Back end over takes me on heavy braking

Hi,

Just a quick few questions to see if anyone can help.

When I brake heavy in my gti the back wheels lock up before the fronts then the back end swings out so I have to do some crazy driving skills to battle the back in a straight line.

The car is a gti with the rear disc conversion..

It is lowered slightly however I've taken all of the adjustment off the bias valve to try and prevent this. I've checked the front flexi hoses for damage/kinks and all is well.

It has a 16v master and servo.

Could it be that the previous owner didn't change the bias valve for the 16v type? Or could it be the way the brakes are lined? I have noticed a few connectors through the lines. There are only 2 copper pipes coming from the servo?

Any ideas?

shouldnt pass an mot like that

have you still got the 239mm brakes on the front as these need to be bigger before you convert the rear to discs.

there should be a few brake line t's about so check that each pipe from the mc is split diagonally so that it goes to front right +rear left and vice versa.

is the bias valve spring tight as you can stretch it a bit with a car jack

they should test the brake lockout in an mot place so you can get it checked when you have fixed it.

I have stretched the spring so it's hardly in use and it still does it. I think it is lined diagonally and the front discs are as big as I can go without changing the wheels. I am wondering if it either the bias valve or the connectors in the lines?

Have you removed the little one way ball valves (if fitted) as i believe you are supposed to.

I'll have a good look around for it today. I could only find joining connectors with a hole through which would be bolted to the chassis.

Could I not just re line it and take two pipes direct from the master to the front calliper and two pipes from the master direct to the bias valve to the rear. Then from the bias to the rear calipers? Or is that not how it works?

They are hexagonal connectors, up front down in the depths under the servo somewhere.

how many outlets are on your mc

it should be plumbed in like that anyway but if your mc only has 2 outlets then you can use the t's

what size calipers do you have on the front

you could take the spring off and see if it still does it but id say you wont be able to adjust it on the bias valve so maybe swap for the valve that go on the mc like these

http://www.billswebspace.com/vwscirocco251.jpg

could be the valve itself is shot, i made a bracket so i could fit a mk2 bias valve which was built with rear discs in mind, plus its easier and cheaper to get than the mk1 item.

you shouldnt need to upgrade the front brakes if the bias valve is working correctly.

oh and you can put the fluid reservoir on the right way round with the abf dizzy cap