Front suspension adjustment with bonnet removed

[mach2andy]

I'm about to adjust the camber & castor and it occurs that I need some weight on the bonnet frame to substitute the weight of the bonnet? So, roughly how much does the bonnet weigh? Also, if at a later stage I need to reset the torsion bars to adjust the ride height, will this upset the suspension settings that I'm about to make?
Thanks in advance.
Andy

[abowie]

Wheel alignment is the last thing you do when the car is complete. Even to fuel load and tyre pressures.

If you try to approximate it now you'll still have to do it properly later.

[johnetype]

No, use the setting links as detailed in the service manual and you can set castor, camber and toe now.

No need to know the bonnet weight and the torsion bar adjustments won't upset things unless you set a ride height a long way off standard (since that's what the setting links are doing).

[abowie]

While the service manual does suggest the use of setting links that fix the suspension in the mid laden position it is common that front camber and castor fall outside of spec when the completed car is actually on the road.

This is why it we don't bother to set then until the car is on the road ready to drive. Saves doing it twice. It makes the process easier if you hold off fitting the splash shields until after you have done the alignment too.

[mach2andy]

Thanks everyone. I should really have mentioned that the car has adjustable fulcrum shafts fitted so I'm not going to be fiddling around with shims. I don't really want to drive my car without knowing that the suspension geometry is at least somewhere close to correct. The tyre pressures are correct, the car is on level ground, and I can simulate a full fuel load. Rechecking and fine tuning the geometry once the car has been driven for a while should hopefully not be a big deal with the adjustable fulcrums fitted.

[bitsobrits]

On my last two projects I was able to get camber/caster/toe within .25 degrees (each) of desired specs by careful setup without full load (caster and camber were equal side to side, btw). The Elan setup was done with a bare chassis (no wheels) and the E-type with a rolling tub without engine/gearbox or bonnet. Once the vehicles were were complete, only a sight tweak of toe was required on the E-type.

In both cases the vehicles were built up to a designed front/rear ride height and by adjusting the suspensions to provide that ride height after the cars were complete, the suspension specs came in as intended.

I do agree that it is typical that post build suspension adjustments are required. But I do like to have the suspension close enough for confident test driving after build, and after doing this for 40 years it's a bit of a game to see how close I can get things first go.

[mach2andy]

I'm in a position to adjust the front suspension now, and was going set about marking chalk lines on the floor to show when the wheels are turned the same amount left and right as suggested in another post. But surely, my assistant turning the steering wheel exactly the same amount L & R achieves the same result? Or have I missed the point?

[mgcjag]

Hi Andy.....do you have slip plates under the front wheels...makes turning the wheels much easier and stops the tyres gripping on the floor.....2 thin sheets of greased steel work.....or a glossy magazine is better than nothing...yes the wheels should turn the same amount....if your just adjusting track then thats quite simple..if setting camber/castor then each time you jack up the car you will need to settle the suspension...bounce or move backwards/forwards.....Steve

[mach2andy]

Hi Steve
When rebuilding the car, I fitted the fully adjustable upper fulcrum shafts. So, no need to jack the car up at all. What I did in the end was to set a plumb line just in front of the wishbones so that I could measure when the steering axes were upright. Having got the steering axes perfectly vertical I then wound in 2° of positive castor. 5 turns of the fulcrum shaft or counting 20 flats as I did. Turning the adjustable shafts alters castor and camber at the same time so I then measured camber with the gauge that I had made up and tweaked it until it was 1/2° neg. I'll drive the car for a while and see what it's like, and then check it again when the suspension has settled in.