Mk1 Cortina some questions about suspension

[PePeFIN]

Hello to all!


I'm building a mk1 Cortina and my goal is to build a car that will handle good on track. It's going to be a trackday toy, so I don't have to comply to any APP K rules or anything like that, but I also want to end up with a car that will offer an "authentic driving experience". So I have decided to stick with stuff like steering box, instead of upgrading to a steering rack. Engine will be a Zetec with 45 DCOE's and bunch of other goodies. Gearbox type9.



I have been lurking on these forums reading up all I can and it looks like there is quite a lot of experience with these cars here so I'm hoping to get some advice.


To the front end I'm either gonna source a GT / Lotus type steering box with the quicker ratio or shorter steering arms. I already have a set of GAZ coilovers with 225 lbs springs and adjustable dampers, adjustable top mounts and M16 vented Grp1 front brakes.


For the rear I will install anti-tramp bars, Quaife ATB diff, GAZ adjustable shocks and Fiesta Discs with Sierra calipers.


Adjustable pedal box will go inside the car too. I think these cover the most important bits.


Now for the questions. I need to order rear leaf springs. I have been reading that a lot of racing Cortinas seem to run about 140 lbs single leafs. But then again racing Cortinas tend to have about twice stiffer front springs than mine, so I'm wondering if the 140 lbs would be good choice. Mind you I do prefer a car that rotates easily so I would really like to avoid springs that are too soft on rear. Any opinions? Also can you recommend where to buy? I already send some inquiries to Jones Springs ltd and Team Deville but these are simply what I found with google.
I'm leaning towards the 140 lbs leafs, because the front springs would be easier and cheaper to replace for stiffer ones at a later date.


Then the front ARB. The car in question has a 19 mm ARB, is there any way this could work in track use, or am I going to have to swap for a stiffer one? Stiffer or not I'm definitely going to either fab or source an anti-dive kit (with third mount on the middle). If I'm not misinformed, Cortinas tend to have a problem where the ARB moves on it's mounts when driven hard, so that has to be addressed. Can you recommend where I could find a bigger ARB and mounts / bushings for it?


Also tires. These are a big part of what makes Historic competition cars handle the way they do. Am I incorrect in assuming that most Cortinas typically run 450M13 DUNLOP CR65 at front and 525M13 DUNLOP CR65 at rear?


Then again I don't have to follow any particular set of rules. Are there any cheaper alternatives that would handle similarly? I would assume crossply is the only way forward, so maybe the Dunlops are my only option.


Apologies for the long message, but I do have quite a bit of thoughts racing in my head about this!