Thread: Viscous Coupling working?

Originally Posted by disconut

The efficiency of the coupling is directly proportional to the size of the hole in the side of the house!

Trev.

ROLMAO!

It probably doesn't help much, but the following is an excerpt from the workshop manual for Viscous Unit - Rolling resistance bench test


NOTE: Testing should be carried out in an
ambient of 20 °C.
9. Secure the output shaft in a vice fitted with soft
jaws, gripping the shaft on the drive flange
splines.
10. With the viscous unit still installed in the front
output housing place the assembly on the rear
output shaft spline.
11. Apply a clockwise torque of 27 Nm to output
flange nut. If no resistance to turn is felt, unit
requires replacing.
12. If resistance to turn is felt, apply a clockwise
torque of 20Nm,to output flange nut for 1
minute, this should result in a rotation of
approximately 25° - 30°. If no rotation or a
greater force is required, unit requires replacing.

Right, Finally got around to jacking up the rangie, wheel spun very nicely, car did'nt want to move at all,Ergo..dos'nt go.., any advice on the best solution?, get a 2nd hand, new, replacement?, cheapest solution is the best for me..

Er, the advice of the Freelander guy only applies to Freelanders, as they are front wheel drive with a viscous to the rear wheels.
So you must jack up ONE FRONT wheel as the Range Rover is rear wheel drive ie there is a direct connection from the transfer case to the rear driveshaft and the viscous coupling is between the transfer case and the front driveshaft.
Get a large screwdriver and try to turn the front driveshaft with the screwdriver jammed in the UJ. It should turn VEEEERY slowly with a lot of effort. If you have done this and the screwdriver turns easily then it is stuffed , but I doubt you have done this. 99% of the time it is seized and you cannot turn the front shaft.

Regard s Philip A

does lifting a front or back wheel make a difference?I lifted a back wheel and it spun freely, but hav'nt done a front one yet..

Our service manual for the viscous transfer case says to remove EITHER the front OR rear propshaft and then try to drive the vehicle. The vehicle should drive, excessive engine speed indicates a failing viscous unit. The book doesn't say how much engine speed is excessive, nor does it mention siezed couplings.

YES it matters.
If you had the transmission in neutral and the handbrake off the back wheel will turn easily. If you put the handbrake on the back wheel wouldn't turn, and if you put it in gear/park the back wheel wouldn't turn.

As I stated the viscous works only on the front driveshaft.
Regards Philip A

PS you have to have the tranmission in neutral when doing this.

The driving thing without a driveshaft will work as the viscous allows only a small difference in revs between the two driveshafts, but do not go too far as it is pretty hard on the Viscous. I have never tried this but I would remove the rear shaft as that means all the drive will be through the viscous, and you will soon see if it drives. I would expect a lot of slip at first but then it to tighten up as the viscous fluid heats up until it is like a solid coupling within a couple of seconds.
Regard sPhilip A