In the midst of my minor '91 project that I let take a huge turn towards "major" I came across a '89 2.5l. I got it at a bargain. Needed minor frame patches, ran terrible, and 4x4 didn't work
which brought about the bargain
but I digress.
I first moved the c-clip on the disconnect fork shaft. Worked fine but got a lot of cyclic vibes above 35mph. So I took it apart and did the homemade posi-lok cable for the front axle disconnect. However, I didn't follow the common path
- used the 9' recommended NAPA 731-xxxx cable $32 (in stock!)
- 1/4npt X 1/4 compression from ACE Hardware $4
- Control handle bracket made from bent 2-1/2" x 1/8" steel left from patching frame $1?
- 2 3/16" self drilling sheet metal screws (for bracket) $0.50
- 8 feet of 5/16" i.d. clear plastic tubing from ACE $3-ish
- 1/4" x 3" heat shrink tubing $3.49 (pkg)
- 1/4" stainless hose clamp from ACE $1.18
- 2 brass barrel cable stops for 1/16" cable NAPA overpriced at 2 for $4.59
- blue Locktite $6.49 NAPA
- RTV sealer ACE $4.95
So about $60 total cost.
Note there is no spring in the parts list...
I had a tapered pipe thread tap so drilled the housing with 7/16" final bit size and threaded it - dry. If you take your time and don't let the aluminum chips build up (and thereby gall, ruining the threads) this can be done dry. "Tap Magic" is a good tapping lube for Aluminum, but you still need to be careful with the chips, withdrawing and cleaning the tap fully each time the gullets start getting full of chips. An alternative tapping lube that works OK on aluminum is olive oil...
Don't go too deep- you want nearly all the threads of the fitting to go into the tapped housing when final tightened, but don't go too shallow as you could split the housing or break the fitting trying to get it to go home if too tight. I installed mine with blue locktite as the thread lubricant, and cranked the fitting in properly tight. This left about 1 thread width on the outside with about 1 thread width protruding inside.
I didn't install in the 'blank' spot in the dash as it is plastic, electing instead to mount it to a bracket I made which I screwed to the bottom side of the dash. There is a metal piece here that runs from side to side and seemed like a solid mount. In hindsight, the cable works so well it probably would have been quite fine in the usual blank spot... Anyway, I screwed the bracket to this metal strip just a bit left of the fan switch. It's out of the way of knees and screws won't interfere with the switch. One of the other benefits is that the cable won't have to be removed if I have to pull a trim panel for the instruments, speedo, heat controls, etc. I guess that makes this position best in my mind. (If the vehicle wasn't dripping slush I might have mounted it to the transfer shift lever.)
I drilled a 7/32" hole in the grommet for the wiring harness firewall pass-through and sent the cable through that. It was a tight fit, but that was the goal. This lines up nicely with my mounting location. The cable passes over the valve cover and winds below the heater hoses. I didn't cut the extra 24" from the cable at this time to leave options for later LOL but I probably should have. I then slid the clear vinyl hose onto the cable, cutting it so it was just about a 1/2" short of the spiral cable sheathing end. This gave me room to work the heat shrink onto the cable sheathing, sliding it about 1" into the vinyl cover. The hose clamp was then install over the vinyl tubing, cinching it over the heat shrink- water proof! I fed the compression nut and ferule over the cable, slid it into the fitting, and tightened it down. Final waterproofing was the RTV sealing the heat shrink to the compression nut.
Inside the housing, I had drilled two 1/8" holes in the 'shallow' portions of the cast aluminum shift fork. I had fed the drill bit right through the fitting, drilling first left of the center rib, and then angling to the right of the center rib. The cable core itself was fed through one of the cable stops and then one of the holes in the fork. I moved the fork to the disconnected position, forced the cable stop tight to the fork, applied blue locktite to the threads, and tightened it with a screw driver. Then I bent the cable with needle nose and fed it BACK through the other hole. After working the "slack" (tough to do!) I slipped on the other cable stop and cinched it down. Note again- no spring!
At this point I installed the housing bolts being careful to engage the shift collar. Sealed the housing with RTV.
To engage the front axle, I turn the handle to unlocked position and pull. A gentle roll of the vehicle to align the axle disconnect splines and the front axle was locked. Turning the handle locks the cable, holding the spline collar in the connected position. Then, to disengage, I unlock the cable, push it in and twist it to locked. This slides the axle collar back to the disconnected position. Transfer case lever is needed of course to engage the front driveshaft for 4x4.
So no spring- no struggling to pull out cable. The t-handle locking cable locks and unlocks the axle perfectly and I didn't have to spend $80 + shipping for a new but still failure-prone vacuum motor. And I didn't have to experiment with springs. One install, success. (BTW- I also drilled through the vacuum motor diaphragm so it wouldn't impede action. Then I sealed up the 3 vacuum ports to keep out water etc. This should be obvious to anyone who's read the 28 page thread but I thought I would mention this for any newbies to save them trouble.)
A future mod I will likely use on the '91 project is to use the later model shift fork housing that has the switch for the 4x4 light on the end of the shift fork shaft. I don't need
the light, but since sometime it takes a sec for the splines to align and therefore connect the axle shafts I think this is a nice feature since it is available. Waiting for the light could save unnecessary 'slamming' of the driveline upon engagement. I remember breaking an automatic hub on my '83 Datsun King Cab 4x4 when I let out the clutch and applied power.
Time will tell but this seems like a super easy mod with a lot of benefits the vacuum motor can't offer.
I hope this is a very useful addition to a long, good and helpful write-up.