Poor braking performance :S

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Steampunk
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Re: Poor braking performance :S

Postby Steampunk » Mon Jun 03, 2013 1:18 pm

sailaholic wrote: i also don't think this is the problem as i'm sure steampunk would have done fluid when he did the rest of the system.


I wasn't going to comment until you did, so now that you have;

I've stated my "disappointment" in braking to several people, including Sailaholic when he was interested in buying the car so as to avoid his disappointment.

Ever since I bought what-is-now-Sailaholics' car in 2000 with around 86,000km [FYI it's a late 1993 build NA8], I have never felt comfortable with the brakes. About a year after purchase, we bled the system completely, and ran through two bottles of Nulon brake fluid to get all the old stuff out.
Negligible improvement because the previous owner bled it and also used quality stuff not long before selling.

Long story short, lived with it/adapted to it for several years, then joined this forum and drove other people's cars.
I have changed:
- brake lines (braided Goodridge),
- installed BMC brace,
- Hawk HPS,
- slotted & drilled rotors.

All to pursue better braking.

I realise the rotors might be more form over function as some people will say it provides less surface area therefore less bite, but I think it's the opposite, the less the surface area, the more force the pad can impart when it contacts.
Think of 5-puck, 3-puck clutches.

The most tangible difference/improvement was the BMC brace, and although braking was improved somewhat, it only brought it to the same level of all other cars I've dríven, and what I think should be like..... but it was still lacking.

I've bled/changed brake fluid around 4, maybe 5, times in my 11 years of ownership (after every 2nd track event), the last couple of times I've used Castrol Super DOT4.

I followed the Hawk bedding in procedure to the letter, and installed the rotors at the same time (well actually tbro installed them 8) thank you tbro) so I had the best chance of improvement due to having two complimentary virgin surfaces.
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sailaholic
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Re: Poor braking performance :S

Postby sailaholic » Mon Jun 03, 2013 1:55 pm

Thanks for confirming the history steampunk.

I'll still pull the pads and check and take some photos, but i'm starting to suspect either calipers, proportioning valve or master cylinder / booster, as it seems everything else has been changed!

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Steampunk
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Re: Poor braking performance :S

Postby Steampunk » Mon Jun 03, 2013 2:02 pm

project.r.racing wrote:if have no sand paper, then place pads fricton surface down on the concrete and do circle motions 2 or 3 times.

^this, over sand paper using just your hand, but preferably sand-paper on a block for consistency.

I seriously doubt glazed pads/rotors is the problem on yours Nick, I'm afraid it's just "one of those things" :frown:
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manga_blue
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Re: Poor braking performance :S

Postby manga_blue » Mon Jun 03, 2013 2:06 pm

project.r.racing wrote:if a piston was suck, you would be able to lock up the other 3 calipers easier as the pedal pressure is going into 3 pistons, not 4.
That's what I was thinking too.

One way or the other there's not enough friction, possibly:
1. Glazing, most likely at front because the rear brakes do stuff-all in an NA8 with a stock bias. You can just look through the spokes to see rotor glazing.
2. Faulty or wrong sized master cylinder
3. Something has totally failed inside the proportioning valve
4. Faulty booster (except that you checked that already)

BTW do you get rear wheel lock-ups? Is there any judder?
’95 NA8

stb
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Re: Poor braking performance :S

Postby stb » Mon Jun 03, 2013 2:23 pm

I was thinking wrong size master cylinder too. I don't know if Mazda had different MC bore diameters with different models/vehicles, but the symptoms line up with the case of MC bore diameter too big.

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plohl
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Re: Poor braking performance :S

Postby plohl » Mon Jun 03, 2013 4:55 pm

Iirc... the rear pads were glazed. They were pretty shiny...

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NitroDann
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Re: Poor braking performance :S

Postby NitroDann » Mon Jun 03, 2013 6:50 pm

Does it actually not stop or is the pedal just hard?

