series 3 diff lock

[peanut84]

hello,
i have a series3/stage 1 LWB land rover with a rebuild 3.5 twin carbie.
running a 4 speed thats loves to rev on the highway.

anyway i am curious to know how the diff lock works, i understand that is locks the gear box or something

So does it actually lock all 4 wheels like an air locker would or not????

if some one could explain to me how it works, i would be in your debt.

many thanks
dan

[JDNSW]

hello,
i have a series3/stage 1 LWB land rover with a rebuild 3.5 twin carbie.
running a 4 speed thats loves to rev on the highway.

anyway i am curious to know how the diff lock works, i understand that is locks the gear box or something

So does it actually lock all 4 wheels like an air locker would or not????

if some one could explain to me how it works, i would be in your debt.

many thanks
dan

Like the Rangerover and the 90/110 and the Discovery 1 & 2 and Defender, the Stage 1 does not have selectable four wheel drive, but has full time four wheel drive with a third or centre differential to allow front and rear axles to rotate at different speeds, for example when turning. The drawback to this is that if one wheel loses grip, then all drive is lost, so a lock is provided for this third differential. When this is locked the situation is identical to that of a vehicle with selectable four wheel drive with four wheel drive selected.

No, it does not do the same as an air locker, you use it just the same as you would four wheel drive in a selectable four wheel drive vehicle, although it is often considered a good idea to lock the centre diff on corrugated gravel to prevent repeated impact loads on the centre diff as wheels lose grip.

This LT95 combined gearbox/transfer case was used on early Rangerovers, the FC101 and early 110s (and probably 90s, although they were never imported here). It appears to have been primarily developed for the FC101 gun tractor, and as a result is generally considered to be the most rugged and trouble free of the modern Landrover gearboxes, although it only has four gears. Despite this the Australian Army ones are further upgraded to allow them to cope better with military conditions (e.g. drivers).

John

[peanut84]

hi JDNSW

thank for the info, I was looking at getting arb air lockers but thought i should really try and understand my diff lock first as it might be all that i need.

my landy is pretty much a beach 4x4 although i have been up to fraser once in it (cause i haven't had it long) and even then i didn get to test it out in the powder or inland tracks (you know the fun parts) cause i did a wheel bearing just up past eurong.

How well does diff lock work in the sand????
if i just get diff lock checked out and make sure everything is working properly, i should be able to get up some fun little tracks here and there?????

cheers
dan

[JDNSW]

hi JDNSW

thank for the info, I was looking at getting arb air lockers but thought i should really try and understand my diff lock first as it might be all that i need.

my landy is pretty much a beach 4x4 although i have been up to fraser once in it (cause i haven't had it long) and even then i didn get to test it out in the powder or inland tracks (you know the fun parts) cause i did a wheel bearing just up past eurong.

How well does diff lock work in the sand????
if i just get diff lock checked out and make sure everything is working properly, i should be able to get up some fun little tracks here and there?????

cheers
dan

Diff lock will make little difference in sand since all wheels tend to have about the same grip - sand driving is about 50% tyre pressure and 40% driving technique and 10% everything else, including whether you have four wheel drive (well, maybe a slight exaggeration, but not much).

John
(who lived in the Simpson for nearly two years)

[UncleHo]

G'day Peanut84 :)

I would suggest that you get to know the Centre Diff Lock and it's capabilities, before thinking about ARB's, as unlessyou are going into serious hard core offroading, the centre diff lock will do most jobs, you can check out the diff lock yourself by first engageing it , then with the vehicle switched off, and in gear, jack up one wheel, you should not be able to turn this wheel much, free play only, :) Then lower, restart disengage diff lock, stop, jack up, and you should be able to spin that wheel without problems, that test can be done on any FLAT Drivway or Servo driveway, there should be an indicator light come on when Diff Lock is engaged:)


G'day JDNSW The LT 95 was designed for the Range Rover in about 1968, for the 1970 release if it;)

[JDNSW]

G'day JDNSW The LT 95 was designed for the Range Rover in about 1968, for the 1970 release if it;)

The 101 started development in 1967 and proceeded in parallel with the Rangerover. The LT95 was designed to meet the requirements of both vehicles - as the company could not afford to to develop two gearboxes. In particular the design of the transfer case was influenced by the need to provide for a powered trailer required in the military vehicle specification. Your date for the design of 1968 would have been pretty right. Although the Rangerover was released first, the engine/gearbox was designed from the outset to meet both needs. Rover almost certainly did not have the resources to do the non-common tooling at the same time, and this may explain the longer development - or it amy have been explained by a long period of trials and acceptance, which were much shorter with the Rangerover, since it only had to satisfy the company, not the army! And the Rangerover , a completely new type of vehicle, was launched with no market research and no real idea who would buy it.

