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Track session brake pedal soft...what to do?


ironhide

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Hi guys.

 

Did my first track session in the zed at Japfest this weekend and had a few issues with my brakes. I've done Japfest track sessions before in my old Altezza, Celica and MR2 without braking issues so this was a first.

 

By current setup:

 

Motul RBF 600

HEL braided lines

EBC blade discs

EBC yellowstuff pads

 

In the first session the first couple of laps I admittedly held the brake some time going into the first few corners so I could gauge what sort of speeds in and out of Quarry in particular, but after a few laps going into the chicane the pedal pretty much went to the floor and was spongy for the rest of the session so had to take it easy.

 

After the session I noticed that pedal goes right to the floor and feels spongy with a slow spring back. I also noticed a slight blue tint particularly in the rear discs.

 

For the second track session (Zed track time), when braking, the pedal felt soft but by releasing then immediately pressing again the pad bite was much stronger and more efficient allowing for a much more enjoyable track time until my tyres (Kumho Ku31's) started to give way a little, luckily that was at the end of the session.

 

Driving home they felt spongy unless I press, release then press again - that's when they felt good.

 

Today however, they actually feel not to bad on the roads, but then I wasn't pushing them. Also the blue tint has faded and nearer grey now.

 

So my questions:

 

Is the blue tint in the discs anything to worry about?

Could this be a combination of poorly broken in discs/pads? And/or...Could it be an air bubble being present in the system and the track session just made it more noticeable due to expansion and heat and then double tapping the pedal allows the brake to operate before the bubble can expand again?

Will another flush cure this? Or did the fluid boil, if so should I change to RBF 660?

What about a flush and upgrade the pads to DS2500? (assuming the discs are ok?) or are the discs a write off?

 

I've posted pics of the discs below. You can see the rings running through the centre of all the discs, doesn't really show the blue tint that well.

 

NSR

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NSF

null_zpscbefa28a.jpg

 

OSF

null_zpse78b9c8c.jpg

 

OSR

null_zps5ccde46c.jpg

 

Any help much appreciated. Cheers

Edited by ironhide
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How long as the RBF600 been in? Pedal going to the floor is probably boiled fluid - if its been in the car for a while it can absorb moisture from the atmosphere which lowers the boiling point.

 

 

The stock fluid was flushed and replaced with RBF600 in August 2012

 

Front discs and pads were added May 2012.

 

Rear discs and pads added along with the braided brake lines were fitted Jan 2013.

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Wouldn't worry about the blue-ing on the discs, mine look even deeper blue after a bedding in session ;)

 

That's encouraging at least, thanks.

 

So that either means the fluid boiled or there's an air bubble in the system. In either case I assume a flush of fresh RBF600 should suffice? I might upgrade to DS2500's as well.

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As has been said, bluing is nothing to worry about.

 

Pedal to the floor would probably be moisture, air, or some old inferior fluid left in the system. Assuming you have no rubber brake lines anywhere in the system?

 

A flush and bleed with fresh RBF should do the trick.

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A lot of standard lines are braided anyway, you just can't see it when it has a thick black rubber protective coating. Guys will still fall for the marketing/forum chat and change them to aftermarket and insist they have a firmer peddle though.

 

Even if the Zed one's can be upgraded, I don't like the idea of removing a section of hard line and putting in a longer section of braided hose, probably cancels out any benefit. I wonder why they don't sell the shorter 'standard' length and keep the hard line section on the caliper?

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Not a fan of EBC brake stuff, however in this instance a fluid change and a proper bleed, in the correct sequence will fix your issue providing there are no leaks.

 

RBF600/660 and Ferodo DS2500 pads are in stock and good to go same/next day if required.

 

Just drop me a PM if I can help you further mate.

 

Alex. :)

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I think as everybody else says, a flush of the brake fluid and some new in just to make sure and maybe some new pads.

