Brumby 4WD problems

Dean.nabbe · Post by **Dean.nabbe** » Mon Sep 08, 2014 2:32 pm

i had the back of my Brumby Jacked up and on stands to fit my lift kit.. i put it in low range 4WD and 1st gear to try lock the back wheels so i could remove them.. but the back wheels would still turn freely..

i thought being in 4WD would stop them turning... or am i wrong?

steptoe · Post by **steptoe** » Mon Sep 08, 2014 3:21 pm

you've just given yourself the easiest way to turn the engine over from the back wheels, but you are probably turning the other side? If anything, I'd be trying 4th gear, lock up the other side, handbrake on and maybe jerk the nuts with long breaker bar ?

Subydoug · Post by **Subydoug** » Mon Sep 08, 2014 3:39 pm

Oped rear diff, you need to have the other rear wheel on the ground.

Regards

Doug

Dean.nabbe · Post by **Dean.nabbe** » Mon Sep 08, 2014 5:03 pm

i thought, even with both wheels off the ground, the wheel turns the diff, turns the drive shaft, turns the gearbox, turns the front wheels and engine.. front wheels are on the ground and handbrake is on, so using that chain of events, the back wheels shouldn't turn.

i'm not very mechanical, so hence the question..

tambox · Post by **tambox** » Mon Sep 08, 2014 5:42 pm

Doug is correct, you have an open rear diff.
The handbrake works on the front wheels.
You have 2 diffs in your standard Brumby, front and rear.
As these are not limited slip, if one wheel looses traction on a differential, it will be spun freely by the motor, as it is the easiest to spin.
4wd means you need to lift 2 wheels, one front and one rear to spin wheels.
If you put it in 4wd lift one rear wheel off, all other wheels on the ground, it will not spin.
In 4wd you really have changed it from 1 wd to 2wd.
Add an LSD or locker to get 3wd or 4wd.

Spin one back wheel with both the back wheels off the ground, the other will spin in the opposite direction and the tailshaft will not turn.

Look up how differentials work and it may make it clearer.

henpecked · Post by **henpecked** » Mon Sep 08, 2014 5:46 pm

Dean.nabbe wrote:i thought, even with both wheels off the ground, the wheel turns the diff, turns the drive shaft, turns the gearbox, turns the front wheels and engine.. front wheels are on the ground and handbrake is on, so using that chain of events, the back wheels shouldn't turn.

i'm not very mechanical, so hence the question..

Handbrake works on front wheels not back ( which you probably already know)

So I'm thinking -
1) run car in FWD , put on handbrake and lock front wheels , rear will still rotate freely until car stops.

2) Run car in 4WD, put on handbrake and lock front wheels, rear wheels will still rotate with power.

I believe that the diffs enable all wheels to turn at different rates, and that the rate for 1 or more wheels can still be zero, with the engine continuing to turn.

So yes the rears ( I think) will still turn - and perhaps turn your engine over if you are in 4WD as well .

Dean.nabbe · Post by **Dean.nabbe** » Mon Sep 08, 2014 5:58 pm

tambox wrote:In 4wd you really have changed it from 1 wd to 2wd.
Add an LSD or locker to get 3wd or 4wd.

ah ok.. i think i understand now... whilst it is technically in 4WD it is actually in 2 diff drive..

2WD = Front diff
4WD = both diffs

each wheel on each diff will still work independently from it's counterpart.

unless you have diff locks of course

tambox · Post by **tambox** » Mon Sep 08, 2014 6:53 pm

Well done.

Dean.nabbe · Post by **Dean.nabbe** » Tue Sep 09, 2014 12:52 pm

ok, next question... how hard and or legal is it to lock your diffs? whether it be permanently, or manually via a switch or automatically like LSD?

steptoe · Post by **steptoe** » Tue Sep 09, 2014 1:00 pm

research CIG diff, CIG as in plates jammed in and welded up, as in CIG welders

for the rear diff, then those who have this run with one rear axle out, bung it in for off road

outback · Post by **outback** » Tue Sep 09, 2014 2:55 pm

LSD is the way to go.
A locked diff can be a pain in the bum in town.
But as above you could remove a rear axle.

tambox · Post by **tambox** » Tue Sep 09, 2014 4:33 pm

Rear LSD is the most viable for normal driving.
Welded diffs are good for 4wdriving in stuff where you are going to need it, but thats all, its a pain the rest of the time.
Lockers are rare, I have seen Detroit ones, they are great for hard 4wdriving.

Some LSD make 4wdriving much more enjoyable

The front diff is harder, you need more power first.

Dean.nabbe · Post by **Dean.nabbe** » Thu Sep 11, 2014 4:48 pm

is there an LSD anyone can suggest that will fit the Brumby?

AndrewT · Post by **AndrewT** » Thu Sep 11, 2014 5:23 pm

Any R160 diff with stub axels from any Subaru will fit fine.
Just make sure it's the correct ratio to match your gearbox.

The Viscus LSDs are quite common and pretty cheap - found in early Liberty RS.

Clutch LSDs are very rare - found in early L series RX turbos.