Effect of differential tyre pressures on Detroit Locker

[ltwt1981]

Couldn't agree more, I've got one in my 88 and now I've got toughened shafts I hope its OK for a while.

Did you have 3.54 or 4.7 diffs?

[Troddenmasses]

Couldn't agree more, I've got one in my 88 and now I've got toughened shafts I hope its OK for a while.

Did you have 3.54 or 4.7 diffs?

4.7s, with a 2.25 petrol engine. Gutless as ever - didn't seem to make too much difference. Have just been looking on the Ashcroft site. As soon as I can afford the £600 for a rear locker, and strengthened shafts, I will be putting the 3.54 version into my 90.

[John_T]

I have a Detroit locker in my 90 on standard 12 spline shafts and it is fine. To be fair my Disco was OK on 10 spline standard shafts.

I take the point that strengthened shafts in series 3 would help.

I note the comments on handling in a series. Some people say the same can happen in a permanent 4wd but I have never had a problem.

[JimAttrill]

I've got a Detroit locker (no spin) in the back of my 90. The instruction manual that came with the diff definatley says not to be used in vehicles with a wheelbase less than 100". This has nothing to do with tyre sizes

But... When I push the throttle hard the front end pulls to the left and when I let off the throttle it pulls to the right. It under steers going in to roundabouts at speed then suddenly over steers when the diff releases. It undertseers if you coast round a corner at speed. It clunks, clonks, releases inappropriatley making the vehicle jerk. It's sometimes difficult to release the centre diff lock now i've fitted it.

If I knew all this before I bought it I'd have saved up a few more months for an ARB.

Nick... the smelly one

Funny, my manual says less than 120". There was a big discussion on this back in the LRE forum, to the extent that the 90 owner had Ashcrofts remove the locker. I think he let them know that they shouldn't fit a Detroit to a 90. The locker is OK in a 100" Disco (so a mate of mine tells me), fine in a 110 and unnoticeable in a 130. The only time I get clonks in my 110 is if I make sharp turns with the clutch in, like sometimes when pulling into my driveway or a parking slot. The diff locks and unlocks more when the CDL is engaged when in low range, but I suppose it should. I get no torque steer effects, though maybe the tdi doesn't have enough power to cause them

[02GF74]

Well if you really want a definitive answer go and try it,

I just read these comments and have heard it before.

So went to prove the theory.

In my workshop a tyre with OD of 30" at 10psi traveled +- 4"less than the same tyre at 30 psi. (with a car weighing about 1.5 tones)

I have experienced the same thing on my rolling road, tyre pressure does change the speed / RPM measurement. Remember that tyres are rubber and that they also "grow" at high wheel RPM.

Lara.

you don;t need to try it at all. Think if a LR tyre with tall side wall that sits on a tiny wheel, let's make that wheel diameter 2 inches.

Starting with fully inflated tyre, the effective wheel radius (cnetre of hub to gound) will be about 16 inches.

Now think what happens when the air goes out. Discarding tyre thickness your hub is now 1 inch oiff the fround so effective tyre diameter is 1 inch.

Are you going to tell me that that is going to travel as far in 1 revolution as fully inflated?

Tanks tracks, tyre circumference etc. don't come into it - the tyre will be very unhappy when driven on like that, it will probably bunch up, slide and slap about but for sure it will not be the same as on a fully inflated tyre.