Wheel Alignment ... Case Study

[BushWacker]

Took the rig ( LR Dfndr 130) n to do
the wheel Alignment and this is the report:

https://ibb.co/doKd8p/img

It would seem That I need adjust the back axle
and or wheel attitude etc

Problem is ultimately reflected in Thrust Angle
... so maybe vehicle is dog-tracking as some following
vehicle drivers have alleged ... ????

Below is a little background

https://explorationoutfitters.com/pages ... -explained

https://www.knowyourparts.com/technical ... ust-angle/

Negative toe, or toe out, is the front of the wheel pointing away from the centerline of the vehicle. Positive toe, or toe in, is the front of the wheel pointing towards the centerline of the vehicle...

[ThysleRoux]

What vehicle is this?

[KurtG]

Defender 130

[BushWacker]

LRover 130 back axle is generally deemed ‘fixed ‘
by wheel alignment guys who say it should not normally need any routine adjustment ...
... would need be done with shims etc



... I suspect radial arm adjmnts
may largely correct the situation

... negative toe, or toe out, is the front of the wheel pointing away from the centerline of the vehicle. Positive toe, or toe in, is the front of the wheel pointing towards the centerline of the vehicle.

[Apocalypse]

Is it lifted?

the rear diff is well out of alignment... according to the figures, but I suspect the front track rod.

you have rear toe of -4,3 and +5.0 which means the wheels track straight but are directed to the right.

So the diff itself is okay

the Wheel base is more or less the same both sides, which means the axles are straight to the body.

The Thrust Angle indicates that the front and rear diff centres are not centred to each other.

What they have done is corrected the front without centring the axle making the rear appear to be the problem. this often happens on lifteed live axle vehicles with pan hard rods.

The defender Front Panhard is not adjustable as stock, so it would need either a correction bracket or bush or adjustable pan hard.

[Apocalypse]

This is what you need to check.

Park it on very level ground

Set up a plumb bob , and hold it on each arch so that the gut passes the Centre of the wheel vertically.

Measure each corner accurately from the arch to wheel center.

I suspect that you’ll find that the rear diff is center and the front diff is over to the left of the body.

Adjusting the front diff to the right will then correct the rear toe, the thrust angle and the set back ...

[Paul#25]

Really good information supplied here. Thanks for sharing your knowledge guys.

[BushWacker]

Thanks Apoc...

No ... vehicle is not lifted though (double sprung)
rear is higher than fore esp with
little load in bin .
I only got onto this in last few days and will
be addressing problem in week ahead...
Tyre wear seems even which is somewhat surprising.

Thanks for advice and guidance.

[Apocalypse]

Well, the wheels all point ahead and are stood up so there shouldn’t be any wear indicated on the tyres.

It will just crab, but I’d be very surprised if the steering wheel isn’t off Centre after being set up like that .

If it is Centre it means they adjusted the steering link after after a road test .

Not sure what double spring is though? Standard or modded springs ?

[BushWacker]

Standard back springs for a 130 ...
one spring inside the other
on both sides

I think you can put 2.2 tons in the bin
... near to/or heaviest for std bakky ...

[BushWacker]

So back to the alignment problem.
Original alignment rig indicated a
Thrust Angle mis-alignment problem
such that the back axle is dog-tracking
vs the front axle track.
On a recent trip several following vehicles said they could see the front right wheel was tracking to the right of the back right wheel...
... to be readily visible the mistrack would need to be centimetres out rather than the 5mm
indication pf the thrust angle measurement.
And indeed taping the rim distance to a common point on tje chassis indicated the back axle wheels tracking some 2cm on the rhs .
I took the vehicle Mikem suspension guys in Selby and they say will need to shim the Radius arms and/or adjust the Panhard .
Attached utube gives background on Panhard adjustment :

https://www.youtube.com/watch?v=liR1--EHMg8

[BushWacker]

... some time on ...

My Defender 130 somehow developed a thrust angle misalignment as reflected near start of this thread ...

https://ibb.co/doKd8p/img

Further to my last note the shims were put in and the thrust angle corrected to 0 deg as below

https://ibb.co/D969cyB. Alignment nos after Radius Arm shimmed

After my my recent trip to Jansen, on the drive home I noticed the steering gently pulling to the left and took it to Shock Alignment and Suspension guys in Marborough Rd Springfield near Turfontein. They put the vehicle on the machine and most of the angles etc looked acceptable but they then noticed the 4 front radius arm bushes were all messed and recommended changing them.
They also recommended changing the back left sway arm bush though that does not play role in alignment. The following 2 diagrams indicates relevant radius arm items and the parts cost from Dover Spares in Eloff extn

https://ibb.co/dgY4Wwv. Radius Arm ... required bush

https://ibb.co/k8HvKWk. Parts Cost

Having replaced the said bushes the wheel alignment is indicated as acceptable wrt nos though now thrust angle a little out again ... so at some stage shims may need be added or removed to correct again.... seems radial arm bushes may have been original root cause ...

https://ibb.co/FzrDXjg Alignment nos June2019

[grips]

On a SFA 4X4 you can do much to wheel alignment with string and a tape measure.

[Prof]

On a SFA 4X4 you can do much to wheel alignment with string and a tape measure.

Amen...

[Apocalypse]

On a SFA 4X4 you can do much to wheel alignment with string and a tape measure.

exactly.

and even though the Defender has a rear upper A arm arrangement - which (supposedly) keeps the axle centred to the chassis - it's still got a panhard at the front.

Which means the axle moves left and right relative to the chassis depending on load and angle etc.

so you will NEVER repeat a reading - especially not the thrust angle. it will always move.

the best you can do is keep it about right.