Bbb, Brakes Behaving Badly (now Fixed)

[CarlC]

Hi All,

Finally got my car back on the road late last night. Completed a full rebleed of the brake system using 5.1. Brakes previously where spongey and generally crap. However, now when I brake the car does nothing for a maybe one or two seconds and then brakes come on very positively and stops the car nicely. I can here what I think is the brake pressure pump going when I stop which was never really noticable before. Does the fuilds just need topping up or do I have a more serious problem to worry about ?

[mangel]

Carl, can't offer you any asistance about the brakes but just to say I have one in the same colour with amongst other problems a very similar brake issue. Any assisatnce any one can offer would be greatfully recieved.

Then I just need to get rid of the rattly top end and low oil pressure and drag it by the scruff of the kneck through an MOT!!!!!

[CarlC]

Hi Toby,

Wow! same colour really ? Is yours down as a Medina Green ?

I've noticed there is another Green, that in pictures looks the same as mine but is a darker shade. Also the Aqua Blue can look very similar to the Medina Green in certain lights.

I've yet ot see another Medina Green Esprit. Apparently there was another Medina Green S4 at Donnington this year but I never saw it. It is obviously a very rare colour. Looks superb with the sun on it, could lamost be two tone...

You'll have to get your car sorted and get to one of the meets in the next month or so.

[ansellb]

Carl, Toby

I have the same symptoms on my S4 (even though it's not Medina Green...) - and I'm absolutely certain it's because the hydraulic system needs bleeding.

I've just upgraded from Toyota brakes to Brembos, and as I was in a bit of a hurry to get it on the road, I did a less-than-scrupulous job of bleeding it. The "delayed action braking" feeling is only minor - but it's definitely noticeable. And it definitely wasn't there before. I reckon there's still some air in there.

By the way, I installed Speedbleeders (clicky), so I'm expecting it to be quite easy to get the bubbles out.

So that's my advice: give it a thorough bleed-through, and see if that fixes it.

Ben

[CarlC]

Those easy bleeds look like a great idea.

I hope your right about the re-bleed but I went round three times to ensure I got all the old sh1t out of the system and until I could see nice clean fluid coming through and no bubbles. The old stuff was black and disgusting.

It does sort of feel as if there isnt enough fluid in the system becuase once it pressurises after a second or two the brakes have tones of bite and feel good. Just done the 40 pumps on the pedal, ignition off and check the level. There does appear to be fluid in there, about half full. But it was yellow in colour and not the normal transparent colour ?

[mangel]

It is indeed a tru Medina Green and a 96 S4 which I believe makes it rather rare.

Its been sat around the back of te PO house for the last 7 years so its a little rough to say the least. Was debating what to do colour wise, it needs paint and not covinced they'll ever get a good match to it so was going to change!? Not sure though.

Going to employ some bright coloured distrction techniques in the mean time to keep the eyes occupied on things other than bad paint work!!!

[Bibs]

I dread to think!

[Backmarker]

Boys,

Sounds like air in the system.

Could any be creeping back in. Seem to remember this is a two person job. Girlie to pump the pedal and chap to tweak the nipples tight..........then move on to the brakes.

Try again Carl. I'm sure Sam'll be ok with that plan.

Graham.

[CarlC]

It is indeed a tru Medina Green and a 96 S4 which I believe makes it rather rare.

Its been sat around the back of te PO house for the last 7 years so its a little rough to say the least. Was debating what to do colour wise, it needs paint and not covinced they'll ever get a good match to it so was going to change!? Not sure though.

I had a scratch on the side of the car so I got the Chips Away people in and the colour matched it perfectly. Took a bit of looking on their system and colour guides but sure enough they had a colour card for it and it was spot on. Personally I couldnt change the colour as its origonal and very rare.

So a 96 Medina S4. It must have been near the end of the production of the S4 then. I hope your planning to get her back on the road.

... Seem to remember this is a two person job. Girlie to pump the pedal and chap to tweak the nipples tight..........then move on to the brakes.

