ADD use(less) ? [Automatic Disconnecting Differential]

[xychix]

First a good write up on the workings of ADD:
http://www.off-road.com/trucks-4x4/tech ... 19259.html

I do have some doubts in the usefullness of ADD.
It adds components prone to failure. If it's disconnected the right halfshaft will run normal speed, the main driveshaft might come to a standstill, which will mean the first part of the disconnected shaft will run fullspeed reverse.

effects:
~2 bearrings don't have to turn
- 1 bearring runs reverse
How does that give advantaged over all the added components and the added breakdown risk?

I'd love to be convinced.

Basically I see the ADD system as 1 freewheeling hub on the left front wheel. (electrically steered, vacuum operated)

The big advantage might be that it would be possible to run LOW (front and rear axles locked together) without having 4wd and it's potential windup. However if this is the only big advantage, why didn't Toyota build in this feature?

[xychix]

http://www.4x4wire.com/toyota/tech/add/

Some more good reading on how to disable / remove the ADD capabilities for a simpeler drivetrain setup.
Not something I'm planning on doing on a new truck mut might be wel worth the effort if you go remote places with a way older truck.

http://www.automobilesreview.com/auto-n ... ns/101412/
another interesting feature 'auto 4x4 on hilux invincible" ??
as far as I could find there are no hiluxes with center diff. could the 'auto' part being a ADD that disconnects when steering sharp / making decent speed?

I'll try and find a straight gravel road and drive over 35 Mph, just to see if the add light goes off...

[martynvella]

try ding a search, there is a thread on it in this forum

[xychix]

try ding a search, there is a thread on it in this forum

I assume you mean this thread:
viewtopic.php?f=13&t=1290
on howto electronically steer the ADD. I've red that and will apply that mod when time is there.

Question remains, what is the use of ADD in it's current form?

[nicebike]

try ding a search, there is a thread on it in this forum

I assume you mean this thread:
viewtopic.php?f=13&t=1290
on howto electronically steer the ADD. I've red that and will apply that mod when time is there.

Question remains, what is the use of ADD in it's current form?

It stops the front tail shaft spinning in two wheel drive, without the need to separately lock or unlock anything.

Spinning front tail shaft is potentially a source of vibrations, and with no torque on it, has a tendency to wear front tailshaft universals prematurely.

[xychix]

so now the front shaft isn't turning and spiders in front diff run double speed. Meaning we're saving the bearings at cost of the front diff.

still don't understand why ADD is useful.

[nicebike]

without the need to separately lock or unlock anything.

Maybe you missed this bit ?

Whether the convenience is worth the complication to you, only you can decide !

[xychix]

without the need to separately lock or unlock anything.
Maybe you missed this bit ?
Whether the convenience is worth the complication to you, only you can decide !

Maybe I was hoping ADD was even more intelligent. For example detecting windup and then releasing the front axle.

But as I now understand it's just 1 electrically steered vacuum operated left front wheel locking hub... correct?

[andy666]

The only benefit of ADD is a slight fuel saving, from not having the front drive shaft and transfer case turning all the time.
I agree that it is an unnecessary extra that Toyota should simply do away with.
I would rather they bring back manual locking hubs that are simpler, less prone to failure, greater fuel saving benefits then ADD, can use 2wd low without modifying the electric and you can still drive home with a blown cv by simply unlocking the hubs.