I hate my car :@

[aragorn]

Every time i try to do anything to the *** thing it goes wrong.

I had it out on track at ADI (for all of 10 minutes!), and for some reason when i got in to drive home the brake pedal was on the floor. Some pumping gave enough response to stop the car, and i managed to limp it home thinking i'd just boiled the brake fluid.

I had to remove the MC/servo assembly anyway as i need to fit a throttle sensor as part of the ME7 conversion i have planned, so i decided to get stuck into that and bleed the brakes to fix them once done. Managed to break the brake fluid reservoir so swapped it for the one off the track project, and built everything back up. Bled the front brakes and tried to bleed the clutch, but couldnt. Tried for hours, just wouldnt work. Removed the pedal box again, and in the process realised that the previous owner of the track shell had seeminly fitted a new reservoir and hadnt cut open the feed pipe stub for the clutch MC. I hadnt noticed when i swapped it, and obviously didnt think to check as it came from a working car. Fixed that and bolted everything back in again, then set about bleeding the brakes and flushing the old fluid thru.

Flushed a litre of ATE blue thru it, then realised i still had a **** pedal. Ordered another litre, tried bleeding all four corners again, still have a **** pedal.

So now i'm stumped, i'm thinking either theres still magically air stuck in it, which seems unlikely, or i've broken something else. Current contender is the Master cylinder, i thaught the one off the track car would fit, but ETKA suggests they're a different part number, and i dont really want to bleed another zillion litres of expensive brake fluid thru it to find its wrong in some way and doesnt work, so now i'm ****** off and fed up with an undrivable car.


To make matters worse, the exhaust which was blowing slightly on the way to ADI is now more or less completely detached and the car now sounds like a tank.

 

[Tom_B]

Sounds frustrating Aragorn. Audis eh? Nothing but expense and frustration interspersed with anxiety about the next investment of time and cash....

 

[Bradderz_1988]

I had similar on a citroen C4 at work basically came in with a **** pedal having no recent work done on the brake system it had me stumped, i must off bleed it 8 times or more i contacted citroen technical who said to check calipers were sitting true which i had replaced all disc and pads on, they then said one of the piston seal could be drawing air in ??? Never heard of this before ??? So i clamped off all the brake lines at the calipers and whey the pedal was solid with little drop, i then cracked each pipe off at the abs block one by one whilst someone was giving the pedal a pump. I then moved on to the calipers individual obviously starting furthest away from the abs block, and still to this day no air came out of the system to my knowledge but it cured it and has not been back since in 3months+. I can onky imagine you pulling your hair out with this one and hope you get it sorted.

 

[Ste_Nova]

tip : always flush and test bleed with cheap fluid

 

[aragorn]

Spent all day changing the master cylinder for the S4 one and bleeding 3 trillion litres of fluid thru it, and its still exactly the same.

REALLY fed up with it now.

 

[PAULF]

Bummer

Have you tried checking the flexi-hoses? They can let go and bulge when you brake - especially if you have been 'spirited' with the brakes. I assume you have checked the calipers for leaking seals - it can take a while to leak out of the bellows?

As for the exhaust - a can of Special Brew (empty it first!), tin snips, jubilee clips and Gun Gum will keep you quiet until you get a proper repair.

 

[aragorn]

Four of the 6 lines are stainless braided items that are only a few months old. two of them are original, however i've put my hand on them and had someone stand on the pedal as hard as they can and theres no obvious bulging.

Tonight however i've noticed a few spots of brake fluid on the nearside rear wheel rim. The same caliper did appear to have a small amount of fluid under the bellows, so now i'm thinking i've blown a seal on that caliper. What i cant figure out is how exactly i could have driven the car all the way home from ADI, and yet didnt lose any appreciable amount of fluid, nor have any signs of leaking fluid on the wheel rim when i started the job.

The exhausts blown at the flexi, which makes it somewhat difficult to bodge up a repair.

 

[spartacus 68]

The rear caliper 'o' rings are relatively inexpensive. Did mine this year. £20 for a pack, does both sides. Soak the rubber 'o' ring and bellows in the fluid that comes in the kit for an hour or so prior to doing the job. I bled my brakes but was still surprised to see the fluid was discoloured and contaminated when I popped the piston out. I suppose this brake fluid is past the bleed nipple, so will always be there and can't be removed unless you remove the piston bore. Use a little Lockheed red grease under the new dust sleeve prior to rebuilding.

 

[aragorn]

These calipers were already rebuilt a year ago. The NSR (the one i suspected is leaking) is also binding slightly so needs changed anyway.

I decided last night to check the front pads out, after suggestions that they could have delaminated. Inspecting the pads showed that the outboard pad on both sides seemed to have slightly come away from the backplate at the edges so i chucked them in the bin and swapped in a spare set i had in the garage from the old 2.8 i broke for parts. Not ideal, but certainly better than what was in there!

Took the car out for a drive to bed in the new pads. The pedal is now better, marginally, but its still really long and soft and nowhere near how it should be. Unlike before the brakes now feel powerful once you get past the sponge/travel in the pedal, so i'm hoping its just some air in the dodgy rear caliper.

