More Brake Problems

[PHaTGRoB]

MOT cancelled!

On my way to the MOT station at last, I noticed that the brakes were quite poor.
I'd tested them on the drive after fitting the new ABS module and they'd seemed fine but this had been a limited test.
Today though, there was a lot more pedal travel than I remember and poor stopping performance. Twice, when braking heavily from speed, the ABS light came on and then came on and off properly after switching the ignition off and on again.

The hydraulics were not disturbed by changing out the ABS module.

So, this afternoon I've tested the following:

• Pedal travel with the engine running is a good few inches and pumping the pedal makes no difference. However, back to trialing the brakes on the drive, stopping from slowish speeds seems OK.
  
• Pedal travel without the engine running is much less and pumping the brakes reduces pedal travel to "normal" levels after 3-4 presses.
  
• Pedal travel with the engine running but the servo vacuum line disconnected and closed off, the pedal is rock hard but stopping is difficult as expected if the servos not operating.
  
• The ABS is working properly (except when the light came on twice - see note at top).
  
• There are no visible hydraulic leaks, no reduction in fluid level in the reservoir and there is no noise from the master cylinder suggesting it's passing fluid when brakes is applied.

I don't think that pedal travel was ever very short but the brakes were quite effective. Even allowing for the Ex standing for 2 months, I wouldn't expect the brakes to be quite so bad.

I have followed the testing procedures in the repair manual and these suggest that the servo, master cylinder, et al are all working.
So I then tried bleeding the brakes.

Both rear brakes had air in them and this is now removed.
The next one was the O/S/F brake but the bleed nipple is stuck solid!
I can't move onto the N/S/F one till the O/S is done.

Has anyone else had these problems?

Does anyone know how to remove a stubborn bleed nipple without usign a bfh and wrecking the caliper?

Yet again, I'm trying to think what I've done recently and how it could have caused this latest problem.

At least I found out before I wasted another 48 quid on an MOT test!

- A very frustrated and miserable GRoB.

 

[BIGHVM]

Bugger problem mate- feel for you- is the servo working ok, no hoses loose, broken, cracked? adjust the rear shoes, I do mine on my own and make sure I cannot turn it at all with one hand- then back off just the smallest tad and drop her- job done.
Failing that mate I would suspect the abs module is not making good contact- unplug and replace a few times, just to see if it gets better- Good luck?

 

[kevin p]

Hi Grob,
My brakes have always been crap and tried no end to sort them out. I'm restoring underneath and took the calipers off to paint them and put new seals in. I also put braided hoses on the front and deglazed the discs. Worse than ever!!!!
So I've just put on new drilled and slotted discs all round with new pads. First signs are good. They actually have 'feel' to them. The pedal still seems to go down more than I would like though, but they definatly feel better.
You could try a small soldering blow torch to locally heat the bleed nipple to try and shift it. Good luck.
Kev.

 

[PHaTGRoB]

Thanks for the advice fellers.

I've just taken the Ex for an illegal nighttime thrash round the lanes to see if this could sort things out. Heavy braking was used wherever possible and it seems to have made a difference (more false hope!!!). The pedal still has significant travel but feels more familiar and actually stops it pretty well, certainly as well as it used to.
The lanes are fairly muddy and the ABS is working really well now. The light came on early-doors and I reset it by switching off and restarting. After that, the light stayed off.
The brakes got very hot and are now ticking away to themselves outside.

It almost looks like a couple of the calipers may have been seized, with the Ex having sat outside for a couple of months doing nothing but feeling sorry for itself, in almost continously wet and cold weather.

I may give it another couple of blasts this week. Then MOT later in the week I think/hope...

Then I'll try and sort out the front brake bleeding issue.

Thanks again lads. A slightly more optimistic / less miserable GRoB.

 

[janolsson]

Hey grob
try wire brushing around the thread of the nipple then a sharp little knfe or screwdriver to remove as much crud as you can. After exposing as much as you can get a quality penetrant (not WD40), i use "3in1" penetrant, and soak it a couple of days in a row. Then as said above heat the nipple quite hot then allow to cool. Lastly get a tight fitting six sided spanner or socket in it and try to tighten a tiny bit then try to undo.
Worked on my 98 and they looked like they had not been touched in years.

