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[JamesV6CDX]

Driving to work today, in my V6 Omega, noticed something i wasn't very happy about.

I was descending a steep hill, and the traffic in front all stopped quick, so I did the same, I used my brakes very firmly.

The thing that worried me, is that although initially the braking was good, when I let my foot off the brakes and re-appled them firmly again, the pedal felt VERY hard, (I was nearly standing on it!) with little braking effect. It was like there was no servo assitance - maybe I emptied the servo on the first jam of the brakes, so it wasn't ready for the second? Scary. Recently I reckon I need more brake pedal effort than I used to in general.

Any advice would be great.

Cheers
James

[Gwilym]

James,

You aren't having much luck are you.

How is the other project coming on

[JamesV6CDX]

No, I'm no having much luck. Beyond disks/pads etc I'm not a brake man.

The other proect - no progress at all.

[Tony H]

Sounds like brake fade what make pads have you got on the car? what speed were you doing down the hill? worth having a quick look at the pads to see if they've glazed

[JasonH]

I'd check the vacuum pipe from the plenum, just behind the ICV. I think you may have a vacuum leak.

[hotel21]

I agree with both the above, both vacuum leak and brake fade.

A test for vacuum (unsure if it still applies to omegas, but still works when I tried on mine) is to switch off the engine and pump the brake pedal several times until it goes hard.  Keep foot depressing the pedal (left foot?) then start the engine.  Pedal should sink further as the vacuum builds back up.  If not, it points to a vacuum problem somewheres.

For glazed pads, I usually try a few hard braking sessions on an empty roadway.  Give a few mins between applications for the discs/pads to cool a bit then repeat.

Uses a few hundred miles of Ferodo in a short time, but good for clearing the genteele driving results!

HtH

B

[JamesV6CDX]

If this helps....

I have tried braking really hard on an empty road, to try and clear the pads. Interestingly, when I do this, the brakes get MUCH sharper for a few miles, and then go back to their old selves.

Tried the vaccum procedure, it doesn't indicate a leak.

So - Disks/pads?

[JamesV6CDX]

Speed - about 60mph

[hotel21]

Are the pads newly fitted?  If yes, genuine Vauxhall (preferred) or aftermarket?  If aftermarket, may be too hard and are, effectively, racing pads that require heat before reaching optimum operating temp.  When they cool, back to wooly brakes again.

Car new to you?  If yes, then see last couple of statements above re hard pads.  If no, then thinking more a stuck caliper(s) causing pad(s) not to release clean from disc, gently rubbing and causing reglaze.

Park on a very gently slope - empty car park type camber -  and release the brake.  Car should gently roll downhill.  If not, brakes are binding a tad/calipers not releasing.

Once it all cools down again, (tomorrow morning best) then go for a gentle drive (couple of miles) trying not to brake for as far as possible or if you have to, brake lighttly.  What is then suggested is to (gently, it may be hot) touch each disc around the car to see if its hot.  If yes, then problem wheel found, see sticking caliper option.  If no, then kinda stumped!!    

HtH

B

[hotel21]

Just realised your car has been off the road for a while.  I recon the calipers are stuck somewhere.

[JamesV6CDX]

Noooooo

This car is my V6 CDX - NOT the project car. I do 500 miles a week in this one!!!

[hotel21]

Noooooo

This car is my V6 CDX - NOT the project car. I do 500 miles a week in this one!!!

OOOps!  

[JamesV6CDX]

No worries mate, I reckon i need new disks and pads..

[Tony H]

No worries mate, I reckon i need new disks and pads..

Not a bad price T.C did my fronts earlier in the year discs + pads cost around £80 ish if my memory serves me well

[sounds2k]

now this is guesstimation on my part as I'm not a brake expert either ... but how long is it since the brake fluid was changed, sounds to me like it could be boiling as it's good initially then very poor?

then again, I could be talking rubbish ...  

[JasonH]

Good point Sounds2K. If the fluid is old and contains a fair bit of moisture it will boil at 100C in the calipers. That means no brakes, well braking on steam rather than brake fluid.

New brake fluid boils at around 300C.

[Markjay]

Good point Sounds2K. If the fluid is old and contains a fair bit of moisture it will boil at 100C in the calipers. That means no brakes, well braking on steam rather than brake fluid.

New brake fluid boils at around 300C.

300C? 300C? anyone mentioned 300C?  

[familyman]

If servo action okay worn pads and discs below min thickness can do this as mentioned. check fronts but check min thickness of rear discs as well, often overlooked, rear brakes work nearly just as hard as the front due to abs and no load propotion valve, brake balance slightly different with abs.  Not sure of price of pads from vauxhall but i have nearly always used EBC greenstuff pads, ignoring the max power boys brigade these pads especially with new discs give nice sharp brakes with good feel. although as i said i'm new to Omega so not sure how they would be, I would suspect as good as if not better than original. also no noticeable difference in pad/disc life

[Matchless]

I had exactly the same symptoms on my Elite when I first got it running, very scary with caravan on the back.
Couldnt find any cause so fitted a set of genuine Vx pads and transformed the brakes, much more responsive and no fade.
I think the ones fitted were marked Powerstop or something similar.