Useful look inside the 80 tansfer box

[Chris]

Ok this is a vid from 4WD Shed where they fit a part time 4x4 mechanism to an 80. Now, I don't actually hold with what they say in that it will improve the economy. I drove my 80 in 2wd only for some time when my diff was out for repair and my economy most definitely suffered and so did my handling. But that aside, it's a very interesting look at taking the rear housing off a Tbox in situ and a look at the centre diff. No special tools required and useful to just know what's in there should you ever be in trouble. I'm not exactly sure why the kit is necessary. With the FWH at the front, you could presumably just lock the centre diff? If anyone has an explanation I'd like to hear it. I genuinely didn't get replacing the Centre diff component; I'm clearly being a bit thick. But effectively it would seem to be mechanically locking the transfer box. Perhaps some of the Aussie models don't have a diff lock?

Bloke is pretty methodical and other than the complete lack of a torque wrench, not a bad teacher.

Here it is.

 

[Towpack]

From what I could see, all he's done is lock the front and rear props together and the '2wd' option is just the locking/unlocking of the front hubs, or have I missed something? If that's the case then it isn't quite the same as fitting FWH to a selectable 2wd/4wd transmission setup as in Suzuki SJ, old series LR etc where the front diff and prop would be stationary in 2wd with the hubs unlocked. In the setup in the vid the front prop and diff will always be turning so I'm not sure where the extra economy will come from. ??

 

[Chris]

And that's exactly where I was TP. Agreed. It's just a locked CD

 

[frank rabbets]

That car obviously did not have a centre dif lock. As such if just free wheel hubs were fitted there would be no drive to either the front nor rear wheels with the front free wheel hubs free wheeling. With the free wheel hubs in operation the drive to the front dif would still be there but not transferred to the road. That car was designed to have permanent 4wd so I can't see any point in altering it.

With the early Land Rovers there was no centre dif and the front axle was being forced round by the wheels nearly all the time on tarmac. I fitted free wheel/selectable hubs to prevent this but in that design nothing was compromised. That did save fuel but I can't see the subject mod saving fuel.

As an aside I also fitted a "Fairey" overdrive that bolted to the PTO output access. That gave me overdrive in every gear so I had 16 gears. A bit of a hand full if one drove through all 16 gears.

 

[Chris]

I have not heard of an 80 with no CDL feature. No locking fronts or rears for sure but no centre lock? Did they really make such a model? Did it have a viscous coupling at all? To have no CDL and no VC it's not really a full-time 4x4 is it. Only when on tarmac and all 4 wheels have equal grip. Rather than fit FWHs to it, they'd have been better fitting lockers!!

But again the point was not to show the modification, but the insides of the t case

 

[frank rabbets]

They are big gears Chris. Do you know what breaks when the transfer box fails ?

 

[Towpack]

1990-91 models had an open diff with DL. From '92, models with ABS also had the VC. Africa, Australia and Japan had an OEM 2wd version but on the permanent 4wd versions only the F&R lockers were optional, not the CD so I just don't see the point of the mod in the vid.

They are big gears Chris. Do you know what breaks when the transfer box fails ?

The 2 main gears looked pretty substantial but I thought the gears on either end on the F&R drive shafts to the props looked quite feeble by comparison. JMO

 

[Chris]

The mod is for the 80 AND 100 series, so the set up must be common to both.

Sorry Frank, I have no idea why you are asking me that. I've no experience of ever breaking a transfer box.

I'm going to say it once more. It's not about the mod, it's simply a nice video that shows how to take the rear housing off and what's inside when you do. Nothing to be scared of. So, if you want to replace the output seal or bearing in the extension, getting it off and putting it back on is pretty simple. Of course ferreting around inside the housing itself is quite another story.

 

[nielsc]

With this mod you have 2wd to save wear on the front diff and possible improved economy and lighter steering.
You select 4wd by locking the front hubs if fitted and pressing the centre diff lock button.
The diff lock is now used to engage the front drive shaft.
So 2wd on pavement and selectable 4wd by the push on a button. But no centre diff so not possible on pavement.

