ADD front diff?

other way around. youd need to put it in 4hi to turn the front drive shaft to meet the speed of the driver side before engaging the add

and i think all youd need is a spst switch

 

you had 3 tcase actuators go bad?

 

That link said to come to a complete stop. If moving and the add is off the driver and passenger side axle are moving forward (connected to the wheels) but since the front drive shaft isn't moving the spider gears are turning. So the passenger side coupler would be spinning backwards and the axle will be spinning forwards. That would be a nasty thing to try and engage the add

By shifting to 4hi first the drive shaft will turn allowing the spiders to stop allowing the side coupler to spin the same speed as the axle so the coupler and axle can be connected via the add

 

http://www.tacomaterritory.com/forum/showthread.php?t=140171

On our trucks and most any truck for that matter. The relay for the ADD is triggered by the transfercase position sensor only allowing the front add to engage when the tcase first goes into 4wd

 

yes but you cant engage the ADD while moving if the truck isnt in 4wd.

think about it...

if the front drive shaft isnt spinning the passenger side coupler will be spinning backwards. You have to have the front driveshaft turning so the side coupler speed matches

the ECU controls it but it will always shift the tcase to 4hi 1st then the add

the shift limit control is for the speed limit and changing from 4hi to 4lo

 

the reason is why i explained. it has all to do with making the front drive shaft turn so the spiders stop turning. I just want to prevent somebody from hitting an ADD switch while moving if the tcase isnt engaged.

Imagine this... manual hubs.

if you were driving and the tcase was in 2 wheel, the front drive shaft wouldnt be turning and neither would the axles; but the wheels would be. imagine locking the hub with the wheel spinning and the drive shaft not... no good!

if you put the truck in 4hi the drive shaft and axles would be turning the same speed as the wheel/hub so you could lock the hub because the wheel and the axle are turning the same speed...

BTW the reason you really should never shift a lefty case on the fly is because its gear driven and not syncroed. whereas our case is chain driven and syncroed

 

yes but only if the ADD is already locked in and left locked

Edit: the reason is the same... with the add locked you can go from 4hi to 2hi at any speed since the axles and wheels will keep the front drive shaft turning the same speed so you dont need a syncro

 

OK Just to clear up any confusion. Anytime I do a swap to a manual t case for someone that has the IFS front still I always make it very clear that you must first have the ADD switch on before you go into 4wd in the t case. At that point you can shift from 2wd to 4wd while on the fly in the t case anytime you want. The same holds true for someone like myself that has a solid front axle and a t case that has synchro's. As long as I have my front hubs locked in I can shift from 2wd to 4wd while on the fly.

Now, Because of the way the ADD system is set up from the factory, you should be able to turn the switch on while moving and engage the front ADD system. When you do the t case swap you have not changed anything in the front drive system mechanically and your just providing power to the add system to fuunction as if you turned the stock dial on your dash.

When you turn the dial on your dash a signal goes to the computer telling the ADD front system to engage first before it allows the t case to engage. Once the front system has reached it's limit switch and is fully engaged, it now allows the t case to engage because the front drive shaft is now spinning. I have not tried this yet and because of that I have not allowed any on my customers to do so either but I will test out that theory on the next project. For now I tell everyone to first turn the ADD switch on while sitting still and then you can shift on the fly from 2wd to 4wd and back to 2wd anytime you want as long as you are below 50mph.

 

If your going with the Tacoma T case your going to need a lot more wiring than just the 4wd ECU. That system is fully iintegraded with the rest of the vehicle and you'll have one hell of a time trying to ge it to work right if at all if you don't have a good understanding of the wiring harness for the 4wd and prerunner trucks. You'd be much better off doing an FJ T case instead. Just my two cents.

 

You MUST ALWAYS have he ADD switch on FIRST before you out it into 4wd. Period.

The switch you want is a momentary on momentary off switch. You do not want to supply power to the ADD unit all the time.

 

I'm sorry my friend. Your wrong. You MUST have the ADD switch on first before you go into 4wd. You need to have the front system moving first at the same speed so that you can get the t case to function.

