I am getting ready to replace both the transfer case (TC) and the differential on my 06 Escape Hybrid 2.3L 4WD.

Issue: Loud clunking noise coming from the TC. Binding in the driveline to the point of stopping forward motion when rolling slowly. Happens in neutral, drive, or reverse.

Took it to the shop: The mechanic I took it to said that mismatched tires (fronts worn, but rears almost new) caused the differential to "constantly slip" which eventual welded the differential gears together and then caused the TC to fail as well. Never heard of anything like that. Anyway $5,800 to replace those and get 2 new tires.

My solution: I think I can do it myself for $1,500 or so, including 4 new tires and an alignment if I use salvage yard parts from LQK (6 month warranty, 30 day free return: Diff and TC are $310 each.) I've read all the the steps in the Haynes manual and think I can do it. Not too sure how all the rusted bolts will react, but hopefully a good dose of penetrating oil the night before will help.

A couple questions: Anything special I should know before beginning that isn't in the Haynes? I will doing this in my garage and borrowing tools any special from Auto Zone.

Any safety concerns removing the rear coils? Since there are no safety warnings in the Haynes manual, I assume that if I follow their steps it should be pretty safe, but you know what happens when you assume.

A crazy idea: Why can't I convert my 4WD Escape into a 2WD Escape? If I remove the rear drive axles, differential, driveshaft, and TC, and then install a 2WD Escape TC, won't I then have a 2WD Escape? Will a 2WD TC fit? Is the transaxle the same on 4WDs and 2WDs? Will any sensors "wonder" where the differential is and why the truck won't go into 4WD drive mode? Could it cause engine problems?

Seems a lot cheaper than replacing everything. I don't need a 4WD, its just what I found when I bought it used. I've seen a couple articles about going from 2WD to 4WD, but nothing about going the other way.

Anyway, thanks for at least reading this and I really appreciate any advice you can provide.

Dave

 

A couple of things here. The 2WD doesn't have a TC. The 4WD doesn't engage in reverse. It engages every time you leave from a dead stop and disengages at 30-35MPH.

If I were you, I'd first remove the drive shaft and see what happens then. Every time you make a turn both front/rear and side to side are turning at different speeds so if you really have a rear end issue it'll show up on sharp turns.

 

From what I have gathered, the TC is a 'bolt on' to the original transmission. The difference in 'distance traveled' or 'tire radius, front to rear' is taken up by a viscous coupling, which 'stiffens' when friction from differing rotational speed causes it to heat up.
There will always be a bit of difference as the path taken by each tire will be different, the radii are different, and there may be slippage.
It would take a LOT of radius difference between front and rear to wear out the TC and the coupling along with the rear differential.

The description of the differential gears being 'welded together' won't fly real high. If that were the case, it would not turn. OTOH, if the gears have been damaged by being run without lubrication in the gearbox, the surfaces of the teeth can get very rough, and will generally cause real loud whining or howling as the teeth pass by each other, the sound changing with load or unloaded condition.
From the rest of the post, I'd say go for it. The used TC and differential are bolt-in replacements. You will have to remove the rear drive axles to allow the rear differential to drop out of place (unless you can make them drop far enough there's a spread to allow the differential to be aligned, and then raised into position. The axles drooping would have to clear the sides of the differential. See what happens when you remove the replacement at the boneyard. Pull the axles, or let it drop???)
As far as going to 2WD, the bolted on TC would have to be replace by something. I don't know if the casting is different, but read that one drive axle goes through the TC, so it may just unbolt. Unlikely. A 2WD transmission would bolt in place. The rear drive axles could be removed, and the rear differential removed or left, and the driveshaft from the TC to the rear differential removed. The alignment would likely have to be adjusted to compensate for the weight loss, the at-rest camber likely being incorrect.
If the system is 'selectable', you can drive with the center driveshaft removed, letting the rear differential free-wheel, by selecting the 2WD option. If you were to select 4WD, the power would go to spin the output of the TC, and you'd have no motion, I think.
tom

 

By "viscous coupling", you mean that the 2006MY 4WD had that fluid coupling?

The two diff spider gears are meshed with the two side gears, rotate on pins, radius backsides are burnished, rub in/on mating surface in the diff case and remain still if driving in a straight line. They are the first thing that goes south without lube.

On the F-250 rear end assembly line they ran out out lube oil on a weekend, sent a guy to get a barrel, nobody was in the oil house so the guy self served himself. They found out later that a bunch of rear ends were shipping with cutting oil!

