Thread: whats the difference?

Originally Posted by blitz

As I own a 94 change over model I will assume I have the stronger case, is the strength of compenents between the defender and the disco in the early jobbies the same?

Defender and early Disco I both use the LT230T transfer case, the main difference being the high range ratio.

The input gear that drives a gear on the intermediate cluster is the same for both. There are 2 other gears on the intermediate cluster - one for high and the other for low range. The low range gear is the same for both.

For high range because the Defender reduction is greater, the gear on the intermediate cluster is smaller than that for the disco.

Now for the same torque applied to the intermediate cluster, the tangential tooth load will be greater for the smaller Defender gear than for the larger Disco gear (torque = tangential force x radius of gear pitch circle).

Also when the diameter of the gear is reduced, for the same size teeth, there will be fewer teeth sharing the work/wear, and the thickness through the teeth at the root of the teeth is less. For tooth strength it is this thickness at the root of the teeth that has the greatest influence.

So greater load applied to teeth that aren't as strong when comparing Defender high range gears to Disco.

A gear designer has a number of options (material, helix angle, addendum correction, tooth width) to increase strength within limits. I haven't compared these between Defender and Disco LT230's.

Originally Posted by Hardchina

Has anyone ever broken teeth or anything else on a disco Q transfer?

I don't know of any failures, though I recall Scouse mentioning some, but those failures may have been due to something else (possibly lubrication).

As Slunnie said, the transfer case is stronger than the rest of the rover driveline. The driveshafts have to be offset as much as they are to clear the engine and gearbox. So Land Rover had little choice but to make the transfer case (and the gears inside) as large as it is.