Front suspension assembly

I’ve just tightened up my front suspension and fitted the split pins, using Bob’s helpful gauge for 140. I now realize I’m not going to get the downward deflection needed to allow the torsion bars to fit, so I need to loosen it all off again.
With it loose, I can use the longer hole set in the gauge to get the torsion bar and all front suspension loosely assembled. However, with no engine or gearbox in, I’m guessing I’m not going to be able to move the suspension up into position to insert the gauge to the correct position for tightening the wishbone rubbers etc. again.
Is this right? Do I need to fit the torsion bars, then wait until the car’s pretty much finished before tightening everything else up?

Just realised I have to tighten up the lower rear wishbone castellated nut to spec, as once the torsion bar collar is on I won’t be able to get to it. Bit of a catch-22 going on here…

Hi Roger…yes without the full weight of the complete car/engine on the suspension it will sit really high with the torsion bars fitted…also you dont want to fully tighten any of the bushes until you have the car completed…you can then set the torsion bars for ride height then tighten bushes…Steve

The way the factory did it was they had a distance gauge piece.
Here is the one for Mark VII. I think the XK140 one would have been similar. It may be in one of the manual supplements.
They would put this in, in place of the shock absorber. Then fit all the suspension pieces in and tighten them. Leaving the long brass torsion bar adjustment nuts at the rear end very loose, they could go on assembling the car. Then when the car was assembled they could tighten these long nuts, and by trial and error, find the point where the car would sit at the right ground height.
You could make this gauge piece out of wood.
Don’t crank on the brass nuts with the weight of the car on them. Raise the car, make an adjustment, then lower the car to see how you did. Lastly tighten the lever clamping bolts.

Yup, I have the gauge, thanks to Bob!
Doesn’t solve the conundrum, though. You have to set the torsion bar first. If you use the gauge to set the wishbones etc. and tighten them, you can’t then move to the extended position for the torsion bar settings because, er… you’ve set the position for the loaded suspension, which won’t twist down far enough for the torsion bar. But, to set the torsion bar, you will cover up the rearwards 7/8" nut on the lower wishbone, thereby stopping you from tightening that later.
I think it’s no big deal - you just have to set the suspension to the ‘ride height’ setting with the gauge, then tighten the one rear lower wishbone 7/8" castellated nut only, no others, and split pin it. Then remove the gauge, force the suspension down to the torsion bar hole on the gauge, and assemble the torsion bar. Leave all the other suspension nuts loose until the car is properly loaded, probably 9 months from now, and tighten them up under full load. I would guess that once the engine is in, it might be possible to get the torsion bar to twist enough to enable the gauge to be used in the ride height position.

Gauge in action:

Put some liquid dish soap on the rubber bushings before you put them in, then the arms will move easy enough.
Leave the rear adjusting levers loose until last.

Also, it bears repeating whenever someone is putting in torsion bars; there is a left and right, and it is imperative not to mix them up, because they are pre-stressed for twisting in one direction only. They are marked on the rear end NS and OS for Near Side and Off Side. Look up Obscure British Terms for a translation, and be sure not to get on Far Side or you’ll never find your way back. :grinning_face_with_smiling_eyes:

Hi Roger…the distance guage is a two function tool…the lower hole used to set the torsion bars ( ride height) the hole above used to set castor…so to assemble the suspension as you are doing only needs the widest holes to be used…You will only set castor once the car is fully built…iv used similar setups befor on E types…where there are two distance guages one for torsion bars and one for castor instead if a combined guage…however dufferent E type models (weights) have different guage dimensions…are we sure this guage is correct for your model…is there a list that gives guage dimensions for the different XK models…Steve …Edit just found this “Distance Gauge” suspension XK 140 & 150 | Jaguar XK 140 FHC Part & Assembly Information

Hi Steve, yes, that’s Bob’s design which I have copied. It works very well.
I think this has got a bit over-complicated! I was trying to use the shorter gauge setting to tighten up the front suspension fasteners before the car was weighted fully. This can’t be done, because you have to set the torsion bars first, using the gauge’s longer setting - and once you’ve done that you can’t get enough deflection on the torsion bars with the car unweighted to tighten the wishbone nuts etc. It’s exactly the same when working on the suspension of any car, not just torsion bars.
Unfortunately you can’t leave the rear wishbone bolt until it is weighted before tightening, because the torsion bar forward lever casting bolts over it, covering it completely and making later access impossible. Therefore the rear lower wishbone nut and split pin is the only suspension bolt that has to be tightened to spec at this stage, before it disappears under the torsion bar lever.

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Hi Roger…would it not be possible to leave bushes not fully tightened…set torsion bars and ride height…then mark torsion bar/muff positions and remove torsion bars…fully tighten bushes…refit torsion bars to orignal position…Steve

I don’t think so, because you have to attach the torsion bars with the suspension in the fully dropped position, or you’d never get the torsion bar reconnected!

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Yes full droop to remove torsion bars…then push wishbones back up to the position they were at ride height and tighten bushes…refit torsion bars…this brings us back to your first post…bushes will be tight so you may need to lever the wishbone down…Steve

Something sounds wrong. It shouldn’t be this difficult. The bushings should not be so tight that you can’t move the arms at all. You do have the steel sleeves inside them, don’t you? They limit the compression of the rubber.