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Sorting out your rear camber

Sorting out your rear camber with Peter Gibb

 peterg2

What you will need to change the rear camber on your buggy…

A pair of axle stands.
An 8 foot piece of decent rope, at least half inch diameter or chain.
A homemade fixture (stop plate 170 x 40 x 3 (min) with three holes in it) to hold the torsion bar in place while the spring plate is levered off.
New genuine inner and outer rubber bushes, these seem to be slightly smaller than the urethane ones and are easier to fit, the ones I took out were 30 years old and still in good nick, urethane is very popular now, but I would rather use originals just out of preference, fit whichever you feel happiest with.
A tin of talcum powder, (this is the right way to lubricate a rubber bush).
Some 3 in 1 oil to lubricate the torsion bar cover bolts and shock absorber threads, and aids reassembly.
A decent hydraulic jack, NOTE: a scissor or bottle jack must NOT be used.
Two large flat blade screwdrivers.
A standard size milk crate.
Penetrating oil. Apply a day or so before to the axle mounting bolts, shock mounting bolts and torsion rubber cover plate bolts, this will help ease disassembly.
Do the job one side at a time, making sure you understand the principles involved with the differing number of splines, before you start.
Ensure the car is standing on a surface that is known to be horizontal, this is important, as we use a plumb line to get the angle of the wheel before we start.
You can get your adjustment details by dropping a plumb line made from very thin fishing line, attach an M8 or M10 nut to one end to keep it taught, drop it down from the wheel rim lip at 12 o’clock (top), and measure with a rule, the distance the line is from the lip of the wheel rim at 6 o’clock (bottom).
Basically, Opposite over Hypotenuse is Sine. The 15” rim diameter (410mm measured lip to lip) = the “Hypotenuse” and the distance the line is away from the bottom lip = the “Opposite”.
So, Opposite divided by Hypotenuse = Sine. Shift and Sine on a calculator gives you the angle of the wheel.
Spline adjustments can be made to give you anything you want in 5mm (50 minute) chunks, I wanted the minimum negative camber possible to keep the wheels nearly vertical.
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There are 40 INNER splines 9° apart and 44 outer splines 8° 10’ apart, simply put, adjusting 1 inner spline clockwise and 1 outer spline anticlockwise will give a clockwise shift of 50’.
Remember that to drop the offside of the car will require the torsion bar to be rotated clockwise in the chassis and the spring plate anticlockwise.
Where as, to drop the nearside of the car, the torsion bar is rotated anticlockwise in the chassis and the spring plate is rotated clockwise…………………………….. To raise the car, the reverse is applied.

Torsion bar inner end has 40 splines     =     9°    /spline
Torsion bar outer end has 44 splines     = 8°10’ / spline

