These brakes are awful pls HELP - with video!

[fesuvious]

If all goes to plan there'll be a video here that'll show the problem. 

The fluid in the rear chamber keeps getting badly contaminated with air, plus the issue at the pedal...and the brakes are, shall we say, not the best!

Advice, or even better, has anyone had this problem and cured it?

http://www.youtube.com/watch?v=OAFi-dgd2HM

Edited October 12, 2010 by fesuvious

[MartinL]

Sounds very like the problems I had with the S4, see thread calling all brake Gurus.

In the end I gave up and changed the whole system and fit a "normal" vacuum assisted servo and master from a MR2 , disabled ABS .............job done! very light and very strong stopping power! Hawk fast road/ track day pads and even from cold I can stop without fuss or undue effort.

Lots of talk on hear from people with similar problems and solutions, I tried many ideas with no improvement, I hope you have more luck than me in sorting your system !!

[Bibs]

I may need an S4s with a brake pressure switch problem to go to the factory to test replacement switches, fancy it?

[fesuvious]

Bibs - count me in.

Let me know when you are thinking and Im there!

[Vulcan Grey]

black fluid in the rear only usually means the parking brake is dragging...

replace the fluid and then.

Try adjusting the parking brake.

[fesuvious]

I have fluid in both pots just fine.

Just the rear pot = fluid that looks the colour of milky caramel! The front pot is just fine.

Plus of course the free movement and 'clack' that you can hear in the vid. 

Edited October 12, 2010 by fesuvious

[Jonathan]

Bless you my son - you have reached the Powermaster III brake system ministry.

Love the movie clip btw - GREAT way to

OK, lets quickly straighten some stuff up.

Pump sounds perfectly OK so it's likely NOT the pressure switch - the pump sounds exactly right, and SHOULD come on every 2-3 presses.

The system is a pump pressurised assist - this was from the infancy of ABS and some bright lack decided to forget servo asistance from a conventional vacuum system and use this instead.....I wonder why it never cottoned on ?? (cus it's shite)

The pump runs to charge the system, the accumulator is there simply to store pressure so the pump doesnt run every press - but runs every other press or every other 3 presses - so that operation is normal

The clack sounds like something in the rear chamber.

The 2 chambers OK - front governs the FRONT brakes ONLY

Rear chamber does the power assist and the rear brakes ONLY

IMO there is a problem with the boost system.

The boost system works by using the presursed oil to force the master cylinder piston forward, once forward there is a pressure relief to cut off the oil flow and provide back pressure to the pedal - I think this is the part that is making the clack.

It's like a shuttle collar on a slide hammer, my guess is the rear system is not bled at all or correctly.

Make no mistakes it is a difficult and HORRIBLE system to work on hence the reason why it never caught on and was infact changed for the later Esprits V8 and late GT3's.

I honestly dont think this is a pressure switch at all, it sounds like a master cylinder fault or severe air lock in the boost chamber.

If I could get there and help I would becuase I know how frustrating it is (i'm sure mine did this once or twice before)

TRY this :

Key off and pump the brakes until the pedal goes hard or you fall asleep (about 40 times)

Then walk away for about 20-30 mins - watch TV, have a cuppa

Come back and push the brakes in about 1/2 way - then key on (no need to start the car just to pos 2)

Pedal SHOULD rumble like ABS is coming on - thats the self bleed procedure for the rear chamber.

Repeat about 10 times keeping moderate pressure on the brakes

Come back - inspect the levels

Switch on and let the pump run, wrrrrrrrrrrrrrrrrrrrrrrrrrr...nope still going....wrrrrrrrrrrrrrrrrrrrrrrrrrrr.....

and try it - no garauntee but it might work.

Failing that it's a case of bleeding the back ends like anything.

One thing people EVEN lotus garages get wrong is they PUMP the rear brakes to bleed them....dont, you only need to press the brakes in about 1/4 pressure, they bleed by the boost chamber and the pressure from the pump/accumulator.

Goto halfords and get their 5 litre brake fluid and push about 2 litres through and see if that helps. It's really easy just apply brake pressure and crack the nipple and make sure the level stays topped up and it just flows like a river out.

There are the brake nipples on the master cylinder itself - you shouldnt need to do this, I found they didnt help at all.

You must ensure 100% there are no air bubbles in the back chamber, as the pump runs it'll suck them into the system.

