ABS, MK4 rear calipers.....I need someones help tonight!!

[mrbeige 0]

I had to replace the rear calipers on my C at the weekend cos it had failed the MOT, due to seized caliper and handbrake with to much travel.

 

Anyway, I fitted the calipers no problems, until I went to bleed the system. Bled the rears no problem, then went to do the fronts and the bleed nipple sheared off in the offsdie front caliper!! Tried a stud extractor, and that then snapped off in the caliper too! Gutted. :(

 

I do have two early VR6 calipers (curtosy of Kev) to go on, so it is not a big problem, but now my ABS light is on and the ABS isn't working! The pedal is really crap too. :(

 

Have I knackered it or what :?:

[Supercharged 2]

Check you didn't disturb the ABS sensors when working on the fronts...

[mrbeige 0]

Check you didn't disturb the ABS sensors when working on the fronts...

 

I'm going to fit the early VR6 calipers up front this week, so I'll have a look, but is sounds like there is air moving about in the ABS unit. Is that likely?

[Supercharged 2]

Hmmm - How did you bleed them, It's best to get ABS systems pressure bled to prevent the posibility of Air getting in...

[mrbeige 0]

Bugger! Just did the normal tube and bottle job!

 

Is it easy to remedy air locks in ABS units? Could I just get the system pressure bled now?

[olly elworthy 0]

also when bleeding abs systems you need to have the ignition turned on so the pump energises,, try and bleed again,, tube and bottle method will be fine but make sure you have the ignition turned on,,

[mrbeige 0]

also when bleeding abs systems you need to have the ignition turned on so the pump energises,, try and bleed again,, tube and bottle method will be fine but make sure you have the ignition turned on,,

 

Okey dokey! I've just ordered 280mm discs from GSF, to go with the new calipers, and then I'll bleed them with ignition on!

 

Cheers guys!

[RW1 0]

also when bleeding abs systems you need to have the ignition turned on so the pump energises

 

Nope! Not the Corrado in Europe & UK. See the bottom.

 

As per...... http://the-corrado.net/.archive/forum/viewtopic. ... 98&start=0

 

 

Corrado Brake bleeding 1989 - 1995.

 

(Also includes the clutch circuit)

 

2 man job particularly when flushing through the clutch circuit.

Require 1 ltr of DOT 4 brake fluid. System is not designed for DOT 5.

 

BRAKES:

 

Applies to all UK models, 1989 – 1995 whether fitted with ABS, ABS/Traction control or just plain conventional.

Just like any other VW of the era with standard brakes. ABS or not, they are all the same procedure.

 

Assumes here that the pumping pedal and bleed collection bottle method is used. Auto bleeders etc, treat the Corrado as standard type brake circuit.

 

Bleed sequence is:

 

1 - Rear right (offside) caliper

2 - Rear left (nearside) calliper

3 - Front right caliper

4 – Front left caliper

 

Carefully pump the pedal with the bleed nipple open at each wheel and close caliper nipple on a brake pedal pressing action. Do this until the new fluid becomes visible in the collection jar.

 

*** Don’t let the brake fluid reservoir level drop below the clutch fluid feed of the main reservoir, about half way down the side wall of the plastic reservoir otherwise that will introduce air into the clutch circuit.

 

If you jack up the Corrado with the rear wheels off etc., as Chris VR6nos has said, you will need to depress the proportioning valve on the rear sub chassis nearside. Bleeding flow rate shouldn't be affected with rear wheels on the ground at full weight.

 

CLUTCH:

 

Definitely two people.

 

With the main brake fluid reservoir full, connect a feed pipe to a collection bottle and open the bleed nipple on the slave cylinder on the top of the gearbox.

 

In the cabin, grab hold of the clutch pedal (as it is sprung assisted to go up into the dash!) and gently push while holding the pedal.

At the bottom of the stroke, close the slave cylinder nipple and pull up the clutch pedal back up to the top again. Open the slave cylinder nipple again and repeat 5 more times.

