design - Land Rover section


Land Rover FAQs


QUESTION - Can you decrease the stress on rear axles by increasing the backlash on the drive flange? Wouldn't this allow shafts to twist a little and absorb torque?


ANSWER - ( From: Bill at Great Basin Rovers as a reply on the LRO mail list) The biggest problem with Land Rover 10 spline drive flanges is all the backlash. Even with a brand new drive flange and axle there is 5 to 10 thou of it. This causes accelerated wear, which increases the backlash even more. The backlash spikes the shock loads going to the axles. The last thing stock Rover axles need is another thing going against them.

The elasticity in the drivetrain should not be supplied by the drive flanges as evidenced by the experience of Series Salisbury drive flanges. They are very soft from a metallurgical standpoint (approximately 40 to 45 on a Rockwell C scale) and tend to strip out with extended usage. This is why we supply our remanufactured Salisbury axles assemblies with specially hardened drive flanges (RC 62 the same as coiler Salisburys).

The elasticity in the system should be supplied by the axle shafts. To do this effectively they need to be constructed of a suitable material and be of a proper design. This is the problem with stock Land Rover axles, the material is marginal at best. It flexes but also yields at a very low point. This means it doesn't return to its original shape or position. This is the definition of metal fatigue.

The other problem is the design. Ideally you want a fully waisted design so the flex is distributed along the entire shaft so that it acts like a torsion bar. A waisted design means that the smallest diameter of the axle is the shaft, not the minor spline diameter (smallest part of the spline). Rover 10 spline rear axles have a minor spline diameter of .985" and a shaft diameter of 1.05 inches. What this means is that the elasticity of the shaft is concentrated on one part of the spline i.e. where the shaft exits the side gear of the diff or the drive flange.

This concentrates the elasticity in these two spots instead of distributing it along the entire shaft. Not surprisingly 99% + of all Series Rover 10 spline rear axle breakages occur at the end of the splines.

In conclusion, the reality of the situation is that stock Land Rover rear axle shafts are crap and not up to the robust standard as is most of the rest of the vehicle. I'm sure this note will start all of the usual hand wringing that Land Rover did this on purpose to build a shear point into the drive train. If this were true, why didn't they put the shear point on the flange end so it would actually be easy to change your broken rear axle instead of the most difficult spot? Maybe it was to punish you for exceeding the theoretical load capacity of the drivetrain! (Take that you bad bad Land Rover owner!!)

Anyway, strong drive flanges don't break axle shafts, strong axle shafts don't break differentials (actually a strong and flexible axle shaft will reduce drive line shock loads), strong diffs don't break drive shafts etc.

If you don't enjoy doing any of the following:

1) doing field repairs

2) carrying spare axles and all of the related parts

3) considering axle shafts a service item (belts, fluids, filters, hoses, axle shafts!)

consider getting better ones.

Great Basin Rovers

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