compare 4runner and sienna's awd/4wd system

[tcpoob]

I did some search here and came up short. I am sure some of you have a Sienna or looked into it. How does its AWD system compare with our 4th gen 4runner? i know 4R's are more trucky, rugged and has low range, better for towing and offroad use. Aside from that, from what i have learned so far:

1. sienna has *open* center diff. it's able to shift power 100% to either front or rear depending on road condition but normally power is distributed equally at 50/50. while 4R's has rear biased limited slip Torsen center diff with (normally) 40/60 front/rear power distrib.

2. both vehicles has the (ABS based?) traction control system

I wonder how the systems comare in snow, wet, icy road conditions - why Toyota chose one type for the minivan and the other for our truck.

Thanks.

 

[dcampen]

1. sienna has *open* center diff. it's able to shift power 100% to either front or rear depending on road condition

Eh? That is a new definition of "open" differential. "Open" normally means that if one output shaft slips then the other output shaft gets no more torque than the one that is slipping i.e. the torque is _always_ distributed 50/50.

 

[toybox]

If you are considering the Sienna awd I heard there were some problems with the tires that come on the awd versions. I don't remember the specifics but there is a forum like this for the Sienna. I believe it is siennaclub.com

 

[Thai]

Sienna's AWD system uses a viscous-coupling center diff (i think). It allows power to be transferred front to rear depending on traction. VSC controls your path (prevent over/understeer). Traction control works on the front tires to distribute power.

4runner 4wd system uses a gear-based Torsen center differential (no fluid viscous-coupling like in Sienna's). Viscous coupling diffs use special fluid and clutch-packs. VC diffs are OK for mild-moderate conditions (all-weather)...but for off-roading, these clutch-packs may wear down and you need to change out the fluid often. Thus, it is better to have 4runner's center diff for off-roading purposes.

 

[tcpoob]

i heard due to the extra parts under carriage on a AWD Sienna, they've to do away with the spare tire to use run flat tires. i'll check out that link you provided.

heck, most of us dont like the stock tires on 4Rs either - dunlop or Bridgestone H/T.

If you are considering the Sienna awd I heard there were some problems with the tires that come on the awd versions. I don't remember the specifics but there is a forum like this for the Sienna. I believe it is siennaclub.com

 

[tcpoob]

dcampen -

good catch and clarification. thx. i may have misrepresented the info. read it as though i was making 2 statements rather than the later "defining" the preceding. ;-)

Eh? That is a new definition of "open" differential. "Open" normally means that if one output shaft slips then the other output shaft gets no more torque than the one that is slipping i.e. the torque is _always_ distributed 50/50.

 

[toybox]

BTW I absolutely love my 2005 Sienna. It is a base XLE (no leather which I prefer but with all the little extras that come when upgrading to the XLE) and I added an aftermarket 10" dvd player. Much better than the last gen Sienna.

 

[adamhoffmann]

Sienna Tires

If you are considering the Sienna awd I heard there were some problems with the tires that come on the awd versions. I don't remember the specifics but there is a forum like this for the Sienna. I believe it is siennaclub.com

We have a 2005 Sienna LE AWD and love the heck out of the van. It's a tank in the snow and we tow our ATV trailer all over creation with it. The tires were an issue with our van, they came with run flats and they kept popping and they were super expensive so we put normal passenger tires on the car and took one of the run flats and put it on a steel rim and are using it as a spare.