 

[Towpack]

You select 4wd by locking the front hubs if fitted and pressing the centre diff lock button.
The diff lock is now used to engage the front drive shaft.

If that's the case then I guess the front diff and driveshafts will be idle in 2wd mode. Still can't fathom out from the vid how that happens though seeing as how the CD has been removed.

 

[Chris]

No I can't either TP. I don't think that this is selectable by using the CD at all, because I don't think there is one.

On this vehicle the only way to get 4x4 is to get out and turn the locking hubs.

As I said previously, I had mine in 2x4 for some time and it was awful to drive and the economy very definitely suffered. I can't really see how it saves wear on the front diff. Well I guess I can, but why would you want to do that particularly?

This particular mod on this particular vehicle looks to have mechanically locked up the centre diff so all of the front shaft and front diff IS turning, it's just not under much of a load. As TP said, the diff is physically removed in the film and consigned to the bin. They even say that.

Still, anyone wanting to see what's inside the transfer case could always watch the vid and not worry about the mod, couldn't they.

 

[Roger]

I once read (way before the internet) a paper on how long it would take for the free wheeling hubs fitted to a LR Series 2 to pay back the investment of the equipment - it was something ridiculous like 1.2 million miles as the effect was minimal.

I used to love the Fairey Overdrives, used to make some nice pocket money off those things, buy a scrapper Series LR and and sell the overdrive unit for decent money - very often more than the purchase of the whole car. I had one fitted to my Series 2a - Im not sure if it did anything more than reduce noise levels!

With the regard to dipping in the transfer case, nothing too scary in there, the key as always is to keep spotlessly clean. The first time I cracked open a cruiser one I was very surprised at the amount of force needed to break the fpig (RTV) factory sealant - seems Toyota thought of that, there are nice little casting tabs to fit a pry bar in!



This pic is from when I went in to fit crawler gears to the transfer case - thats the residue of the factory RTV.



Just for interest - this is further into the TC.

 

[Towpack]

Whatever, with regard to the main reason Chris posted the link to the vid it is interesting for those of us who haven't worked on a transfer box to see inside one. Not as complex as I was expecting personally and I'm assuming the VC (where fitted) would be sat on the front of the diff and easily accessed/changed if need be. Wouldn't have any reservations about tackling the job myself albeit with the car on stands.

 

[Chris]

The VC is actually sitting in the rear housing which is the bit that the guy removes. The inside of the T box, having taken one to bits, doesn't have much in it, but what is in there is massive. Swapping the VC out is pretty easy. It's once you get past that that the fun starts. It's very tight and you need three hands and a grinder to shave down all your regular tools so that they fit in the gaps to remove circlips etc.

 

[nielsc]

http://www.marks4wd.com/mfk1210-80hd.html

 

[Chris]

Nice link. Thanks nielsc. I should have looked. I've had some of their products and they've been very good.

Still don't quite understand though. There's something I'm missing still.

What their blurb suggests is that the CD is removed and now inoperable. OK we knew that. But also that the front drive train is disengaged from the power. Only by pressing the CDL button does the front prop get drive. That's the tricky bit. I know that the CDL system uses a splined collar to lock the drive front to rear 'cos I've taken it to bits. What I don't quite get is how you lock the actual diff without locking in the front axle too regardless of the button. IN other words, how does the front axle get drive under normal conditions when the diff hasn't been meddled with. If you have the VC fitted like most of us have then the front is already getting drive. That may be the trick, that in most cases the Aussie ones do NOT have the vc and therefore their T boxes are completely open.

I need to go and play with one of my spare T boxes.

 

[clivehorridge]

I don't have a VC

 

[Chris]

My GS didn't. So I put one in. It does make a difference. Interesting that in the blurb, if you DO have a VC it gets junked. So I guess that is the answer. You need a completely open diff to do this mod or it doesn't work.

I still wouldn't do it in the first place.