mrnick1979

i want to swap over to manual hubs on my 94 4runner. i now have add hubs which is just a plate bolted on the hubs. i read that all i need to do is remove the plate and bolt on the manual hubs.is this it? i bought a set of aisin hubs to swap on it. my axles boots are leaking and i want to swap out hubs when i do the axles. i dont want my front axles spinning when i am not in 4wd.what do i do with the vacume lines going to the front diff?

Jay351

Leave the Vaccum lines connected, thats for the ADD, keep it. Its nice being able to shift on the fly to 4x4.

Its true. To swap to manual hubs just unbolt/remove the ADD flange, then bolt up the hubs. Set the hubs to FREE and the cv-axles will not move in 2wd.

Also, having 2wd LOW is awsume

4Crawler

iTrader: (3)

If you lock the front hubs (w/ or w/o ADD) you can shift on the fly in and out of 4WD no problems. If you want to defeat the ADD system, see:
- http://www.4x4wire.com/toyota/tech/add/
- http://toyota.off-road.com/toyota/ar....jsp?id=399612

Jay351

I thought you had to slow down too(5-10mph?) shift into 4wd without ADD. (provided the hubs were already locked)

4Crawler

iTrader: (3)

Might say that in the owner's manual or something, but as long as the hubs are locked, the front and rear drive shafts are synced up and you can pop in and out of 4WD at pretty much any speed. I've done so at speeds over 50 w/ no issues. Only time you need to slow/stop is to get into low range, since you have a non-synchro mesh gear in the t-case. So either stop and shift or learn how to double clutch to change low<->high range.

And if you have unlocked manual hubs (and no ADD system) you will not be able to shift into 4WD in motion at all. There is nothing there to spin up the front drivetrain and since it is stopped, you need to stop the rear drive as well to shift into 4WD.

Jay351

Ahh. Thanks for clearing that up Roger.

I guess it won't be that bad when I finally remove the ADD stuff.

devldogs55

Are you sure about that? I just finished reading the writeup on http://www.4x4wire.com/toyota/tech/add/ where he states clearly that...

"Eliminating the ADD system works with either the ADD hub flanges or manual hubs. With either hub type, you retain shift-on-the-fly capability: however, with manual hubs you eliminate any front drivetrain "drag" with the hubs unlocked and in 2WD. Upon completion, you have a greatly simplified and bulletproof 4WD activation system that works the same as stock!"

Are we talking about the same thing here? It looks like completely removing the ADD system as described in his writeup - you may either keep your ADD hub flange, or ideally, install manual hubs, and still retain your shift on the fly into 4x4.

4Crawler

iTrader: (3)

Not 100% sure as I am not terribly familiar with the transfer case internals on the ADD trucks. But if the ADD transfer case includes some mechanism to spin up the front driveshaft prior to engaging 4WD (i.e. some sort of synchromesh feature), then yes you should be able to shift on the fly with unlocked hubs. If not, then if you have the front driveshaft sitting still and the rear shaft spinning, there is no way to mesh the front wheel drive gears to engage 4WD.

Perhaps someone with this setup (disabled ADD and unlocked manual hubs) can give it a try and report back the results.

Brenjen

Hmmm, not sure I get what you guys are driving at but if you leave the ADD mechanism intact & just replace the ADD flanges with manual hubs your system will be identical in operation as it was before with the exception of locking the hubs in. If you leave them locked all the time (instead of in the "FREE" position) it will be no different than the flanges.

All the ADD vacuum mechanism does is slide a metal sleeve over the axle on the drivers side iirc. The advantage of the manual hubs is less wear & tear on the CV's & better fuel economy & the process is just like Jay351 said; unbolt the ADD flanges & bolt on the hubs & you're set.

4Crawler

iTrader: (3)

Two different options. One is to leave the ADD stuff intact and just replace the drive flanges with manual hubs. In that case, hubs locked = no difference to normal ADD operation. Hubs unlocked = no front driveline parts moving at all.

The other option is to disable and/or remove the ADD actuator with a non-ADD part. In this case, you have essentially a non-ADD front diff, just the diff and the drive axles on both sides. Hubs loncked = normal 4WD operation, shift on the fly in and out of 4WD, etc. Hubs unlocked = 2WD.

What is up for a question is whether there is anything inside a transfer case on an ADD truck that lets it shift into 4WD in motion with the front hubs unlocked (without having the ADD actuator working). I know for sure in a non-ADD transfer case, front hubs unlocked there is no way to shift into 4WD while in motion. That case will grind and grind all day long if you try. Lock the front hubs on the same setup and you can pop in and out of 4WD all you want in motion, no need to even use the clutch.