The switch that is needed is a momentary on and momentary off switch. You do not want to supply constant power to the ADD unit.

 

Please people.

Go here for all the information on these swaps.

http://www.rocksolidtoys.com/forum/showthread.php?t=116

http://www.rocksolidtoys.com/forum/forumdisplay.php?f=31

http://www.rocksolidtoys.com/forum/showthread.php?t=236

I don't want to see people make mistakes when trying to do these swaps.

Register at RST and ask questions. We have done plenty of these swaps and have figured what and what wont work.

 

Your wrong on this matter. In both trucks whether they are the first gen or the second gen Taco's the ADD system must engage forst before the t case will engage. It's that simple.

 

No your wrong here as well. Any type of electronic ADD system on Toyota's must have the ADD system engaged first at it's limit switch before it allows the t case to go into 4wd. It's just simple mechanics. Try to put a manual t case into 4wd with out the hubs first being locked. it wont work. Same goes for the electronic Taco's.

 

Yes, I'm actually looking into something like this right now for those that want the system to function just like the factory system does.

 

Cool, Here is my email address if you want to send it to me.

rocksolidtoys@gmail.com

 

If you have the wiring harness already, and all of the wires will go to the 4wd computer and tranny correctly then you should be OK. There are a bunch of wires that need to go all over the place for the 4wd system. I don't mind electonics and have wired up my fair share of complete cars but I wouldnt look forward to that. One thing we found while doing Max's truck in Australia is that Toyota does not always put the extra's wires in the trucks during a vehicle run at the factory. Sometimes they have been know to switch in the middle of a run and caused a a bit of a headache with his truck.

Also, make sure your dealing with the same year harness as your truck requires because if not the wire colors will change on you and so will the pin locations on some of the systems. Found that out the hard way as well.

Study everything you have before you jump into it and triple check everything.

If you need any help with anything you can email me at rocksolidtoys@gmail.com as I'm not always over here.

Wyatt

 

the chain driven t case is synchronized right? the older gear driven t cases where not synchronized so you could not shift on the fly unless the hubs were locked right?

With the front ADD disconnected, the axle moves forward and the side coupler rotates backwards due to the spiders since the driver side turns forward. How does the ADD connect when the truck is moving and the components turning opposite directions?

 

First of all the coupler is a clutch sleeve that slides over a clutch hub that is rotating in the direction the wheels are moving. You have two axles that are moving in the same direction. They are not moving in opposite directions. The clutch sleeves slides over the clutch hub and brings the passenger side axle shaft into "Powered" rotation with the drivers side axle. Now the system is acting just like your rear axle system that too is turning in the same direction. It's not moving in opposite directions back there.

Here, let me walk you through this.


If you look at the sequence of actions in the 4wd CPU it goes dial switch first, then to the ADD limit switch then to the transfer case limit switch.

This is how I know it works this way. When we did my swap to a solid front axle we had taken the IFS front diff out and unpluged the ADD pig tail. We then tried to switch the truck into 4wd and all it did was blink at us. Hubs were locked but the system did not allow the transfer case to shift into 4wd. We then tried to get a fancy "BOX" with relays to try and fool the system into thinking that the front diff as still there but it still didn't work. Transfer case would not go into 4wd at all. It wasn't until we bolted back the actuator that had the limit switch in it that it allowed the trasnfer case to go into 4wd.

If what your saying is correct, then we would have had at least the front drive shaft spinning to catch up as you put it to the front wheels but none of that happened for us. The system must first "see" that the ADD is engaged before it will allow the transfercase to go into 4wd.

Also, the coupler you speak of is the differential clutch sleeve which is in the front differential tube. There is a fork in the differential vacuum actuator assembly that is used to slide that clutch sleeve over the differential clutch hub. Both axle shafts will be turning in the same direction while the truck is moving, Not in opposite directions and it is this clutch sleeve that brings the two axle shafts together so that they can be driven by the t case. Nothing is in the spider gears nor does it matter if they are turning in opposite directions because the engaging action is in the front differential tube assembly not the front diff carrier.

I can get the Toyota drawings for you so you can see how this all really works.

 

Yes, the geared case's are not synchronized but the chain case's are.