Having been obliged to spend maths and physics lessons confined to a store room due to my disruptive influence on fellow students all those years ago at school, I have only a tenuous grasp upon the laws of physics, but I figured that if the CoG is lower, then there's effectively less weight to act on the suspension (using whoever's theory it was of weight X distance and leverage and that sort of stuff) and so cause roll, so a lower car would lean less.

Also, if two cars lean at the same angle, but one is taller, the actual distance that the taller car moves laterally would be greater - the circumference of a small circle/arc being less than that of a larger curve drawn around the same centre point etc. Hence why motoring press always complain about SUVs and MPVs leaning through corners.

So what have I got wrong, apart from my attitude to education?........

 

You could just put weights in the back?

Sorry I'm not helping

 

I have to admit, I originally said that wrong. I originally said "lowering the CoG increases the roll", and the hastily went back and edited my post before anybody noticed.

Lowering the CoG does reduce the roll for all the reasons you say. However, lowering the car changes the angle of the wishbones, which changes the "roll centre" which is the imaginary point the car rolls around. The important thing is the distance between the roll centre and the CoG, and as it happens lowering the car lowers the roll centre more than it lowers the CoG, hence more roll.

It's all very complicated, and I wouldn't claim to fully understand.

In practice, lowering springs are stiffer than normal springs, due to the reduced travel, and so the car rolls less. But in theory if you lowered with the same spring rates (for example you cut the springs), then it would roll more. You'd also possibly kill yourself the first time you ran out of suspension travel.

Ideally you need roll centre adjusters which correct the change in the angles of the wishbone in a lowered car.

 

I was told by Chris at COG no more than 20mm, hope this helps

 

Thanks, Dembo. I sort of understand now and will spend several hours pondering your explanation, I'm sure, before classifing it under the heading of "clever sh1t & voodoo" in my poor little head

 

Sad as it may be, I once sat in open-mouthed shock as I listened to two lads I worked with at the time (mid 90's) discuss how loading the boot of a Cavalier SRi with 2 kerb stones arranged in a 'V' pattern would help grip and handling.

When I did finally regain my power of speach, I commented that it was probably a brilliant idea as I'd heard that Ferrari fitted carbon fibre replica kerbs in the back of their F1 cars.

 

Back on topic for a minute.

I originally fitted just coilovers to mine (about an inch lower), and then went back and got the anti-bump steer bits. It was fine with just the coilovers; I probably posted here how good I thought it was. But the anti-bump steer bits were like being handed the keys to a completely different (and much better) car.

 

Again, please excuse my ignorance, but what are the anti-bump steer bits?............

 

I was originally lowered 30mm on coilovers alone, but gradually fitted the bump-steer mods, in this order:

Steering rack spacers
Rear control arms
Tie rod ends
Roll centre adjusters

After fitting the Roll centre adjusters, the difference was night and day - I could elaborate but I think it makes more sense to say that the bumpsteer mods are mandatory if lowering as much as I did. It'll cost a lot less to have them fitted all at once too; all or nothing, I'd say.

I've found that stiffening up the chassis has helped too.

 

I must be missing something.
I've been at 35mm for 14k miles now and had no issues.
In the real world on the road I'm not sure you need to go to those lengths!