Will try and get that swapped out tonight after work and see how it goes.

 

[warren_S5]

Stolen from another forum (e.g. not my own knowledge!)

dont go by looking at the servo and working what ones furthest away as the lines run funny in VAG - to do with them being converted form LHD the lines are still in the same place but the servo is moved and lines extended.

should be
> rear driver
> rear passenger
> front passenger
> front driver
> clutch
> master cylinder

failing that you may need to vcds bleed the ABS pump. i needed to do this after my brake pipe burst

One thing you shouldn't do it push the brake pedal fully to the floor as this can flip the seals in the master cylinder!


Appreciate you may have done all of the above already, so ignore if you have!

 

[aragorn]

yeh i've followed the bleeding instructions from ETKA.

Those above are probably for an A3 though, as theres no bleed nipples on the Master Cylinder on the A4, and ETKA doesnt make any suggestion of bleeding the ABS unit either.

 

[warren_S5]

I've just re-read the thread and I'm an idiot, it reads like it may be a B7, not a 5! Soft brakes after disc,pad,line and fliud change - TorqueCars car forums

 

[aragorn]

Changed NSR caliper this evening, no difference to pedal and the new caliper is sticking more than the old one was. REALLY testing my patience now!

 

[LeeT]

Ive got similar issues after fitting the Porcshe Brakes. I'll fit a new master cylinder before i put my engine back in and hope this helps. I also managed to pop the reservoir and £50 for a new one

 

[PAULF]

I'm assuming you're pressure bleeding them?
If not, I'd suggest that you do. (So Nan, if you drill a hole in the top of the egg BEFORE adding the straw......)

One other way of tracking down this type of thing is to disconnect each caliper in turn, and blank the hose end. You may find it easier to blank the rigid pipe. Then pressurise the reservoir, and crack the blank to bleed the pipe, then feel the pedal. Start at the caliper end, and work your way toward the master cylinder at each convenient joint, until the pedal gets hard.Don't reconnect anything until you have the culprit. If the pedal doesn't get hard, it's the master cylinder (unlikely, as it's been changed). Once the pedal is hard, reconnect the other lines one at a time bleeding and checking the pedal each time until you only have the dodgy line left.
At least that way you'll know where in the circuit the fault is.

 

[aragorn]

good shout on blanking the hose!

I was thinking of clamping off the rear lines and seeing if that made any difference which i guess is the same idea. Issue is that four of the 6 lines are stainless braided, and you cant really get away with clamping those, however on the rear two of the lines are normal rubber, so i could clamp them and see, however removing the pipe and installing a blank is a much neater idea!

I'm away for a few days, so something to try when i'm home.

 

[Jonion]

I'd agree with that.
I have similar problem ona racecar with new brakes, by blocking off various parts you can hunt down the problem.
Bit of messing about but better than being eternally frustrated by it (yes we've been there)

 

[aragorn]

Ok so i didnt get round to blocking bits off, however i did decide that i needed to buy new calipers anyway as one was sticking and the other has a damaged dust boot (so while its not sticking now, it'll be sticking soon enough...) so ordered up a pair of calipers from brakes international.

I'm really impressed by their product, the calipers were £237 for the pair, but i'll get £70 back when i return the knackered ones. They look brand new (casting is datestamped 2011 rather than 99 like the old ones) and seem spot on quality wise.

I went out tonight in the cold and dark and set about changing the sticking caliper, quick and easy job only taking me an hour start to finish, and the brakes are now FAR better. Still not 100%, but i'm hoping that'll go when i change the other caliper (tomorrow night if the weather stays dry!)

Interestingly, they were supplied pre-bled and full of brake fluid, with a grub screw in the fluid union, so presumably the manufacturer knows they're an absolute **** to bleed!

 

[adamss24]

Just bear with it mate, these cars are nice when running right but they can give you a bad headache when something goes wrong ! Would not want it any other way though, i like a challenge every once in a while...

 

[Bradderz_1988]

I bleed my brakes at weekend as well gave a more solid pedal for a day at the most now it seems to have become spongy again all the calipers were visually ok when a did the brakes (2-3 months ago) might try another bleed this weekend.

 

[aragorn]

Bradderz: that sounds like a leak, perhaps a bleed nipple or fluid union isnt quite tight?

 

[Bradderz_1988]

There was no signs of a leak is it worth checking the bottom of the servo for BF while i check the rack mountings ???

the only thing that seemed odd at the time was the o/s/f and n/s/r didnt seem to force any fluid out it was as though it trickled out down the caliper were as the other two were forcing it out so much it would hit the wheel arch liners. So i used a fluid sucker and locked them off whilst sucking and it seemed fine but it seems its back !!

 

[PAULF]

Bradderz, it sounds like a seal in the master cylinder could be on it's way out as one circuit is poor.

I'd be interested as to how you get on with the new caliper Kev - I may be looking for new front one in the not too distant future and was not happy with the way the last lot started to corrode the piston after 6-12 months.

 

[aragorn]

For the fronts i just rebuilt them myself on the avant, wouldnt spend that sort of money on front calipers as they're really simple things. The rears are really fiddly and you cant really proper rebuild them without dismantling the handbrake mechanism, which i found effectively impossible.

