Franknbeans

iTrader: (1)

So, I'm still having to do a quick double pump on the brakes for them to feel firm. I don't mind because I'm used to it now, but it would be nice to have a real firm pedal on the first press.

I was thinking about plumbing in either a 2 or 4 lbs valve.

Anyone use these yet? Technically they are for when your calipers are lower than your reservoir. (Hotrod)

https://www.jegs.com/i/Wilwood/950/2...B&gclsrc=aw.ds

https://www.jegs.com/i/Wilwood/950/2...B&gclsrc=aw.ds

g356sp

!?

These are for older cars with enough play in the hubs/bearings that the rotors push the pads/pistons back in to the caliper. The best way to deal with this is knock-back springs behind the pistons or these valves, but they are both 'band-aids'.

The 350z is new enough (by a decade or two) to not have this problem. If there's something wrong with your brake system, which I'm guessing there is, these will not solve it.

Franknbeans

iTrader: (1)

Unsure what would be wrong with my brakes. It holds pressure but like I said the second pump of the pedal makes the brakes feel a lot stiffer. The second pump feels like the brakes on my Solstice GXP.

So, what's your take on my baking system? I've had 2 different shops look at them and tell me it's fine.

g356sp

Good question. Fun side note: I was helping a buddy diagnose the same problem on his silverado. Long story short, after throwing all kinds of new parts at it we noticed a small puddle had formed after a bleed, turns out at some point a rag had fallen between the bed and the cab, coming to rest on top of a frame rail. He has a cabin up in the mountains, so the rag was regularly soaked in deicer and left sitting in the cold, and over time the deicer worked its way though one of the brake hard lines leading to the rear axle. Back to your Z, assuming you/the shops have checked every connection for leaks (inc. master cyl, piston seals, hard lines etc), it could be a swelling rubber brake line. If the lines have ever been bent (ie hanging the caliper by the line during a rotor change) it can cause the inner sleeve of the line to burst, which would release pressure in to the rubber casing while the other calipers build up enough pressure to slow the car. Might be worth finding a empty lot and slamming on the brakes at relatively low speed to see if it pulls, and definitely worth checking out all the brake lines for the slightest bubbling.


edit: just checked your build thread and saw you have z1 stainless lines. Still possible they've ruptured, but much, much less likely.

260DET

Loose wheel bearings will cause pad knock back every time. Otherwise if all else fails I'd try caliper springs or one of those pressure valves although my guess is that their thread will not suit Japanese cars.

Franknbeans

iTrader: (1)

Yeah, heard that before too. All wheel bearings are good.

guitman32

iTrader: (15)

Knockback is very common on this platform (and all platforms). Congrats on being fast and sticky enough to notice!

Even though your bearings are fine replacing them if they are old will help.

Residual pressure valves and antiknockback springs both work well to a degree, if you search their performance has been discussed in the past.

Even 997 Gt3s require the tap...

Franknbeans

iTrader: (1)

Best brand for the wheel barings?

guitman32

iTrader: (15)

I use OEM Nissan for the front and rear (which are NTN if memory serves?).

260DET

Ordered a set of aftermarket calipers for another car, anti knock back springs were an option. If the calipers have done a lot of work then they may need new O rings, I recall reading somewhere (Stoptech?) that square section O rings helped retain piston pressure against the pads.