Polo brake bleed question (replaced front calipers)

**noone** · 17-03-2013, 04:07 PM

Background:

I've been running TT brakes for a few years with an ongoing issue. The brakes would rattle when going over bad roads, concrete slabs that don't meet well. I've asked about it, taken it to mechanics, lots of googling. No real answer, or help. Its only when off the brakes, if I'm braking lightly, there is no noise (so i softly ride the brake over these areas)

i decided to buy another set of TT brakes (particularly the calipers) which I today installed.

What I've done:

So I swapped out the calipers, trying to minimise the amount of fluid lost during the process. Once the new calipers were on I did a brake bleed in the order Jmac recommends:

Passenger Front, Driver Front, Passenger Rear, Driver Rear. Done with an assistant on the brake pedal pusing 2/3rds down.

Not much in the way of bubbles after the new piston chamber filled.

So far I've only used about 200-300ml of brake fluid to get the system going. I've gone around 4 points twice.

So the new brakes don't rattle when I'm off the brakes! VICTORY!

Now the pedal travels further to bite, a bit soft for me. I can pull up hard, but not as hard as it was.

Question / Advice:

As I've only used a small amount of fluid, should i keep going to flush out bubbles further up?

As I only changed the front brakes, should I focus on the front brakes only?

I understand that it takes about 600-1000ml to do the full fluid change over, but if I'm not seeing bubbles for a while, I'm not sure when enough is enough...

I've also read about bleeding the master cylinder, not sure if this relates to our car or if it may help.

Thanks.

**Jmac** · 17-03-2013, 05:11 PM

Please bare in mind that method isnt the norm, just incase it gets misleading, that method is strictly for the Polo and only when a bleed is nesc and not a fluid change. No nipple on the polo master cyl mate so doesnt relate to that. Sounds like it needs further bleeding. Must admit though a pressure bleed is much more effective.
Jmac

**noone** · 17-03-2013, 05:33 PM

thanks mate.

I'll keep going, this time in reverse.

Cheers.

**Redliner** · 17-03-2013, 06:27 PM

Good to hear that you got rid of the rattle. I remember you mentioning that when I picked up the strut bar.
sometimes those little rattles drive you nuts.

**gldgti** · 17-03-2013, 07:01 PM

Usually rattling brake calipers is due to the absence, or wear, of spring clips that usually fit between the carrier and the pads or the calipers and the pads, or both.

It depends a lot on the type and style of caliper, but just about all OEM brake setups have some kind of spring clip system for eliminating this rattle.

On the question of the bleed method, I agree that generally its a good idea not to push the pedal to the floor when bleeding.... but given that our modern brake setups nearly always have aluminum master cylinders, its usually pretty safe to push to the floor if it helps the bleeding process. Did it on my Octavia just this morning.

**noone** · 17-03-2013, 07:16 PM

Thanks gents, the retainer clips have been changed, I made custom pad shims, did a full seal replacement, tried different pads, everything I could think of.

It's so much nicer, I drive with the windows down so would hear it all the time.

Will do some more bleeding with the normal method and see.

Cheers

**GTiPilot** · 19-03-2013, 09:54 AM

Hi noone,

Just wondering where you got your brakes from? I need to replace my front discs and pads and thought I may as well go TT ones for the right price, otherwise I'll just get stock discs and better pads.

Cheers,

**noone** · 19-03-2013, 10:43 AM

I bought mine from a wrecker in the UK through ebay, cost me around $175 for the carriers, calipers, springs & pads.
You will still need rotors and fluids.

otherwise, if you can source the calipers (try posting in the wanted to buy section), then you might find a set and you can have my spare carriers and pads (and retaining clips if you need them) cheap. I'm using a basic fluid, was using the martini stuff, but didn't feel the difference, so back to the fairly generic fluids.

If you are considering both, ask QFM (sponsor) for a quote on new rotors for the TT's and pads and rotors for your current setup. Might help you decide.

**noone** · 19-03-2013, 11:32 AM

Think my rotors are getting a little thin (seem ridiculous to have a massive rotor, you take 1mm of either side and they're done).

Do I go for generic rotors for about $130 or DBA4000 series for $200?

Or, do I keep my rotors on past their minimum thickness? really 1mm off either side can't make that much of a difference... can it?

**seangti** · 19-03-2013, 12:13 PM

Originally Posted by noone

Think my rotors are getting a little thin (seem ridiculous to have a massive rotor, you take 1mm of either side and they're done).

Do I go for generic rotors for about $130 or DBA4000 series for $200?

Or, do I keep my rotors on past their minimum thickness? really 1mm off either side can't make that much of a difference... can it?

I've always ran an RDA or DBA rotor, though don't believe they were the fancy series, just a slotted street style rotor. With quite extensive track work on the two cars that have ran them and over a period of a couple of years, I've never had any issues with the rotors. I'd be inclined to ensure the pads and fluid are quality items along with a reputable rotor.

Oh, GSL is the sponsor, not QFM. QFM are a brand of brake pads they stock.