Rear Diff, Viscous Coupling HELP

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OK

Garage couldn't source viscous coupling (even through Ashcroft Transmissioms) other than OEM at £600 and LR at £1300. So I went ahead and ordered one for £200 from Famous4 as they had one in stock.

Garage are happy to do the rear diff but refuse point blank to fit the viscous coupling as they didn't supply it, even though it is a Britpart or Allmakes one.

Read a couple of posts on here about replacement and although it is not too complicated I have only the MOST basic of tools, socket set, screwdrivers, hammer, spanners. So no Multimeter, torsion wrench, or other bits of useful kit. With my birthday coming up I could ask for the wrench and multimeter i suppose, but back to the point.

With my basic kit and no ramps, or axle stands, or pit, is there any way I can replace the viscous unit myself? Furthermore, how difficult is it, I can and have removed the BeCM, taken apart the door panel and looked at rangerovers dot net lots but that is the limit or my mechanical experience. Can I do this? HELP
 
adamrharding said:
OK

Garage couldn't source viscous coupling (even through Ashcroft Transmissioms) other than OEM at £600 and LR at £1300. So I went ahead and ordered one for £200 from Famous4 as they had one in stock.

Garage are happy to do the rear diff but refuse point blank to fit the viscous coupling as they didn't supply it, even though it is a Britpart or Allmakes one.

Read a couple of posts on here about replacement and although it is not too complicated I have only the MOST basic of tools, socket set, screwdrivers, hammer, spanners. So no Multimeter, torsion wrench, or other bits of useful kit. With my birthday coming up I could ask for the wrench and multimeter i suppose, but back to the point.

With my basic kit and no ramps, or axle stands, or pit, is there any way I can replace the viscous unit myself? Furthermore, how difficult is it, I can and have removed the BeCM, taken apart the door panel and looked at rangerovers dot net lots but that is the limit or my mechanical experience. Can I do this? HELP
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You make it sound as though Britpart is a recommendation! It isn't. Can't say I blame the garage! (In my experience Britpart = sh*t).

Would be worth asking them why they won't fit it (just to get their take opn it). I suspect it's because they didn't supply it and they know what britpart are like,. How long did Ashcroft say before they had more stock?

Guy
 
OK, got car back late yesterday, back up and running no thumping noise type problems. No chirruping while turning corners before or after, garage reckoned the viscous coupling (VC) caused the failure of the rear differential but the front differential gives no issue as yet. Is it correct that a car that heavily towed prior to ownership, presuming my seller lied through his teeth, would weaken the rear differential and NOT be down to the VC? The rear differential had its rack and pinion very worn with a few teeth missing, causing the noise.

If this is the case, then do I need to fit the VC?

If this is not the case, do I need to replace the VC quickly before it bu**ers the front differential?

Should I just fit it anyway seeing as it's bound to help? Even if it is an unmarked Bearmach one, costing just £200.

Many thanks for your help so far.
 
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Just check the existing VCU is working, jack one front wheel, it should be just possible to turn the wheel with a great deal of effort. If you can move the wheel, the VCU is OK.
 
adamrharding said:
OK, got car back late yesterday, back up and running no thumping noise type problems. No chirruping while turning corners before or after, garage reckoned the viscous coupling (VC) caused the failure of the rear differential but the front differential gives no issue as yet. Is it correct that a car that heavily towed prior to ownership, presuming my seller lied through his teeth, would weaken the rear differential and NOT be down to the VC? The rear differential had its rack and pinion very worn with a few teeth missing, causing the noise.

If this is the case, then do I need to fit the VC?

If this is not the case, do I need to replace the VC quickly before it bu**ers the front differential?

Should I just fit it anyway seeing as it's bound to help? Even if it is an unmarked Bearmach one, costing just £200.

Many thanks for your help so far.
Click to expand...

The garage are talking through their arse. The rear diff is constant coupled to the drive, it recieves most of the load when towing. That is the cause of it's demise. If the viscous coupling was seized it would do the front diff long before it damaged the back one. The damage would be to the planet wheels mainly rather than the crown wheel and pinion.
 
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If the viscous coupling is shot, and you aren`t doing any serious off-roading just take off front propshaft until you can get hold of a replacement v-c. This should stop further strain & damage to diffs etc.
 
BUGGER GTLAND .... you stole my post ..................THATS DEFFO the way to go ... drop out the front prop & away yer go ..... mine ran fer 6 Months with no front prop & the guy I sold it to is STILL running it "Front Propless" ....Does NO DAMAGE AT ALL!!!!
 
the hooded claw said:
BUGGER GTLAND .... you stole my post ..................THATS DEFFO the way to go ... drop out the front prop & away yer go ..... mine ran fer 6 Months with no front prop & the guy I sold it to is STILL running it "Front Propless" ....Does NO DAMAGE AT ALL!!!!
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But there's nothing wrong with his VC. A seized viscous coupling will damage the centre diff, it will damage the front prop, it will damage the front diff sun and planet wheels. But it won't have a great affect on the rear diff because the rear diff is direct coupled through the drive. It will put weight on it yes but nothing like what the front diff has to take. A seized VC CANNOT destroy a rear diff in the way his was damaged without going through several front ones first. By the way how are you mate?
 
adamrharding said:
Thanks folks, all sound advice, will do the test later today and post back results. Not owning an axle stand or any other jack than the Landy one, will that do the job?