Try again Carl. I'm sure Sam'll be ok with that plan.

Graham.

Hi Graham,

Ill get some pictures of the nipple tweaking and you can let me know if I've got the technique right next time we meet up!

[Backmarker]

Carl,

Better PM them...........don't think Bibs approves of that sort of thing.

Graham.

[CarlC]

.... some tweaking later ...

Ok, I think I may have an idea on the brake problem. Just 'nipped' out to get some more 5.1 and top-up the system as it was a little down. I also stopped to check my tyre pressures. My right rear tyre was very hot to the touch with all other wheels including turbo/manifold side nice and cool.

Could this be I ahve some how inbalanced my brakes with the right rear biting first then the rest coming on later ?

Edited July 9, 2007 by CarlC

[Backmarker]

If the rear is that noticeably hotter than perhaps the brake is binding on. Can you push the car with the handbrake off? The heat can cause the fluid to to turn into a vapour, which is why brake fluid with a higher boiling temp has to be used in race cars/bikes. Extreme heat puts bubbles back into the system and reduces the amount of fluid. Free that rear brake off first I think.

Graham.

[CarlC]

Thanks Graham,

I know I could turn the disc by hand, 'with a bit of force' as the last thing I did before I put the wheels back on. But its a great point you make about the heat and the air build up.

However this was a problem the moment I got the car of the axel stands. The brakes were dreadful. I just let the car roll slowly out of the garage and the brakes didnt come on. The only things I have done is to remove the rear calipers when checking and cooper slipping the pads and bleed the brake system. I have not replaced any of the pads.

Could it be that the other calipers/brake lines have air in them to cause such an inbalance?

If I wanted to stop at any reasonable speed 50+ then it can take about 2-3 seconds for the car to really start to slow down.

Edited July 9, 2007 by CarlC

[mangel]

Yep its on the way to a come back!!

Oi Bibs, I've never been quite s Ostentatious as Karl, I like my mods with a little more subtlety.

If they can match the colour then the green stays!!

[Backmarker]

Carl,

You need to try it again. It might have rolled out the garage when you first did it but will it roll now?

If that brake is binding on it needs releasing. The system should then in my opinion be re-bled. Those air bubbles can make there way just about anywhere.

Graham.

[andydclements]

As you've not got an answer that's resulted in rectification lets just clarify what has been done exactly.

Rear pads- removed, copper grease used on metal mating faces (back & sliding areas?)

Front pads- Did you do anything to them?

Changed fluid, by prolonged bleeding of system. New fluid is of what type?

Do you know the type of the old fluid?

Is there any chance that any copper grease/ other contaminant may have found its way onto either the friction material or the discs?

Handbrake- is the handbrake as effective on both rear wheels?

Are the handrake cables set to the correct free length?

Have you got a balance scale (type of thing used to weigh fish etc) , if so, when the back is on axle stands and handbrake off, what force does it take to rotate the wheels?

Andy

[CarlC]

Carl,

...You need to try it again.

Topman, thanks Graham.

Ill get the wife to pump me up so I can start on those nipples tomorrow.

Ill also check the car for roll and re-bleed the system.

Pictures via PM when done!

Hi Andy

Thanks For your reply....

Q1) Rear pads- removed, copper grease used on metal mating faces (back & sliding areas?)

A1) Yes, but just the backs of the pads. Obviously not the disc face of the pad

Q2) Front pads- Did you do anything to them?

A2) Removed pads and copper geased back of pad.

Q3) Changed fluid, by prolonged bleeding of system. New fluid is of what type?

A3) Yes, Wife in car pumping, me nipple locking/unlocking into milk bottle to watch for bubbles.

Q4) What type of old fluid?

A4) New fluid is Dot 5.1. Old Fluid was probably Dot 4 at a guess and probably hadnt been changed for years.

Q5) Is there any chance that any copper grease/ other contaminant may have found its way onto either the friction material or the discs?

A5) Some trace amounts may have got onto the disc from general handling of copper slip/oil but nothing visibly obvious.

