So that's why my brakes suck!

Wheels, Suspension, Brakes & Tyres questions and answers

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Sasso

Why do my brakes suck?

Postby Sasso » Sat Aug 23, 2008 1:24 pm

Hmm my friend Gavin had/has the same problem in his NB8B with abs, I drove his car and I could push the pedal 'till it stops and the car would not brake very hard at all, it was very hard to get the abs to kick in. I initially thought there was air in the system because my car had a similar problem and that fixed it. However we bled Gavin's brakes at the track and he said there was only a slight improvement.

pads are newish bendix advance front and rear


There is your biggest problem, I have these on the rear of my na6 and they are RUBBISH. They don't do anything except polish the surface of the disk, they haven't worn them away at all and I have been to several track days, the Hawk HP+ on the other hand are brilliant, stopping power is amazing and I was surprised how slowly they wear despite the dust.
Go get some Hawk HPS for the street or HP+ for the street and track days, you will then experience what brakes should be like.


Pumping the pedal once or twice brings back some pedal and the brakes work 'normally'


Second problem, if you are having to pump the pedal to get the brakes to work, then you either have air in the system, or your pads are being pushed away from the rotor too much and you're have having to pump the pedal to get them to move in. Bleed the brakes properly, im not too sure how the whole abs thing works, I would have thought its all the same fluid and you just bleed like usual (pump the brakes and undo the nipple with a hose on it). Then take apart your callipers, buy some metal toothbrushes, clean up all the buildup and crap with them and brake cleaner then buy some high temp brake pin grease and put it all over the slider pins and the part where the pads slide (not the surface). Then perhaps get the disks machined.


I'm not sure how Gavin's car is now with the new pads but you could sent him a PM if you want to ask him, I think he got the Hawk HP+.
But I definitely think you should take off those advances.

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garettb16
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Why do my brakes suck?

Postby garettb16 » Sat Aug 23, 2008 1:48 pm

sounds like air in the system too.. id be going to a brake place and getting them to check it over..

brakes are not over-rated.!

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CT
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Why do my brakes suck?

Postby CT » Sat Aug 23, 2008 4:39 pm

Hey Caff, flush that garbage dot 5 out of the system and replace with good old dot 4 - castrol super response is all I ever use in the NB8B. For a race style fluid, try Elf HT10 (?) which is what I use in the race car. The NB system does not like dot 5.x in my experience. Then, when you bleed it, try doing it with the ignition switched to on as it opens the ABS valves in the motor unit so that if there is any air, it will pass into the lines. Apart from that, sounds like it's just the fluid that is the issue.

You don't have speedbleeders do you? If so, I've found them not to be as good as everyone reckons as well......they don't always seal on the caliper properly. Another option is to make sure your pads are wearing evenly - I had a seized slider on the road car not long ago too.
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Why do my brakes suck?

Postby rjastra2 » Sat Aug 23, 2008 9:30 pm

your ABS cycles when you first start the car after a few moments, correct? I had the hardest time getting a firm pedal with the ABS unit. I started to notice I would bleed the brakes and everything would be great until i started backing out of the driveway and the ABS would cycle. So I threw it back on jackstands, and let the rear wheels spin a tad and hit the brakes, since they lock up instantly the ABS cycles....after I did this a few times and bleed again, I found a huge amount of air and old fluid. Brakes were much improved.

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Caffeine
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Why do my brakes suck?

Postby Caffeine » Mon Aug 25, 2008 8:08 am

CT wrote:Another option is to make sure your pads are wearing evenly - I had a seized slider on the road car not long ago too.


Bingo! :cry: As Garry hinted at too, Rodd and I took the whole system apart, and 2 seized lower caliper slider pins, and 2 very unevenly worn pads! (8mm vs 3mm on the left front, and 8mm vs 0.5mm on the right front!)

We managed to clean up one of the slider pins and bore, but the other is seized solid. Looks like I'll be ringing round today to source a new frame + slider pins for both sides, plus new pads.

The rubber boots both has small nicks in them, which obviously let the grease out and the crap in. Funny part is the slider pins and pad wear were ok at my recent dodgy day! :shock:


P.S. I find the advances to be a very good road pad, and I had no troubles with them at the track either.
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Supreme Blue NB8B, 1:16.98 at Wakefield when stock, but it's not stock any more...

Sasso

Why do my brakes suck?

Postby Sasso » Mon Aug 25, 2008 10:00 am

Caffeine wrote:
CT wrote:Another option is to make sure your pads are wearing evenly - I had a seized slider on the road car not long ago too.


Bingo! :cry: As Garry hinted at too, Rodd and I took the whole system apart, and 2 seized lower caliper slider pins, and 2 very unevenly worn pads! (8mm vs 3mm on the left front, and 8mm vs 0.5mm on the right front!)

We managed to clean up one of the slider pins and bore, but the other is seized solid. Looks like I'll be ringing round today to source a new frame + slider pins for both sides, plus new pads.

