Long brake pedal after a couple of hard stops...

[Ian C]

Not strictly Supra-specific this, but it's a question that applies to Supras anyway. I've got a car where, if you do a couple of hard stops from say 70mph to around 10mph, the brake pedal start to get really long. You can still get the ABS to kick in, and if you let it cool down a bit they come back fine (until you heat it up again).

 

Would I be right in saying that there is still some air trapped in the brake system, and the heat from braking makes it expand, so the pedal has to go further to compress it? I'm fed up bleeding brakes but I've got a track day in a week's time and coasting around all but two corners isn't fun

 

I don't think it's the fluid as I've got it in other cars and their brakes are fine. Plus, y'know, only two hard stops shouldn't cook the fluid I don't think anything is binding either, no rolling resistance, no overheated calipers, no brake disk blueing.

 

Thoughts?

 

-Ian

[Dnk]

Try using a vaccum bleeder, has it got old rubber type brake lines fitted

[Ian C]

Yeah, it's rubber hoses. I'm looking at the Gunson easy bleed thing but it doesn't fit the reservoir of an MX5 apparently. Is a vacuum one similar to that?

[Dnk]

Are the hoses ok ?

 

I've used one of these and it was superb, its a vacuum bleeder so you just push the pipe on

the bleed nipple and it draws the new fluid through the system rather than pushes it through.

 

Its a hand pump as well so no need for compressors

 

http://www.amazon.com/Mityvac-7400-Liter-Fluid-Evacuator/dp/B000JFJM14

Edited August 7, 2012 by Dnk (see edit history)

[Ian C]

I've just ordered a Sealey tool that does the same job, didn't know these things even existed! Thanks very much - this might improve my Supra's brake pedal as well

[Dnk]

Best brake bleeder i've used and so simple, glad to help

[Thorin]

Yeah, it's rubber hoses. I'm looking at the Gunson easy bleed thing but it doesn't fit the reservoir of an MX5 apparently. Is a vacuum one similar to that?

 

Hi IanC, welcome to the forum.

 

This "mkiv technical" sub-forum is for technical issues regarding the MKIV Toyota Supra. I do not believe the MKIV Mazda MX-5 is out yet, might I suggest www.mx5oc.co.uk?

[Ian C]

I meant MkIV Supra, it was a typo, the keys are right next to each other

[Ian C]

Just to update this, I got a Sealey vacuum bleeding tool, and tried it out on my Mondeo. I had to replace a rear caliper due to a siezed handbrake mechanism (again) and the pdeal feel felt a bit worse afterwards. Now, it's fantastic - shorter travel, less takeup, nice and firm.

 

So I hit all four calipers on the Supra and transformed the pedal feel in about an hour flat woohoo! (So there, Thorin, Supra relevance at last )

 

I've yet to do the MX5 but I expect good results. Here's what I bought:

http://www.amazon.co.uk/gp/product/B001EVZG9E/ref=oh_details_o00_s00_i00

All of £30!

 

It's repeatable, effortless, quick, and cheap - why do it any other way? The only thing you need to know is to use grease to seal the bleed nipple thread, otherwise it draws air through the threads rather than brake fluid out.

[Dnk]