Done a bit of tinkering, but nothing major.
I'm considering swapping out the original M3 brake servo and master cylinder and replacing them with e34 m5 equivalents. My reasoning for doing this is that the M5 servo is a smaller diameter meaning that I might be able to use an unmodified inlet plenum rather than the original which has a recess welded into it to give increased clearance. (See pic below) This recess must effect airflow to cylinder 6, the plenum afterall is quite a clever system which has a variable resonance flap to aid mid range torque.
Standard plenum:
There is also a benefit in changing to the M5 master cylinder. The car already has M5 calipers with larger pistons than the M3, so it would make sense to use the matching master cylinder.
Continuing on the subject of brakes, I'm also making a change to the rear brakes. Originally it used a 300x20 rear disc from an e32 750. The inner diameter of the drum section was too large for e30 handbrake shoes so an steel insert was used to reduced the internal id from 185mm to 160mm. This ring was held in place by two measley m4 retaining screws and the whole setup was a bit dubious.
I noticed recently that several 1 series and 3 series cars use a 300x20 rear disc with the correct size drum for the handbrake shoes. I've trial fitted one and it looks good, I just need to make the spacers between the OE caliper carrier and the Hartge adaptor 2mm thicker and then get holes machined for the disc retaining bolt as they are in the wrong place on the 1 series disc.
Other than this I have just been amassing more parts for the car and I'm now in a position to but the engine back together and trial fit it to the car to check that all clearances are ok.
I'm also considering changing the gearbox and final drive from it's current overdrive box with 3.73 final drive to a dogleg box with 1:1 5th gear coupled with a 2.93 final drive. I really like the ratios on the dogleg box and it would increase the theoretical top speed by a few mph. The dogleg box also has a detachable bell housing which makes clutch changes a lot simpler. This swap would need a new crown wheel building into the 40% locking Hartge LSD, plus modifications to the gear linkage and possibly a slight shortening of the propshaft. Hmmm.
