auto diff lock

[plank22]

Is a viscous coupling type diff-lock as good as a manual diff-lock on a rangie auto box? I'm thinking about converting to an auto box in my hybrid series and not too clued up on them. I have an old auto box kicking about and think its a 3 speed but know no more so can i tell from the casing numbers as to what type of diff-lock the t.box has? Also I have had the offer of another auto box (complete with t.box) that has a viscous coupling diff-lock. Out of the two boxes are the t.boxes interchangeable to different gearboxes? The second box I have been offered is a 4 speed. Thanks!

[bishbosh]

Viscous is equivalent to a manual diff lock, only better! It is on when you need it and off when you don't and you don't even have to think about it!

Check out Ashcrofts for T-case identification, but I don't think 3 speeds had viscous couplings.

The t-cases will be interchangeable, but the propshafts (definately the front, possbily the rear) will need to be changed if you want to replace an LT230(manual dif lock) with a Borg Warner (v/c)

[plank22]

Viscous is equivalent to a manual diff lock, only better! It is on when you need it and off when you don't and you don't even have to think about it!

Check out Ashcrofts for T-case identification, but I don't think 3 speeds had viscous couplings.

The t-cases will be interchangeable, but the propshafts (definately the front, possbily the rear) will need to be changed if you want to replace an LT230(manual dif lock) with a Borg Warner (v/c)

But with a manual diff lock you will get 50/50 power front and rear but with a viscous coupling lock you will lose alot of power through the spinning wheel and end end up with say 20/80, this is what im lead to believe, any truth in it? the LT230 and the borg warner, are they both just the t.box you are refering to? Thanks alot.

[kellyv8]

can i have me box back mines gone pearshaped

[FridgeFreezer]

The very early 3-speeds had Ferguson boxes which, it seems, were viscous. Then everything went LT230.

[bishbosh]

But with a manual diff lock you will get 50/50 power front and rear but with a viscous coupling lock you will lose alot of power through the spinning wheel and end end up with say 20/80, this is what im lead to believe, any truth in it? the LT230 and the borg warner, are they both just the t.box you are refering to? Thanks alot.

This is not correct - a viscous centre diff should be thought of as locked all the time and unlocks (slips) to facilitate cornering.

[FridgeFreezer]

This is not correct - a viscous centre diff should be thought of as locked all the time and unlocks (slips) to facilitate cornering.

Really? I thought they were unlocked all the time and only locked up when one end slipped more than t'other?

[paintman]

For a simplistic view of how it works http://auto.howstuffworks.com/differential5.htm

[bishbosh]

Really? I thought they were unlocked all the time and only locked up when one end slipped more than t'other?

You are correct John. I don't know what came over me this morning!

The fluid in the diff thickens to effectively lock the diff when slippage occurs.

Need brain rest.......

[plank22]

can i have me box back mines gone pearshaped

Errrm kind using it to invent new g.box x.member if i dont uend up using it will let ya know asap!

On a visous coupling box if I took a prop out and tried to drive would it drive just the same as a manual diff lock?

[ChrisV8]

Basically yes but it will quickly make the fluid thick and stop working properly, if you want one with rubber in it instead of the fluid i have two seized ones in the shed you can have !!!

[Henry Webster]

But with a manual diff lock you will get 50/50 power front and rear but with a viscous coupling lock you will lose alot of power through the spinning wheel and end end up with say 20/80, this is what im lead to believe, any truth in it? the LT230 and the borg warner, are they both just the t.box you are refering to? Thanks alot.

When they lock, which they do pretty quickly when you lose traction they give you a true 50/50 torque bias.

I have one in the racer and I must say I wouldn't have anything else now, I think its great. I've got an LT230 in the road car and it was horrible in the snow last winter - if the diff was in it wanted to go straight on, if it was out you ran out of traction. Borg Warner is a fit and forget!

[plank22]

i was just thinkin that if you were stuck and your front wheel was spinning with a manual lock you could at least one wheel to turn at the back but with a viscous coupling it couldnt handle the massive lack of resistance at the front and send all the power there.

[Henry Webster]

Nope - no problem with that. Once one end starts spinning it'll soon distribute equal power to both ends. You are thinking, maybe of how a Torsen-type differential, like a Quaife ATB or a Truetrac works. It is true that they need some resistance to work, but a viscous, the more the differential in speed the more locked it becomes.