The rubber boots both has small nicks in them, which obviously let the grease out and the crap in. Funny part is the slider pins and pad wear were ok at my recent dodgy day! :shock:


P.S. I find the advances to be a very good road pad, and I had no troubles with them at the track either.


Glad to hear you found out the problem, but do try some better pads, you might be amazed, or might not...worth a try now that these are shot. Hawk HP+ for the street and track I recommend.

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Caffeine
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So that's why my brakes suck!

Postby Caffeine » Mon Aug 25, 2008 10:31 am

MX5Plus and MX5Mania both don't have the NB8B brakes available (damn all you NA6 owners upgrading :P )

Looks like Mazda may be my best bet, probably hideously expensive though... :evil:
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So that's why my brakes suck!

Postby Charlie Brown » Mon Aug 25, 2008 11:12 am

Caff, take the old calliper down to your friendly local brake repairer and get them to free the frozen one up. They can then grease and refurb them if required.
Far cheaper than replacing them.
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Caffeine
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So that's why my brakes suck!

Postby Caffeine » Mon Aug 25, 2008 11:18 am

Charlie Brown wrote:Caff, take the old calliper down to your friendly local brake repairer and get them to free the frozen one up. They can then grease and refurb them if required.
Far cheaper than replacing them.


I thought of that, but it's very well stuck at the moment. The slider pin that we did manage to free was pitted and scored too, so I'll need new ones of them at a minimum.
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Supreme Blue NB8B, 1:16.98 at Wakefield when stock, but it's not stock any more...

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Caffeine
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So that's why my brakes suck!

Postby Caffeine » Mon Aug 25, 2008 11:27 am

Caffeine wrote:Looks like Mazda may be my best bet, probably hideously expensive though... :evil:


Yep, $747.40 a side! :shock:

That's for a full caliper assembly, as the service guy claimed the parts weren't available separately.

Strangely enough, I called the same service centre up on saturday and asked about the slider pins (before we'd taken the second side off and found the completely seized one) and I was quoted $17.50. So the parts ARE available individually, just that this guy couldn't find them on the system I guess.
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Supreme Blue NB8B, 1:16.98 at Wakefield when stock, but it's not stock any more...

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Caffeine
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So that's why my brakes suck!

Postby Caffeine » Mon Aug 25, 2008 11:54 am

Helps to phone around, called up another dealer (incidentally the one i bought the car from :D ) and the parts guy there found all the individual parts I was after (driver and passenger side caliper mounting supports, 2 each of the upper and lower slider pins, and 4 slider pin rubber boots) for $436 :D and they'll have them for me tomorrow afternoon, so I can put everything back together on Wednesday!

Hurrah, just need to get some brake pads and I'll be all set!
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Supreme Blue NB8B, 1:16.98 at Wakefield when stock, but it's not stock any more...

wun911
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So that's why my brakes suck!

Postby wun911 » Mon Aug 25, 2008 1:00 pm

Can you just replace the pins?
http://ww2.mx5parts.co.uk/product_info. ... cts_id/897

Do you notice that one of the pins has a grove (I think to hold the grease) and the other one doesnt? Are both the pins the same size and lenght or what?

Im tempted to replace them all with groves has anyone done this?
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Caffeine
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So that's why my brakes suck!

Postby Caffeine » Mon Aug 25, 2008 1:46 pm

wun911 wrote:Can you just replace the pins?
http://ww2.mx5parts.co.uk/product_info. ... cts_id/897

Do you notice that one of the pins has a grove (I think to hold the grease) and the other one doesnt? Are both the pins the same size and lenght or what?

Im tempted to replace them all with groves has anyone done this?


Well I would just replace the pins, except one of them is frozen solid in the frame, and I can't get it out!

The upper pins have a groove (well 3 flat sides) for grease.

The upper and lower pins are a different shape, so aren't interchangeable.

The breakdown of parts cost is as follows:

Mounting Frame (#9 on the attached picture) : $154 per side (2 required)
Slider Pin - Upper & lower (#2 on the attached picture) : $19 each (1 upper and 1 lower per side, 4 in total)
Slider Pin Boot (shown in circular breakout on attached picture) : $13 each (4 required)

brakes.PNG
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Supreme Blue NB8B, 1:16.98 at Wakefield when stock, but it's not stock any more...

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Caffeine
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So that's why my brakes suck!

Postby Caffeine » Mon Aug 25, 2008 3:04 pm

Phew, Mania will have some hawk HP+ pads for me in the next couple of day too, $195 for the front set isn't bad :)
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Supreme Blue NB8B, 1:16.98 at Wakefield when stock, but it's not stock any more...

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So that's why my brakes suck!

Postby Garry » Mon Aug 25, 2008 3:28 pm

Caffeinne,

Are the rubber sleeves on the bottom slider pins available as a seperate part? One of mine is warn a bit.

Wun911,

The slider pins on the NB8B are different to the ones on my NA8, but the NA8 ones might be the same as the NB8A ones.
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