transfer question sas

[blue88b2]

I'm new to the world of electricity. I've been into first gen rangers for too long.
So i've been reading around here for a few days now, but haven't found a clear answer for my question. I've got a 97 explorer i'm putting a tranny in now. and it's got the electric t-case. I've got a dana 44 with 4.88 gears and matching AMC model 20 that i'm going to be swaping in soon. ( they were for my ranger, but i rolled it and found this explorer for $700 instead of fixing the ranger)

So the question...

With the solid axle installed do i need to leave the hubs turned in while driving in auto 4? (even with 2wd, also have the brown wire mod.) will it burn anything up or cause any problems in the t-case if the hubs are left unlocked?

Thanks!
-Jas

 

[blue88b2]

I know there are like pressure plates or clutches in there, but i'm just not sure how they work, and even with the brown wire mod. because this isn't temperarily spinning tires or losing traction, it's full time no turning from the driveline. Thanks, i'm sorry if this has been adressed somewhere else, i've looked as best i can before askling.

-Jas

 

[IZwack]

You can leave the hubs in the "ON" position even on dry pavement (as long as you havent welded the axle carrier) -- everything upstream (driveline) of the front axle will be exactly the same as before so you can ignore it.

 

[blue88b2]

guess what i'd like to know is, if hubs are unlocked, will there be a constant "signal" to the computer that my rear tires are spinning out?

 

[IZwack]

Oh good question -- technically the front driveshaft will spin even if the lockouts are in the "OFF" position because there is some drag in the transfer case which forces the front driveshaft to spin (even if you have the BWM). But heck, even if it stops spinning, just put the hubs in the "ON" position and drive away.

 

[blue88b2]

alright! Just didn't want to risk burning up the guts of the t-case i'll probably just leave one hub "on" since the gears will be welded up, along with using the BWM. but i'm aways out yet, still working on the tranny for now. this is a great site, been glued to it for days now.

thanks
-Jas

 

[IZwack]

Well if you're going to weld up the gears, then you really have to leave the lockouts in the "OFF" position or else you'll never make a turn (unless this is a trailer queen that only sees dirt)

 

[blue88b2]

Wish i could afford a trailer queen. no i'll be driving it pretty regularly for now. But if i leave one hub unlocked then i'll have no problem turning, cause the tires won't be "linked" but all the drivetrain will still spin so as to not burn anything in the t-case. cause even with the BWM i think the driveline still needs to spin to stay up to speed with the discs or whatever device is in the t-case that engages the driveline.

What do most guys do to the t-case after a sas?

thanks again!
-Jas

 

[gijoecam]

With a locked front end, yes, you will need to leave at least one front wheel unlocked to corner. However, how are you going to be feeding the signal to the transfer case to start with? The t-case is ultimately controlled by the GEM, which bases its responses on the wheel speed inputs from the front ABS sensors and rear axle speed sensor. If the new front axle won't be wired into the ABS (which I'm guessing it won't be?) then the automatic 4wd will not function, and it's likely the 4wd lights will blink.

Now, IMHO, there are three perfectly viable options: First, use an ABS-equipped axle with custom tone rings to simulate the front ABS signal to the system... not simple, but it would work.

Second, bypass the entire control-trac system for control of the transfer case lockup, and perform the brown wire mod... It'll require you use the method for the 95-96 trucks to manuall control t-case lockup. The disadvantage is that you'll lose range selection, so you may still need to somehow fool the system into working, otherwise you get no low range.

Third: Install a manual 13-54 out of a 1st-gen and be done with it... Honestly, that would be my suggestion... it'll cause the least headaches, and still provide you with the range selection you need.

-Joe

 

[blue88b2]

so the switch on the dash will not work at all (even with the brown wire mod) when i put the axles in. so it won't put it in 4 high or 4 low?

 

[blue88b2]

where can i read up on the BW13-54 swap? that's probably the way i'll go. Hope it's not to spendy. I'm cheap

 

[gijoecam]

so the switch on the dash will not work at all (even with the brown wire mod) when i put the axles in. so it won't put it in 4 high or 4 low?

Using the OEM control system, it's unlikely. Without the speed sensor signals, the system will detect the fault, disable the system, store the code, and blink the lights 6 times. You won't be able to engage either 4high or 4low, and 4auto will be disabled.

I think the 13-54 swap is a sticky in the transmissions and transfer cases forum here on this site... A quick search should turn it up.

Good luck!

 

[IZwack]

Joe -- arent the transfer case's sensors on the transfer case itself (at least for the front axle) ? In other words, aren't the sensors at the front wheels only used to control ABS and not 4wd engagement?

 

[corkey]

in the second gen it uses the pulses to tell the gem that front wheels , and the back are not turning the same speed , telling the tcc to lock up, (right ??)

 

[IZwack]

in the second gen it uses the pulses to tell the gem that front wheels , and the back are not turning the same speed , telling the tcc to lock up, (right ??)

But I thought wheel speed is irrelevant because its not the wheels that the transfer case is interested in, its the driveshaft. Wheels on the same axle can spin at different RPMs because of the differential's spider gears.

 

[gijoecam]

But I thought wheel speed is irrelevant because its not the wheels that the transfer case is interested in, its the driveshaft. Wheels on the same axle can spin at different RPMs because of the differential's spider gears.

Joe -- arent the transfer case's sensors on the transfer case itself (at least for the front axle) ? In other words, aren't the sensors at the front wheels only used to control ABS and not 4wd engagement?

Ooooh, Good point... I must've had a brain fart... Yes, you are correct (for a 98-01 at least). But now that you mention it and I think about it a little more, the speed sensors for the front ABS, as well as the rear axle speed sensor both feed into the ABS control module. That CM processes the three signals, then outputs the vehicle speed signal to, among other things, the GEM. Now that I think about it, I'm not entirely sure how it uses that signal in the algorhythm that the programmers used, but I *suspect* it's not going to play nice without it.

Here's a simple way to find out how it'll affect it: Unplug the front wheel ABS sensors and take it for a ride. The plug is next to the frame rail right inside the wheel well, and you can unplug it without getting dirty. If the 4wd still works, then you're golden provided you don't swap the rear axle too. If you're planning to swap the rear too, unplug it, and see what it does there too... I *suspect* the 4wd will detect the issues and not function properly. There's a *chance* it might work with the fronts unplugged, but I doubt it'll work with all three signals out of commission...

-Joe

 

[blue88b2]

well i priced a bw 1354 and front driveshaft. $150 from the wrecking yard, and they'll pull it for me. So that's the route i'm going. also heard from my friend at the tranny shop, said he found a spun bearing and grooved shaft. so with a few parts, shift kit, and torque converter just under $700 so looks like i'm staying on my budget. thanks for all the info yalls! keep it coming!

 

[IZwack]

Thats a good decision blue88b2! Dont forget to get the shifter with that 1354!