As a precaution order a couple of spare nipples (usautomotive.com ???)
good luck.

 

[ahmos]

man if the abs light comes and go... there will be an error code dtc
so i advise you before any thing to got a scanner tool and check for the error it will help you a lot...brakes needs very good experience to be fixed

 

[chrisquelch]

abs module and rear speed sensor

hi
just remembered i sold an rear axle to a customer and after they fitted it and bleed the brakes they had poor brakes first we thought it was the problem with air in the lower abs pump valve. but for some reason they put the rear speed sensor from the old axle onto the new axle and the brakes became good again. poss the rear speed sensor has to be a match with the abs module some how. cheers chris

 

[PHaTGRoB]

Thanks all.
The brakes seem to be behaving themselves now. There's still a fair degree of pedal travel but I think there was before. The problem yesterday was that the car didn't slow down with significant force being applied to the pedal but it does now, pretty effectively. It also tracks straight and true and the ABS holds it online when braking on split surfaces - mud/gravel/tarmac.
Thanks again, since all advice will come in handy at a later date...especially with respect to getting the old bleed nipple out.
GRoB

 

[PHaTGRoB]

I know I said they were ok, but I still wasn't entirely convinced.
I've failed to get the travelling diagnostic man here, so I'm still not sure what the light flashed on for but I have checked out the full brake system again and everything seems to be OK.
Disconnecting the ABS module and running the brakes makes no difference to how it brakes or feels.
So, today, I enlisted the help of my daughter and fully bled the brakes running a significant quantity of new fluid through the system.
Having soaked the seized bleed nipple in WD40, it came out using grips and both front ones were replaced with new.
So, did bleeding them help? The pedal still travels a long way but they seem to be working a bit better. We also confirmed that the pedal is not going to it's mechanical end stop during normal use by getting said daughter to stand on the pedal with the engine running and then me opening the bleed valve - the pedal drops quite a bit further down.
The ABS is working brilliantly on our slippery drive.
I think that once on back on the road and the brakes have been used properly, this will help - sitting around for a couple of months can't have helped.
So, I'm going to bite the bullet and book it in for MOT...again.

 

[ahmos]

how much is the distance from the pedal when you fully push it with engine running from the floor ?
i will measure mine and inform you ...

 

[PHaTGRoB]

Hi Ahmos. It moves by about 4". It's always had a fairly long travel and this wouldn't worry me but for the fact that pressing hard on the pedal that much still only produces half-hearted stopping performance, certainly not the fairly good braking I remember before I took it off the road.

Because it was sunny today, I've tried a few more things:

I dismantled front brakes and found that the pads were stuck in the caliper bracket. I cleaned it all up, applied copperslip, reassembled it all and made sure it all moved as it should - no improvement in braking at all.

I also removed the ABS module from the HCU and tested the brakes with it removed - no change. I then refitted the original "faulty" module and the bloody thing worked properly - the light came on and went off! Again, no change to the braking.

Anyway, I refitted the "new" module and returned everything as was.

It actually "feels" like there's air somewhere in the system but where, I don't know. If it's in the HCU, I can't deal with this.

Apart from getting the ABS DTC's which may give me a clue, I have no recourse but to give in and get the garage to look at it when I take it to fail it's MOT again!

So, there we have it...unless I have a eureka moment, I've just about given in. GRoB.

 

[PHaTGRoB]

At last...after 2 months...MOT PASS!

The ABS light comes on after a fair distance, so I need to get the DTCs, but everything worked as it should during the MOT and the tester commented on how effective the brakes are!!

All that work has paid off.

Now I can get on with sorting the other things that need work, but I can do them in my own time.

The dogs are happy too, since they now have "their" wheels again!

Thanks to all who helped me over the last couple of months - even to use you all as a sounding board is a real help.

GRoB

 

[Howard]

Well done.

 

[janolsson]

good oh, what what

 

[BIGHVM]

Good show ol chap!