Front brake locking / pressure valve

[oneandtwo]

My parents have a 56 plate 90csw, 

The brakes have never inspired me with confidence, although it passes mot each year with no problems. They do stop ok, but are nowhere near as sharp as my own defenders, however I noticed in the wet when braking hard will lock up the offside front wheel consistently.

Last month I fitted new TRW servo, new Delphi master cylinder, new calipers all round, new pads, new discs, replaced every hard brake line with new and fitted goodridge hoses. I rebuilt both axles / new bearings / new swivels etc while I was at it. All the tyres are matched General Grabbers, and luckily it is the County version without ABS.

Still after all this it is still doing exactly the same - locking the offside front wheel up first. It will lock it in the dry if stamped on hard enough. The only part I haven’t changed for new on the whole vehicle last month is the brake pressure valve on the footwell - NTC8836

Does anyone know how the pressure valve functions? The plumbing of the brakes is that the near side front brake is fed directly from the master cylinder, whereas the offside one with the problem routes through this valve along with the rear brake pipe;  my thinking is that there may be an internal fault with the valve and the offside front is receiving a boost in pressure from the rear.

Edited May 14, 2018 by oneandtwo

[Scotts90]

It's a pressure reduction valve so it won't boost anything. Fitted on 90 models to stop the rears from being over braked, it's a ball that moves inside to limit flow to the rear circuit dependent on vehicle attitude under deceleration.

 

 

[oneandtwo]

I though that was the function of the G valve on earlier vehicles- this valve block is mounted transversely across the vehicle so not sure how a ball and spring would function as it would need to be mounted lengthways like the old G valve / series PDWA valve was?