 

Oops.

Guy in 80-86 once told us of a F150 coming off the line with both disk & drum brakes, one side was built different than the other.
Chit happens.

 

Kind of doubt that because of associated hardware, brake lines, parking brake, etc. would be different. Wouldn't all trucks be drum brakes back then anyways??

 

No, even the lowest-end F100 had front disc brakes but non-power... but I can't say the same for 1979 & prior, they may have had drums up front, dunno. But I could see how something like that could conceivably happen on a high-speed assembly line.

 

I'm thinking rears not fronts. I understand that the building of the F-150 front ends stopped where I retired from but as I remember they were shipped incomplete with the brakes missing which somehow saves on cost.

I started there in 1972 but I didn't work much in assembly areas but mostly the manufacturing of the ring&pinion, side gears, pinion spider gears, driveshafts and all their components but that's just about all gone now, all outsourced.

 

Not saying you are incorrect, but not allowing 4wd in reverse is the dumbest thing ever. I'll check the Escape's FSM tonight to see if that is correct, it would be a good thing to know if ever stuck in the snow. Heck even Chrysler minivans awd is designed to work in reverse!

To the original poster: As for how the 4wd works:
Hopefully someone will reply if the 06 hybrid 4wd is different than the 05 system. Anyhow, if your Escape has the same system as the 05 and is binding up in turns then it is likely the computer controlled clutch is stuck full on for some reason (mechanical or electrical issue). You need to determine why it is stuck on before throwing parts at it. As for a Haynes manual, I have several older ones and unless they have gotten much better I wouldn't count on them to do anything major or use them for any electrical work. Vehicles are just too complicated anymore and have too many variations for anyone but the factory to keep up with. Investing in the factory service manual (FSM) is the only way to go when doing more than just maintenance work on a vehicle imo.

 

FWIW: I'm about 99% sure my '01 doesn't care about what gear you select when it's in 4X4 mode.
I like getting what I want instead of what "intelligent" systems THINK I want. I just wish there was an override for ABS because I've been in 2 accidents due to it. And I should add that both situations did not involve excessive speed, just wet blacktop and tires that had over 50% tread left as noted in the police reports.

 

The Hybrid has a separate motor for reverse only and IIRC, it has a quirk that if you say put a 2x4 in its path, it will stop the backup motor as soon as it hits it. If it has a full lock position, it might have 4WD in reverse. Easy to prove but not in July!

I love that wording, "it can even predict slip and preclude it from happening". Just think about that, is it clairvoyant? Must have come from the same tech writer that had a moving graphic of different road conditions which showed torque shifting from back to front and side to side on a Ford site. Of course, it can't/doesn't work that and probably why it was pulled.

Get a Scan Gauge II, program it to read rear wheel torque and see when/how much rear wheel torque. I first connected a scope to mine in 2009 because the dealer couldn't answer any of my questions. The owner of a 2006 Escape Hybrid from another forum(CarlD. or Desert Dog) came up with the programming for the SGII for rear wheel torque and revised it after seeing my scope captures.

If I remember I'll check if anything shows on my SGII the next I back out of my driveway.

 

Just to be clear, the issue does not involve turning. Whether going straight down the road or making a tight turn in either direction, the noise and binding is the same.

 

Also, I believe it has the same (or similar) automatic 4WD system as described above for the 05 Escape. There are no switches in the driver's area and nothing on the hubs. I couldn't select 4WD if I wanted to! The Escape just does it when it needs it.

 

Well on my non-Hybrid Escape, it does show rear wheel torque in reverse which makes sense. Don't know where I heard that it doesn't? Maybe the Hybrid doesn't because of the reverse only motor?

 

The 05 FSM didn't show any difference between the hybrid and regular 4wd, but the FSM was a big disappointment with its lack of information. It only confirmed what you said, that 4wd is engaged when wheel slip is sensed and also during heavy acceleration to prevent wheel slip (maybe engaging it during heavy acceleration is the clairvoyant aspect of the system that the advertising exaggerator was referring to when he wrote it could predict slip, lol). No mention if it works in reverse. No explanation of how the clutch works. No exploded view of the clutch or the rear differential (which they call an axle), just the statement that the clutch and rear axle assembly cannot be repaired and must be replaced as a unit. Maybe the Haynes manual is better??