If that doesnt work the thing that got mine to go was to drain the front reservoir and that allows much more stroke on the pedal so it can push air out of the rear chamber - if you bleed the fronts 1st the system provides it's own resistance to the pedal (otherwise the brakes woiuldnt move) so by cutting the system loose the pedal can freely move, try bleeding the rears again but using FULL stroke on the brake pedal a few times.

They're a pain in the arse for sure, if you have any probs pop back / pm me or what ever and I'll see what I can think of - I'm pretty sure this is an air lock though.

Edited October 12, 2010 by Jonathan

[fesuvious]

Now that sounds like a plan.

Later this week Il stick her up on axle stands and give it a go. I have read about all the brake upgrades but it strikes me that with front calipers of such a size there should be no problem with 'oompf' at the wheel end ! As such all issues for me must rest with the brake unit itself.

In other words, I am hoping that if I can get this sorted the brakes will be good !

[Jonathan]

Hehe contrary to popular belief the brakes are good - I upgraded my fronts with the S350 AP calipers (about 2x the size) and HUGE 330 mm disks (largest you can realistically get under the wheel) and there isn't a major difference for fast road driving imo, the Brembos are perfectly good with a decent pad.

What you're getting here imo is no rear brakes AT ALL and no assisntance to the fronts - which is why they feel bad.

If you have a laser thermometer you can check the brake temperarture and see which ine is doing the work after a few stops.

I did a HUGE write up on this a while ago, buggered if I can find it.

The main thing is people dont know what importantce the rear chamber has - the front chamber is a basic master cylinder / caliper arrangement and is basic stuff.

The rear is much more complex and the over-riding thing I came out with after working on this for a week solid and dismantling it completely - was that you must ensure any tiny microbubbles of air are removed, or left to settle.

We were leaving the car sometimes overnight for the fluid to settle.

The reason being is that this reservoir is where the pressure pump sucks oil from, any air in there is sucked straight into the tiny capilaries and chambers in that boost circuit and can end up being trapped.

Before any time key position 2, ensure that oil is 100% bubble free....you dont ahve to replace the reservoir cap all the time just rest it on top.

Worse case scenario it might be worth completely draining the back part and re-fitting, SLOWLY - but I wouldn't advocate that becuase as thats what cuased all my probs - it's a last resort hotel.

Lastly I did also wire up the ABS solenoid relays manually to be able to activate them - when I did (for about 30 seconds or so which the brake pedal on/off proceedure wont do) there was a lot of air coming out.

It's a LOT of cocking about and a lot of fluid (which is why I say use cheap stuff, halfords is fine, done a lot of super hard breaking with it, no probs) - perhaps next time I do it I do a video like that - much better than bashing the keyboard !

[fflyingdog]

Intresting thread and we all seem to have been there,when you say brakes are shit what exactly do you mean? when you brake does the front dive as though the rear calipers are NOT working at all?On my S4s the pump does not come on after only 3 pumps more likely nearer 5 (am not at home so cant give you a definitive answer on that one),but the pump running does depend on the pressure switch, and which switch you have as Lotus changed the operating parameters on the later (Grey moulded,,pump runs at 2220psi and off 2700psi) switches so the pump running after 3 pumps could be an anomaly.To me the clacking sound could (as jonothan said) be that the rear calipers are still not bled properly and its the solonoid/shuttle valves moving backwards and forwards.According to the sevice manual there are 3 solenoid valves 2 for the front wheels and one for the rear wheels it could well be these that you can hear clacking(these solenoinds realese system pressure back in to the assembly)..One last thought have you had chance to hook a reader up to the ABS module and got any fault codes from it? This can sometimes throw you a curve ball but on occasions could point to a electro-hydraulic snag.

All the best

Nick S4s

Edited October 13, 2010 by fflyingdog

[fesuvious]

Thanks

Ok, so, rear chamber = rear brakes. 

Rear chamber is the one that is turning milky, and, so, I can (with man flu) determine that the problems have to be the rears somewhere.

Am I right to presume it is air causing the fluid to go milky?

The clack : It is 'free movement' and it caused by the top 1" of pedal travel which has zero resistance.

Brakes shit : Yes, now I think about it, the rears can barely be working as lately the fronts will lock (especially front right) very very easily indeed. The car requires serious effort to stop from normal speeds (normal for me, which is @20-30% more leptons than is 'traditional'). 

Right now I will not at any point use full acceleration, or even 75% as I just do not have confidence Il be able to stop any better than a 1997 Ford Fiesta from the same given speed.

