trd90toyota

I have searched, I was wondering if you can take an ADD Diff and turn it into a non ADD diff. I want to remove all of the ADD parts and not mess with it. IS this possible by removing the right side of the diff where the tube connects to the diff?

Thanks for your help

John

Flygtenstein

Yes, that's it.

The centers are the same, it is the stub axle that differs.

leiniesred

Tip: you'll have to get a new inner oil seal when you go from add to non-add. (the ADD oil seal is outboard so the ADD stuff get lubed.)

Otherwise it is indeed a bolt on.

Oh, another tip. the easiest way to get the shafts out of the diffs is not with a slide hammer. Just pull the front cover and pry on the ends against the cross pin (open diffs only) try not to mar the cross pin (don't worry, it is very hard.) the shafts will pop right out. no fuss. Plus, you get to inspect the gears before you turn a broken ADD diff into a broken nonADD diff.

meatmonkey

What exactly do I ask for when I walk into a dealership looking for the new inner seal? If I say driver side inner oil seal will that suffice?

And I mine as well ask if it's installment requires any special tools before it gets tore apart in the driveway.

We did this to a friends truck and then wondered why it leaked a little fluid...

Glenn

Yes, it's an easy swap. For mine, I had to get some star shaped sockets for the bolts holding the axle tube and diff together. I think I still have them somewhere. It's the only place I have ever seen that type of bolt on my truck.

trd90toyota

Thank God I work at a stealership... Now to find those darn star sockets...

In all honestly, this sounds fun and messy!!!

dfoxengr

im still unclear as to why add is unwanted.
any one want to shed some light

leiniesred

yeah, driver's inner axle front axle seal for a 1988 4runner. (No ADD back in 88.) I'll try to find the part number when I get home tonight.

I used regular head bolts from the nonADD when I put mine back together. Indeed, those are the only ones on the truck. Why?

I guess ADD is unwanted when you have swapped to manual (or even automatic) lock-out hubs since it would be redundant.

dfoxengr

can anyone please fully explain add.

like whats it got to do with the transfer case shifter?

thanks

Flygtenstein

ADD, automatic differential disconnect.

There is a small collar that is vacuum actuated when you engage 4wd. It slides over and grabs the stub shaft.

In extreme applications, it provides a failure point.

If you have put on manual hubs, it is redundant since the hubs already effectively disconnect the shaft farther down stream.

Many people replace ADD flanges with manual hubs.

Even more mistakenly say this impacts ADD.

All of them are wrong.

dfoxengr

oh ok, ADD is for those who have the button that turns on and off 4wheel. i have the stick so thats different.

gotcha

Flygtenstein

Wrong.

ADD is on all trucks that ever came without manual hubs from the factory (please don't protest this). It is not button dependant.

All 3rd Gen Runners have ADD, even the ones with buttons for 4wd.

dfoxengr

so why does my taco with a stick need the vacuum when the stick activates 4wd.

Flygtenstein

The stick moves the case, the vacuum moves the sleeve. This assumes you do not have manual hubs.

dfoxengr

ok i understand. thank you.

Glenn

The stick only affects the transfer case. The front axle still needs to be engaged to have 4wd. Hence the vacuum "automatically" engages the axle--which is why it is called Automatic Differential Disconnect.

dfoxengr

ok i had previously thought that the stick put the front driveshaft "in gear" along with the rear when you chose 4wd. i just didnt know about the collar deals that connect the fr. shaft and the cv's.

leiniesred

Flygtenstien: gotta debate you on the ADD on all non-manual hubs. "Automatic" hub trucks, like my 89 originally had, didn't have ADD either.

PS The automatic hubs sucked. I ditched 'em the first winter I had the truck.

GTRio

can anyone direct me to a how to write up outlining the ADD to nonADD conversion? What nonADD parts do i need to buy, just the driver side stub shaft?

Thx,
Brandon.

leiniesred

need the inner axle seal as well as the non add shaft and housing.