The first vehicle prototype that was recognisably a Rangerover was the '100" Station Wagon' of 1967, but this still had the 3 litre six and conventional Series transmission.

John

[peanut84]

yello,

i just ran some test with the landy and this is my findings:

TEST 1
rear right wheel jacked up, front right wheel jacked up.
start engine and select 1st gear, low range (so if it jumped of the jacks there is no high speed launching ha ha ha)
release clutch and rear wheel spins only, but if u hold the rear wheel to a stop, power is transfured to front wheel and it starts spinning.

TEST2
same wheels jacked up, 1st gear, low range with diff lock ON
release clutch and front and rear wheels spinning, try to grab rear wheel, wont stop, try to grab front wheel, wont stop. (not being able to stop the wheels i assume is a good thing as this shows that diff lock is working) complete drive BUT with a lot of slack in the drive train.


What are your thoughts????

dan

[JDNSW]

yello,

i just ran some test with the landy and this is my findings:

TEST 1
rear right wheel jacked up, front right wheel jacked up.
start engine and select 1st gear, low range (so if it jumped of the jacks there is no high speed launching ha ha ha)
release clutch and rear wheel spins only, but if u hold the rear wheel to a stop, power is transfured to front wheel and it starts spinning.

TEST2
same wheels jacked up, 1st gear, low range with diff lock ON
release clutch and front and rear wheels spinning, try to grab rear wheel, wont stop, try to grab front wheel, wont stop. (not being able to stop the complete drive BUT with a lot of slack in the drive train.


What are your thoughts????

dan

Sounds like its working properly - a somewhat simpler and safer test:- jack up as above, engine stopped, gearbox in neutral. Turn front or back wheel, turns freely, other wheel stays put. Run engine to provide vacuum and engage diff lock, turn front or rear wheel - the other one will turn at the same speed.

The slack you see is probably the accumulation of a lot of little bits of slack - side play in the two diff centres, slack on splines at both ends of each axle shaft, output of transfer case etc. No real problem, unless there is slack in any of the prop shaft U-joints - this can lead to an out of balance situation and sudden failure, which you definitely do NOT want to happen if you are travelling fast.

John

[peanut84]

HMMMMMM

TEST3
diff lock on, in netural, motor off, turn front wheel and rear spins.
ok i know diff lock is now working. good good

Now i am a little worried about this SLACK i just measured the slack by turing the rear wheel till it took up the slack, then marked the tyre with chalk and the guard as a referance point then turned the wheel the oppsite way untill slack was taken up again, marked the tyre with chalk and then measured the distance from the 1st mark to the 2nd

AND.................


it was 25cms
i think that is a lot of play

dan

[JDNSW]

HMMMMMM

TEST3
diff lock on, in netural, motor off, turn front wheel and rear spins.
ok i know diff lock is now working. good good

Now i am a little worried about this SLACK i just measured the slack by turing the rear wheel till it took up the slack, then marked the tyre with chalk and the guard as a referance point then turned the wheel the oppsite way untill slack was taken up again, marked the tyre with chalk and then measured the distance from the 1st mark to the 2nd

AND.................


it was 25cms
i think that is a lot of play

dan

As I said - the amount of play is not really what matters, but where it is. You can work out where it is - hand brake on - repeat your test above for front and rear wheels separately. This will show up play in the centre diff if you repeat the front one in gear with diff lock disengaged.

Now turn the wheel slowly as before, but watch for the prop shaft to start moving. This will show you the free play in the diff on that axle plus the axle splines - and removing the hub cap will enable you to see the movement on the spline there.

