Poor braking performance :S

sailaholic · Postby **sailaholic** » Sat Aug 17, 2013 6:34 pm

Super keen so see how your development goes mark

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MattR · Postby **MattR** » Sat Aug 17, 2013 6:39 pm

Be careful on dropping the mastercylinder size, smaller means less fluid, if you are marginal on the fluid volume, dropping the size could mean you haven't got the volume you need. I got caught out with my zed, upset the brakes by doing something simple and it enough to need to go from 15/16ths to 1" to make sure I had enough volume of fluid to fill 12 cylinders of fluid when I hit the pedal. Wthout going up a size the cylinder rod was going to full travel and I still hadn't pushed the pistond to vet the pads onto the rotors with new pads, let alone worn pads.

Magpie · Postby **Magpie** » Sat Aug 17, 2013 6:55 pm

Thanks MattR my readings pointed out the need for a larger fluid volume, brakes is not something I want to get wrong. I will pick your brain again

sailaholic · Postby **sailaholic** » Sun Aug 18, 2013 1:39 pm

The ideal way from my reading is to run twin master cylinders, keeps volume up while keep piston size (and effort) down.

Using a bias bar is more efficient the a pressure reducing bias valve as the bias valve "wastes" the pedal effort it bleeds off the rear circuit.

Which rotors and pistons are you planning mark? Na8 nbb? Or a Willwood setup?

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Magpie · Postby **Magpie** » Sun Aug 18, 2013 2:42 pm

At the moment running NB8B brakes (including the proportioning valve) on the NA6. After driving my sons (now mine) stock NA6 I would say that my NA6 (with the NB8B's) needs a bit more pedal effort. However there is also a difference in the cars pads in that the NB8B's have low initial bite and need a bit of heat in them. Bias bar would require a pedal box and then I run into CAMS issues.

MattR · Postby **MattR** » Sun Aug 18, 2013 7:39 pm

Magpie wrote:At the moment running NB8B brakes (including the proportioning valve) on the NA6. After driving my sons (now mine) stock NA6 I would say that my NA6 (with the NB8B's) needs a bit more pedal effort. However there is also a difference in the cars pads in that the NB8B's have low initial bite and need a bit of heat in them. Bias bar would require a pedal box and then I run into CAMS issues.

A pedal box and twin master cylinders with bias adjustment are fine Mark, the pivot point needs to be within 75mm of standard, and I can't remember if the brake bias can be adjustable on the go. Easiest to check cams website for 2b cars, on phone at the moment so don't have the latest rules with me. For my build I'm lucky, all the Nissan brakes and hardware are interchangeable, so all I need to do is get a bm50 master and I'm away with the bias pretty much spot on for the z32 fronts and r33 gtr rears and that will pull up 1200kg all day everyday with no problems.

sailaholic · Postby **sailaholic** » Wed Sep 25, 2013 6:27 pm

Bit of an update, changed the booster out for a second hand unit, figured the 200 dollar saving was worth the risk.

Also fitted a new check valve. The booster was definitely the problem, but I thought the check valve could be improved.

Pedal effort is down, but brake performance still dosent feel rapid. Going to do some back to back tests with another na on different pads to check what I believe it should be then probably change pads out.

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sailaholic · Postby **sailaholic** » Wed Jan 29, 2014 9:45 am

OK an update!

Project R and Manga Blue were correct as well it seems. I was dealing with two problems from the start.

Pulled the front pads last weekend and they were pretty shinny. I had a set of pretty much used QFM A1RM's given to me for testing so rather then sand the pads back i just dumped the used ones and took it for a test.

First stop bedding in stop with the A1RM's and i nearly flat spotted the tire the pedal effort was that different!

Not sure why they were glazed seeing as andrew said he followed the prodedure to the letter and installed them on brand new rotors?

Big thanks to the guys at GSL Rally Sport / Brakes direct. I ordered a new set of pads @ 10.30 Am and they were sitting on my desk by 2.15 Pm the same day! Couldn't belive it.

hks_kansei · Postby **hks_kansei** » Wed Jan 29, 2014 10:20 am

You can glaze pads at any time, it's not just a during bedding thing.

If I recall, glazed pads are often from constant light application.
So, heat + not enough force to grind the face down

Do you ride the brakes on long downhill sections? are all the calipers sliding freely? are they releasing fully?

You can un-glaze them by either re-bedding, or just take them out and rough up the face on a concrete driveway or something.

sailaholic · Postby **sailaholic** » Wed Jan 29, 2014 10:47 am

No don't ride the breaks, tend to engine brake for light stuff. Having no booster might have influenced breaking to be longer but lighter.

Calipers all looked to slide ok when changing the pads, had obviously been greased etc. had no problems pushing pistons back into calipers.

Did notice a bit of a faint dragging sound this morning though.

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Magpie · Postby **Magpie** » Wed Jan 29, 2014 11:15 am

sailaholic wrote:Big thanks to the guys at GSL Rally Sport / Brakes direct. I ordered a new set of pads @ 10.30 Am and they were sitting on my desk by 2.15 Pm the same day! Couldn't belive it.

I second the people at Brake Direct for customer service.

I ran in the wet at the night sprints with the QFM A1RM's and found them very responsive, so much better than the EBC Greens. However based on my current setup of the vacumn for the booster coming from the ITB's the pedal feel is a lot different to a stock NA6 and to be honest I prefer the current feel (less boost).

It may be worth pulling the calipers all the way off and do an inspection you could be suprised at what you find. My brakes will be going in for a rebuild in the near future as the front slider pins (without the rubber boots) are very pitted, the rubber boots on the other slider pins are stuffed plus the piston boots have deteriorated. Also one of my rears had a broken caliper wind in/out adjuster. Just because it slides does not mean all is well

They will be rebuilt and sleeved so hopefully will last for a very long time, just changing pads, rotors and greasing the slider pins.

sailaholic · Postby **sailaholic** » Wed Jan 29, 2014 6:00 pm

Had the front calipers completely off when doing the pad chang. Slider pins looked in good condition, still shiny golden, all the boots also looked in good condition.

Rears didn't come completely off but again sliders looked ok. Adjusters in the back of the calipers unwound fairly easily.

I'll stick my head in the foot well and check the pedal free travel. Maybe it is insufficent and is causing some dragging.

project.r.racing · Postby **project.r.racing** » Wed Jan 29, 2014 6:51 pm

I'm always right 5% of the time, the other 5% is google, and the other 90% is the wife. :lol:

The theory about being glazed went bedding in sounds right. Yeah you can follow the process 100% correctly. But if the parts required to do the process aren't working 100%, then it isn't gonna do it right.