Corner weight adjustment, I'm way out!

[GreenV8S]

Mignon said:

I really don't see the problem here.

The corner weights indicate there's about 47Kgs worth of jacking in there i.e. it needs about 47Kgs removing from the 'heavy' corners and adding to the 'light' ones. 47 Kgs is quite a lot and I'm advising the OP to understand what is causing that before trying to correct it. It might be caused by a twisted chassis, or a bent suspension arm, or a collapsed bush, a spring that has sagged/broken or the wrong length or rate. Most of these are things you'd want to correct rather than just move the spring seats to compensate. If the problem is actually that the ground wasn't quite flat, which I think is more likely, then this exercise will be making the corner weights worse not better. It shouldn't be particularly complicated or difficult to do, but it needs doing.

[Mignon]

GreenV8S said:

The corner weights indicate there's about 47Kgs worth of jacking in there

Where are you getting that number from?

[chrisgtx]

Well chaps. I will now eat humble pie. I got fussy with the spirit level. And tried again. Also I realised the front right tyre was under pressure. Watching the weight change as I pumped it up was a good indicator of how height can change the weights.
I weighed it each time after changing one thing.
On its own the car is actually ok, with me in it it's out. But seeing as I had to get the scales back today and I'll be making changes over the winter I'll set it again on my mates MOT ramps which are level.

[chrisgtx]

And with me in it.

[Mignon]

Told you. You can't change actual static weight distribution by mucking about with corner heights. Nor can you change Front/Rear or Left/Right in total. All you can do is change the corner totals.

Edited by Mignon on Friday 9th December 13:03

[Mignon]

Without you in it the car is near as dammit balanced. With you in it it's 70kg to the right hand side. You can only fix that by moving actual mass.

Edited by Mignon on Saturday 10th December 06:33

[GreenV8S]

Mignon said:

Where are you getting that number from?

I calculated the ideal corner weights for that weight distribution i.e. with zero weight jacking, and it differs from the measured figures by 47Kgs.

[chrisgtx]

Although I hope I just didn't get the levels right and they just tipped in my favour! :-)

[GreenV8S]

chrisgtx said:

And with me in it.

Glad to hear you've eliminated most of the error. That's within a couple of kilos of spot on, and you can probably assume those last few kilos are caused by stiction, and the floor not being perfectly flat and so on.

Corner weight adjustment is IMO a waste of effort most of the time since the only situation where it does any good is when the weight is significantly offset sideways and you also have very different wheel rates front/rear. The rest of the time, any difference between your ideal and actual corner weights is telling you there's something wrong with the vehicle or your measurements, and adjusting spring seats isn't the right solution for any of those problems.