2nd Gen Front Lincoln Locker.
Postby Bruce C. Anderson » Sun Jan 06, 2019 9:10 pm
I have a 10 bolt front limited slip differential, the power brute TL14-4. Turns out my son wants it more than I do, so I will probably give it to him to put in his 89 Trooper that has a second generation 3.2l V-6 in it. I was going to put it in my 98, but there is a question whether or not it will work in the 98. I haven't dug into the 98's diff yet, but I've gotten some hints that it has a 21 spline differential. On the other hand, other sources say that it's a 17 spline diff.
If I give the LSD to my son I know it will work in his Trooper. If I keep it, it might not work in mine. If it didn't fit in my 98 I'll have wasted a bunch time and work. Lazy I am. While hemming and hawing about this it occurred to me that the TOD system might accommodate a front Lincoln Locker. I could tear my trooper apart and if it fits, use it and if it doesn't fit I could do the Lincoln Locker mod. :shock:
Bear with me now. Here is what I've been thinkin:
The 1998 Trooper has the TOD (Torque on Demand) system. I'm not gonna go into the details about the TOD system. Briefly, it has an electronically controlled transfer case that when TOD is engaged it engages the transfer case sending torque to the front wheels. Also, the front hub to axle connection consists of a flange and bolts, that results in both outboard front axles are engaged 100% of the time. On the drivers' side of the axle housing, the drive axle is split and Splined with a collar that engages or disengages the front drivers' side axle. The color is engaged any time TOD or 4-wheel low are engaged.
So let's say that I weld up the front differential, changing it from a differential to a spool. What could possibly go wrong? Well, let's see what could possibly go wrong. (Here is I would welcome any constructive criticism. Feel free to point out any flaws you might find in my logic or character.):
The first scenario has the vehicle with TOD on. The drivers' side axle is now connected to the spool and the transfer case could apply torque to the front axle. In 4wd Low, the transfer case is set to a 50/50 torque distribution. In this case, the front axle will act as if is Locked, which it will be, and exhibit all the characteristics of a locked front axle. Things can break but they won't break because of a flaw in the TOD/locker system. So no real problem there, just remember when TOD is engaged, it's a locker and drive accordingly. Put it in 2wd and there is no practical difference between having a spool or a differential. Since neither would change the way the diff/hub spins. Looks good so far.
The second scenario is TOD is engaged. The drivers' side axle is connected, and it acts like it's locked. WELL, That ain't good. Imagine going down the road at 70mph and accidentally hitting the TOD button. Things could go REALLY bad driving those speeds on pavement. So this locked front diff idea ain't lookin so good.
The third scenario The transfer case is set to 4wd low range. TOD locks up the transfer case, and the vehicle acts like any other 4wd low with a locker front. Ok I can live with that though it might be a hassle in rough terrain, might quite often be forced to shift from 4wd to 2wd to make turns and such. (More on that to follow)
BUT if I separate the drivers' side axle switch from TOD's computer to manual things might work out better. So far the worst case scenario is that if TOD is engaged at speed on pavement. With the front axle connector controlled by a manual switch set to the off position, 50% of torque will go to the front spool and drive the passenger side wheel, the drivers' side axle will remain disconnected and freewheel. The vehicle will act no different then a TOD with a differential. In the interest of keeping things from getting interesting, I will use a protected switch to control the axle, one that is covered and difficult to accidentally activate.
An unexpected benefit of putting a spool in the front diff with TOD/4wdL engaged and the drivers' side axle disconnected you will have full-time 3wd. With only one driving wheel in the front, there could be adverse steering behavior if the passenger side wheel after spinning gains traction. Might be a bit of a hassle though being aware of that behavior there should be no problem maintaining directional control. I will not be forced to change from 4wd to 2wd when using the front locker. If I need to turn or turn off the locker for any reason, I can just disconnect the drivers' side axle and stay in 4wd low (really 3wd low).
Still, there may be issues with the computer if it gets confused by a conflicting axle connector activation circuit condition and the actual axle connector position indicator. I have no earthly idea what TOD would do or not due if that conflict exists.
Anyway, I'll be tearing into the front end of my Trooper starting tomorrow and I am seriously thinking about doing the Spool mod.
So, do you think it will work as described?