Brake bleeding issue. Spongey pedal


Smithy18

EK4 VTI-S B18C6
Joined
Feb 15, 2009
Messages
725
Alright lads, I'm having a nightmare bleeding the brakes on my EK. I'm running the following setup

DC2 front calipers
DC2 Master Cylinder
Hel braided lines
Ferodo Ds2500 pads
Plain discs
Endless Rf 650 fluid

I stripped everything and I mean everything from the rear of my EK to address some rust issues. The braided hoses were also removed and the lines would of emptied themselfs of fluid over time.

I've finished with the rust problems and re fitted everything back onto the car.

I've bled the brakes in the correct sequence like I normally would. This time I've bled over and over again but I'm still left with a spongey pedal.

So I've bled the master cylinder on both lines, the pedal got harder but still not happy with It. I've moved onto the ABS unit aswell without any results.

I've tried bleeding the brakes manually with 2 people. Also with a vacuum bleeder and non return valve bleeder.

Nothing seems to be working. Could the MC be at fault ?

Someone shed some light on this issue please.

Cheers
 
Yes the master cylinder could be at fault. It could be either worn or built/rebuilt incorrectly, and sucking in air through use.

But you don't want to start there first of course, that's costly.

Have you checked for leaks at all connections? I've found I have to really crank those fittings down to stop all leaks (except the bleeders, those seal without having to put a lot of ft/lbs.) Best to check for leaks when the fitting is completely dry.
And are you using a brake line wrench for this, not just an open ended wrench? An open ended wrench usually can't produce enough force before slipping on the fitting.

Are you using a clear tube attached to the bleeder that goes down to a bottle when you bleed it? This sounds dumb but some people don't know that. The fluid filled tube doesn't let air in during the process if it's a tight fit around the bleeder.

Are the calipers installed on the correct left and right side so the bleeders point upwards? I actually forget if this can even be done on this setup but I'm pretty sure it can.

When bleeding are you keeping the MC filled constantly so it doesn't run dry?

Are the braided lines worn to the point of leaking, with leaks hidden underneath the weave? This can happen with un-coated braided lines.

Also make sure your brake pedal is adjusted to the right height, this can help a bit.

Good luck.
 
Would the prop valve need changing if you've changed front calipers and master cyl?
 
Thanks for the reply dino. I was doing eveything the correct way with the correct tools.

For future reference to anyone that gets a similar issue here's how I sorted the problem.

I took the car out and locked the abs up a fair few times. Come back to my workshop and bled the ABS pump. Bleeding the lines 1 by 1. A fair amount of air come out of each line on the abs pump.

Once I was finished with the abs pump I then bled all 4 calipers again in the correct order.

After that the pedal had a very good feel with no spongey feel what so ever.

Result !

Cheers
 
Another good reason for the list of reasons to remove abs
 
Hey Smithy I hope you won't mind if I add one more brake issue?

I bought an EK4 while ago with standard brakes and found out that in high speeds and hard breaking the car had a tendency to "twist" - assumption was that there is some air in the system and front right brake was braking more then the left side. I didn't do anything about that because I upgraded to EK9 calipers in front and overhauled the rears. (plain discs, ordinary pads, hoses stay the same)

The system has been bleed in the local service, pedal was firm -> brakes done.

Then I was driving for a while and I noticed that the problem is still there. As the brakes getting warmer it's more and more noticable and since I go to track few times a year a I went to ?MOT station? and tested the brakes. Test was OK - I was surprised (the speeds on the machine are quite low and I think the person also didn't put a full pressure on the pedal).

Everytime I brake hard the ABS kicks ONLY at the front right side (left wheel is not blocked).

Summary: All calipers are checked and functional, system bled out several times, all pads are new, pedal is firm -> yet the right wheel is braking more then the left one.

I want to buy the HEL lines and switch to MB6/DC2 master cylinder and see what it will do.

Do you guys have any idea what it could be?

Sorry for my English but I'm lost :( I want to go to B18 but
 
Delete or change the abs, I think that's your issue.
 
I would love to delete it but I wouldn't pass the MOT test in our country. So I will change it. I was hoping that ABS will be the only thing I won't have to change :))
 
On the other hand it brakes more on the right side even if the wheel is not blocked. Is this also influenced by the ABS unit?
 
Check all your brake lines while your at it, if a line is kinked or a hose is ballooning then that could be your issue aswell.
 
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