I too went on track at japfest with my new brakes which is just about the same setup as you except I have standard hoses and ds2500 pads, so I have same fluid and discs and mine were great I was actually rather surprised how good they were and towards the end they were brilliant when they was nice and warm:)

Edited by kiingsi
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I'm keen to see the outcome of this. I've been considering EBC's BSD Blade discs as an upgrade. I have HEL lines, 660 fluid and yellowstuff currently, and I consider my brakes to be excellent. The HEL lines, if nothing else, simplify and reduce weight of the large amount of tackle in the OEM system - all those pipes, unions and corroded fittings now gone.

 

In your instance, IMHO as other said before, it sounds like air in the pipe or bad fluid, causing expansion on heavy use leading to binding and overheating.

 

Just my 2p's worth. :thumbs:

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How long as the RBF600 been in? Pedal going to the floor is probably boiled fluid - if its been in the car for a while it can absorb moisture from the atmosphere which lowers the boiling point.

 

+1

 

Stick a new bottle of fluid and it will probably be ok and it's relatively inexpensive and easy to do. just get a one man bleeding bottle for about 3 quid from your local brakers

Edited by CrumbMC
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Cheers guys, I'll probably get x3 bottles of RBF600 and get the system completely flushed using a pressure system to draw out the old stuff. I can't see the need to use RBF660 as it's not a race car and a more than twice the price a bit overkill for my needs.

 

Seems the consensus is boiled fluid though. I think i'll probably upgrade the pads before the next track day as the yellowstuff still has plenty of life left in them for the moment, but will inspect them when I flush the fluid next weekend.

 

Cheers for the help chaps.

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Even if the Zed one's can be upgraded, I don't like the idea of removing a section of hard line and putting in a longer section of braided hose, probably cancels out any benefit. I wonder why they don't sell the shorter 'standard' length and keep the hard line section on the caliper?

 

Braided lines just replace the rubber bit between the hard pipe and the caliper, not the entire pipe. When I first did them I definitely felt there was more force coming from the brakes, but it's difficult to gauge as I had new discs and pads done at the same time.

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What Watshot is referring to is the hard line that goes to the caliper.

 

This has to be removed when fitting Hel lines.

 

That is why the Goodridge lines are my personal preferred choice as the hard line to the caliper is retained.

 

Alex. :)

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What Watshot is referring to is the hard line that goes to the caliper.

 

This has to be removed when fitting Hel lines.

 

That is why the Goodridge lines are my personal preferred choice as the hard line to the caliper is retained.

 

Alex. :)

 

Ah, I'm with you. I'll wind my neck in then lol. I forgot about the small hard pipes. Aren't they just the rear though?

Edited by ironhide
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This lot comes off with HEL...

32a261a15efb9eac963e7c4d559142d7.jpg

Is it now thought that its better to have a solution that retains some of it? Goodridge are the best of course, although HEL seemed to be in fashion when I bought mine. We do also have the 1 (or 2) P clip requirement with HEL - to cut down or eliminate line wobble/scuffing - which has worked for me. Hmm...

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OK, got the system bled at the weekend. Went through 2.5 bottles of fresh RBF600 using the pumping the pedal technique keeping the nipple open.

 

The rear lines were definitely bad, the fluid was brown and even had a few bits in it with some air, clear sign of boiled fluid. However got the car back on the ground drove away and the pedal felt as soft as butter. Back up she went for another round of bleeding (Just as well I had spare fluid) this time did the old school way, open the nipple, press, close, release on all 8.Pedal feels much better now with much better direct force on the brakes.

 

I'm not as confident with the yellowstuff pads, they're great on the road but will likely be upgrading to DS2500's soon along with new front tyres as they are starting to loose grip under heavy braking.

 

I do have a question though about the bleeding process, is the best method the open, press, close, release?

 

I'm just a little concerned as to why the other attempts didn't work and wondering whether the master cylinder could have an internal leak - is there a more efficient way to test this?

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Yep, it is really a two man job. The zed seems particularly fussy where brake bleeding is concerned.

I find the best method is press the brake, open nipple, close nipple(before pedal has bottomed out) then release. Then repeat in the correct order.

 

Any other method seems to introduce air and even auto breeders don't seem to work very well.

 

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