Drakes Posted July 26, 2009 Share Posted July 26, 2009 I have a RR with an auto box and BW viscous transfer box 93my. Can anybody tell me how to do a quick test to make sure the viscous unit is working properly as I have a feeling something is not quite right. Ideally a test with the box still in the vehicle as I don't really fancy taking it out. Thanks Quote Link to comment Share on other sites More sharing options...
David Sparkes Posted July 26, 2009 Share Posted July 26, 2009 I'm sure it's been detailed on here before, so searching should help, but it's probably easier to find on the Ashcroft Transmissions site. By all means do it an 'easy' way, but (IMV) you will get more certain results if you put more effort into it, by disconnecting the front prop shaft and measuring, with a torque wrench, the force required to move the VC with the handbrakle applied. Good Luck Quote Link to comment Share on other sites More sharing options...
bishbosh Posted July 26, 2009 Share Posted July 26, 2009 The simple way: Jack up one front wheel. Grab the wheel you have jacked up and try and rotate it. You will really need to try hard if the VC is OK, but it will turn with a constant resistance. If the VC is knackered the wheel will either spin freely or not at all. Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted July 26, 2009 Share Posted July 26, 2009 You need the transfer box in neutral when doing this test! Quote Link to comment Share on other sites More sharing options...
scube Posted July 27, 2009 Share Posted July 27, 2009 The easest way to tell if the viscus unit has or is failing is to make some tight turns, round mini roundabouts should do. If the steering fights you the viscus unit is knackered or on the way out. Quote Link to comment Share on other sites More sharing options...
ThreeSheds Posted July 27, 2009 Share Posted July 27, 2009 You need the transfer box in neutral when doing this test! Sorry - don't understand.. Am I missing something? Isn't it enough to have the main box in neutral? AFIK, this test from BishBosh does the job perfectly: Jack up one front wheel.Grab the wheel you have jacked up and try and rotate it. You will really need to try hard if the VC is OK, but it will turn with a constant resistance. If the VC is knackered the wheel will either spin freely or not at all. I used this technique yesterday and if I lean on my (lifted) front wheel with all my weight it turns smoothly, but slowly (a couple of inches per second at the circumference). Quote Link to comment Share on other sites More sharing options...
DrRob Posted July 27, 2009 Share Posted July 27, 2009 I have a RR with an auto box and BW viscous transfer box 93my. Can anybody tell me how to do a quick test to make sure the viscous unit is working properly as I have a feeling something is not quite right. Ideally a test with the box still in the vehicle as I don't really fancy taking it out.Thanks Ashcrofts website (LINK) has the correct procedure. Essentially as others have said: tranny box in neutral, main in neutral, handbrake on, lift 1 front wheel and it should still turn with some resistance. The scrubbing when on tight turns as others have said is also a sign - it tries to fight you! Remember that if knackered it can be replaced with gearbox in situ - see Ashcrofts advice under installations instructions on the same link.. HTH Rob Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted July 27, 2009 Share Posted July 27, 2009 Sorry - don't understand.. Am I missing something? Isn't it enough to have the main box in neutral? As the above vehicle is auto, they aren't 'naturally' left in neutral, so just easier to stick the transfer box in neutral. If you are measuring the torque required to turn it, having the transfer box turning as well will of course upset the reading by a small amount. Quote Link to comment Share on other sites More sharing options...
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