Hi there, it was kind of getting there befor taken of the road few years back. I had lots of good advise from here but looking on net etc I couldn’t find a definitive ‘lower by this much and use this spring rate’ I guess folks have there own preference for handling. Anyway... iv got koni front and spax rear shocks. Spring rates, I started with 400lb front and 200 ish rears, standard ride hight sold as ‘rally/fast road’. These were fine on road but way to soft on track. Had load of roll and still under stear. I basically had a car that was impeccable on road but on track understear, roll and lifting inside rear up and couldn’t get power down even with an old v8 that’d be no more than 200hp.I didn’t fancy spending another £200 on springs for just a stab in the dark so what I’m writing next is certainly not advice to anyone on what to do but was to help me find out what direction to go in. I cut coil out front= improvement but still roll. Cut coil out back=turn in better but very very nervous on the limit. It was perhaps hitting bump stop which would massively randomly increase spring rate but also felt it had altered original geometry to much and it didn’t like it. Again next is not advise but was to help me have a better idea what to order next. I put some of those crappy rubber spring assisters allround that would effectively increase spring rate. I also rased rear back to near gte ride hight. This helped a lot, roll was cut down and no longer felt nervous on the limit. Unfortunately car was then taken off the road for engine rebuild and gearbox swap. However instead it sat in a garden for years! Iv nearly finished getting back on the road now though after much welding. A further point... I’d guess even then my shell would of been getting quite rotten so would be quite floppy, also was only poly bushes at rear.
long story short😂- 400lb -200lb springs way to soft for track. Lower back to much on standard set up it gets nervous. Rear anti roll bar... I think this was to try and keep back wheels on the floor... it will give similar effect as softening rear which will promote understear as you have less weight transfer to front on turn in.
My priority atm is to get back on road and see how it feels now shell stiffer (now has roll cage and box in chassis rails) and take it from there. But in long term I’m going to convert rear to coil overs so will be cheaper to buy stiffer springs and play with ride hight. Also guys on here recommend more caster and camber. This will be next year though, get the dam thing on the road first. Sorry if post to long, had half hour spare!! 😂