stuck Posted February 14, 2011 Share Posted February 14, 2011 Gent's, Can somebody please tell me what the viscous handbrake is on a R380 box? Is it just the normal park function or something else? Thanks, Mick. Quote Link to comment Share on other sites More sharing options...
David Sparkes Posted February 14, 2011 Share Posted February 14, 2011 The viscous handbrake is a new device, never mentioned in any workshop manual. Who told you about it, or where did you read about it? Quote Link to comment Share on other sites More sharing options...
stuck Posted February 14, 2011 Author Share Posted February 14, 2011 The viscous handbrake is a new device, never mentioned in any workshop manual. Who told you about it, or where did you read about it? Guy I bought my CCV motor from mentioned that a lot of the lads were fitting them instead of the usual transmission brake, he said they were available on some R380 box's but at the time I didn't think to ask more than that. Quote Link to comment Share on other sites More sharing options...
David Sparkes Posted February 14, 2011 Share Posted February 14, 2011 Ah Ha, I have heard of this practice, but never seen it practised. As I Understand It, they fit a Viscous Coupling to the centre differential, presumably sourced from late Range Rover Classics. This means they have permanent four wheel drive, but the centre differential isn't mechanically locked as it would be with a standard diff lock. Now when they apply the handbrake the rear propshaft is 'stopped', but by applying a lot of throttle the VC slips and thus the front wheels are powered. This technique enables the car to turn in a very tight radius. If you have seen front wheel drive cars on a driving test (manuouvering round cones, on a tarmac surface) you will have seen this technique displayed. I don't know the life expectancy of the VC when thus abused. HTH, David. Quote Link to comment Share on other sites More sharing options...
stuck Posted February 14, 2011 Author Share Posted February 14, 2011 Ah Ha, I have heard of this practice, but never seen it practised. As I Understand It, they fit a Viscous Coupling to the centre differential, presumably sourced from late Range Rover Classics. This means they have permanent four wheel drive, but the centre differential isn't mechanically locked as it would be with a standard diff lock. Now when they apply the handbrake the rear propshaft is 'stopped', but by applying a lot of throttle the VC slips and thus the front wheels are powered. This technique enables the car to turn in a very tight radius. If you have seen front wheel drive cars on a driving test (manuouvering round cones, on a tarmac surface) you will have seen this technique displayed. I don't know the life expectancy of the VC when thus abused. HTH, David. Thanks David. Quote Link to comment Share on other sites More sharing options...
elbekko Posted February 15, 2011 Share Posted February 15, 2011 I don't know the life expectancy of the VC when thus abused. About half a second, I'd think. Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted February 15, 2011 Share Posted February 15, 2011 If it's an RRC VC then once it has slipped slightly it should lock up as the fluid in it heats, negating any speed differential between front and rear axles, and probably ripping the handbrake mechanism from the back of the transfer box. I have seen but never practised knocking an LT230 out of difflock and applying the handbrake to perform a tight turn on loose surfaces, but never with a VC in the middle. Quote Link to comment Share on other sites More sharing options...
Snagger Posted February 15, 2011 Share Posted February 15, 2011 If it's an RRC VC then once it has slipped slightly it should lock up as the fluid in it heats, negating any speed differential between front and rear axles, and probably ripping the handbrake mechanism from the back of the transfer box. I have seen but never practised knocking an LT230 out of difflock and applying the handbrake to perform a tight turn on loose surfaces, but never with a VC in the middle. A friend of mine says he did it at RTV trials with an LT230. It can't be done withe the viscous unit as it'd lock up.. Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted February 15, 2011 Share Posted February 15, 2011 A friend of mine says he did it at RTV trials with an LT230. It can't be done withe the viscous unit as it'd lock up.. Exactly what I thought.... Quote Link to comment Share on other sites More sharing options...
David Sparkes Posted February 15, 2011 Share Posted February 15, 2011 I did say I have heard of this practice, but never seen it practised.As I Understand It, ... But as no-one else was volunteering a response ... Quote Link to comment Share on other sites More sharing options...
Snagger Posted February 15, 2011 Share Posted February 15, 2011 To be honest, I had thought that the diff/viscous unit were fitted at the front of the transfer box's main shaft, with the rear prop attached to the back of the shaft, much like how the Series' transfer boxes work (if you substitute the 4wd engagement mechanism for the diff). That would mean that putting the hand brake on would just lock the main shaft, so drive wouldn't be transmitted to the front axle either because the main shaft wouldn't be turning the aft end of the diff. The LT230 must have its centre diff driven directly by the intermediate gear cluster, with a ring gear around the outside of the diff carrier and the front and rear shafts subsequently turned by the diff, much like the crown wheel turning and axle diff carrier, which then turns the half shafts. Quote Link to comment Share on other sites More sharing options...
Range Rover Blues Posted February 26, 2011 Share Posted February 26, 2011 The VC doesn't turn very fast without locking up, as a check you chould be able to undoe the wheelnuts against the resistance it offers at the wheel. The described practice of driving against the handbrake to manouvre is tight spots, definitley best kep for the LT230 I think. You might also find (to you cost as I did) that the VC makes a rubbish handbrake ont he frnot wheels, if the back end looses grip then car will roll slowly forewards (or fall slowly off the jack) and the lackof a propper diff-lock is the thing that spoils an otherwise great bit of kit. Not sure what a Viscous Handbrake is though. Quote Link to comment Share on other sites More sharing options...
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