Perhaps someone with an ADD truck that has disabled the ADD actuator and added manual hubs can drive down the road w/ hubs unlocked and try shifting into 4WD and see what happens and report back with the results.

However, it is sort of a moot point as "shifting on the fly" from 2WD to essentially 2WD (4WD with hubs unlocked = 2WD) really does nothing, you are still in 2WD. I guess the only benefit would be that you could then go into 4L (or 2L in this case), but since you usually need to almost stop to change into low range, you could make the shift into 4H then 4L at the same time.

Brenjen

So you guys are basically wondering if there is a synchronization mechanism in the SOTF transfer cases, gotcha.

Well the OP has all the info they asked for at any rate.

devldogs55

Removing ADD and just locking the sleeve in the locked position just removes any weaknesses you may be vulnerable to - i.e. vacuum lines failing, electrical wiring failures etc... You would simply need to get out, lock your hubs and engage the t-case in 4x4 and never worry about vacuum leaks.

Hmm.. so is the question only whether the 4x4 will engage in this situation while the hubs are UNLOCKED? Wouldn't it only matter if the hubs were LOCKED?

I'm kinda confused here too. Shift on the fly would mean someone has locked their hubs while on the trail (or has ADD) - and without stopping or slowing down is able to engage 4x4 - yes?

If so, then why would you want to engage 4x4 with your hubs unlocked? Is this just to get into 4LO in certain situations? Also, does that mean that it is agreed upon that with your hubs locked - you can completely remove ADD and still shift on the fly?

dlbrunner

My 89 did not have ADD. I could shift into 4H at just about any speed, with the hubs locked.

devldogs55

If I read correctly.. I just read that really the only time shift on the fly is not possible is with "auto" hubs. They are different than either manual hubs or ADD hubs. Having auto hubs is the only time you must completely stop to shift into 4x4

runethechamp

I know for sure there is an extra synchro inside the ADD transfercases that makes shift on the fly possible before the sleeve is locked in. When I had to change my transfer case, I got one without this synchro, and I lost this capability. I have manual hubs, but even with these locked, there is no way I can change into 4wd now at speeds of more than just a couple of miles per hour. I am considering rigging up a manual switch for the sleeve (instead of having the transfer case control it) so I can lock it before I start going up to the mountains when I go skiing. That way I will keep the shif on the fly once I hit the snow.

devldogs55

Sweet deal, Champ! I believe that was the info we were looking for.

RobD

Okay, my two cents.

When I did my 3.4 swap, I opted to not worry about reattaching any of the VSV components that operate the actuator.

As previously posted: http://toyota.off-road.com/toyota/ar....jsp?id=399612

So, since I didn't have 4 wheel drive, I decided to switch from the ADD system and change my hubs to a set of Warns. Yeah, yeah, I know I should have spent the money on Aisins, but I got the Warns brand new and cheap. They've survived quite nicely thus far.

Anyhow, to install them, all you have to do is remove a few cone washers and the old flanges (save them if you're offroading in case you blow a manual hub, all you have to do is pull the hub and bolt the flange back on). All in all, I did the job in about 45 minutes. Now, since I didn't have the vacuum system working, the sleeve that engages on the front axle was in the open position. All I did was run a permanent (until it leaked...) vacuum line to the one side of the actuator and plugged the other side.

Now, what about how it operates, you ask? With the hubs unlocked, the front wheels no longer turn the CV joints, which seems to be your main concern. So this saves wear and tear. As for better mileage with them unlocked, I've noticed zero difference. I do know that with the hubs locked, but the transfer case in 2wd, the steering does feel a bit heavier.

As for shifting on the fly...all I need to do is leave my hubs locked and I can shift in and out of 4wd high at pretty much most sane speeds. Out is easier than in, obviously. I sometimes have to clutch in at higher speeds, but not really bothersome. I have left the hubs locked for 400 miles and only went in to 4wd a couple times for short periods of time. No big deal.

devldogs55

Thanks for clearin that up, Rob. Good info there.

Brenjen

I find it strange you don't see any MPG increase with the hubs unlocked. I got about .25 - .5 increase when I did it.

RobD

With winter gas and cold temperatures, it's nearly impossible for me to tell. Now that things have warmed up substantially and they've changed the gas formulations, I'm getting about 100 kms (60 miles) more distance per tank. Noticing a .25-.5 mpg increase means someone is taking an anal retentive approach to tracking mileage!