Bradderz: i found the fluid just trickled out on one of mine, and the bleed nipple was chock full of alloy corrosion particles.

 

[PAULF]

Rebuilding them is a good idea, but as the pistons are corroded I'll have to get new pistons- and don't want to get one with duff plating again!

 

[aragorn]

yeh i guess thats the issue.

I went with BiggRed for the pistons on the front calipers, but obviously wont know for a while if they're any good.

I think brakes international will do pistons as well. Where did you get your crappy pistons from?

 

[Sandip]

If you found the fault then ignore the photo, if you haven't then check the vac line i've circled

 

[aragorn]

no idea what the fault was TBH, that lines fine, its been on and off a few times throughout the process.

Seems at this point its just air.

At a guess, i think i've probably blown a caliper seal and/or boiled the brake fluid (or maybe even both!) then made it worse by introducing a tonne of air when i removed the master cylinder to sort the pedal box thing. since then its just been a tonne of air trapped in it.

 

[dubster67]

I can sympathise with this.

Recently had both rear calipers seize up, after a short run in the car the rear discs were really hot, as were the wheels.

I got seal kits from Brakes Int.

When I took the calipers apart I noticed that the pistons aren't a tight fit in the caliper bore. They seem to be held centrally in the caliper bore by the handbrake mechanism screw, then the piston seal does the rest.

On my calipers the problem was the small amount of corrosion/muck behind the dust seal had caused the piston to stick due to the piston seal getting gradually deteriorated/damaged.

So new piston seals, dust seals, and the seals behind the handbrake lever, did the trick.

When bleeding the calipers, I used an Easibleed on a very low pressure, but it still took loads of fluid to get all the air out.

It was even worse when I had the rear subframe off the car, I think it took about 3 litres to get a good pedal.

So stick with it aragorn, you'll get it sorted.

 

[PAULF]

yeh i guess thats the issue.

I went with BiggRed for the pistons on the front calipers, but obviously wont know for a while if they're any good.

I think brakes international will do pistons as well. Where did you get your crappy pistons from?

I got two car sets of front calipers from brake parts superstore, good guy to deal with, but I'm not happy with the corrosion. Problem is even if you took them apart, there would be nothing to see until some time later. I suspect crap chrome plating is the problem. The rears were from Audi and are fine.

 

[B5NUT]

A few years back I replaced 1 rear caliper and could I hell as like get the air out, gave up and handed £50 & one hour of my life to the local Audi dealer, but it was job done. I have just replace all the calipers on my A4 and golf and got the air out without any problems on both cars, I think it's just luck of the draw.

 

[Bradderz_1988]

If it was the vac line wouldnt you have a rock hard pedal as the servo is not giving any pedal assistance ????

I may remove the bleed scews completely and see what happens if i give the pedal a pump !!

 

[aragorn]

OK, i ****ing hate it again, and i'm completely fed up with it now.

Fitted other caliper tonight, its still the same.

I'm still not convinced there isnt some master cylinder involvement or something else going on. First press of the pedal is "long" and if you release and immediately repress it comes up hard. If you wait a a few seconds between presses, it stays long. HOWEVER, on the long press, you can feel the pedal sort of jump about 2/3rds of the way down, feels weird, and i distinctly remember it only started doing that after fitting the S4 master cylinder, so now i'm wondering if its somehow damaged from sitting for a year with no brake fluid in it...

 

[aragorn]

So today i started off by disconnecting the rear lines and trying the brakes. i didnt drive it on the road, but on the drive they felt much sharper. I then bled and bled and bled the rears and got it to where i thaught it was good, and took it out for a drive.

Slight improvement, but still a crappy feeling pedal.

I decided at this point that since i wasnt 100% about the MC (it had lain in the S4 for a year with no fluid in it...) i would swap the MC out for the one i got from Pierce on here. Swapped it out, bled it all up, no change.

They work, and you can get ABS to activate if you try to stop hard, but it just feels horrid.

Pumping the pedal twice doesnt make much difference to how it feels physically when stationary any more (whereas yestarday it did), but when moving the car definitely stops sharper on the second press.

Thaughts at this point...

I guess it COULD still be some air in the rear calipers, they are after all notoriously hard to bleed. I'd have thaught at this point though, i'd have shifted any last air bubbles!

The other thaught i'm having is that it might be something to do with the front calipers. Perhaps the seals are binding and not letting the piston smoothly move, so its getting snagged and thus backing off when the pressure lets off. The reason i'm thinking this is I had something similar happen last year on the avant, where the pads were sorta stuck in the carriers, and the first press of the brake gave huge travel then subsequent presses they worked ok until you left them alone again for a few minutes.

I gave my spare calipers to rob though and he hasnt sent me them back yet, so i cant test out my front caliper theory!

 

[Ste_Nova]

i wonder if you can 'shake' any trapped air out of the rears?

 

[aragorn]

Yeh at one point i unbolted the caliper with the bleed nipple open and shook it around and got a few bubbles out. Maybe i just need to try that again in a more vigorous manner!

 

[Ste_Nova]

i was more thinking along the lines of a concrete vibrator