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MG MGB Technical - Chassis alignment numbers

As part of getting my car road legal again it had to go off to be certified and part of that was sending it off to make sure the alignment was all correct. The results are interesting.

It passed with one small thing noted on it. They gave me a sheet with the numbers on it. I understand what the terms mean and what they measure. I am not sure what some of their effect on the car are.

There is a written comment on the sheet saying the right front caster 'needs to go forward'.

This is what it says:

Left front:
Camber: 0.06' Specified range: 1.15' - 1.45'
Caster: 6.08' Specified Range: 5.35' - 6.35'
Toe: 0.1mm Specified Range: 0.5mm - 1.5mm
SAI: 8.40'
Included Angle: 8.46'

Right front:
Camber: 0.16' Specified range: 1.15' - 1.45'
Caster: 4.57' Specified Range: 5.35' - 6.35'
Toe: 0.8mm Specified Range: 0.5mm - 1.5mm
SAI: 8.39'
Included Angle: 8.55'

Front Cross Camber: -0.10
Cross Castor: 1.12'
Total toe: 0.9mm

Left Rear:
Camber: -0.13'
Toe: -3.3mm

Right Rear:
Camber: -0.01'
Toe: 4.6mm

Rear Total Toe: 1.3mm
Thrust Angle: -0.19'

Anyone else had this done and how do the numbers compare?
Simon Jansen

The Workshop Manual quotes caster as 5 to 7.25, camber as -.25 to 1.25, toe in as 1.5 to 2.3mm. So the toe is quite a bit out as well as the right camber. The difference in toe left to right is a factor of the different castor, the side with the greater castor will run straighter (i.e. less toe) than the other, as your figures show. That will cause the car to pull to the left on a flat, straight and level road. With correct total toe this would scrub both tyres, one on the outside and one on the inside, but as your right tyre is only slightly low you probably wouldn't notice it on that, although left scrub may be significant. There is no normal adjustment for caster on the MGB, you may be able to do it by slackening the damper bolts, lower trunnion bolt, inner A-arm bolts and wishbone pivot to crossmember bolts, then tightening them all up again while forcing more camber into the king-pin to take advance of the small amounts of play in each. Or shimming the front of the upper trunnion and the rear of the lower, but I've never heard of that being done. Other than that it would be a case of bending both right-hand A-arms forwards a bit.
Paul Hunt 2010

There is another area of potential adjustment that might help with castor. On the front leaver arm dampers one half of the A arm is pressed on to the shaft and the other is held by a pinch bolt. If you loosen the pinch bolt you may be able to move that half a bit. I have never tried this.
David Witham

At the moment I don't think I will do anything. I went out early to the local giant hardware place and was seeing how straight the car tracked in their big, flat carpark and it didn't seem to pull either left or right. Will keep an eye on the tyre scrub.

The car is lowered at the front with shorter springs and stops and stiffer dampers. I do have a proper CB front end in storage to rebuild one day and could look at putting that on the car someday with suitable mods made to the steering rack/column of course so it will fit on my RB car.
Simon Jansen

This thread was discussed between 09/06/2010 and 14/06/2010

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