NOTE: If sprung coil/over shocks are fitted, REMOVE them before taking measurements
Release the handbrake cable at the drivers end (in the car).
1.  Jack up the car and drop it onto a pair of axle stands.
2.  Remove the rear shock and bolts.
3.  Before releasing the 3 rear axle mounting bolts, use a small hacksaw to make a tiny cut on top of the spring plate and rear axle mount, this sets the tracking alignment of the axle and spring plate when reassembled.
4.  Remove the 3 axle / spring plate mounting bolts.
5.  Withdraw the handbrake outer sheath from the chassis (aids axle movement rearwards).
6.  Pull the axle assembly rearwards to clear the spring plate and set down on the milk crate (being very careful not to stretch and fracture the flexible hydraulic brake pipe).
7.  Remove the 4 screws from the torsion arm cover and remove the cover.
8.  Lubricate the threads of these 4 bolts to aid reassembly.
9.  While the spring plate is still resting on the step, mark the ends of the splined torsion bar and splined hub, do this at 12 o’clock and 6 o’clock (use an old chisel for a nice sharp line or a centre punch). Tippex either side of each mark to aid visibility.
10.  Fit the homemade fixture plate diagonally across the torsion cover bolt holes using 2 lengths of 100mm long M10 studding and 2 nuts, this stands the fixture plate away from the torsion housing and allows the spring plate to be levered out and off the chassis step. Put M8 studding or bolt through the fixture plate ( a nut on either side) and midway between the 2 pieces of studding at a point central to the torsion bar, and screw it down onto the end face of the torsion bar. It will hold the torsion bar in place so that its inner set of splines do not disengage from the chassis while the spring plate is being levered clear of the chassis step.
11.  Position an hydraulic jack under the spring plate, wrap the rope or chain under the jack and up over the chassis shock support member, continue and wrap the rope again under the jack and up over the shock support, tie the ends together so that when the jack is slowly pumped up under the spring plate, the spring plate will lift up and off its step.
12.  With the spring plate 1mm off the step, lever it towards you so it is clear of the step.
13.  Now lower the spring plate to its unloaded position. IT IS VERY IMPORTANT NOT TO REMOVE IT YET!!
14.  Scribe along the top edge of the spring plate and onto the cast chassis member so as to have a reference line for the original spring plate setting as it was before it was removed.
15.  Now you can lever the spring plate off the splines and remove the homemade fixture plate.
16.  When disengaging the inner splines, get snug and comfortable so you are steady and in complete control, gently wiggle the torsion bar from side to side while twisting it in the direction you want to adjust the bar, ie clockwise or anticlockwise, and pulling it at the same time.
You will feel the torsion bar slowly coming out, as the torsion bar clears the splines, you must stop pulling, and gently feel for the next spline as the torsion bar is turned, it is important to stop pulling as soon as you feel it disengage, as the torsion bar will sit on a chamfer while you rotate and FEEL for the next spline. When you are satisfied you have moved (counted) the required number of splines and in the right direction, PUSH and engage the torsion bar back into the splined housing.
17.  Now fit a new rubber bush to the inside boss on the spring plate and refit the spring plate with your calculated spline adjustment in the opposite direction to the previous inner adjustment, remember to lubricate the new inner and outer rubber bushes with talcum powder before and after you refit them to the spring plate.
18.  As the spring plate is unloaded and off its step, NOW is the time to refit the outer cover plate so that it is clamping the assembly and the bolts are well started in their threadsit is a good idea to use long, 30mm M8 bolts, in two diagonally opposite holes, to align the cover plate.
19.  Position the jack again under the spring plate, fit the rope or chain as before and lift the spring plate until it clears the chassis step.
20.  Finally tighten down the cover plate in diagonally opposite holes, until it is fully seated, the cover will have sucked in and seated the rubber bush assembly as you tighten down.
21.  Refit the axle and align the toe in marks you made with the hacksaw, bolt down and refit handbrake outer sleeve, shocks, wheels etc and you are finished.
If the resulting camber is too much or too little, you can do it all again, I know from experience that having a helper is the way to go, as, when you have done this once, you can set a world record with subsequent strip downs, I was doing it from start to finish on one side in 25 minutes..

This job really is not as difficult as it may at first seem, preparation with penetrating oil and tool gathering before you start will always pay off, do not rush it and measure and understand the principles of the splines.
Positive camber is wider at the top than at the bottom and negative camber is the opposite.
Before I started to make adjustments, I checked the state of the camber, and found that using the plumb line, i had a nearside rim measurement of 10mm out at the top of the rim, this is positive camber of 1°24’, and an offside rim measurement of 20mm out at the top of the rim, which = 2°48’.
This shows that over the years the torsion arms can lose some strength and differ from side to side, so now is a good time to get the chassis stance balanced again.

NOTE………….. Settings below are DROPPING the buggy, to RAISE a car, just apply the reverse to the direction of spline rotation.

INNER has 40 splines
OUTER has 44 splines

To DROP the body…
Nearside inner anticlockwise, outer clockwise
Offside inner clockwise, outer anticlockwise

To RAISE the body…
Nearside inner clockwise, outer anticlockwise
Offside inner anticlockwise, outer clockwise

Setup 1 achieves the minimum negative camber on both sides and gives me 16’ and 32’ negative camber respectively, as close as I could get to a vertical tyre attitude.

Setup 2  would give me slightly more negative camber than above, 1°06 and ’1°22’, the chart on the right shows the drop in mm for any equal inner/outer spline adjustment

splines_1

Setup 1:
Nearside camber before resetting = 1°24’ positive
Rotate inner 2 splines anticlockwise = 18°00’
Rotate outer 2 splines clockwise  = 16°20’
Actual adjustment = 1°40’
Negative camber produced = 1°40’- 1°24’ = 16’

Offside camber before resetting = 2°48’ positive
Rotate inner 4 splines clockwise = 36°00’
Rotate outer 4 splines anticlockwise = 32°40’
Actual adjustment = 3°20’
Negative camber produced = 3°20’-2°48’ = 32’

Setup 2:
Nearside camber before resetting = 1°24’ positive
Rotate inner (40) 3 splines anticlockwise = 27°00’
Rotate outer (44) 3 splines clockwise = 24°30’
Actual adjustment = 2°30’
Negative camber produced = 2°30’-1°24’ = 1°06’

Offside camber before resetting = 2°48’ positive
Rotate inner (40) 5 splines clockwise = 45°00’
Rotate outer (44) 5 splines anticlockwise  = 40°50’
Actual adjustment = 4°10’
Negative camber produced = 4°10’-2°48’ = 1°22’

ar55