drive line problem

[Iwan]

If you've saw in my 81 thread. I posted a photo of my good friends, 2 brothers who bought an 80 to restore and they did a very good job and they got it on the road after 2 1/2 weeks of ownership. They changed the driver's side quarter panel. And more!

As you can see he's a hard working lad now and is happy with what life demands! Towing about 4 ton from job to job!
The problem is that the front passenger side wheel is wearing (evenly) and it seems to be binding or driving with the rear. I looked at it doing this today a bit like a 70 thats been left in 4wd with the hubs locked! They said that it's particulary bad in low box.
I said that there is centre diff lock switch and looked but there isn't one on it. Is that normal for a 12v?
There's a viscose coupuling on it.
Is there a problem with the cdl or vc or front diff?
The latter cause its only happening on the passenger side front wheel?
Be interesting to hear people's views. .
Thanks in advance!

 

[clivehorridge]

Mine’s got a dash mounted CDL switch but if there isn’t one, it just means you can’t lock it in Hi.

In Lo, the CDL activates all the time.

If I were him, I’d fit a dash switch and disconnect the auto-lock switch and tape up the plug under the truck.

The versatility of having the choice is great, especially towing in Lo, it’s not always pleasant to have the CD locked, especially when reversing up hill or round tight curves.

I do a lot of off-road in Lo with an open CD.

I’ve not got a viscous coupling though.

As for the problem, I can’t really understand what you’re trying to describe. Anything only affecting one side sounds odd though.

 

[IRLGW]

is the wheel wobbling when driving, or has the tie rod got bent

 

[Dave2000]

Looking at the terrain the 80 is being used in, I would suggest check the viscous coupling may have seized?

It is easy to remove, then throw it in the bin, if you want diff lock in hi range fit the centre diff lock switch, the wiring is behind the dashboard.

Driving continually in low range in very slippery condions without diff lock overheats the VC, they then eventually fail.

Regards

Dave

 

[Firewout]

Did you check the fuse for the cdl?

 

[Iwan]

Thanks very much for the replies! I've got a non VC output here which is on my old auto box transfer.

I'm wondering if the VC rear prop will end up being short as the VC is 225mm long and the non VC is 140mm (just been and checked!).

Also as this problem has been going on for a long time.. thinking that the transfer could have had a fair punishment from binding etc..

I've always noticed centre diff lock switches for sale and never understood why they're for sale! As my 81 has one. Now I understand why Lol!

So a longer rear prop, cdl switch and to disconnect the auto lock switch should cure the issue. For them to keep and eye on the front diff as most of the binding seems to be showing up on the passenger side wheel!

Thanks again guys will add the result as it evolves!

 

[karl webster]

I've got switches in stock Iwan second hand or new.
Had the same as your mate has in the past. You could take the prop off the front to see how it is. Cdl could be stuck engaged? I thought the vc seized unengaged not engaged??

 

[Dave2000]

I thought the vc seized unengaged not engaged??

No they seize engaged, if it seized not engaged no one would even know about it, the VC activity when working normally is so transparent, then you would not sell any Karl, throwing them rather than purchasing is the norm though.

Normal complaint is tyre squeal when tight cornering on tarmac, tyres protest much in the same way as a locked CDL.

Regards

Dave

 

[Iwan]

Interesting last 2 posts! I did see the "tyre squeel" yesterday even though it was on a muddy track and the ps front wheel was kinda clicking like a gear if you can see/imagine what I'm saying.

My mate said that when he bought the truck that the seller stated that he'd just refitted the front prop. I'm thinking what could of happened previously and it's heavy new usage has done. Transfer windup is bound to add gear wear. Suppose to drop the oil out of the transfer to hopefully show clean oil... only had wind up on a 60 or 70 and you reverse and get a bit of a bang to release the tension when you go back into 2wd.

Definitely needing a cdl switch and non VC manual rear prop @karl webster

 

[karl webster]

No they seize engaged, if it seized not engaged no one would even know about it, the VC activity when working normally is so transparent, then you would not sell any Karl, throwing them rather than purchasing is the norm though.

Normal complaint is tyre squeal when tight cornering on tarmac, tyres protest much in the same way as a locked CDL.

Regards

Dave

They would know though Dave. A truck that has the vc should drive like it has help like the cdl being locked. This has been talked about regarding driving in the snow.
A way to tell that the vc works is jacking the truck and feeling if you have resistance on the wheel?

 

[Dave2000]

The VC has to rotate for a period before it engages to any degree, and agree it helps but, it really is just a token gesture. Unless it has seized it is more like a weak LSD which is barely noticable.

