rear disks locking up!!!!! HELP!!!!

Hi guys ive recently put disks on the back of my cabby and since then the back brakes have locked up a few times and scared the s*it out of me!!!! i have done the 16v servo and m/c upgrade and i have 239mm vented and drilled disks and greenstuff pads on the front. i looked under the back of my car the other day and i do have a load sensing valve but when i changed the brake pipes (when i changed the m/c) i noticed that i have 2 limiter valves on the pipes that go to the back aswell!!!! they are down the passenger side next to the hole where the steering rack goes through the chassis. i need to do something cus i do drive fast, but i hate the though of it catching me off guard one day and going through a hedge backwards!!!!!!

serves you right for trying to look bling!!





you need to alter the brake bias. i don't know how to do it but i do know it is a shit if a job. trial and error job i think. i'll never ever attempt to even think about rear discs.

i wasnt tryin to look bling!!!!! honest!!!! :mrgreen:  would bigger brakes on the front help do u think? there drilled and groved disks with greenstuff pads but there only 239mm i have been looking for a set of 256 or 280mm disks and calipers but there so damn expensive these days!!!!!

I used the pressure limiting valve from an 'F' reg Scirocco and I have no problems with locking. I read somewhere that the later Scirocco's have the same valve as the 16V, but earlier versions were different. It's only a spring inside the valve, so you can tune them. In this case you would want a softer spring so the valve shuts earlier.

ok but have you got any idea why i have got a pair of limiter valves under the bonnet and a load valve under the floor at the back?

Ive just done mine and dont really fancy backing it into a hedge either,  I have however fitted a bias valve so hopefully this should prevent any off roading the first time I get my car out you could always try this

jamiegolf said

ok but have you got any idea why i have got a pair of limiter valves under the bonnet and a load valve under the floor at the back?

What years the cabby? If its post 84 I don't think it'll have the valve on the beam as there's not room due to the larger fuel tank.

If you need appropriate inline valves then you'll need 16v scirocco ones, none of the 8v ones are suitable, whatever age of the car.

Alternatively you need to find 2 mk2 astra 16v's and rob the valve with the M10 thread off the master cylinder on each. They have 2 valves, but one is M10 and the other is M12, hence needing to find 2 donors!

my cabby is a 1980 model, and it has got the rear beam valve and its got a smaller fuel tank than my other gti thats on a 1985 plate. mine must just be odd!!!!!! is there any particular astra that i need to get the valves from? or is it any one with the rear disks? i did think about putting an adjustable bias valve in but i was wondering how you would plumb it in cus theres 2 brake pipes going to the rear of the car? do i need 2 adjustable bias valves?

Ha you put mega brakes on the back and wonder why they are locking up? sorry to seem a see you next tuesday but are you serious?

Scrap all the vw stuff (I know its all good but setting it up is a sod) and fit an adjustable bias valve with a lil bit of gental playing in wet car park you'll be sorted

jamiegolf said

my cabby is a 1980 model, and it has got the rear beam valve and its got a smaller fuel tank than my other gti thats on a 1985 plate. mine must just be odd!!!!!! is there any particular astra that i need to get the valves from? or is it any one with the rear disks? i did think about putting an adjustable bias valve in but i was wondering how you would plumb it in cus theres 2 brake pipes going to the rear of the car? do i need 2 adjustable bias valves?

You shouldn't have, and don't need the in-line valves. You'll need the load compensator off an 8v mk2 GTI, that should do the trick. I think it is possible to adjust these, not recommended but possible.

Fitting an inline bias is feasable but you'll loose the dual split circuit and need to re-plumb the front to rear lines, a lot more effort than actually fitting the correct items for the set up you've got.

jamiegolf said

i have been looking for a set of 256 or 280mm disks and calipers but there so damn expensive these days!!!!!

Look for a set of vauxhall 16v calipers & carriers. Cheap as chips and easy to find. Just need some sleeved bolts. There is a how to somewhere on the forum…

i found out today that the things that look like limiter valves at the front of my car are acctually just straight joiners!!!!! while i had it on the ramp at lunch time i adjusted the compensator at the back, i never did it when i lowered my car  ops:  and it was holding it open  (car thought it had weight in the boot) :roll:  now it thinks its at normal ride height and it's behaving itself again!!!!! :clap:  it used to lock up in a sraight line on tarmac but now it wont even lock up on loose gravel!!!!! RESULT!!!!!!! its guna be on the road the first of march CANT WAIT!!!!!!!!