2002 Mazda Tribute 3.0 Auto. 4x4 AWD? 180k
This car had a bad transfer. It was totally thrashed from what I suspect is a bad rear differential clutch being constantly engaged. It has made some rear end noise for a while.
The first question is with the car up on stands (not running) should the drive shaft be able to turn the rear wheels? With no electrical power to the clutch shouldn't it be disengaged, It does turn the wheels, which seems wrong.
I put in a replacement transfer case and after ~150 miles it got the transfer case so hot it melted the rear seal and most the fluid leaked out. It might still be usable, but I think I need to replace the rear end, or possibly the clutch.
Ideas?

 

The rear wheels should disengaged at that time. Other than seals, no parts are available for the rear end.

 

That's what I thought. Guess I'll be looking for a bone yard rear end.
Not that I would pay what they want, but fordparts.com has many parts listed for the rear end including the clutch for $600 some dollars!

 

That's what I thought. Guess I'll be looking for a bone yard rear end.
Not that I would pay what they want, but fordparts.com has many parts listed for the rear end including the clutch for $600 some dollars!

So is it likely that the constantly engaged rear diff clutch is what caused the original transfer case failure and possibly ruined the replacement one?

 

I was going by the Ford manual for an '09 but it uses the same rearend which states, seals only and anything else, replace the whole rearend.

Yep, 100% rear wheel torque and something has to give. Wasn't it hard to turn corners or getting wheel hop?

 

I only took it on a short 1 mile test drive and all I noticed was a bit of noise which I attributed to a known bad rear tire. I gave it back to my Mom who drove it the 150 miles before it started acting like it was bound up and jerky.

 

Well I'm still confused about the correct operation even after talking to a Ford service guy(not a technician). BTW the part in question is technically called the rotary blade coupling.
Here's a quote from a service manual
"The rear axle drive pinion receives power from the engine through the transmission, transfer case, driveshaft and rotary blade coupling (when engaged)." When is it engaged is the question.
I got a replacement rear end today and while checking it out it appears to act the same as the one in the vehicle. Just setting on the floor turning the yoke on the front of the rear end you cannot stop the axles from turning, which seems to indicate it's engaged. So does the rotary blade coupling require power to DISengage?
I do hear some noise (bearing like?) out of the rear end while driving, even with no driveshaft. SO the 6-8 hours of labor for the swap seems inevitable but I hate to waste the time without knowing for sure it will solve all the problems in the driveline.
I guess I might be rambling on so here's a simple question- What is the most likely cause of transfer case/PTO failure in this system? And are the rotary blade couplings known to stay locked/engaged upon failure and then cause failure of the transfer case?

 

I don't have one of these, so I can't really help. But these links may be of some value:

How the Escape's 4x4 System Works

http://www.fordtechservice.dealercon...es/36S08T0.pdf See Lesson 2 for the RBC

I just googled "Ford rotary blade coupling"

Just a thought... is it possible that with just an open axle assembly with RBC attached laying on the floor, no real load on the axles, that the through-frictional loss of the non-energized RBC is enough to "drive" the rear axles without a load?

 

Nice link for the RBC! If there is a clutch pack that needs to be compressed either by the blades or the 4x4 override, it seems that the input to the unit should turn freely. If there is enough friction that one can't rotate by hand that would generate lots of heat I'd think.

 

I didn't explain that very clearly. I was thinking that the through-friction, from the input of the RBC to moving the axle shafts, may have some minimum value, like drag between the clutch plates. Not drag/friction from RBC input to the case, that would get toasty.

These multi-plate clutch power units have been around for years in one shape or another, Chevy Astro vans had them years ago for the AWD version.

In normal operation, both the clutch plates driven by the RBC input shaft (the rear driveshaft), and the interleaved clutch plates connected to the rear axle pinion gear, would both be turning at the same speed due to the front wheels pulling the car along, and the car's movement causing the rear tires to drive the rear axle's ring gear, therefore the input pinion and the clutch plates connected to it.

Having the axle out laying on the floor, and turning the RBC input seems like that would be acting like the front wheels were slipping, as the "Front" clutch plates are being turned by hand, and the "Rear" clutch plates are sitting still initially, as there is no road speed to drive the rear axles.

Just thinking...

 

They did stop using the RBC unit in the Escape for some reason. Used the JTEKT unit through 2012 but the 2013 uses the new Ford designed unit. The old rear end was a Dana I think. Not sure what/how it's done now. Ford is assembling the RDO(rear drive unit) at the plant I worked at which builds/assembles truck and rear driven car rear ends. Don't know if they ship to Dana or doing a in house full rear end? Should ask my neighbor who still works there, he might know.

 

For 2010, the shop manual is basically hands off, just simple seal replacement like you mentioned previously. Black boxes!

 

Just like the EPS system. Got a bad motor, replace the entire steering column.