basically ive striped out the back end of my 98 uk classic wagon after having a wide arch kit put on but when braking heavilly the back end is all over the place! it feels like the back end is coming off the ground. apart from obviously putting the seats ect back in. its got brembos on all round but i think it needs the brake effort to be up'd on the rear! cheers

 

Yep, the stripping of weight in the rear has left significantly less weight pressing down over the rear wheels.

So the rear tyres now have significantly less friction on the tarmac compared to the fronts because, in conjunction with the fact that the rear is already lightly braked compared to the front, plus the fact that weight transfers forwards when you brake, this is why it feels like it wants to "cartwheel"...

As you say, you need to shift some braking effort back to the rear with by installing a brake bias line... or bigger calipers/bigger discs/higher friction pads at the rear.

 

ok, ive just been looking at the bias valves but thinking of the way they work if there in line on the rear brakes will that not only allow the pressure to be lowered?

 

ignore that lol, put it in the front line!

 

TBH I'm not entirely sure on how they work re the pressure.

Presumably they cut some of the pressure in the brakes lines from the front and direct it to the rear (or vice versa if you needed it that way). After all, the overall pressure in the system is fixed, so the valve would just move the allocation rearwards or forwards to a lesser or greater degree (depending on the posItion of the valve-controlling lever).

I might be talking utter tripe, but this is how I've always understood brake bias valve systems to work.

 

thanks for the help matey, if i put one on the front system then that will lower the fronts pressure so should balance it out!

 

If that's how they work, then yes.

I'd give somewhere like Demon Tweeks a ring/email. They'd know and be able to advise you, etc. They also obviously sell the brake bias kits too...