Understanding wheel Alignment

[whitehillbilly64]

Hi All.
Trying to under series wheel alignment and a Solid axle, series Land rover.
With a solid axle, we have no caster adjustment ????
The two front rods, adjust toe in to out and what does the relay to LH Wheel, rod do ????
Relay arms 90 degrees to each other, steering box at its lowest vertical position ????
Well that doesn't make much sense !!!!
Better have another Black Douglas.

whitehillbilly

[debruiser]

Series land rover you only adjust the track rod length to get the correct toe. There is no other adjustment, the drag link/drop arm/longitudinal arm length is just left to right steering more to do with lock to lock than wheel alignment.

Easy as really... I have paid for a wheel alignment before but really it can be done with a tape measure in the shed.

[mox]

There is the question of the best the best places to measure from on the front wheels to ascertain the toe in. Seems to me the best to try is to jack up each wheel, spin it and hold chalk in the middle of the tread. Then measure the distances between these chalk marks round the tyre tread at hub height between each wheel at front and back after lowering to ground again.

On vehicles where something obstructs direct line of tape between these, do it on level concrete or whatever, use a large square or improvise with something suitable, then put marks on the ground directly under where measurements are taken from and measure from these. More accurate when done properly than measuring from rims next to tyre beads or sides of tyres because doesn't matter if a rim is slightly buckled or tyre has varying bulges around its side. Chalk needs to be held firm and kept steady so there is only one narrow line around middle of tread, which tends to be a bit more difficult when tyres have large lugs compared with smoother ones.

When steering wheels are pointing straight ahead, normally they are if anything pointing slightly inwards by a very slight prescribed amount rather than exactly parallel. The design of exactly where tie rod ends are compared with king pins or whatever where each front axle pivots from is designed on "Ackerman Principle" On turns there is "toe out". Centre of turning circle on a four wheeled vehicle is somewhere out from the line of the back axle. On a turn, for front wheels to not scruff, if you take a lines from centre of turning circle to each front wheel hub, the wheels should both be at about right angles to this.

This automatically happens on things like trailers with turntables or billycarts with a solid front axle which only pivots in the middle. However, there are good reasons it is overall not favoured for vehicle steering. With a simple steering setup like 4WDs with a solid front axle, when wheels straight ahead best of made with straight lines each side between king pin, tie rod end and centre of back axle to achieve Ackerman principle. ie Shorter distance between tie rod ends than between king pins if tie rod is behind axle and longer when it is in front. Note that sometimes on amateur builds of eg small 4 wheel garden trailers they are the same - and scruff when negotiating turns.

[Homestar]

The adjustability of the rod between the steering relay and LH wheel, and the rod between the steering box and relay are only there to get everything even so everything goes left and right completely to the stops. The toe in/out is the only adjustment to worry about as far as alignment goes - as mentioned in the other posts, it can be done in the driveway with a tape measure, piece of chalk and a large square or similar.

[alien]

Hi All.
Trying to under series wheel alignment and a Solid axle, series Land rover.
With a solid axle, we have no caster adjustment ????
The two front rods, adjust toe in to out and what does the relay to LH Wheel, rod do ????
Relay arms 90 degrees to each other, steering box at its lowest vertical position ????
Well that doesn't make much sense !!!!
Better have another Black Douglas.

whitehillbilly

See if this helps as I think I know where you're coming from...

With the solid axle the camber and caster can not be adjusted, they are set in the axle building process.

The steering box pitman arm as you noted is vertical in the straight ahead position.
When the steering is turned it rotates the ball joint connection forward or backwards in relation to the vehicle chassis.
The rod to the relay and the relay change the front to rear movement to left and right at the end of the relay lower arm.
The drag rod from the relay lower arm then moves the left front wheel.
To adjust this the steering box should be in the centre of it's movement being the straight ahead position.
Ideally the left wheel is then adjusted to 1/2 off the required toe in.
Once the left wheel is set the track rod is adjusted to gain the required toe in off both front wheels, 3/64-3/32 in(1.2-2.4 mm).

Most folk adjust the toe in first and if required adjust the drag rod to straighten the steering wheel when doing it at home with a tape measure.

[Tins]

Most folk adjust the toe in first and if required adjust the drag rod to straighten the steering wheel when doing it at home with a tape measure.

Not sure if I'm with you there. Unless someone has stuffed with the drag link before, or if it is bent, that should not be necessary. Count the turns lock to lock and halve them (easier, and best done with the pitman arm disconnected ). Steering wheel should be in straight ahead position. Then, hold the wheel ( somehow ) in that position and adjust the toe then.

Or, am I missing something?

[Homestar]

Not sure if I'm with you there. Unless someone has stuffed with the drag link before, or if it is bent, that should not be necessary. Count the turns lock to lock and halve them (easier, and best done with the pitman arm disconnected ). Steering wheel should be in straight ahead position. Then, hold the wheel ( somehow ) in that position and adjust the toe then.

Or, am I missing something?

You're missing that the whole assembly has been removed, rebuilt and refitted. The entire alignment and setup needs to happen from scratch.

[alien]

Not sure if I'm with you there. Unless someone has stuffed with the drag link before, or if it is bent, that should not be necessary. Count the turns lock to lock and halve them (easier, and best done with the pitman arm disconnected ). Steering wheel should be in straight ahead position. Then, hold the wheel ( somehow ) in that position and adjust the toe then.

Or, am I missing something?

The drag link shouldn't need to be adjusted if nothing has been bent, played with or has wear, that's why I said " if required"

[Tins]

You're missing that the whole assembly has been removed, rebuilt and refitted. The entire alignment and setup needs to happen from scratch.

In that case, my scenario is correct. The very first thing to do in any wheel alignment is determine straight ahead. Nothing is more important than to start from that basic position. Count turns lock to lock, check pitman arm is straight ahead and go from there.

[Tins]

The drag link shouldn't need to be adjusted if nothing has been bent, played with or has wear, that's why I said " if required"

Indeed, that you did.