4r70w trans

[MalcolmV8]

I don't know what all the fuss is about. The 2WD '98 Explorer 4R70W had a plug in the tail housing that was removed and the stock cable was inserted.

Sounds good if you have a 2x4. Also remember it will depend on the year 4r70w you have. Mine for example did not have provision for the worm gear on the output shaft and switching the output shaft basically means rebuilding because it's the first thing in an empty case and basically the last thing you pull out when tearing apart a 4r70w.

If you are running 4WD and the transfer case doesn't have a speedo output, then swap transfer cases to an earlier one that does.

That's about the best I can think of. In my case I had a 2000 AWD transfer case which had no provisions for a speedo cable. I then got a 97 AWD t-case and it had the speedo cable provisions but the front yolk was not compatible. I had already spent the money on a custom driveshaft and CV adapter to get it on the t-case.

So I took apart both t-cases and used the front half from the 2000 and the rear half from the 97 with the speedo gear and put together my own hybrid t-case that works just fine.

[cgrey8]

87ranger, I didn't say the tranny should be weaker than the engine. You are right, that would be like putting a 1000w amp on a 50w speaker.

I think what he was trying to say in that article is that the way a tranny built to handle 350hp operates is going to be different than the way a tranny built to handle 600+hp operates. If it is your intention to make a street vehicle that is putting out 350-400 horses, a tranny that can handle 700 horses is not likely to give you a decent ride and will shift excessively harder than it needs to at any given throttle position. If the expected torque isn't there to back up the hard shift, it can cause other complications inside the tranny and COULD cause (not would cause) premature failure, but will most definately give you a bad ride on the street at even light throttle conditions. Thus, build a tranny to handle the application.

cjcnomor4, I wasn't aware that some Explorer Tcases were true 4wd. Did they also contain the viscous clutch to make them AWD or were they standard 4x4 t-cases?

[MalcolmV8]

I wasn't aware that some Explorer Tcases were true 4wd. Did they also contain the viscous clutch to make them AWD or were they standard 4x4 t-cases?

They are standard 4x4 t-cases. Most Explorers I've seen where 4x4. My wife's is somewhat electronic and has no true 2x4, it has auto 4x4, 4x4, and 4x4 low. Auto 4x4 is 2x4 but as soon as it detects slippage it automatically engages 4x4. It's rather loud and abrupt and the first time it happens you think the tranny just exploded or something. But no it's not awd and there is no viscous clutch.

[cgrey8]

Interesting....I've heard of "Auto 4x4", but never gave much thought to how it worked. It does seem that an Automatically engaging 4x4 without a "clutch" wouldn't be very smooth. After all, if you are slipping the back tires, you are probably under load so an immediate engagement of the front tires (which aren't slipping) on the driveline would be quite a jolt. I'm surprised that they weren't a constant source of customer complaint.

The whole concept, to me, sounds more like a disaster waiting to happen.
Was this Ford's 1st attempt at AWD?

[MalcolmV8]

The whole concept, to me, sounds more like a disaster waiting to happen.
Was this Ford's 1st attempt at AWD?

Doubt it. She has an 04.

[cgrey8]

I'd have never guessed that. Did they get away from the viscous clutch concept since they had problems with them or is the 04 also available in AWD (w/the viscous clutch)?

[cjcnomor4]

the viscous clutch set-up was an awd only system. it sent torque 35-front 65- rear untill it detected slippage then locked 50/50.the driver has no control or input. the automatic system has a switch on the dash and an electric motor on the t-case. it allowed auto, 4wd h,4wd l. if you wanted constant 50/50 lock up you select h or l. otherwise you had rear drive until slippage occurs and the unit sounds like it comes apart and locks up. putting stock wheels on the front and oversized rears (say 16 on front 20 on the back) will really freak out this system. it looks like the viscous clutch has left this mortal plane as of the 05 model year. theres still an available 1-speed t-case but it uses and electromagnetic clutch.

[cgrey8]

Wasn't there an AWD Expidition there for a while too? Did it use the viscous clutch or was it a lock/unlock when slippage was detected?

[cjcnomor4]

the awd expidition was/is an electromechanical clutch. it never got a viscous unit. i dont know if weight or towing ability was a factor it just never happened

[cgrey8]

It's sounding like the viscous clutch was a good idea that just wasn't able to be made reliably. Without knowing the details of the viscous clutch's interal workings, I assume the clutch had to slip in order to allow differentation between the front and rear axles (thus preventing the 4wd bind). It couldn't be allowed to lock up during times when it needed to slip (i.e. around corners), only under excessive slippage. When it had to slip, I'm sure it generated some heat from time to time which is likely what made them go bad. If Ford ever revives the idea, I wonder if a water or oil cooled version would work better? Unfortunately, that'd add a significant amount of weight and complexity to the transfer case.

[Dave]

Expedition x-fer case, was that the BW 4406 unit? I've heard that you can change them into a true 2x4 doing the "Brown Wire Modification". Too big to fit into a Ranger? Torque rating, any idea?
Dave