Agree you test by rotating a wheel, yes you get resistance, and if it was possible to rotate the wheel considerably faster,the VC would tighten and increase resistance however, it never locks completely and in my experience no way replicates a locked CDL, Would it help in snow? Absolutely yes, when a wheel spins due to lack of traction, instead of the car coming to a standstill there will be assistance from the other axle, hopefully enough to get to a surface with more traction. If the VC were to help in the same manner as a locked CDL, you would be able to remove the propshaft and drive in 2wd, which we know you cannot, unless the VC has seized.

There is a caveat here, I will explain later as I have an impatient 'Cookie' waiting to go walkies.

Regards

Dave

 

[Dave2000]

So back to my thoughts on the VC.

We know that the fluid in the VC responds to the different rotational speeds of the two propshafts, and releases when the two shaft speeds match i.e. no slippage of any wheel front or rear.

If all four wheels have no traction and both propshafts are spinning at the same speed, and the VC was helping as a locked CDL how would it remain locked? In my opinion, if the VC was truly locked both propshafts would spin at the same speed, but the VC by it's very design would simply unlock as if all four wheels had traction causing both propshafts to rotate at the same speed.

Something else, if all four wheels are spinning and the VC is acting as a CDL, then let's as an example assume it is both front wheels that suddenly come into contact with tarmac, you have the engine and drivetrain mass rotating at speed, it would be akin to you dropping the clutch on a 2wd vehicle on tarmac, the result being screeching tyres.

There must be some variable slippage in the VC at all times, I have driven my 80 and one other with no front propshaft, and without the CDL engaged, progress is slow indeed, similar as if the clutch wss slipping.

So IMHO there is assistance, but certainly not enough to be even close to a CDL being engaged.

I could be completly wrong, but am offering my experience with Pow R Lock LSD differentials and results using my own 80 as a test bed.

Regards

Dave

 

[Iwan]

The more I hear about the VC, the more I don't like the fact that I have one fitted to my 81 after converting to manual etc. I suppose they operate fine but if you're in high range with no traction and you forget to activate the CDL then the weak point would/could be the VC.

I wonder if there's a way to take the VC out of the housing and to machine up a connection to the rear output? To save having to buy a longer rear prop and the non VC output housing? etc!

 

[Dave2000]

Nothing has to be fabricated, remove rear prop, remove rear cover from transfer case, get some snap ring pliers, remove clip, slide VC off, put back together.

Add oil!

The difference in cases that had or did not have the VC is why there were propshaft size differences.

I am no expert, but had to learn quickly a few years back when I broke my transfer box.

Regards

Dave

 

[Iwan]

Ahhh the penny has dropped Dave! I was thinking that the housing has to be swapped to the non VC.

Excellent there's no changing of parts just to remove the VC and refit! Superb explanation!

I have to drop the rear prop on mine to change the rusted out diesel return pipe... So I'm going to ditch the VC whilst the prop is off!

Thanks for the info Dave

 

[Dave2000]

I think as the VC gets older then the fluid shear capacity becomes more for want of a better word 'gunky'? Eventually the ability to release the VC back to minimum effort/resistance becomes lost.

TBH Ivan, if yours is working OK I would leave as is, it can do no harm.

I have read in the past that the ABS is reliant on this part, as of yet I have not seen any proof of that. True the ABS is disabled when the CDL is engaged which makes sense, the ABS for example would be useless if the system tries to brake and release a wheel that is being continually driven by the wheels that have traction.

A pro point though, is NO ABS is better on surfaces such as gravel, so the ability to turn ABS of is a good one.

Regards

Dave

 

[Chris]

My experience has been slightly different having had a VC and a non VC 80. I found the VC version better in poor conditions including snow and when I dropped the front prop to see what effect it had I found I could drive reasonably well without the CDL engaged until I came to a hill called Steep Lane where the vehicle finally came to rest. I think that with age, they're all going to tell a different story. But as I say, I was impressed to the point that this 80 I have now, I swapped the T box and prop to put a VC in it.

 

[Dave2000]

I agree Chris they certainly age and this would vary peoples experience, but the ageing process does not appear to increase slip, it tends to push the VC towards seizure as the viscious fluid starts to heat and dry up over time, that would possibly explain why you felt it drove ok?

I had forgotten I have a spare in the garage, it moves the vehicle in the same way as the one presently fitted. You may recall I was trying to diagnose a transmission problem a few years back, so that is two VC's with similar characteristics, this makes three for comparison.

Knowing what I do now, if I had a perfectly good 80 that came without a VC transfer box, there is absolutely no way I would change a transfer box and propshaft just to get the VC.

If this is the only reason you made the change Chris I must say I am surprised.

Regards

Dave