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after fitting the rt615's i've noticed that i can pull up a lot quicker on the track but what I also noticed was that when downchanging and engaging the clutch the rear would come close to locking up but that It pulled up even faster As my car is an NA 90' I know the bias is meant to be very front oriented, what i want to know is if fitting an NB brake bias (thing) is going to be only slightly better or should I go for something that can put even more bias on the rear. What do you race guys do/think?

I have found that same phenomena with my NB, where you brake hard and load up the rears with a little engine brake and car basically stops dead...

I think the reason for this is less to do with brake bias and more to do with the effect of the engine's torque being applied throught the rear wheels... Dunno for sure though and am just hazarding a guess...

Either way it works wonders!!!!!!!! (If you can afford a new clutch every second week)

well I do my best to heel toe it so that there isnt too much stress through the clutch on the hit nor the rears lock up. I'll first try putting some better pads in the rear before I do anything else.

I used some very heavy (for me) brake applications yesterday at QR and had no rear lock up when heel/toeing the change down. I messed it up once though and got a bubby chirp from the rears . So maybe the 1.8 bias arrangement is a bit better. I'm using OEM brakes and no fancy fluid.

It's called a compression lockup and it's not really recommended. A bias vavle won't fix it, braking harder first and then downshifting with a blip will.

CT thats what I thought I said in the first post I do the blip when down changing and hard on the brakes with the fronts getting a quick chirp from being on the locking point. But as mentioned, when changing down I notice that it stops even better, when it does the slight compression lock (not locking though) Hence wondering if the change in brake bias is the way to go? I'll keep playing with my braking and see if I can get better results with what I got

Ok then, I obviously didn't get your first post. Probably yes then, most road cars don't have enough rear bias. A 1.8 NA one will be better - Matty has done the research. For me, adjustables are the only way to go!

cheers