Brake Load Compensator

[Dave_R]

Basically where to is it? My rear end was locking up badly at Pembrey but I put it down to the hairpin off the main straight (115mph down to a 2nd gear corner). But took it for a test drive this morning ready for Combe Saturday and the back is locking up all the time, something it hardly done before.

 

[Dave_R]

Been searching ETKA for the past 2 hours and still no joy! Does the Ibiza have a rear load bias valve?

 

[Seatmann]

It's on the rear axle, it goes between the axle and the chassis on the left somewhere so the more weight or lower the rear sits the more force it allows to the rear wheels. If your car's lowered you might need to adjust it to suit.

 

[jcs356]

I don't think you can adjust it, it's just a very basic system. I'd guess it's got stuck.

I seem to remember someone had fitted an in-car bias dial a few years ago - can't remember who.

 

[Dave_R]

I'm thinking it's stuck Jason, cars been lowered for years and never had a problem before so don't think it needs adjusting just a good clean. Left I guess you mean by the passenger side.

Thanks

 

[crezz]

is it the old school type with a big spring that opens the valve with weight?

 

[Dave_R]

thats what im expecting to find later, just going to follow the brakes line back from the rear brakes. Hopefully a bit of WD40 & grease and jobs a good one!

Just looks like I'm going to get wet doing it lol

Think I will be looking into changing it for a in car brake bia's next, at least I can alter the bias for wet & dry to then.

 

[Dave_R]

Right I've the car up on axel stands, been looking around the rear beam & following the brake lines and I cant see a valve or switch anywhere!!!

The brakes come straight from the abs unit under the car towards the passenger side rear then split off over the petrol tank to the drivers side rear.

Any ideas quickly? I'm getting nice & wet under the car at the moment lol

 

[jcs356]

Right, just consulting the Haynes manual:

A pressure regulating system is incorporated into the braking system, this helps to prevent rear wheel lock up during emergency braking. The system is controlled either by a single load-dependent valve which is linked to the rear torsion beam assembly, or by a pair of pressure-dependant valves which are screwed into the master cylinder outlet ports, one valve fitted in each rear brake line.

So they changed the mechanism at some point. My L reg ibiza definitely had the spring loaded gismo on the rear beam. As your Ibiza is newer I'd guess you've got the valves on the master cylinder Dave.

 

[Dave_R]

Nice one! So how the hell does that work??

Thanks Jas!

 

[jcs356]

It's all on page 9-16 & 9-17 of Haynes if you have a copy Dave.

The valve on the torsion beam is on the left-hand rear torsion beam pivot.

The valves on the master cylinder can also be mounted in two positions - either directly into the master cylinder outlet ports, or mounted on the engine compartment bulkhead. Haynes notes that you can't adjust these - either they work or they don't.

So replacement is basically:
Get an airtight seal on the brake fluid reservoir cap.
Undo the valves, with a rag ready to catch escaping brake fluid and something to plug the hole in the reservoir so you don't lose all your brake fluid.
Fit the new one.
Bleed the brakes.

 

[Dave_R]

This is now a misery, I have no valve on the rear beam, no valves on my master cylinder. There are two pipes on it and both have normal connections.

The pipes come/go from the master cylinder along the bulkhead to the abs unit, from there pipe goes to the drivers front, passenger front and another pair run down from the abs unit to the bottom of the bulk head and along the underneath of the car.

Not a pressure valve in sight??? Defiantly confused now!

 

[Fl@pper]

load valve ? never seen one on the rear except Inca I think ???

abs cars go through the abs unit and straight back - all pipes

non abs cars (drums rear) have an inline pressure regulator normally on the bulkhead - pipe in /pipe out

 

[Seatmann]

This is now a misery, I have no valve on the rear beam, no valves on my master cylinder. There are two pipes on it and both have normal connections.

The pipes come/go from the master cylinder along the bulkhead to the abs unit, from there pipe goes to the drivers front, passenger front and another pair run down from the abs unit to the bottom of the bulk head and along the underneath of the car.

Not a pressure valve in sight??? Defiantly confused now!

You don't have a regulator valve thing with abs , abs = anti lock brakes? It has its sensors at each wheel which detect lock up and activate the abs which prevents locking up, if you have lock up on the rear then something's wrong with the abs system. Maybe you should scan the abs unit with vagcom or some other suitable scanner, maybe the light in the dash doesn't work.

 

[Fl@pper]

better still bin the abs unit and plumb in a bias valve

easy to fine tune to track and conditions then

 

[Dave_R]

Yea I started to work that out later but I know on shity French cars that have abs also have rear bias valves that play up when lowered.

Abs light does work, comes on when you turn the ignition, did have the light start on before & turned out to be a loose wheel bearing.

The abs speed detect spigot is on the back of the rear brakes, right?

Any How to's on binning the abs?

 

[Seatmann]

Yea I started to work that out later but I know on shity French cars that have abs also have rear bias valves that play up when lowered.

You don't get load compensators on any car that has abs, they just don't need it but yeh shitty is one of the many words I'd used to describe most french cars

Surely a motorsport site would have info on bias dials/valves etc, might be worth a bit of googling.

 

[Fl@pper]

all depends how far you wanna go ?

keeping servo and original master cylinder ?

 

[Dave_R]

Basically by pass the abs unit then? Will be looking into this now

 

[jcs356]

Ah, my old Ibiza didn't have ABS.... Sorry for any confusion. Haynes manual isn't clear!

I'd also be interested in a bias valve instead of ABS option.