But to repeat, the problem you need to look for is play on the U-joints on the prop shafts, although having the drive flanges loose on either the diffs or the transfer case is not good either. I would expect though, that the majority of the free play is on the various splines and in the diff centres, and is nothing to worry about. from the handbrake to the rear wheel there are effectively seven splines (remember the diff means you see the play form both sides), and only two of these are locked with nuts, and in the front there are nine, again, with only two locked, plus clearance on the diff lock dog. And any clearance on the gears in the diff centre shows up as free play as well.

John

[peanut84]

okie dokie will go test it now

back soon

[peanut84]

ok

HAND BRAKE ON:
rear has 5cms untill tailshaft moves
front has 5cms till tailshaft moves

rear complete left to right play is 5cms
front complete left to right play is 25cms

[JDNSW]

ok

HAND BRAKE ON:
rear has 5cms untill tailshaft moves
front has 5cms till tailshaft moves

rear complete left to right play is 5cms
front complete left to right play is 25cms

This sounds like most of the free play is in the centre diff - was this with the diff lock engaged or not? But check there was no lost motion from one end of the front prop shaft to the other.

Free play in the centre diff is probably mainly wear on the thrust washers, and is not a very big job to do, but is perhaps better left to someone with experience in these, although with the workshop manual anyone with reasonable workshop skills should be able to do it. But it is unlikely to be a symptom of impending failure, although it does increase the skill level needed for driving smoothly.

John

[peanut84]

ok cool

so when the hand brake was on the front diff had 20cms more play then the rear because it was taking up the slack of the centre diff. but the rear didn cause the handbrake is on the rear on the gearbox and not allowing it to turn the center diff???

is this about rite????

[JDNSW]

ok cool

so when the hand brake was on the front diff had 20cms more play then the rear because it was taking up the slack of the centre diff. but the rear didn cause the handbrake is on the rear on the gearbox and not allowing it to turn the center diff???

is this about rite????

yep, you've got it.
John

[peanut84]

hmmm think it will be expensive to fix the center diff plus fit lockers and need suspention and has rust blah blah blah

prob should just buy a defender diesel turbo

dan

[JDNSW]

hmmm think it will be expensive to fix the center diff plus fit lockers and need suspention and has rust blah blah blah

prob should just buy a defender diesel turbo

dan

It is unlikely that the centre diff is going to fail - replacing the thrust washers is cheap as far as parts go, and if you do it yourself it is not an enormous job - but of course, once you pull the front extension of the transfer case apart, you will, of course replace any seriously worn parts, all bearings and seals - and then it starts adding up, particularly since you don't know what you will find, and the labour costs would be significant .

I would think that the rust would be the most important fix, followed by any work needed on the suspension, then the centre diff. If you are thinking that you need to fit lockers, I suggest that you read relevant threads here first - some have suggested that they are something you hardly ever use, although this depends on the way you use your vehicle.

John

[mark2]

Make sure the diff lock warning light is working - it pays to check it regularly as the switch can play up. Reason is that if its not working, its easy to inadvertently leave the diff lock on which can cause a lot of damage to the drivetrain if driven on sealed roads.

Not engaging the diff lock when its required can also burn out thrust washers in the center diff - I think the best way is to engage it in the same situations when you would shift into 4WD on a part time 4WD.

[peanut84]

hey mark

yeah the dash light works fine so no problen there.

BUT i went out to kholo bridge in ipswich, brisbane
and there is some little 4x4 tracks out there. i went out to test the diff lock out and i have an expensive sound coming from the front diff or some where up the front of the car, but only when its in diff lock and only when you turn left or right. and its a CLUNK CLUNK and the clunk gets faster as the landy gets faster.

any ideas??????

dan

[JDNSW]

hey mark

yeah the dash light works fine so no problen there.

BUT i went out to kholo bridge in ipswich, brisbane
and there is some little 4x4 tracks out there. i went out to test the diff lock out and i have an expensive sound coming from the front diff or some where up the front of the car, but only when its in diff lock and only when you turn left or right. and its a CLUNK CLUNK and the clunk gets faster as the landy gets faster.

any ideas??????

dan

If it is only when turning, it just about has to be a CV joint, although just possibly it is a dry U-joint on the prop shaft. Is there any oil in the swivels? Although if the CV joints are noisy the damage is already done.
John