Ensure the slave cylinder is fully closed and test the clutch pedal for firmness and operating the clutch.

 

Finally, open up the bleed nipples on the brake and clutch master cylinders and let out a little fluid into a rag while observing that there are no ait bubbles.

 

Finally check the main reservoir fluid level is at the mark near the top on the reservoir side wall, usually a solid triangle symbol.

 

Bleeding now complete, check the pedals are operating with no lag or sponginess. Test drive and all should be OK.

 

--------------------------

 

NB.

The USA Bentley procedures, particularly the ABS brake fitted Corrado procedures do not apply to the UK models.

ie. Forget the ignition on and all that with VAG1551 connected. That’s the Teves 02 system not the Teves O4 ABS system

 

There will always be some old fluid left in the ABS pump and valve block. So, just refresh the brake fluid at a shorter intervals than the 2 year recommended. It will dilute this factor over time.

 

Also, now the Corrado’s are drawing pensions, after 1 month from changing the fluid, check all flexible rubber hose pipework at the wheels and sub chassis. The hoses can rapidly deteriorate resulting in weeping leakage or bulges on the outer rubber walls. This more likely to happen if the Corrado is used infrequently or stored of periods like over the winter. The new fluid for some reason breaks down the inner pipe of the rubber brake hose which show up as a bulge or the outer hose having wet areas.

[mrbeige 0]

So, no ignition, full weight on the rear, and the following sequence

 

1 - Rear right (offside) caliper

2 - Rear left (nearside) calliper

3 - Front right caliper

4 – Front left caliper

 

using tube and bottle method, and don't let the brake fluid reservoir drop below the midpoint.

 

Just to confirm, that is correct?

 

Can I put Dot 5 in it? (Goodrich braided brake lines are on it)

[Henny 0]

mrbeige, NO. don't use DOT 5....

 

DOT 5.1 IS Ok to use though... :roll:

 

They are VERY different fluids even though they have a similar name... DOT5 is silicone based and will eat the seals inside your hydraulic system resulting in probable brake failure (not good!) DOT5.1 IS safe to use in normal DOT3 or DOT4 systems as it's not silicone based...

 

It really is a silly naming convention and is based on the properties of the fluid rather than what the fluid is for... Someone needs to make up a decent naming convention for these fluids to prevent problems occurring... :|

 

The rest of what you say is right though... 8)

 

RW1, it's interesting what you say about not needing the ignition on when bleeding the UK spec ABS... mine definately felt better after I bled it with the ignition on... :|

[mrbeige 0]

Cheers Henny, that could have been very depressing!

 

Dot 5.1 it is then!

[Roger Blassberg 0]

No, I do not believe that you can use DOT 5. The seals in the system will not tolerate it.

 

Best wishes

 

RB

[Roger Blassberg 0]

Oh well, too late but on the right track.......................

 

Best wishes

 

RB

[olly elworthy 0]

 

RW1, it's interesting what you say about not needing the ignition on when bleeding the UK spec ABS... mine definately felt better after I bled it with the ignition on... :|

 

mine was better too,,

[mrbeige 0]

Now what do I do :?

 

That's two people who say do have the ignition on and one says not....

 

maybe I should run a tally on this and then do what most people do!

[Henny 0]

put it this way, it's not going to hurt to have the ignition on... ;)

[mrbeige 0]

put it this way, it's not going to hurt to have the ignition on... :wink:

 

Sounds like a plan to me!

[RW1 0]

mine definitely felt better after I bled it with the ignition on...

 

There is a warning about running the ABS pump for long period, ie. over 2 minutes. And the pump has to be shut down for 10 minutes before starting it again. Yep, I've run it longer as well, so one wonders on that one. But the reference only appears against the Teves 02 brake system as fitted to Left Hand Drive Corrados.

 

Teves 04 ABS & ABS/EDL (Traction control) brakes systems are where the Brake Master Cylinder and the ABS Pump & Valve Block are on separate sides of the rear engine bay. Fitted to RHD UK Corrados from December 1991 onwards.

