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        General >> Problems >> Brake Imbalance
        
(Message started by: shooshyneman on Jun 24^th, 2008, 5:35pm)

Title: Brake Imbalance
Post by shooshyneman on Jun 24^th, 2008, 5:35pm

Scorpio 2.5TD Estate R Reg MOT!! Nearside FRONT brake is 50% weaker than O/S front brake?
I have changed flexible rubber hose. Made No difference.
So I fitted a NEW N/s brake caliper Still made no difference.
Discs are in good shape and pads are nearly new similar wear on both sides. Has anyone any Ideas?

Title: Re: Brake Imbalance
Post by a900one on Jun 24^th, 2008, 7:23pm

I think its a split system, so may be master cylinder.

Title: Re: Brake Imbalance
Post by shooshyneman on Jun 24^th, 2008, 8:50pm

master cylinder has single pipe to ABS system so unlikely.

Title: Re: Brake Imbalance
Post by Highlander on Jun 24^th, 2008, 9:47pm

http://www.fordscorpio.co.uk/manual/brake/BrakeDescript.pdf

There is a seperate circuit for each front brake.

Title: Re: Brake Imbalance
Post by shooshyneman on Jun 24^th, 2008, 10:44pm

So does the master cylinder feed the two circuits? or is it this hydraulic unit ?? 97 on as its a '98

Title: Re: Brake Imbalance
Post by Tompion on Jun 25^th, 2008, 12:11am

2 pipes from the master cylinder on my 2.3, I assume the same for yours.

Title: Re: Brake Imbalance
Post by Snoopy on Jun 25^th, 2008, 7:39am

The picture of the TWO pipes can be seen at no 5 HERE (http://www.fordscorpio.co.uk/manual/brake/MasterCylinder.pdf)

Its only the ABS unit that changed with the years . its all on the brake manual on the main site

Title: Re: Brake Imbalance
Post by gozz on Jun 25^th, 2008, 9:39am

shooshyneyman.
On my R reg 2.3,the front m/cyl pipe goes to the ABS unit and thence to the rear brakes,the rear m/cyl pipe goes to ABS unit,thence via two pipes to the front brakes.Could yours be the same ? Maybe your problem is being caused by a faulty ABS unit.
GOZZ.

Title: Re: Brake Imbalance
Post by shooshyneman on Jun 25^th, 2008, 3:08pm

OK I have two pipes from the master cylinder both go to the ABS unit.
Then one set must split to a front wheel and both rears and the other must go to the other front. As I have an imbalance on the two front ones what is controlling the pressure? Master cylinder? or ABS?

Title: Re: Brake Imbalance
Post by Highlander on Jun 25^th, 2008, 3:15pm

As far as I understand from reading the brake manual, one pipe controls one front wheel and both rears.
The rears are common to both circuits.

That being the case your rear brakes will still get the effort they require from the "working " circuit.

I'm still with the dodgy master cylinder theory ;)

Title: Re: Brake Imbalance
Post by shooshyneman on Jun 25^th, 2008, 4:17pm

Looking at the pipes on the car, both rears are connected at the back, a single pipe comes forward to the abs where a front wheel pipe goes in. This seems to be fed from the master cylinder. The other pipe from the master cylinder goes to the other side of the ABS and seems to feed the other front wheel. I dont know what is going on in the abs but I feel that the brake pressure is generated in the Master cylinder supporting the idea that this is at fault

Title: Re: Brake Imbalance
Post by shooshyneman on Jun 25^th, 2008, 5:40pm

On closer Inspection It seems my original premise was wrong, now the manual makes a little more sense. The master cylinder feeds the abs with one pipe which then goes to the rear brakes. The other master cylinder pipe feeds the abs which feeds the two front pipes. The master cylinder seems less likely now. So what is going on in the abs? A crushed pipe came to mind but can find no evidence of that.

Title: Re: Brake Imbalance
Post by Tompion on Jun 25^th, 2008, 8:39pm

I managed to put one of the spring retaining clips on wrong, it caused excess travel on the pedal, a bit like air in the system. I haven't a clue how it affected the balance, but worth a check they're as shown here:
http://www.fordscorpio.co.uk/manual/brake/FCaliper.pdf

Title: Re: Brake Imbalance
Post by Highlander on Jun 25^th, 2008, 8:43pm

I dont know how the ABS system actually works but i would assume it is passive until actually called into action and has no input into "normal" braking.

Its still screaming master cylinder seals at me :)

Title: Re: Brake Imbalance
Post by gozz on Jun 25^th, 2008, 10:47pm

You could always try swapping the two front pipes on the ABS unit,then test the balance again.That would put the ABS theory to bed.
GOZZ.

Title: Re: Brake Imbalance
Post by shooshyneman on Jun 26^th, 2008, 9:47am

Thanks Gozz that seems a good idea. But in his wisdom Mr. Ford has put different size connectors on those pipes. To stop me doing it wrong I presume.! But looking carefully at this

Title: Re: Brake Imbalance
Post by shooshyneman on Jul 2^nd, 2008, 12:50pm

Ahh the simple things---- After trying swapping the pipes problem disappeared!
I now think there must have been air in the pipes. After a good bleed problem gone MOT passed till next time. :)