H

[plank22]

ok thanks alot for your help all!!!!

[Clive]

A bit of info which may help.

The factory fitted 3-speed GM auto boxes and the early 4-speed ZF autos used the manual LT230 transfer box.

The later 4-speed auto boxes were fitted with the Borg-Warner box (with the introduction of ABS). This box has a mechanical differential controlled by a viscous coupling. All the coupling does is lock the differential, it does not transfer any power, the power split is controlled by the diff itself.

Schuler fitted their uprated Range Rovers with 3 and 4-speed GM autos and 5-speed SD1 manual boxes all fitted with their FF based viscous transfer box. This was a true viscous differential and had a 36/64 split front rear and are claimed to be good for at least 300bhp. Some of these Transfer boxes were also fitted with a Dunlop anti-skid braking system.

Clive

[jules]

I'm another fan of the VC transfer box I prefer it over the LT230 for challenging and Racing as its one less thing to worry about when driving

[plank22]

A bit of info which may help.

The factory fitted 3-speed GM auto boxes and the early 4-speed ZF autos used the manual LT230 transfer box.

The later 4-speed auto boxes were fitted with the Borg-Warner box (with the introduction of ABS). This box has a mechanical differential controlled by a viscous coupling. All the coupling does is lock the differential, it does not transfer any power, the power split is controlled by the diff itself.

Schuler fitted their uprated Range Rovers with 3 and 4-speed GM autos and 5-speed SD1 manual boxes all fitted with their FF based viscous transfer box. This was a true viscous differential and had a 36/64 split front rear and are claimed to be good for at least 300bhp. Some of these Transfer boxes were also fitted with a Dunlop anti-skid braking system.

Clive

most interesting! I havnt herd much bad stuff about the viscous t.boxes so now im definitly gonna go through the hassle of moving the engine about to fit the box in! that christmas sorted!

[tblandy]

I always thought they were poop, as they never seem to work????? any old rangerovers we'ed used as pay and play busess never seem to work, or stick out or something? got one sat outside thats the same

[jules]

I always thought they were poop, as they never seem to work????? any old rangerovers we'ed used as pay and play busess never seem to work, or stick out or something? got one sat outside thats the same

Firstly its a straight swap no moving of anything

second I have had people people say that they don't work. how do you know it doesn't work a simple test is jack up one wheel if you can turn it, it's not working.

The gearing is high as well on the BW VC transfer box

I want to swap out the transfer box in my racer as the LT230 has not really impressed me and I have one on the floor but its the gearing which I don't want to change

[DaveSIIA]

I can confirm it's a straight swap as I fitted one in place of the LT230 on my 300Tdi 110. High/Low linkage coupled up no problem. Only other part I had to change was the front propshaft as the BW one is 2" longer.

Box was changed 8 months ago and my only regret is not having done it sooner. On road handling was more sure footed through corners. Off road, it's one less thing to think about - it just works. On snow and ice the vehicle handles the same as with an open diff until extra traction is called for. I tested the traction recently on compacted snow by parking faced up hill with the rear wheels on snow and the front on clear, dry tarmac. Dumping the clutch in first left two small prints in the snow where slack in the driveline had taken up and then clear tyre prints with no sign of wheel spin as the vehicle moved forwards.

[plank22]

I can confirm it's a straight swap as I fitted one in place of the LT230 on my 300Tdi 110. High/Low linkage coupled up no problem. Only other part I had to change was the front propshaft as the BW one is 2" longer.

Box was changed 8 months ago and my only regret is not having done it sooner. On road handling was more sure footed through corners. Off road, it's one less thing to think about - it just works. On snow and ice the vehicle handles the same as with an open diff until extra traction is called for. I tested the traction recently on compacted snow by parking faced up hill with the rear wheels on snow and the front on clear, dry tarmac. Dumping the clutch in first left two small prints in the snow where slack in the driveline had taken up and then clear tyre prints with no sign of wheel spin as the vehicle moved forwards.

I will have to do a bit of moving me thinks as its a hybrid series 3. I put it in the rangie section as its half rangie half series and wanted to know about the rangie boxes! I used to run the 3.9 on a series box and the auto box is double the length and would leave me with a rear prop about 4" long. Im guessing that a series t.box is completley different to a rangie t.box?