bad brakes

[booomer]

Just been trying to improve the brakes on my 316i (M50B25 conversion) as they've always been pretty crap. Its got new shoes and cylinders on the back, new discs and pads in the front, 325i calipers and new flexi hoses, a clio servo and new brake fluid and the brakes still feel as bad as they did with the old knackered components. There is loads of pedal travel and not much braking. They bled up fine (or seemed to at least), so i'm wondering what else could be causing the issue. Obviously the master cylinder could be at fault but its not leaking anywhere.
any suggestions?

[Speedtouch]

Perhaps try adjusting the brake pedal height - I gather the rod linkage is adjustable:

http://www.e30zone.net/e30zonewiki/index.php/Brakes

[bmw9818]

change rears to discs, get bigger caliper or ebc pads

[jmc330i]

Was a spacer fitted to take up the slack between the pushrod in Clio servo and the Master cylinder?

[booomer]

Yeah I fitted a spacer of the correct size but the brakes were bad before I put the Clio servo in. If I adjust the push rod between the pedal and the servo I can get a really good pedal and brake performance but the front brakes are then dragging on and getting hot. If I then slacken the push rod off the brakes don't drag but there is then loads of pedal travel

[Speedtouch]

I take it you have fitted the 325i ventilated front discs, along with the 325i calipers?

[booomer]

I take it you have fitted the 325i ventilated front discs, along with the 325i calipers?

Correct

[booomer]

Right, car now has brand new master cylinder and the problem continues. Literally no brakes! Worryingly before the brakes were bled, if I pushed the pedal down I got a loud clonk clonk. I will check rear brake adjustment first, but after that I recon its gonna be something to do with the Clio servo conversion

[jmc330i]

If fitted correctly, the servo won't cause bad brakes unless there's a lack of vacuum - the brakes should still work perfectly well, albeit with no assistance and a very firm pedal.
The servo will have no effect on pedal travel unless the spacer is too short or too long - the length can vary from car to car, so 20mm for mine might be 15mm for yours.

As you said the brakes were bad before you did all the work, I'd be surprised if the Clio servo itself will be the cause of the problem.
If you're happy the brakes are bled correctly, I'd be looking at the pedal adjustment and length of the spacer.