I decided to develop my car for track use, while keeping it acceptable on the road, and without spending a fortune; I’m a professional engineer, which was very handy when it came to carrying out the necessary calculations and design work for the changes I wanted to make.
I focussed mainly on handling and braking as most of the tracks I compete on are pretty tight, so being fastest around the bends gives an advantage over notionally more powerful cars.
Briefly, the things I did were as follows:
1.Uprated front antiroll bar and uprated / slightly lower rear springs, to my own design. This stiffened up the whole car and gave much more precise handling - a major improvement.
2.Watts linkage converted to a plain bearing on the centre pivot, and adjustable rose – jointed arms, all to my own design. This tightened up the back end considerably, and also allowed the De – Dion tube/A-frame to be centralised accurately in the car.
3.Front radius arms converted to spherical joints from the original “rubber washer” arrangement (my design again); this gives full control over the castor angle to allow accurate setup and adjustment; made quite an improvement both in terms of “feel” and steering accuracy. (The original rubber setup was all over the place & never gave the same reading twice on the setup rig).
4.A-frame central rubber bush replaced by SZ – type spherical bearing: frankly, this didn’t seem to make much difference, though it probably would if the original bush was worn out.
5.A full set of Avo adjustable shocks; these are only single – adjustable, but turned out to be pretty good once dialled – in; setting them up was quite easy too, because the adjusters are on the bottom of the shock and are accessible without taking anything off or jacking the car up, so changing from “road” to “track” settings is easy.
6.Full strip and rebuild of brake callipers, master cylinder, etc.; skimmed and drilled brake discs and fitted EBC Green Stuff pads all round, and Goodridge hoses; then spent a considerable bit of time making sure rear pad / disc clearances were ok (set at 2 thou), and bleeding everything properly. Much improved braking, and still plenty of “feel” (unlike some of the "big brakes" out there).
7.Yokohama A048 (medium compound) tyres on standard 7J wheels; great in the dry, ok in the wet, they don’t last long though!
8.CSC exhaust system fitted, with the front silencers removed (just for weight, they don’t restrict it): the old system was goosed, this sounds better and gives a bit more power too.
9.Gearbox stripped, inspected and rebuilt with new synchros; I spent some time setting up the internal shift mechanism (it’s adjustable), which together with the new synchros improved the change no end!
10.Driver seat swapped for a Sparco clubmans seat, fitted on the original runners so still adjustable – so my wife can race the car too.... and a four – point harness.
11.Fuel, Optimax or equivalent, and if your local MOT station is friendly it’s worthwhile adjusting the “mixture” setting (Allen screw, top of the airflow meter) to the richest legal setting on their emissions rig.
12.Engine – wise no serious changes, just a comprehensive service using OE filters (all of them, including the fuel filter), Bosch plugs, and time spent getting the valve clearances & timing and ignition timing absolutely bang – on (set at full advance & let the “retarded” setting take care of itself). I do this service every 2000 mls, with a full check – over after every race meeting. I always do the work myself, as I don’t expect the average garage mechanic to have the same interest / commitment as I have.
All of this has resulted in a car which is loads of fun on the track, still completely useable and a pleasure on the road, and has been totally reliable for the last five years: what more could you ask?
Anyway, hope all this is of help to someone!