Full time d/r 5 speed

[galopagus]

Hi I am prepairing to build a 88 GL-10. I have long messed around with wagons but this time I really want to build a perfect setup. I love to mess around with the car in the mountains but most of the time I drive around town and use it on icy highways in the winter. I have been scared recently by the full time d/r as it spun me around on the highway a few weeks ago (I didn't realize what should have been obvious I guess)

 

So I was thinking of trying to find the full time d/r 5 speed with diff lock. That would offer the advantages of my box and just lack the front wheel drive option right? With diff lock it goes into a part time box correct? Also what is the final gear ratio from these. Is it the common 3.9 or the 3.7? I am still learning and would love to hear what you guys think. Also if any of you have one for sale let me know please. Thanks,Drew

[[HTi]Johnson]

All the diff lock on a full time box does is split the power 50/50. I think it's 70 front 30 rear without the switch on.

 

Someone correct me if I'm wrong. I need to know too.

[MilesFox]

locking the diff on a full time tranny makes it behave as a part time unit engaged in 4wd, same handling, same dont use on dry pavement.

 

if the full time center diff is non viscous then it is possible to have as much as 100% to the front or rear, or anywhere in between.

 

the 87 rx with lsd and diff not locked can still spin one tire on the front. with my car, diring hard cornering WOT, the inside front tire wants to peel out before the back end wants to come around

 

the full time trans, if it came from a turbo, will have 3.7 gear ratio and 25 spline axles. if your gl-10 was a manual then its a direct swap. automatics are also 3.7 gear but the 3at has 23 spline axles, the 4eat has 25

 

if the gl1- was a single range push-button 5spd, then the vac solenoids and all that hook up the same to the full time tranny for the diff lock.

 

on my particular car(since now has been parted out) i had the rx driveline in a gl10 wagon. the center console had the diff lock switch, but the plug was different. i simply kept the 4wd shifter knob off to the side and its button to lock the diff

[[HTi]Johnson]

I think he has a Full Time box now, without a diff lock switch. I always thought all full times had switches.

[MilesFox]

if that is the case, then go get the vac solenoids and lines off any pushbutton 4wd to use the diff lock if the transmission is presented without it's donor car. otherwise, grap that part from the donor.

[Gloyale]

Johnson']I think he has a Full Time box now' date=' without a diff lock switch. I always thought all full times had switches.[/quote']

 

All of the EA82 Fulltime boxes had diff lock. Locked w/ one wheel in the air = at least one wheel on the other axle getting power.

 

Without it, it's a completely open diff. One wheel in the air = Zero power to anywhere else

 

Legacy Fulltime boxes use the vicous coupler LSD ceter instead of the difflock. *auto locking* if you will, except it never really fully locks.

[galopagus]

Thanks, that is good information. So the full time 4wd on these transmissions is quite a bit different than an AWD system huh? Does this transmission really have any advantages over the part time box then if it is still only putting power to one wheel?

 

Does it improve handling over front wheel drive or handling on slick icy roads? I would assume that this box would get somewhat worse gas mileage to than a front wheel drive selectable box and they also do not have as low of a low range is that correct? So I guess, bottom line is is it worth it?

 

I am looking into buying the black turbo wagon that has been for sale on craigslist a while. It is a 4 speed automatic now and I am hoping it has a rear LSD but I don't know. That car would be a 3.7 ratio so a normal 5 speed pt hi/lo box would not just be a drop in then if I understand correctly but a Turbo RX full time box would be.

Thanks

[Gloyale]

Thanks, that is good information. So the full time 4wd on these transmissions is quite a bit different than an AWD system huh? Does this transmission really have any advantages over the part time box then if it is still only putting power to one wheel?

 

It put power to all four wheels, as long a they have traction with the road. In thi function t is dentical to the newer AWD boxe. Definately adds to better handling over the 2wd.

 

But for true off-road or snow, you can get stuck with one wheel spinning. The difflock makes it so you have power to both axles no matter what. Now, with open diff at each axle, you can get stuck with 2 wheels spinning! LOL

[MilesFox]

so if you have power gong to one axle, wther it be front or rear you will have nothing to lose over FWD, but overall this makes the power more spread out for handlling and sport driving vs FWD.

 

for example cornering in a FWC could spin a wheel and understeer, whee the full time could let that power out th the rear to kick the back en dout.

 

and with the diff locked you get what you are used to already.

 

so really, the only thing you have to lose is FWD only, which is not a bad thing

 

it is possible from what i have been reading to put a viscouls center diff from a legacy nto the rx trans to make it a true AWD with lo range.

[GeneralDisorder]

The low on FT4WD's is only 1.2:1, and the diff is 3.7 unless you do a custom build. That makes them basically the same as the high range on a 3.9 D/R when they are in low. So in a sense they really don't have low at all, but rather a "higher" high.

 

The low on a normal part-time 4WD is 1.59:1, and the diff is 3.9. Making them a completely different animal. Much more suited to slow speeds.

 

The 3.7 (in high range) can give better fuel econemy, but it's really designed for the higher power output of the turbo's that it came on, and to be able to run in 4WD all the time without breaking stuff.

 

GD

[mikeshoup]

The low on FT4WD's is only 1.2:1, and the diff is 3.7 unless you do a custom build. That makes them basically the same as the high range on a 3.9 D/R when they are in low. So in a sense they really don't have low at all, but rather a "higher" high.

Hmm. 3.7*1.2 = 4.44 so, low range is still actually lower than the PT boxes. Not to mention the gears on the FT boxes are shorter than the PT boxes. So, it is essentially somewhere between the PT boxes' High and Low range.

 

Not necessarily good for off road, but great for other things. Turbos aren't necessarily the best for off road anyways.

[discopotato03]

Actually I think you need to double check that one , from my Australian spec 87 FSM all turbo L boxes were wide ratio as in same 1st but slightly larger gaps between ratio's . The differences add up to 2345 being taller than non turbo 5spd L boxes .

 

To get the viscous coupled centre diff you need the longer Legacy cases and shafts because the viscous "drag" and centre diff are the opposite way around to an AWD L box's center diff and diff lock . In other words L box has the lock in front of the centre diff where the legacy has the viscous drag behind its center diff .

The best system would have been a viscous coupling and a diff lock . The problem with the L box is you can lose all power out any wheel , really need LSD's at both ends .

 

Yes I also agree about the overall final drive being ~ 4.44 in low range and that's why the rally people ran them in low range on the dirt .

 

Cheers A .