[Rich H]

Wtches with interest as bleeding the brakes is next on the list...

[Jonathan]

No its the de-pressurisation through a small orrifice, it stirs the fluid - I thought you could cure it but it does depend on how rapidly and smoothly you push the brake pedal on de-pressurisation.

Some people hammer it up and down, I'm more gently and get less aggitation in the fluid.

The valves dont make that noise, you can test them, they make a clicking noise, but not that HUGE clacking sound.

When you push the brakes the master cylinder piston moves forwards obviously but that motion allows presurised fluid to enter a boost chamber - the boost chamber has a thing called a power piston which is forced by the pressurised fliud - I think you have a catastrophic air lock in there which is providing that piston with no back pressure and so it is free to slam into the housing.

Either that or there is something broken inside.

I think someone had a broken system and I was going to offer to disassemble it but it never came to fruition, sadly the drawings I have are not totally clear.

You might search for it on the internet - the unit is called the Powermaster IIIa - there are some sites out there for it.

[fflyingdog]

Moisture can make the fluid appear milky,can you "feel" the booster assembly when you tap the brake pedal and feel where the clack is coming from? Also as Jonothan has said my brakes are standard and work really well so dont give up just yet ! Pity you are not closer because i would quite like to have a look at this for you.

Edited October 13, 2010 by fflyingdog

[fesuvious]

Kent - Dorset - And I am in the Midlands

F**KIN TYPICAL

[Jonathan]

I would say come down here but it's a mad house atm (always is really)

if you do all I say then you've done a lot more than most will do on these brakes - you just ahve to give it a go and take your time.

We did get an awful lot of air out when I sucked the front chamber dry, put a rag under the union to the brake hose and crack it open and let the pedal do an unrestricted depression right to the end of the stroke.

I found afterwards I didnt thave to re-bleed the fronts either - the front being totally isolated from the rear you shoudl always get teh rear right 1st then the front.

Have a go, ask questions, make videos

[fesuvious]

Thank You again

Il clear the man-flu, get her up in the air and give it a go as per what you have written. 

Maybe Il go a step further and broadcast via webcam the work taking place, with audio, let peeps on here watch, laugh, advise, laugh, laugh a little more, get bored, go to bed

[Jonathan]

hehe I thought it was a great way to describe the problem - more ppl should do it.

What you need is a 2 way link - webcam in the garage or something............computer dunse here so I wouldn't know what to do.

[Rich H]

Bled my brakes this evening, followed the instructions - sort of backwards though...

Ignition on with braek pedal down for 3 secs ten times then bled the rears first before dumping the pressure, paving slab on the pedal...

Rears bled OK the fluid was clearly v.old and had a couple of small bubbles.

Then dumped the pressure down and had a look in the reservoir - eurgh!!

The rear compartment was full of milky yellowy mess!! Sucked it out with my oil sucker but as it sucked it looks like it was just aerated fluid. Replaced it with fresh anyway and bled the fronts, again a bit of air and old fluid cleared up nicely. With one of the bleed nipples wide open I pumped a fair bit of fluid through and noticed that at full stroke a squidgy noise...!

A few bubbles fomr the rear MC section so looks like it might need bleeding again but we'll see (Rears are easy!)

Ignition on pump runs and cuts off no worries, just need my freescan cable to arrive so I can reset the IACV then I can test drive it...

[fesuvious]

Disconnect the battery for a hour. That will reset the ECU and surely will reset the idle air control also?

[Rich H]

Maybe but I think it's lost track of where it is so I want to reset it properly, worked last time.

My freescan cable is on the way hopefully...

[fesuvious]

You could just take it out and reset it to 20mm and then re-fit, along with a battery disconnect that'd do the same job.

The IAC itself doesn't know where it is! Only the ECU can tell where it thinks the IAC position is.

Stop faffing and get out there and try your damn brakes - I want to know if they are any better FFS !

[Rich H]

:wallbash:OK-OK I'll have a look later when I get home!

[Rich H]

Been out for a quick drive around the block in traffic, they are better but not amazing, I'll try them at higher speed later on.

I think there was a large amount of air in the rear section that messed things up.

I'll bleed it again this weekend if I get the chance (Got the start of man flu now )

[Wilf]

I have a vacuum pump I use to bleed brakes, suck the fluid out from the bleed valves. Worked well on my yr quattro which had a sod of a system