Posted by Ben on November 29, 00 at 13:08:40:
In Reply to: Re: Front diff noise in 2000 Suburban posted by Ben on November 29, 00 at 12:47:10:
We own TRUCKs. Yes they are now called SUVs and are being fitted with evermore "minivan" attributes because the masses demand/expect. One attribut that can cause great expense is the confusion between 4x4, AWD, FWD, lock, etc.
Think it's time to discuss this again for those who do not know the differences, as they can cause themselves great expense when these components break. These are my opinions.
AWD is "all wheel drive", which is used mostly with unibody (monocoque) vehicles like the Suburu, Volvo Cross Country, RAV4, etc. They do not have ladder frames and are passenger vehicle based, not truck based. These do not have transfer cases with multi speeds (they do have a transmission with multi speeds). These can be driven on pavement because they have a complient component in the drive train (slips the torque to all wheels and allows them to travel at different speeds).
FWD is front wheel drive and only two wheels are driven.
4x4 is 4 wheels driven and the second "4" is for a second speed gear set in the transfer case. These typically are truck based and have a transfer case that has 2 or more speeds in addition to the normal transmission. They are switchable form "normal" to "lock", or more precisely 2wd to 4wd. That "lock" is like putting a solid shaft connecting the front differential to the rear differential with NO SLIPPAGE, that is why it's called "lock". There is "high" and "low", which are the two gear sets in the transfer case.
Auto-xxx, like GMs Auto-Trac is a component added inbetween the front and rear diff so that there isn't a "solid" shaft between them. That component will "slip" and allow the front & rear to rotate at differing speeds and not break things. All makes have this but with differing names.
A very simple explianation and hope everyone will jump in with their comments.
-Ben