If the test proves OK then that part is going back and I am getting my £200 quid back as well!
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Landy jack is fine. You only need to lift it enough to turn it.

There are some torque figures mentioned somewhere in one of these threads as it's not quite as cut and dried as it sounds. The VCs gradually seize. It should turn a certain number of degrees in a certain amount of time given a certain torque on the hub nut. Unfortunately I can't remember the figures now, but as I recall, you don't have a torque wrench yet anyway! If it turns at all then that's good.

Guy
 
kooky_guy said:
Landy jack is fine. You only need to lift it enough to turn it.

There are some torque figures mentioned somewhere in one of these threads as it's not quite as cut and dried as it sounds. The VCs gradually seize. It should turn a certain number of degrees in a certain amount of time given a certain torque on the hub nut. Unfortunately I can't remember the figures now, but as I recall, you don't have a torque wrench yet anyway! If it turns at all then that's good.

Guy
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From memory VC should turn 90 degrees in one minute having a torque of 27lb feet applied to flange. So as you are turning the wheel. And the diff ratio is 3.54 to 1 that would be 95.58 lb feet applied to half shaft nut. Or about 65 lb feet if you use a wheel nut.As i say that is from memory, maybe you would like to check it out, i think the figures are on Ashcrofts site somewhere. Think they maybe listed under Classic gearbox checks. But same set up as P38.
 
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I read this thread a coupla weeks ago when I had similar symptoms on my P38. The local RR specialist diagnosed rear diff and VC which were replaced. I now have vibration at the front end, which doesn't transmit through the steering, which is worse at low speed and kinda blends into a rumble at higher speeds. I'm pretty sure its not the UJ's as the front propshaft has fairly recently been replaced and I can't find any play there. Apart from slight leakage of juice from the f/n/s CV boot I can't see anything wrong so I was wondering whether the front diff - perhaps strained by the VC's demise - is on its way out. Does anybody have experience of this? I only did about 15 miles of highway driving to the garage with the VC showing symptoms.
Thanks for any advice.
 
Baloney999 said:
I read this thread a coupla weeks ago when I had similar symptoms on my P38. The local RR specialist diagnosed rear diff and VC which were replaced. I now have vibration at the front end, which doesn't transmit through the steering, which is worse at low speed and kinda blends into a rumble at higher speeds. I'm pretty sure its not the UJ's as the front propshaft has fairly recently been replaced and I can't find any play there. Apart from slight leakage of juice from the f/n/s CV boot I can't see anything wrong so I was wondering whether the front diff - perhaps strained by the VC's demise - is on its way out. Does anybody have experience of this? I only did about 15 miles of highway driving to the garage with the VC showing symptoms.
Thanks for any advice.
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Well, as mentioned before, a seized VC is likely to damage your front diff, not the rear. You mention that your front propshaft has recently been replaced - that's a possible indication of transmission wind up due to a seized VC. This will strain the front diff.

How can you tell the vibration is coming from the front? Or is the vibration really that bad that it's obvious?

Have a read of this (viobration from front driveline), might be applicable...

http://www.rangerovers.net/newrremedies.htm#vibfront


Guy
 
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Thanks for that Guy; the local RR specialist suggested that the problem lay with old tyres so I invested in four new boots! (Dunlop GrandTrek TG35) and it has made a world of difference. The tyre guy also realigned the steering and the tracking and not only has the vibraaaation gone, its like driving a new car!!! At last I am experiencing the smoothness that Range Rovers are famous for!

Thanks for the pointer to the section on the landrovers.net site, it might come in useful in the future.
 
Trust me, and I speak from experience, a knackered VCU can damage front diff, cv joints, rear diff and halfshafts. The one front wheel off the ground test is the real diagnosis. One front wheel off the ground, handbrake on, tranfer box in neutral then try and turn the wheel by hand, it should move slowly with a reasonable force, you don't need to be superman, just steadily applied force, if it's rock solid once you have taken up the backlash in the transmission, then the VCU is dead. Remove the front prop fast before you break anything else.
 
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a seized viscous will take out weakest part ,including rear diff ,its the same as running with centre diff locked,on a vehicle thats done a lot of towing that may be rear diff ,unequal tyres will help to reduce viscous life,
 
jamesmartin said:
a seized viscous will take out weakest part ,including rear diff ,its the same as running with centre diff locked,on a vehicle thats done a lot of towing that may be rear diff ,unequal tyres will help to reduce viscous life,
Click to expand...

Yes it will, but it will under normal circumstances take out the front one far quicker, as that has the most pressure on it because of steering stresses.
 
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