Diff locks and tyre sizes on a TD 100 series

Submitted: Saturday, Feb 14, 2004 at 22:24
ThreadID: 10530 Views:1992 Replies:5 FollowUps:7
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Hi all ,

I have a Landcruiser 100 TD and one person said I needed front and rear diff locks and another said I only need the front done because I have LSD on the rear . What do you reckon ?

I am also tossing up between 10 ply 285 / 75 and 10 ply 265 / 75 . I thought I might have more sidewall cuts on the 265 / 75 , but I worry about the engine braking on my auto for hill descents with the higher gearing on the 285 / 75.

Has anyone made decisions on these issues ?

Thanks ,

Mike
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Reply By: Wayne (NSW) - Saturday, Feb 14, 2004 at 23:09

Saturday, Feb 14, 2004 at 23:09
A quote from the ARB accessorie book." Newer vehicles with limited slip differentials may offer some improvement over standard differentials, but more often you'll find the slipping is not "limited" enough to maintain forward progress" Now I don't always agree with wat ARB say or print, but in this case I do agree.

If you buy front and rear diff locks from ARB they were wired up so that the rear diff lock had to be engaged first then the front diff.

Nissan in their TI only supplied a rear locking diff.

Toyota in their Sahara and option on the 80 series has the rear diff engaged first then the front diff.

I think you can see a patern developing here.

Buy the way, I did see a air locker for the front of a 100 series(IFS) at the 4wd show on the weekend.

Wayne

AnswerID: 46728

Reply By: Truckster (Vic) - Saturday, Feb 14, 2004 at 23:36

Saturday, Feb 14, 2004 at 23:36
Toyota LSD is famous for lasting 20-30,000 then flopping..

if you have the $ do it, but remember one thing with rear locker, when your driving on the road, you only have a 1970's style Single Spinner... 1 WHEEL DRIVE...
AnswerID: 46734

Follow Up By: Member - Andrew & Jen (Melb) - Sunday, Feb 15, 2004 at 07:42

Sunday, Feb 15, 2004 at 07:42
Though the Landcruiser is fulltime 4wd which I would have thought meant that one of the front wheels might be working all the time as well.2001 Landcruiser 100S Turbo Diesel
"We do not stop playing because we grow old; we grow old because we stop playing"
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Follow Up By: Phil G - Sunday, Feb 15, 2004 at 08:34

Sunday, Feb 15, 2004 at 08:34
Andrew and Jen,

With a fulltime 4wd (centre diff unlocked) if you lift one wheel, all the power goes to that wheel (Trucksters 1-wheel drive).

If you engage the centre diff, then power goes 50% to front and 50% to rear, so if you lift one wheel, then the other axle still powers you forward.

If you lift one wheel from each axle, then you're going nowhere, unless you have diff locks, or a LSD that does a lot more than the standard Tojo LSD.
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Follow Up By: Member - Andrew & Jen (Melb) - Sunday, Feb 15, 2004 at 09:07

Sunday, Feb 15, 2004 at 09:07
Phil G
Thinking about it logically, with all the diffs open, I guess that as you say, if one wheel spins, all the others lose power. Hadn't thought about it logically before. I remember seeing a car at the snow and the guy had put a chain on one front wheel and another on a rear wheel. The chainless rear wheel just spun uselessly when he was going up an icy hill.
How come in my Landcruiser I didn't use chains as they said I didn't need them, but my rear or even front wheel didn't spin uselessly the same. You would think that if all your diffs were open that you would only have to lose traction on one of the four wheels and you would be stuffed. I never engaged my centre or cross difflocks.
Andrew2001 Landcruiser 100S Turbo Diesel
"We do not stop playing because we grow old; we grow old because we stop playing"
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FollowupID: 308706

Follow Up By: Wayne (NSW) - Sunday, Feb 15, 2004 at 09:31

Sunday, Feb 15, 2004 at 09:31
Phil G

Keeping 4 wheels on the ground will give drive to front and rear even when the centre diff is not engeged. Having drive in the snow could be because the tyres, weight of cruiser and the rate of acceleration.

The centre diff allows the front and rear drive shafts to spin at different speeds eg. when going around a corner, just as the front or rear diff allows the inside and outside tyres on the same axel to spin at different speeds. Lock the centre diff and both front and rear drive shafts must spin at the same speed.

Wayne
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FollowupID: 308714

Follow Up By: Phil G - Sunday, Feb 15, 2004 at 10:52

Sunday, Feb 15, 2004 at 10:52
Andrew, Wayne,

If you wonder about the LSD on your Landcruiser, then jack up one rear wheel on an axle stand, centre diff unlocked and attempt to drive it off. Chances are that it will do nothing. With a "good" LSD, it will only attempt to drive off with the brakes partly applied. This "loads" the LSD and it springs into its very limited action. Alternatively, some might say that you are simply using "poor man's traction control".

All 3 diffs on a fulltime 4wd are essentially open diffs - front and centre all the time, rear LSD most of the time. If you attempt all your 4wding without the centre diff locked, you are losing drive whenever traction is lost on any one of the 4 wheels.

With these vehicles, you MUST engage the centre diff whenever loss of traction is possible. Sure you'll still get through, but you'll chew up the track a bit more than you should and you'll put high loads on the drivetrain. (Ever wondered about the high number of diff breakages in full-time 4wds?)

Transmission wind up is not a problem once you are off the bitumen.

Cheers
Phil
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FollowupID: 308728

Follow Up By: Wayne (NSW) - Sunday, Feb 15, 2004 at 11:35

Sunday, Feb 15, 2004 at 11:35
Could not have said it any better Phil. Another way to check if your diffs are open or have some type of mechinical traction control.

1.Jack up axel front or rear does not matter which one, with both wheels off the ground.

2.Turn one wheel by hand, if the other wheel turns in the same direction, you have some form of traction control. If the wheel does not turn or turns in the opposite direction, open diff.

Wayne
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Reply By: Member - Mike W (NSW) - Sunday, Feb 15, 2004 at 13:42

Sunday, Feb 15, 2004 at 13:42
Thanks everyone . I will go for front and rear diffs .
Mike
AnswerID: 46780

Follow Up By: duncs - Sunday, Feb 15, 2004 at 22:26

Sunday, Feb 15, 2004 at 22:26
Right decision Mike,

I lived with front and rear ARB dif locks for 6 years and they are wonderful.

When the bucks arrive in my bnak they are going in on the new car.

Duncs
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FollowupID: 308825

Reply By: Member - Bob - Sunday, Feb 15, 2004 at 15:51

Sunday, Feb 15, 2004 at 15:51
I spent about an hour last weekend watching vehicles going round at the Queanbeyan 4WD show. They had a track with various surfaces, including a section designed to get diagonally opposed wheels off the ground. Some of the older style vehicles got badly hung up and just rocked in the air if they didn't approach with enough momentum. Most impressive where the VW Toerag and the Pajero. These vehicles had limited axle travel so both had two wheels well and truly in the air - but it didn't matter. They both just calmly drove through with traction applied to diagonally opposite wheels.Bob
AnswerID: 46786

Reply By: Kiwi Ray - Monday, Feb 16, 2004 at 15:38

Monday, Feb 16, 2004 at 15:38
Hi Mike
Some of the cruisers have a viscous coupling as well asthe centre diff, so it would still provide a limited amount of drive to both front and rear
It is a bit difficult to sort out which transfer case has or has not got the coupling but from what I understand the turboed ones have the coupling
Ray
AnswerID: 46900

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