Q6) Handbrake- is the handbrake as effective on both rear wheels?

A6) I'd need to check this back on the jack. Whilst on axel stands the hand brake was not applied.

Q7) Are the handrake cables set to the correct free length?

A7) Erm... Not a clue on this one. They had not been adjusted/touched in between ok brakes and sh1t brakes.

Q8) Have you got a balance scale (type of thing used to weigh fish etc) , if so, when the back is on axle stands and handbrake off, what force does it take to rotate the wheels?

A8) Great question! I probably have or can get one. I would say that when the car was on axel stands and I rotated the disc myself to check it wasnt locked on, a fish scale/balance scale would probably have not moved it. It did take some force to rotate both rear wheels. I had assumed this was because of the brake bleed done previously.

[andydclements]

Q8) Have you got a balance scale (type of thing used to weigh fish etc) , if so, when the back is on axle stands and handbrake off, what force does it take to rotate the wheels?

A8) Great question! I probably have or can get one. I would say that when the car was on axel stands and I rotated the disc myself to check it wasnt locked on, a fish scale/balance scale would probably have not moved it. It did take some force to rotate both rear wheels. I had assumed this was because of the brake bleed done previously.

Something doesn't seem right there.

There will be slightly more drag on the rear wheels compared to the front, allowing for gearbox/ differential drag and differences in bearings etc, but no great difference.

You should be able to turn the wheel with the car out of gear and on stands using your little finger on the tyre, or using a similar force as the front wheel bearings on an SE are torqued (cannot remember the figure but at wheel bolt it's only a few pounds (or is it 1 pound?).

I'd say, check the hand brake is fully dis-engaging, if it's not it may give extra drag, or will cuse the pads to sit too far away from the disc.

If the hand brake is OK, then look for pistons sticking in the bores. that wheel that was getting hot is the primary suspect.

Andy

[CarlC]

Hi guys,

Thanks for the input so far. Tonight was the first chance to have a go at some of the suggestions and try a few things out. Well I cna say the rear calliper(s) dont appear to be siezed or sticking on as the car rolls ok with the hand brake off as you would normally expect. I've managed to re-bleed my front calipers and all I get is nice clean fluid and no bubbles at all coming through. My drive has a fair slope to it and I cant get to the rear calipers to rebleed them tonight.

Driving slow tonight around my estate road what is now unusual is that when I press the brake pedal I can hear fluid moving ? Normally the braking is silent.

The problem is still the same so far...

How much fluid should I be pushing through the rear calipers when bleeding them later ? I guess on the fronts I did about 35ml.

[andydclements]

the amount depends on a few things, mainly

How much it takes to remove all the old from the system,

Did any air get into the system.

I have put 1/2l through the rears on some occasions, mainly if I disturbed a pipe or connection near the front. I use the ezi-bleed (Gunson's ) system so 1/2l only takes a few mins, mainly time to top it up.

One thing we haven't explored (excluding this noise) is what happens for the firat few seconds of braking.

Uncunciously you (and probably al of us) will apply the brake progressively up to the point at which it starts to have the level of effect we want. On that basis it's quite normal for any delay in action of the brakes to be a lack of action at the given level of pedal action. It may be that as the car doesn't slow down you apply more pressure on the pedal and so get the braking action you need.

So the dealy of effect could be a higher then anticipated force needed, which would all point to air/ soemthing having a negative impact on braking.

Personaly, I'd got for pull all the pads again, and then re-fit them having inspected & de-glazed them and the discs / rotors. (did you de-glaze the rotors ?)

Andy

[CarlC]

Hi Andy,

Thanks for the info. I think Ill get the car back to my dads place, remove all the pads, clean the disc and pads and do a major rebleed of each of the calipers in turn as you suggest. Something is really not right. But there isnt alot to check either which is puzzle.

I get your point about the progressive brake but If I slammed on at speed it would still take a very worrying few seconds before the brakes feel like they are biteing. When using the brakes it inst progressive at all. If you were the passenger it feels like I start to break then slam on! Not quite as dramatic as that but it illustrates the feeling.

