Brakes Not Working

[Guest 2b cruising]

All I can think of is that they are not sitting on there mount exactly in line with your discs, so the mounting is bending under pressure with your servo.

This would explain why when not running your pedal is hard and. At the top when not running. Just hydraulics pressure might not be enough on its own to bend the mounting bracket to line up your calipers to the discs.

If this is the case, it is most likely your new calipers are at fault, not the mounts, as brakes were good before.

I must emphasise that if the pedal is solid without servo, there is no air in the system. If there was your pedal would be spongy and not solid as you reported.

[Dave Ed]

Here is a pic of the drivers side, hopefully it will upload.

I think the flex was just the calipers straightening up the disk when the wheel was off.

I have the original caliper mounts fitted with the new calipers and will check the pipes for bulging.

An issue I have is that I painted the calipers before I fitted them but if they are wrong I'll return them regardless. I've missed my 10 day window for a retest but really want to get this fixed.

I'm going to disconnect the servo and see if it changes the snag but this will be at the weekend now unfortunately.

[Guest 2b cruising]

You will have to block off the vacuum pipe, or you engine will run very rough drawing air in after the fuel delivery point.

[Longboarder]

Rats. That looks like the right early girling type calliper. Might be worth checking the alignment is good. If you take off the front wheels and replace two bolts each side to hold the discs in place. Then press the brake pedal. The calipers should centre themselves on the disc and you should barely be able to get a 10thou feeler gauge blade between either pad and the disc. The piston should not retract. It should just stop forcing the pad onto the disc.

The calliper in the picture is the correct right hand calliper. The left hand calliper should be a mirror image of it and I would expect it to have a different part number. Like the pic below.

Clutching at straws? Sorry to be stating the obvious. Can you even put them on the wrong sides like you can with the Teves callipers?

 

Nigel

Edited July 23, 2015 by Longboarder

[Guest 2b cruising]

When painting, did you paint the mating surfaces on the mounting.

If yes, remove them leaving the pipes connected, clean the mating surfaces down to smooth bare metal, remount and retry.

[Guest mower man]

Been reading this with an open mind and have a couple of ideas 1 master cylinder is goosed why? with bleeding you have pushed things past there normal working area and took the edge of the seals which have been undisturbed for some time anew mc is req 2 the replacement must be exactly the same as orig fitting bigger smaller is getting into dark areas 3 the servo wit either work or not no inbetweens 4 not belittling your abilities is it worth getting a pro to have a look , i was/am onthe tools for 50 years but I some time still need another pair of eyes or a different brain to see the odd prob . I hope some off this helps and will have further thoughts about it and perhaps come back to you later mick

[Dave Ed]

Mick.

I've replaced the m/c a couple of days ago and its still he same. I'm convinced the calipers and m/c are like for like.

Except for the calipers the only thing I touched in the system was the handbrake adjustment.

Front and rears have had a full bleed and refill.

I'm sure it's the calipers, I'll check clearances etc soon otherwise it's going to my local garage for 2nd opinion. I'm away with work again soon so work on the car stops again.

[Grim]

Did you try my suggestion of lubrication the caliper piston seals?

[Dave Ed]

No not yet. It's on the list of things to try before I give up and hand it to a pro.

[Guest mower man]

You say the only thing changed is the calipers and the m/c and you are convinced they are like for like yet you have no usable brakes where you had some [if not perfect] before and probs only started after swapping calipers? it does not make sense, the bit of flex movement you say was with the wheel off? are the discs secured with screws or have you dispensed with them like most and discarded them [ Iran without for twelve years] will cogitate some more mick

[Dave Ed]

Mick.

the disks aren't secured so possibly weren't sitting true to the hubs.

I'm going to check the slide pins and clearance of pads and disk

.I'll also be carefully watching the calipers for movement and the pipes for bulging.

[Dave Ed]

The story so far. Excessive travel in the brake pedal.

 

I have disconnected the front brakes at the M/cyl and fitted bleed nipples.

There was no movement in the pedal with either the engine off or running, therefore I have discounted the servo, master cylinder and rear brakes as if they were at fault I would have had pedal travel.

 

Next I fitted the drivers side brakes to the M/cly and bled the system, the pedal travel was minimal with either engine off or running therefore I don't feel that there is a fault with the drivers side brakes.

 

Lastly I connected the passengers brakes up to the M/cyl and bled the system.

I had minimal pedal travel with the engine off but loads of travel with the engine running.

I dismantled the calipers and checked the seals, all look fine so I put some fluid under the seal like Grim suggested. It didn't make any difference.

 

I then clamped the hose at the caliper end which didn't make much difference.

So I clamped the hose as close to the body as possible, this made a bit of difference but not loads.

This would suggest to me that the issue I have is between the M/cyl and the hose to the caliper, in other words the copper brake line.

 

Just to clarify for all the questions asked:

The caliper movement is the movement on the sliders as the pedal is pressed.

The hoses are not bulging but I aim to replace them at the earliest opportunity to eliminate them from the equation.

The pedal travel is NOT all the way to the floor but it is close,

Normal travel without the engine running is 1-2 ins

With servo/engine running its 6-7 ins (estimated)

I haven't disconnected the servo as I had eliminated it when I checked the master cylinder earlier.

 

Am I right in thinking the caliper on the drivers side is OK when I isolate it using the hose clamp or could it still be operating

I can't see how a solid copper hose could cause this issue.?

 

Thanks so far for all your help and advice. Hopefully I can get this sorted soon.

Dave

[agent_zed]

can you connect the caliper to the m/c with the flexi hose directly? Just put the disc in to stop the piston coming out. That would definitely tell you it is the copper pipe.

[Dave Ed]

I might be able to so long as the threads are the same. I can't see how the copper pipe is at fault. I've looked everywhere and can't see any leaking or pinches on the copper.

 

I think that operating the brakes is overpowering the hose clamp and bringing the caliper into play.

 

It's ironic that the passengers side was fine but I replaced the calipers as a pair and now I have a problem.

 

I'm away with work for a couple of weeks now so will have to contact the motor factors and get a replacement and pick it up and organise the refund.

[Snapperpaul]

You could swap calipers just to test wether it's the copper pipe

If you eliminate all other possibilities and only the improbable is left then it's probably the improbable.

I applause your meticulous approach to solving the problem but don't fail by discounting the improbable