Editing Forums/Z31P/z31-performance-upgrade-forums suspension-chassis-and-brakes/Brake bias

{{ForumImport
|op_user=Augustus Maximus
|op_date=2013-08-12 23:14:37
|post_count=9
|archive_url=/Z31performance_archive/forum/z31-performance-upgrade-forums/suspension-chassis-and-brakes/22368-brake-bias.html
}}

'''Augustus Maximus:''' <small>(2013-08-12 23:14:37)</small>

I seem to have developed a serious bias since I installed Z32 brakes up front. I'm guessing that going with the Z32 BMC will correct this?

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'''G-E:''' <small>(2013-08-12 23:17:08)</small>

The z32 bmc will bias your brakes more forward than z31 bmc… which way are you biased?

I suspect it's a mechanical problem, relube/clean/rebuild your rear calipers first

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'''NissanEgg:''' <small>(2013-08-13 02:51:09)</small>

Most likely haven't bled all the air out of the system in the front. It took me several bleeding procedures to get all the air out.

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'''Augustus Maximus:''' <small>(2013-08-13 03:48:06)</small>

It's biased toward the back. The rear calipers are in excellent shape, I had perfect brakes prior to the swap so I'll bleed it again. Z32 BMC will be my last resort.

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'''adamvann3:''' <small>(2013-08-13 17:53:31)</small>

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Same. I have the toughest time bleeding out brakes on the z31. I normally bleed them the best I can, drive it for a day (safe areas) then re-bleed everything. Pedal should be very firm and bias should be the same. My stock OEM BMC has held up to z32tt and wilwood calipers.

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'''Careless:''' <small>(2013-08-13 18:22:49)</small>

common automotive procedure is to bleed from furthest caliper first, working back. we all (more or less) know this. z31's furthest caliper is actually the driver rear, not the passenger rear. the lines go down the pass side of the car, and across the rear hatch compartment slope.

I would try bleeding from there first and use a one man bleeding kit (they sometimes work better than a helping hand). If that fails, a vacuum pump might be a good investment. mainly because you won't have to spend money on a BMC, and you'll add another tool to your arsenal.

failing that, I do like the pedal feel with the z32 1" bmc compared to the z31 bmc, either way. for some reason it just feels like it's a better balance with the z32 brakes. I'm pretty sure they are valved from within the bmc to flow a bit more fluid up-front, as G-E pointed out. I've had to brake hard in a turn and I didn't feel as if the z32 brakes and hawk hp+ pads + z32 BMC over compensated in the front. It surely would have swung the back out, but i felt more confident with the z32 bmc in turns than I did with the z31 bmc, oddly- considering the bias.

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'''Bremsen:''' <small>(2013-08-26 15:25:40)</small>

Interesting, I didn't notice any major bias change until I installed the rear Z32 calipers and master. Pedal feel/travel got much better with the Z32 m/c, but it is definitely on the brink of too much rear bias. Its not to the point where it wants to swap ends, but I find the rear tire locks up at the same time or sometimes just before the front (Z32 brakes all around, 255/40/17 RS-3s). I currently run slightly less aggressive rear pads to compensate, but might have to install a prop valve.

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'''jaqattack02:''' <small>(2013-08-26 15:55:41)</small>

I'm just going to throw this out there because it's a common mistake, and easy to make if you're not paying attention (did it myself putting on my 88T calipers). Have you verified that the calipers are on the correct sides? If you get them backwards the bleed valves will be facing down and you'll never get all of the air out as it will get trapped in the top of the caliper.

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'''Augustus Maximus:''' <small>(2013-12-30 19:44:21)</small>

Late reply but, installation is correct. Back locks up before the front even after extensive bleeding. I have a Z32 M/C and booster to swap in, which should give a little more action up front. Will report back on this.