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[GRMac]

It was put to me the other day whether or not Land Rover changed the ackerman angles on their steering setups between short and long wheelbase. My assumption (as dangerous as assumptions are) is that they didn't bother changing given that all steering parts, between long and short wheel base in which ever series, are interchangeable.

So, what did LR set the steering up for? 88" or 109"? Did they even bother changing it since the 80"? 

[Calum]

Well in theory it is easy enough to work out what wheelbase it's 'set up' for if we make some assumptions based on a very simple model of the Ackerman principle. Suspension geometry is a bit of a minefield! Swivel pin centre to centre is easily measurable, as is the centre to centre of the track rods, then measure the distance between a swivel pin and track rod end. We can then draw up a right-angled triangle and work out the angle. If you strike a line from the track rod ball joint and through the swivel pin and extend it backwards on both sides, they should intersect at the centre of the rear axle. Now you know the angle and one side of the triangle the other side (wheelbase length) is just a case of simple pythag.

Problem is I think a Land Rover axle is set up with an angle of zero, i.e. both wheels turn on the same arc. It's easier to set up proper angles when the steering arms are behind the wheels as they need to be narrower than the swivel pin centres. Put them front and they need to be wider but then they end up being where the wheels want to be... I hope that makes sense?

So in short, I don't think they were set up for any of the wheelbases - it's an agricultural vehicle!

[w3526602]

Hi,

Ackerman angles!  In theory, lines projected from the centres of the front wheels should cross at the same point as where they cross a line projected through the rear axle. In such a case, all four wheels will be turning about the same point.

In practice, I doubt that that happens very often. Even when going in a straight line, when the axis should cross at infinity, tyre toe-in/toe-out will ensure that the front wheels are pointing in different directions.

I have always suspected that an Ackerman angle is impossible to achieve if the track rod is in front of the axle.

Many yonks ago, I bought a Morris J-type van, which I towed home. Silly me, I did not check where my 'oppo had tied the tow rope. The track-rod, being in front of the axle, seemed (to him) to be a suitable place.  The 10 mile tow home wiped all the beautiful tread off both front tyres. I scrapped the van, and put the two remaining meaty tyres (600-16s) on the front of my 107".

This would have been in the late 1970s, or early 1980. The J-type cost me £15, and I think the 107 was £700 from a dealer. If only I had know then .....

602

[Wittsend]

Akerman angles 

It’s a Land Rover 

[GRMac]

I suppose it does seem a bit far fetched (read laughable) to suggest Land Rover spent long considering steering geometry on an agricultural vehicle.

Also it hadn't really occurred to me that the steering arms on the front effectively meant sufficient angle would be probably impossible.

Next time I'm waiting for paint to dry I'll take some measuring implements and figure out where the wheelbase 'should' be if at all. 

[P4t]

Off road use & limited steering lock are a couple of reasons why it's not that important on our Series, it's interesting to note that the track rod ball joint centres measurement was shortened by 5/8" when steering arms moved to the bottom so effectively all series up to around the introduction of the 2a had more ackerman angle.