Bleeding Fronts Only

[chipstick 382 1 Cars]

Popped some GTi6 calipers on with used but meaty discs and mintex pads.

 

The pedal feel isn't great. I know that the GTi6 brakes with the 205 Master Cylinder provides extra travel than I am used to, but I am not sure if that is the case, or just air in the system.

 

Have only bled the fronts as I didn't touch the back brakes, and the rear caliper nipple shear risk scares me.

 

The car stops fairly well if I heave on the pedal, but coming to junctions and what not it requires more advanced thought that I am used to. My other cars have better brakes, but then they are newer and probably have a better system.

 

Am I going to have to attempt to bleed the rears in order to get some improvement? As the dics/pads have been on a shelf for a while im wondering if they will actually improve over time and give a more sudden bite. I gave them a good stamp this morning on the way to work and it wouldn't lock up. It locked up a few weeks ago with the 1.9 brakes so perhaps I should have left alone

 

My bleeding method is: crack nipple, assitant to push pedal down once, nip up the nipple when the pedal is held down and fluid is forced though a bit, pedal up and repeat.

[MiniGibbo 142]

Ive always used "down down up up"..

 

You can buy "ez bleed" tools that work off spare wheels, I haven't used one but heard they're great so plan to try one when I change the fluid on mine.

 

You do need to bleed them all IMO.

[Anthony 1,002]

Lack of bite sounds like a friction material issue to me. Trapped air normally gives a spongy, over-long pedal.

 

Try re-bedding in the pads and go from there.

 

If your car started life as a 1.9 (ie has a diagonally split brake system) then you will ideally need to re-bleed the whole system, as each half of the MC is shared with one front and one rear caliper, and hence draining the fronts will likely allow air into the rear circuits. On a 1.6 GTi (ie has a front-rear split brake system) this isn't an issue as the half of the MC that feeds the rear will not empty if you're only changing the fronts.

[pugpete1108 62 1 Cars]

Ezebleed ftw.

 

You should really do the rears but I don't see why as air can't travel back up through the mc and into the rear lines?

 

My pedal feels crap on 307 hdi setup. Lots of efficiency but loooong pedal travel . You just get used to it.

 

With the bleed nipples, give em a good soak overnight and a short sharp tap with a hammer before trying to loosen them. Hopefully they won't snap ..........

[pugpete1108 62 1 Cars]

Ah this may be where I'm going wrong Ant.

 

I'm running a 1.6 setup with a 406 mc but have plumbed it as the from two ports on mc as front two lines with one of the rear ports as the rear with the other blanked off?

 

Should I have both fronts on the same side of the mc then?

[chipstick 382 1 Cars]

Excuse my ignorance, but what do you mean by rebedding the pads? Take them out the calipers and back in again?

 

Another way to describe the symptoms is when I approach a car going slower in front, a normally adequate press of the pedal does little until more pressure is added.

 

The discs also have rusty lines on throughout.

 

Would this be a result of knackered pads perhaps? They have a fair bit of meat on them but may be glazed.

[Anthony 1,002]

No you've plumbed it in right Pete - the split on the MC is front two outlets and rear two outlets, so you've done it correctly for a 1.6 brake pipe layout by putting the front pipes on the unions furthest from the servo, and the rear pipe onto one of the unions closest to the servo (and blanking off the other)

 

Mind you, I've never actually found the split redundancy on the MC to work as I believe it's meant to anyway - the theory as I understand it is that you can lose a single brake line and you should still have some brake effort from the other unaffected circuit, but the couple of times that I've had that happen the pedal has just gone to the floor and not "pumped up". In both instances it was an old MC mind you.

[chipstick 382 1 Cars]

Here is a pic of one side

 

 

And the other

 

[Anthony 1,002]

Excuse my ignorance, but what do you mean by rebedding the pads? Take them out the calipers and back in again?

No, not that - bedding the pads to the disks and cooking the pad material.

 

Basically, find a quiet stretch of road and do several 60 to 10mph stops, and then drive for a bit allowing the brakes to cool and if needs be repeat - many manufacturers specify something along those lines for new pads (particularly performance ones) and I've found it in the past to dramatically improve bite and stopping power.

 

Worth double-checking that the sliders on the GTi-6 calipers aren't seized btw

 

Edit - having seen the pictures above, it's no surprise it's not stopping properly if the disks haven't yet cleaned up. Do the bedding in method above and it'll clean up the disks and improve things dramatically I suspect. Certainly GTi-6 brakes should be able to lock the front wheels easily if everything is good.

Edited March 27, 2012 by Anthony

[chipstick 382 1 Cars]

Excellent.

 

Well I only moved it Saturday afternoon for a mile or so and have been taking it easy since incase there was an issue.

 

Good advice Anthony thanks. I will do several emergency stops and see if anything improves

[welshpug 1,646]

i had discs like that on my 309, cleaning them up didnt work, machining may well have sorted them but for the money wasnt worth faffing

[chipstick 382 1 Cars]

Good 20 minute blast round some b roads and they are better

 

 

They lock up on demand now. Probably a bit easier than I'd like

 

The locking up I can deal with, it's the back end twitching (mine and the cars) that unnerves me. At least they function now.

[nickaliath 22]

We got there in the end dan LOL.

 

Hey, im going to buy a pressure bleeder this week after last nights performance LOL

[chipstick 382 1 Cars]

Yeah was great fun, Gus.

 

Well if you get it before Saturday let me know and we can make sure it's done 100%