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speed wrote:If I was to do it again, I wouldn't even consider the supercharger.

sailaholic
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Re: Poor braking performance :S

Postby sailaholic » Mon Jun 03, 2013 7:00 pm

Well its driveable, so it stops,
Edit:
But there has been a few times where I've questioned IF it would stop in time.

Some reading says master cylinder size should be cast on the unit.

I have a willwood bias adjuster on the shelf so if glazed components aren't evident and master size looks ok I'll try installing that.

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manga_blue
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Re: Poor braking performance :S

Postby manga_blue » Mon Jun 03, 2013 7:16 pm

You should put the Willwood proportioning valve unit on anyway because the OEM NA8 unit is crap.
’95 NA8

project.r.racing
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Re: Poor braking performance :S

Postby project.r.racing » Mon Jun 03, 2013 7:53 pm

Steampunk wrote:
sailaholic wrote: i also don't think this is the problem as i'm sure steampunk would have done fluid when he did the rest of the system.
Long story short, lived with it/adapted to it for several years, then joined this forum and drove other people's cars.
I have changed:
- brake lines (braided Goodridge),
- installed BMC brace,
- Hawk HPS,
- slotted & drilled rotors.

All to pursue better braking.
After this bit of info. new booster time me thinkz.

sailaholic
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Re: Poor braking performance :S

Postby sailaholic » Mon Jun 03, 2013 8:02 pm

manga_blue wrote:You should put the Willwood proportioning valve unit on anyway because the OEM NA8 unit is crap.


Yah I was wanting to get the hard lines moved around to get more room for the itbs / airbox, so that's been the delay there.

I guess with this, I'll just put it in and get the lines moved later. Good to hear it's actually worth it and not just hype.

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NitroDann
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Re: Poor braking performance :S

Postby NitroDann » Mon Jun 03, 2013 8:36 pm

It would be good if you had a local track guru to take it for a 5 minute drive.

Dann
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speed wrote:If I was to do it again, I wouldn't even consider the supercharger.

Byron_s13
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Re: Poor braking performance :S

Postby Byron_s13 » Mon Jun 03, 2013 10:44 pm

I did not bother reading all the previous posts but first I'd check...
When you turn the car off wait 1 min pump the break if the pedal is soft= good
Pump the pedal till it go's hard hold foot on break start car pedal sinks = good
If this does not happen
#1 you where drilling holes in your fire wall for a hectic subwoofer and hit your booster diaphragm
#2 your diaphragm split
If good Now check

The pistons in the calipers push in easy and out easy when pedal is applied.
The slides are greased and slide easy.

The bleed nipples are at the top of the calipers.

If all good now bleed brakes!
You will need clear tube that fits on bleed nipple. 8 mm spanner or 10mm hot chick in tiny shorts to pump the pedal.

You start from the Nsr (gutter side rear) pump out all fluid!
Wipe out master with rag and fill.
Pump fluid till it comes through straw clean.
Lock off.
#101# pump pedal till hard hold down pedal! Crack line, when pedal hits the floor hot chick yells out "ahhhhh yeahhhh" lock off line repeat a few times.
Move to OsR( off gutter side rear) repeat #101
Move to NSF (gutter side front) repeat #101#
Move to osF ( off gutter side front) repeat #101#

Always make sure your master cylinder does not run out of fluid! If it does repeat full process.
Your breaks will be sh*t for 2 or 3 days then good.

If you had to read this more than once I highly recommend that you do not attempt playing with your breaks! They are what save your life over 100 times a day

.

Apu
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Re: Poor braking performance :S

Postby Apu » Mon Jun 03, 2013 11:12 pm

Ehh..I found it easier to just gravity bleed the brakes. Just don't have too many beers whilst you're waiting.

sailaholic
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Re: Poor braking performance :S

Postby sailaholic » Mon Jun 03, 2013 11:21 pm

Byron_s13 wrote:I did not bother reading all the previous posts....


If you were trying to be helpful, Thank you I really do appreciate it , however it would have been more helpful if you could have read the other posts.

If you trolling, please go elsewhere.

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