdrianD

the Corsa one would have to become a 3-piece, as the side plates would mount to the D-pillar instead of on the hatch

All in order to avoid clearance issues while opening the hatch? Would it be totally out of question to mount it as a single-piece on the hatch instead?