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viscous center diff?
Posted: Fri Jun 11, 2004 6:55 pm
by muppet_man67
Whats wrong with em? whats right with em? how easy is a conversion? also intersested in the tech on how they actually work? is it kind of like an lsd? thanks
Posted: Fri Jun 11, 2004 7:55 pm
by DionM
Viscous centre diff relies on fluid dynamics.
You know when you have spoon in a glass of water, and you stir it with another spoon, how the spinning fluid also makes the other spoon spin too? Same principle.
You have you input shaft (from the engine trans) and two output shafts, into a metal box full of some type of silicone based goo (there is no mechanical connection between the shafts though). When the input shaft spins, the goo spins and so do the two output shafts - voila, drive.
Small speed differences are tolerable with the goo (ie low speed difference) as it will not cause much disturbance in the goo. Large speed differences (ie, one output shaft spinning more than the other - ie loss of traction) cause the goo to stiffen, thus "locking" the input and two output shafts ... voila, a "locked diff" (not truly, but close).
That's the theory.
Posted: Fri Jun 11, 2004 9:05 pm
by Aquarangie
What's right with them- Not much, apart from the fact they are a nice civilised unit anmd idiot proff for the ininitated who decide to throw in the center diff lock on older Rangies and cause all sorts of expensive damage!!
What's wrong with them- Well, there not truly a locking center diff and as Dion has mentioned. Also they are expensive to rebuild with the parts almost costing up to $3K alone!! Also the Viscous unit stops working effectiveley after 150,000 or so kms and it can vcatch you out if you go off-road on a regular basis
The Lt230 is the best and most cost effective fix to the problem, plus they have a center diff lock with even drive for both front and rear, no comprimise. There cheap in comparison to the BW viscous coupling box and the conversion is much a bolt in procidure as longh as you get all the acccosiated bits with the unit when you buy one.
I did this to my 92 Rangie over a year ago now and it made a dramatic improvement off-road. Ther rear locker works more effectivley and I don't have to drive it as hard like I used to to get up over washoutas and steep inclines, etc...
Just giving you my comments from first hand experience with the Viscous coupling box. Throw it and you will be a happier man!!
Trav