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[Big Rod]

Right guys, I'm really desperate!! (I know I posted this elsewhere, but I haven't fixed the problem yet.)

Sorry for the long post, but Iwanted to post as much info as poss'.

I have an 'L' plate 2.0 16vCD saloon that I intend to travel to Naples in at the end of September on the Staples2Naples banger rally. Anyway, enough about that.

Amongst the jobs that needed doing for MOT and otherwise, was a bright idea I had to 'upgrade' the front brakes to Senator 24v spec'. TBH, while the disks were slightly bigger, I doubt it'd have made much improvement, but the brakes that were on it were past their best anyway, so seeing as I had a brand new set of Senny calipers/rotors/pads lying in my garage, I thought it'd be a good idea to kill two birds with one stone.

Anyway, after replacing the brakes, the pedal was spongy. It would go so far down then sink another inch or so. My friendly local grease monkey tells me that they're not good enough for MOT.

So I set about trying to diagnose the problem and started by bleeding the brakes. I tried an ezibleed and when that didn't work I tried the conventional method and when that didn't work, I tried clamping the flexi hoses and doing each one individually and then I did it again with the engine running. That didn't work either.

So I tried changing the master cylinder then going through the rigmarole of bleeding the brakes again and there was still no change.

I then clamped the front brakes off and the pedal was as hard as a rock, so I deduced that the problem lay with the Senator brakes that I fitted. I surmised that the Omega master cylinder wasn't up to the job of operating the bigger Senator pistons. So I made the executive decision to buy new rotors and pads and give the old calipers a bit of a service and that should rectify the problem.

So I did that last night. Nice new set of rotors and pads and I ensured the calipers were moving freely.

I thought it was slightly better, but grease monkey says they're still substandard!!

So I'm stuck and in a hurry to fix it.

Help!!

S2N is only eight weeks away and I want to use the car to prove it's at least a bit reliable!!

[Marks DTM Calib]

Did you definately get all of the air out of the calipers.

The method that I use is to clamp the flexi hose, open the bleed nipple and squeeze the caliper piston fully in. Then with an ezi bleed fitted and the caliper still fully in, release the clamp on the flexi hose. Once fluid starts to come from the bleed nipple you bleed as normal.

That way you should get rid of all the air in the caliper...


......I assume the flexi hoses are ok?

[Matchless]

When you clamp the front hoses the pedal is hard.
You have tried two different caliper set-ups with same soft pedal.

Could it be the hoses? I havnt seen this happen for over 20yrs but it used to be a problem when the hoses were begining to perish internally. Have someone press the brake pedal when you are holding the hose, if it seems to expand it is duff. Compare with another car to confirm.

Otherwise it has to be air trapped in the calipers. Try removing the pads and replace with something much thinner, then press brake pedal to push out piston onto your thin packer. Now release bleed nipple and force piston fully home to (hopefully) expell any air trapped in the piston.
Brand new calipers can be a problem if the fluid doesnt 'wet' all the inside surfaces properly, leaving an air bubble stuck to a surface. Dismantling and wiping every surface with fresh fluid fixes this.

HTH

[Matchless]

Oi, stop typing so fast, or at least shout that you are fielding it!!!!

[Big Rod]

I did think on the flexi pipes Mark 'cos the symptoms are like one of them's ballooning, but I got my mate to stand on the brake pedal while I inspected them and there was no bulging or anything like that on any of them.

I'm 99.9% certain that there's absolutely no air in the system whatsoever. I've probably run about 4 - 5 litres through the sod!! Costing me a fortune it is!!

[Matchless]

When someone stands on the pedal for you is there any sign of movement in the caliper / mounting / pads etc to indicate something not sitting flat or distorted etc?

[Marks DTM Calib]

Running fluid through doesn't guarantee no air, it just tells you that fluid is getting from the res to the bleed nipple....

[Salty]

Right guys, I'm really desperate!! (I know I posted this elsewhere, but I haven't fixed the problem yet.)


Anyway, after replacing the brakes, the pedal was spongy. It would go so far down then sink another inch or so. My friendly local grease monkey tells me that they're not good enough for MOT.

The brakes on my senny used to do exactly this, it had the larger rotors on it, but it  always sailed through its MOT. I thought there was a problem but obviously not according to my local testing station.

[Big Rod]

Running fluid through doesn't guarantee no air, it just tells you that fluid is getting from the res to the bleed nipple....

OK, I'll see if I can get time to try out the more thorough method tonight.

Cheers,

Rod.

[sounds2k]

there is a known issue whereby if the brakes are bled manually, that air bubbles can get trapped in the ABS unit, resulting in the brake pedal travelling to the floor. The fix for this is to pressure bleed whilst using TECH1 to activate the ABS pump ... probably beyond the average back-street emporium?

[Big Rod]

probably beyond the average back-street emporium?

And remarkably enough, me too!!

The fact that the pedal goes so far, stops briefly then sinks a bit further bemuses me. I always thought that air in the system caused the pedal to be springy. Or am I way off the mark?

[TheBoy]

not a servo problem?

[Big Rod]

not a servo problem?

So far as I can make out, no.

I've done the 'start the car with your foot on the brake test and it seems to work just dandy! The wierd and frustrating thing is that the pedals' absolutely rock hard when the engine's not running.

[sounds2k]

a certain program that will not be mentioned has this to say:

ABS - brake pedal goes to the floor

Models:
Corsa-B 93.5 ..., Tigra 95 ..., Astra-F 92..., Vectra-B 96..., Omega-B 94..., Frontera 92..., Monterey 92..., Carlton 87..., Cavalier 89...

Engines:
All

Option:
ABS

Group:
H - Brakes

Troublecode:
Non

Complaint:
Poor Performance
Brake pedal goes to the floor.

Cause:
Air bubbles are trapped within the ABS unit.

Special part:
No

Production Solution:

Remedy:
Use TECH1 to operate the ABS unit pump whilst simultaneously bleeding the system with a pressure bleeder.

... it may or may not be your problem ... but I'd have thought that the ABS wouldn't be on with the engine off .... ?

[Big Rod]

Don't know what to say Sounds2K.

I wouldn't have thought having the engine running while bleeding the brakes would've made no difference TBH. If there's an airlock, it's there servo assistance or not.

So do you think my best bet is to find someone with a tech1 and get them to run the ABS pump while I'm bleeding the brakes?

Is there no way I can frig it to do that without the requirement for tech1?