4runner ADD (auto. diff. disconnect) & locking hubs...Please read!

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Can anyone give me some insight on this whole theory that the ADD and non unlocking hubs has a major wear and tear disadvantage and off road dis adv. as well.....Is it really worth the $1000.00 to switch to a manual locking option...

I know that it would be nice to cruise the highway with your hubs unlocked and cv's not spinning at 1000 rpm but most trucks are the same way....

I really would like some advice from people that have owned these yotas and have lots of miles under their belt...Is the hub that big a deal compared to other models w. man. lock hubs?

Is it worth it to go to a manual hub disconnect??? thanks
 
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The theory off road is that these systems rely on some sort of vacum to hold 4wd, which could possibly fail at the worst time leaving you without 4wd. While I understand the theory I have never heard of this happening to a Toyota, I have talked to people who plow who say their systems can have issues when pushing too much snow, but these have always been domestics. As far as wear and tear, yes there is a little extra as more components are spinning, but after having several Tacomas with manual hubs and several Runners w/ ADD I have never had an issue with something wearing out on one and not the other. As far as MPG goes you will do a little better w/ manual hubs, but the system we have is not overly easy to swap, you need a lot of expensive parts, IIRC the kits on the market are in the $1k range. So as far as economy if you gain 1 mpg it would take a long time to recoup your initial investment. The ADD system Toyota uses is very reliable and works well, personally I would not swap as to me the pros outweigh the cons.
 
Spending the last 6 years on yotatech and 5 years on here I've never really seen threads concerning issues with the ADD on any Toyota trucks.

I also see alot of 3rd gens with over 200k on them and never seen ADDs being mentioned as a problem.
 
Manual hubs have their problems too. Many require regular servicing to keep them clean and corrosion free. On previous 4wd's I've had Selectro, AVM and OEM Nissan hubs. The Selectro's literally fell apart after a few years, The AVM's rusted up and seized on me, but I never had any problems with the Nissan ones. They were from an '82 MQ Patrol and were still working smoothly when I sold the truck in '05. Actually, Nissan make some great hubs that are automatic with a manual override. Not sure if they are on the Pathfinder or Xterra, but the Patrol (overseas) has them.
 
I would have to say that from an offroading standpoint it is a very good idea to put manual hubs on, due to the fact that you can't lift your truck anything more than about 2"-2.5" without your cv joints buzzing down the highway, which after about 5000-10000 miles will completely destroy them...but this is only really worth the hassle if your gonna try putting a 3"-4" lift on the truck. Otherwise it's just a pain. I'm currently looking for another company who makes manual locking hub conversion kits; was gonna go with Downey but they shut down last year, still a little upset about that one.
 
I know lots of guys that have lifted 3-4" and have had no problems with non selectable hubs. As long as they are not under power it will not eat them up right away, but you should still do a diff drop... the flatter the better. Running around in 4wd all the time or especially under heavy torque load will wear them out with a bunch of uncompensated lift.

Back to manual hubs. The advantage is as follows (I have decided to do this mod soon): When wheeling, you are putting a lot of stress on the CV shafts. When you are wheeling hard with the front diff locked, it is not uncommon to break axles. The advantage of locking hubs is you can unlock them and limp to somewhere where you can fix it, instead of having it slam around in there. People speak of marginal MPG increases from not having to pull the front drivetrain all the time, but my reasoning has been for the survivability factor. The Toyota OEM manual hubs are stronger, and you can unlock them if you get in a trouble. Manual hubs require more maintenance, but I like "maintenance," right?
 
The manual hubs are a little stronger then the ADD, however the Manual CV's are weaker. This has to do with the fact they are grooved for the C-clip that retains them in the hub. The main thing that happens when lifting around 3" or more with ADD is the fins/ribs on the CV boots rub and lead to premature wear/ failure of the boot not the joint from spinning all the time and the rubbing.

I have my front end set at about 3.25" have had it that way for about 35k miles and wheel at least twice a month and have been wheeling every weekend for the past two months. I have yet to break an axle or any issues with ADD. Have I torn a boot or two yes, but never broke or destroyed a CV. In fact have had blown boots on my rig for 6 months now and no issues with the joint itself. No I do not recommend driving around with blown boots, but budget dictated. I am replacing the half shafts and will have the old ones inspected and rebooted so that I can use them as spares on the trail.
 
Of course there is the school of thought that a boot that is being used regularly stays operable longer than one that sits unused most of the time, i.e. dry rot. Not sure I buy it, but I have heard it used in other discussions like these.

Designing a weaker, easily replaceable component into the syste, such as a CV, can be a buffer for the rest of your front drivetrain. I would rather replace a CV then a front diff.
 
I think having manual hubs would be cool because of the 4wd reliability, but seeing as though no one really has problems with their ADD, it costs a fortune to convert, and who the hell wants to have to get out of the truck every time to put it in 4x4 especially when you don't have to now... I wouldn't do it - unless it was a trail rig and not a DD.

In order to save enough $$ on MPGs to break even with the $1000+ you'll spend to convert you'd probably have to wait 10 or 20 years. Most of us will have sold our 4Runners long before that and the future owner will be the one who reaps the benefits (that is if you can find someone who thinks having to get out to lock the hubs is a benefit).

