SkiRig

My 1992 4runner with ADD is really hard to shift into 4wd. My 89 without ADD shifted like butter. The 92 is like an arm wrestling match. It goes in with effort, works fine, no noises or anything. Do ADD trucks require a lot more effort? It has been the same with old oil or new, old shifter seat or new Marlin one. Any ideas?

thook

The ADD itself will have no bearing on the ease or difficulty of shifting the transfer case. ADD is activated by vacuum lines and switches downstream, but can be completely disconnected and still have no effect on the shifter. Does it do this all the time or just sometimes?

SkiRig

All the time when shifting on the fly. I am wondering if the ADD is not quite working right, then the t-case might be hard to shift due to speed mismatch on the driveshafts (say if the ADD was reacting slowly)?

GSGALLANT

ADD only kicks in when your transfer case is already shifted. There is a limit switch that gets made in the transfer case that signals ADD to actuate. When you're moving, all your wheels are turning at the same speed, regardless of whether ADD is actuated or not, unless you are running different size tires front and rear.

SkiRig

So, when I shift on the fly, the front driveshaft is not spinning is that correct? Because the ADD has not connected the axles yet? How hard are your trucks to shift into 4WD?

Anyways, I will just keep running it till I break the lever off

GSGALLANT

Mine is pretty easy to shift on the fly or stopped. How does yours shift when you are not moving? You could try loosening the bolt that holds the linkages together under the truck, then try moving the shift lever and the linkage seperately to see which one is hard to move. That will isolate where the problem is.

SkiRig

My shifter goes right into the T-case, no external linkage. I will take the shifter out and see what there is to see.

bigtrucknwheels

He's got a 5 speed...
But yeah, I'll give the A340H transmission credit in one aspect and one aspect only: the shifts between the various 4wd stages and 2wd are by far the easiest I have ever used. That lever slides like a warm knife through butter. I've come to realize that the automatic transmission and 4wd system thats on my truck is actually handy when I do a little offroading, but nothing compares to grinding gears...

Good luck though! I hope you don't have to resort to breaking of your shift lever!

SkiRig

During the previous 150K miles of this truck's life, the last owner probably used 4wd a couple of times. Maybe it just needs more use to loosen it up a bit.

GSGALLANT

Yep... sorry, I didn't notice you have a 5spd.

thook

If I understand what you're saying correctly, this is like what can happen with 4wd and manual hubs. The gears in the diff and transfer case kind of bind together and you have to back up or move forward a little to get them to line up enough that the transfer case will shift out. In the case of ADD, it's not a fault with the ADD per se.....like something is "wrong". Maybe you do just need to use it more. Have you tried greasing the shifter? And, you said it's the same with the old and new oil. Is that in the t-case and/or the diff?

I had a '78 Plymouth 4wd that was like this. It was full time, though, with LSD diffs. It was very difficult most of the time to get it to go into 4wd high and low lock. Back up, pull forward...grunt....several times...

BTW, the Marlin shifter seat bushing is for the transmission.

SkiRig

Marlin sells a t-case shifter seat too.

New oil in the t-case and diffs.

The shifter seat was greased when I put in the Marlin seat. Feels the same before or after.

SEAIRESCUE

I had a Tacoma with ADD and it was really FU when I purchased it. Gave it to a Toyota dealer to diagnose and fix and they suggested the transfer case be over hauled. Under a warranty, that was done and fixed nothing. Thanks you dumb ship Toyota jerks. Anyway, I got a manual and learned all the components of the system. Mine had a vacuum actuator on the front axle. Had the VSV manifold on the drivers front fender. Had a vacuum accumulator on the passenger side. There are several electrical switches on the transfer case that detect 4wd stick movement. In theory, as you move the 4wd lever forward, the switches go to work and engage the front axle before the transfer case is fully engaged so that the whole process is smooth and easy to accomplish. My problem ended up being a leaking vacuum accumulator.

Regarding your hard shifting problem, the stick does move a fork in the transfer case that engages the front shaft. It will not engage if the front shaft is not moving or not spinning at the same speed as the rear shaft. Need to check to see if the front axle vacuum or electric actuator is engaging, or late engaging, the front end. I suggest removing it and testing it. You can also reach into the axle and move the sleeve that does the actual front end locking. Its possible the unit needs some cycles on it but a dozen cycles should free it up. After that , you need to look further.

Some, lock the front axle shifter gizmo to the 4wd position. Then they install locking hubs. Now you basically have a non-add system.

FYI

sh0kk86

my truck goes into 4hi/4lo easy, but is a pain to get from 4wd back to 2wd, i have to push real hard, my friends 85 4runner is like that too though...

bigtrucknwheels

Our 90 Pickup was the same way. Getting out of 4wd was a PITA...

-MUDSLINGER-

My 84 with a 92 5speed does the same thing have to move a little for it to go into gaer only going back into 2high tho.

javadoody

my 94 as well. if stopped you can rock er in reverse and she'll slide out, but goin down the road over say 30 is a pain at times. a friends 84 did the same. i figured it was the nature of the beast.

SkiRig

Well, it sounds pretty normal. Thanks, Scott