Any other top tips in the mean time greatfully recieved.

[ansellb]

Carl

I've just been consulting the manual, and there's a section that talks about "Non Uniform Pedal Travel". Intriguingly, you need to use the Tech 1 bleeding procedure to deal with it. Anyone know WTF the Tech 1 bleeding procedure is?

Oh yes. That manual extract in full:

JF.8 - BRAKE BLEEDING PROCEDURE

If a Powermaster IIIA booster/master cylinder assembly, or a pump/accumulator assembly has been replaced, or if air has entered (or is suspected in) the brake lines, the entire brake system including all hydraulic units must be bled at each wheel. If only a hydraulic part of the booster/master cylinder or pump/ accumulator has been replaced, and air has not entered the brake lines. It may only be necessary to bleed at the booster/master cylinder bleed nipples.

Manual Bleeding

1. Ensure ignition is switched off.

2. De-pressurise the accumulator by FIRMLY applying and releasing the brake pedal up to 40 times. A noticeable change in brake pedal feel (to a hard pedal) will occur when the accumulator is completely discharged.

3. Clean the reservoir cover and top of the reservoir before squeezing the release tabs and lifting off the cover and diaphragm assembly.

4. Fill or top up both front and rear compartments using only DOT 4 brake fluid from a sealed container until levels reach the full marks.

IMPORTANT - Use only DOT 4 brake fluid. Do not use DOT 5 silicone fluid, or any fluid which has been exposed to the atmosphere for more than a brief period, or any fluid suspected of being wet, dirty or contaminated.

Refit the reservoir cover and diaphragm assembly.

5. If a replacement booster/master cylinder assembly has been fitted, or if there is difficulty when trying to bleed the front master cylinder sections, ensure all air is removed from the master cylinder body by opening the brake pipe tube nuts on the master cylinder (front two only) approximately two turns, or until fluid begins to bleed. Torque tighten the pipe nuts:

- Front pipe (LHF brake) M13: 24 - 26 Nm (18 - 19 Ibf.ft)

- Second pipe (RHF brake) M12: 22 - 24 Nm (16 - 18 Ibf.ft)

6. Bleed right front wheel brake:

- Attach bleeder hose to caliper nipple and submerge opposite end in clean brake fluid.

- Open bleed nipple.

- Slowly depress brake pedal.

- Close bleed nipple.

- Release brake pedal.

- Check fluid level and top up as necessary.

7. Repeat step 6 until the brake pedal feels firm at half travel and no air bubbles are observed in the bleeder hose.

8. Repeat steps 6 and 7 on the left hand front brake.

9. Turn the ignition on and allow the pump to run and pressurise the accumulator. NOTE: Turn off the ignition if the pump runs for longer than 60 seconds, and refer to

[Backmarker]

Carl,

The re-bleed sounds wise.

Do you have to pump the pedal to make the brakes to come on or is "delay then wham"?

It sounds as if there's not enough fluid in the system. This might explain why you can also hear it moving. If there's air in the system then this will stop you from putting the right amount of fluid in. Need to make some space by getting the air out first then top up with right amount of fluid.

Once air is in the system it can be right pig to get it all out.

Graham.

[greenman]

Hi Carl, You state that you have used DOT 5.1 fluid ,and in the manual text it states do not use Silicone only DOT 4.

I have just purchased the Silicone Fluid for my car (not used yet),now having read this I need to know why it should not be used.

Can anyone on the Forum provide the answer ?

Thanks Ben for the manual write up

Trevor.

[andydclements]

Hi Carl, You state that you have used DOT 5.1 fluid ,and in the manual text it states do not use Silicone only DOT 4.

I have just purchased the Silicone Fluid for my car (not used yet),now having read this I need to know why it should not be used.

Can anyone on the Forum provide the answer ?

Thanks Ben for the manual write up

Trevor.

5.1 isn't Silicone, 5.0 is Silicone.

silicone fluid forms a nasty gunge with mineral based stuff, and the rubber seals have issues as well.

Andy