Living in the mountains, I use my 4x4 a lot more than most and on my old trucks, getting out to lock the hubs was a total PITA so most people end up leaving the hubs locked during most of the winter and then there isn't any fuel being saved.

If it's a trail rig I say hell yes, do it! But for a DD, no way.. my $.02.
 
Pikeman said:
The manual hubs are a little stronger then the ADD, however the Manual CV's are weaker.
Click to expand...

ADD uses drive flanges, no hubs are invloved, you can't get anything stronger than that.

Ronmaiden said:
Spending the last 6 years on yotatech and 5 years on here I've never really seen threads concerning issues with the ADD on any Toyota trucks.

I also see alot of 3rd gens with over 200k on them and never seen ADDs being mentioned as a problem.
Click to expand...

The biggest problem with ADD (other than the added front end wear and lower mpg) is failure of the VSV's, they develop leaks in the diaphram and won't lock or unlock the axle. But that's a common problem with all ADD type 4x4's.
 
I have had two Toyota's with manual locking hubs and I can say tearing them down and removing the old grease and re-greasing them was a pain and I do not miss it. I had to do it every couple of years or about every 25,000 miles or if I did a lot of mud running or water play it was done more frequent. Now a days I don't have the time or place to do the maintenance on the manual hubs.

Now I have my 98 Runner and the hubs are sealed and I don't have to get out in the rain, snow, or mud to turn the hubs. All I have to do is pull the gear shift and we be scrapping! :driving:
 
I'm located in Brisbane, Aus and currently have a 1990 4runner with ADD. Was just about to drive onto the beach a few months ago when my ADD failed to lock...

Sounded like tin cans rattling around in my diff. and had no engagement at all. The sleeves finally reset after some time in 2WD and the only time is goes to 4WD is when I'm talking to a mechanic/mate about it.

Been doing some research online to try and fix or diagnose the problem myself, since nobody around here seems to know anything about how to fix the problem. Diagnosis alone will cost upwards of $200.

If anyone knows any good resource or has a mechanic around southeast Queensland, please let me know. Otherwise, wish me luck in learning a new repair technique!

Cheers
 
Mr. Leary said:
I'm a little confused with terminology. What is the difference between a drive flange and a non-locking hub in a semi-float configuration?
Click to expand...

A drive flange is a splined cap that locks the axle to the wheel hub thus when the wheel rolls the axle rolls and vice versa when power is driven through the front axle the wheel is turned. while a manual locking hub has a splined sleeve that is engaged by a dial on the hub locking the hub and axle together. Though now I see your question is about a non-locking hub and I would say a non-locking hub is the same as a drive flange. Though on our runners I am pretty sure that we have full floating in the front. that is why the hub is the same between 2 and 4 wheel drive. the axle holds no weight in the front. clear as mud I know:hello:
 
by the way I would say that the advantage to having manual hubs is that if you do have a CV blow up you can unlock the hub and drive home and fix it in the warmth of your driveway instead of on the trail. and also unless you are buying all new parts it shouldn't cost $1000. and Since ORS is out of business the only choice is to pick a part. I recently saw a 99 taco hit in the front drivers side. the passengers side was complete and the pick a part wanted 100 for the side. so with patience you could do a front conversion for a couple hundred. Leave the ADD in place with manual hubs and you have the best of both worlds. I am going to go back and get the one side to start saving parts for this conversion.
 
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Can anyone wager a guess as to why my non-locking hubs (or always-locked hubs depending on your perspective) don't slide off?

They come out about 1/4" and no further. Something appears to be grabbing it in the center. I need to replace my CV shaft assemblies and was making sure nothing was seized before ordering the parts.

I also found a local ad for some locking hubs and was wondering what years are compatible. My non-lockers have the cone washers (although curiously followed by regular washers instead of split-shaft locking washers).

I would make a new thread but I'm not allowed for whatever reason.

Edit: This is a 2nd gen '93
 
Ballo said:
Can anyone wager a guess as to why my non-locking hubs (or always-locked hubs depending on your perspective) don't slide off?

They come out about 1/4" and no further. Something appears to be grabbing it in the center. I need to replace my CV shaft assemblies and was making sure nothing was seized before ordering the parts.

I also found a local ad for some locking hubs and was wondering what years are compatible. My non-lockers have the cone washers (although curiously followed by regular washers instead of split-shaft locking washers).

I would make a new thread but I'm not allowed for whatever reason.

Edit: This is a 2nd gen '93
Click to expand...


Did you take the bolt out of the end of the CV axle?
 
Thanks for the info. My 1998 Limited with ADD is acting up after 293000 miles. Any idea if anyone makes a cable actuator to replace the vacumn actuator? New member, sorry if I'm doing this wrong.
 
demoman said:
Thanks for the info. My 1998 Limited with ADD is acting up after 293000 miles. Any idea if anyone makes a cable actuator to replace the vacumn actuator? New member, sorry if I'm doing this wrong.
Click to expand...

That would be a cool conversion. I've never seen one, so it would have to be homemade.
 
I have a 1990 22re 5spd. How can I tell if I have ADD?
I don't see the two hoses coming off the front differential, but who knows what the previous owners did.

Any way to tell if I have ADD?
 
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