Residual brake valves

Hi there,

Some time ago I completed my mk2 servo and master cylinder upgrade, which generally went OK.
During the conversion I took a lot of the old brake piping and replaced with new.
Whilst doing this I removed one of the residual brake pressure valves and subsequently lost it…..
Now I have had the chance to drive the car a bit harder, I have noticed that under hard braking one of the rear wheels lock's up and gets me slightly sideways.
Obviously this is not what I need as I'm looking to do a few track days this summer.
I'm pretty sure that this valve is to blame for this behaviour and I want to re-fit one ASAP (can anyone confirm this?), but cannot find any on Ebay and have had no responses to my requests on here.
My question then is would the Willwood type 10PSI items do the same job? If I cant find any Golf ones?

Thanks in advance,

Bob.

 

I'm not sure if they are actually there to reduce force, but for some other reason? im sure it was posted somewhere what they actually do but I forget. since its a GTI it should already have a bias valve which is there to reduce the brake force. certainly mk2 golf with drums dont have these valve things regardless of if there is a bias valve or not…