Bongo Fury

Hi,

just curious - does anyone know the front/rear split of how the power is dished out on 4WD Bongos? Is it 50/50? Or a bit of a rear bias so they handle like the 2WDers?

thanks,

Alex

Hi Shutty

As I understand the system, there is no engineered split built into the 4WD on the Bongo. There being no centre diff there but only the viscous coupling in the middle.

The chain from the gearbox drives, presumably, the bit that goes to the back, so there is always positive drive to the rear and when the front wheels, too, are on solid ground, they are rotating at the same speed as the rears and so no power is being sent to the front - because the speeds of the two bits of the viscous coupling are not different, so no torque transmitted.

So what that seems to imply is that only when the rear wheels, or one of them, starts to spin, does 4WD start to happen. Then what is the torque split? I guess it depends on how solid the silicone goes. I think the way it would be is that the bigger the difference in speed of the front and back axles, the nearer would the split be to 50:50, but never quite getting there because there would always be some creep happening, (I tried to not use the word 'creep' there, to avoid giving opportunies to jokers, but I can't think of another word). I've never met any silicone of the type that goes in these fanglements, so I don't know how solid it can get, but it must be pretty solid when it's worn out, by all accounts. I think what we can say, is that the front will never get more than the rear.

So, surprise, surprise, the 4WD Bongo, is actually 2WD !

Surely that can't be right, sort me out Dandy.

ferdy

thanks, that's a good explanation.

although it does contradict the "Full Time 4WD" stickers on the side, which must be the truth, cos its on a sticker.

I think "Full Time 4wd" is to differentiate it from other types of vehicle that involved the driver having a seperate gear lever, or the other method of fiddling around with a mechanism in the wheel hub to engage the front diff.

Other than a split front CV boot, I am very happy with my 4WD & although I have had not the need to get myself out of a sticky (or slidey) situation, it is good to know it is there just in case.

Good explanation ferdy.........and there's really no split as the front wheels are unpowered until one slips OR SOMEONE FITS THE WRONG SIZED TYRES........oops, sorry, shouting there ....and the viscous fluid will be stressed and shorten it's life.

I still think its something Mazda designed to use as a replacable part in time and thats why I think that fitting matching, new tyres all round is the only way to go to prolong the (expensive) coupling's life..................But we've already been down that road..................

Here's a great link to how it works.........
http://auto.howstuffworks.com/differential2.htm