 

Bottom line, run it at your own risk for longer periods on a RHD Corrado. The pump isn’t doing anything in this mode with just the ignition on. Hence the note above in the small print that all the fluid cannot be changed. I also doubt if the pump is influencing the brake fluid during bleeding while it is on as there is no wheel sensor signals (AC type frequency oscillation) present with a stationary set of wheels so the ABS ECU won’t operate any pressure valves. If they did, the brake fluid would be pumped out via the bleed valve that is open!

 

Brake bleeding for all UK Corrados both with and without ABS (or ABS/EDL) is written above.

When using a pressure bleeding method, the procedure is no different in either sequence or opening bleed valves.

 

For changing the brake fluid, the operation is expected to pass 0.5 ltr through each circuit (ie. 2.0 ltrs in total). Closing off each calliper brake valve once all air bubbles have been flushed through. (Personally I am able to do all 4 circuits with 0.8 ltr by monitoring the change in brake fluid colour from dark to the same as the fresh fluid being put in.)

 

Reference for the information:

VAG Corrado Workshop Manual.

Running Gear Booklet

Section 47 - Brake Hydraulics

Pages 25 to 28 Bleeding Brake System & Changing Brake Fluid

– Conventional & Teves 04 ABS, ABS/EDL Braking Systems

 

Bentley (USA) Workshop Manual only refers to the Teves 02 Brake System as fitted to LHD Corrados.

[Henny 0]

RW1, as always, great info there mate... 8)

[mrbeige 0]

Ok RW1 , thanks.

 

Anyone in the cambridge area want to help me do my brakes this evening?? I'm a bit stuck cos I'm not a local boy!

 

Cheers

[Baz2004 0]

DOT 5.1 is race track stuff not that easy to get & a bit advanced for what you might need.

 

Unless your stopping a V8 or serious heavy V6 using 4+Pot calipers then I wouldn’t bother with it. Normal DOT 4 is well capable of the job + far less expensive than the DOT 5.1. As far as I know 5.1 needs to be changed more frequently also.

 

Good info RW1 ill be printing that off for my archives. :)

[dinkus 10]

You can get 5.1 in Halfords, but it is more expensive than DOT 4. However, I was under the impression that you have to change it far less frequently than DOT 4...

[mrbeige 0]

Couldn't get the bolts that hold the caliper off last night! Only had the use of a 17mm cranked ring spanner! 17mm 1/4" socket on the go this evening! Apparently they are durlock bolts = pain in the bum!

 

To change the fluid is it just a case of bleeding them for longer until the fluid runs clean?

 

I also bought an "eazi-bleed" thing from Halfrauds last night, anyone had any experience with these? You pressurize the reservoir using the spare tyre, which means you can do it on your own.

[corradophil 3]

Eazy-bleed is an excellent tool. From my experience new fluid will be lighter in colour than the old stuff.

 

I had to bleed the my system completely a couple of weeks ago because like a fool I let my master cylinder reservoir empty itself when changing the rear bushes. I had a nightmare getting a decent firm peddle, after 1.5 litres it was still very spongy, no air was coming out of any of the wheel cylinders and I had also blead the master cylinder. I had to leave it at that until I could get more fluid, It appears it had an airlock on the rear because after a couple of days air was present at the rears. It now has a good firm brake peddle again.

 

If your peddle is spongy, it is very likely that the air is trapped in the rear brake pipes, not the front.

[h100vw 0]

Whenever I used an easy bleed it was crap. It filled the reservoir right up so it spilt fluid everywhere as you took the cap off. If you connected a car tyre to it again it blew fuild everywhere cos the seals onto the reservoir were no good. I did sort of get it to work with a bike inner tube with less pressure.

 

Now I always use the pipe work you see in ER. The one the guy that's just about to die is breathing through. It's ribbed(?) on the inside so it won't collapse. I find that generally gravity does most of the job for me.

 

Sometimes the back is hard to do because of the bias valve. This is worst if you have changed the rigid lines and have no fluid in the system at all.

 

Gavin