[janika23]

Hello all,

As the title says I'm curious if its possible to make an AWD 2005 Sienna function as a FWD only, I have seen some posts talking about FWD to RWD conversion but I'm only looking to disabling the rear wheels.

A bit of a back story as to why this project came up as an idea, my 05 Sienna recently had its rear differential fail going about 60mph. I'm not entirely sure if there are any safe gates incase something like this happens to stop any damage from happening to other components such as the transmission. After taking apart majority of the components attached to the diff I came to the conclusion that the entire differentials internals will probably need replacing. It would be around 1 grand to fix the rear diff myself and at this very moment I am not quite sure if other components have taken damage or not. I tried to run the car with rear axles and drive shaft disconnected from the rear diff but it would not move, I had assume there are sensors in place to not let it move without the rear. And another side note is when the rear diff was disconnected and I put it into park the transmission made a pretty nasty sound, this is where my knowledge is limiting because I dont know if 05 XLE Siennas rely on the rear diff this heavily or not because another thing that I did notice was that it would roll in park when the rear diff was still connected and it seemed to have wanted to go in drive/reverse but the rear diff basically doesn't function and it makes a rattling noise. I am not sure if the rear diff plays a role in the car being able to hold park or not (from my knowledge it should only be the transmission doing that).

So instead of spending the money on a differential, I'm curious what the steps would be to make it function in FWD only so perhaps I can test to see if the transmission is still functional along with the other Front end drive components. I'm ok with spending a bit of money on it for a new ECU, etc just have it run in FWD temporary but this is all just hypotheticals I would really love to know if anyone has any idea as to how I would be able to make it run in FWD and if possible how could I be able to test if the transmission is still functional?

 

[sixto]

Theoretically, you can weld the center diff for a 50-50 torque split between front and rear axles, then remove the rear drive shaft. The problem is, from what I’ve read, you have to drop the front subframe, engine and transmission to service or replace the transfer case. At that point, it might make more sense to just use a FWD drivetrain. You might have to cobble a FWD traction control system if AWD traction control intervention makes the van undriveable as FWD.

I don’t know what passive traction controls an AWD Sienna has but if it has three open diffs, it’s not going to hold in park without a rear diff. Park locks the transmission output shaft, not the drive shafts or axles. Park prevents wheels from turning in the same direction, it doesn’t prevent tye wheels from turning at all. If there’s no connection between one differential output and the ground, the remaining wheel can turn while the other end of the diff spins backwards. Apologies if my wording is hard to follow.

Sixto
‘04 LE FWD 207K miles

 

[DC_Dave]

You should be able to somehow fix the output of the transfer case, and all the power would go to the front wheels. The only question I'd have is whether that would wreak havoc with the electronics? Of course, you could just replace the rear axle carrier unit for $800 or so from LKQ, delivered.

Here are some units. LKQ Online

Call LKQ for a lower price and discuss having one shipped to an LKQ near you...

 

[blah415]

Assuming you already called shops for quotes on a rebuild - vs pulling and bring it to the shop. It may be more cost effective to rebuild it then buy any parts you need to convert it. Or like others mentioned, pick up a used one online. I evaluate cost vs value of the vehicle. Right now, AWD siennas are still worth a good amount more. But then again, you could also consider buying a low mileage 2WD previa (140k) for about $2k and lift it.

 

[janika23]

I have gone over and read all the feedback its greatly appreciated and helped a ton, I will most likely go for the option to just pickup a used rear carrier unit. I ended up taking it apart and the main gear was completely shredded. It seems to have had its driveshaft bearing fail internally and it overheated causing the oil to just burn up all on the inside. It smells like burnt oil and everything is charcoal black, After looking for parts to just rebuild it manually it will probably come out to more than a used unit and also the rebuild time/specific tool requirements.

 

[BillG]

Sounds like a great plan. It should go without saying that you may want to consider a differential service and new hub/bearing assemblies just because you'll have it all apart. Brakes, if needed, would also be a great idea too.