Bettter Braking in the Rain

[TomoHawk]

My brakes on the 280Z are fine with the stock discs and normal pads, but in a heavy rain, on the highway, it was sort of scary when I wanted to brake for slow traffic-  it felt like the brakes weren't grabbing at all.  For a second or two, it feels like there are no brakes, then they grab some, and get better..

So is there anything that you can do that isn't too involved to improve the wet-weather braking, like a certain kind of pads?  I though of adding a shield over the disc.

[djwarner]

I'm in the middle of rebuilding my front brakes finding interesting results. On the drivers side one piston was frozen with rust on the piston under the dust cover. But both pads were worn down 5.5mm. It appears that the retainer rings were under the dust covers rather than pressing the rubber against the housing.

On the passenger side the rings and dust covers were in place but there was visible rust on the pistons. I tried to blow the pistons out with shop air per the book but they wouldn't budge. Pad wear was much more severe on one pad compared to the other 7.75mm and 4.5mm respectively.

Looks like I was getting pad dragging.

I am rebuilding the cylinders, replacing the discs and replacing the pads with  Wagner Thermo Quiet ceramic pads. At a standstill at the moment because the one rotor doesn't want to separate and I have to visit my local garage in the morning to let them press the rotor off with their hydraulic press.

I'll let you know how things work out. I'm expecting a significant improvement.

[Patcon]

I would think drilled or slotted rotors would make a large difference. In the rain I use to drag the brake a little if I anticipated needing to stop to get the water out from between the pad and the rotor and to add some heat to dry things out.

[Chickenman]

Assuming that everything else is 100% in proper working condition ( No stuck pistons, glazed or polished  rotors ):

What brand of brake pad are you using? Pad compound greatly affects wet weather stopping performance, particularly on that first application after a run on the Freeway for example. Living in the Pacific Northwest this problem raises it's ugly head with  cars more than you would think. Especially with aftermarket Pads. I've found some pads to be down right scary,  second  others grip right away. There are a few brands that I have found work quite well.

Most Premium quality semi-metallic pad seem to work quite well. Bendix Titanium II or their Premium Semi Metallic Import line works well. Pagid Semi Metallic works well. Hawk HPS seem to work well. Tex-tar semi-metallic's work well, as do Mintex and Ferodo. Generally, semi-metallic's seem to be pretty good in the rain. Exception being some Raybesto's compounds.

I've found some of the so called " Ceramic " brands and " carbon " pads to be quite terrible in the rain. The worst pads I ever had were Stop Tech and WilWood " Polymatrix " Tans " ( Old compound... absolute isht ). " House " brand and " cheaper " brands are a gamble.

Another thing that definitely helps, is to run the factory brake shields. A lot of guys remove those when running bigger brakes and that will cause issues in the rain. Always try and run the brake shields... they are actually designed as Rain shields to keep water off the rotors. It's relatively simple to make some larger shields out of aluminium sheet or SS sheet if you have to.

Audi did a recall on early A4's  ( 1996 to 1999 )when they had an issue with wet weather stopping. They were originally running a " half size " brake shield . They had to install a full size brake shield as they had severe wet weather braking " Delay " when running in the rain on the Autobahn. I had a set of these full brake shields installed on my used 1998 Audi A4 as soon as fall the fall rains arrived ( Vancouver BC ). The full shields made a big difference. Currently I have 12" WilWood rotors on my Z but no brake shields thanks to the PO. I don't drive the Z much in the rain, but full size brake shields are definitely on my fabrication list. 

 

 

 

 

 

Edited February 26, 2016 by Chickenman
Added info

[Chickenman]

9 hours ago, TomoHawk said:

My brakes on the 280Z are fine with the stock discs and normal pads, but in a heavy rain, on the highway, it was sort of scary when I wanted to brake for slow traffic-  it felt like the brakes weren't grabbing at all.  For a second or two, it feels like there are no brakes, then they grab some, and get better..

So is there anything that you can do that isn't too involved to improve the wet-weather braking, like a certain kind of pads?  I though of adding a shield over the disc.

You don't have any shields on the front brakes? That's not good. Someone has removed them at some point. All Z cars came with brake shields. Illustration #20 & 21

[rossiz]

i commute daily 20 miles each way and it's been a wet winter here in seattle. never had a problem on my commute, even in a total downpour. 

however, i drove down to portland a couple of weekends ago and it was an absolute car wash the entire 3 hr. drive and after about 2 hrs. of steady wet cruise i hit the breaks for some traffic and absolutely NOTHING - then it pulled very hard to the left with the second application, so i pumped the pedal and after 3 or 4 pumps my breaks were back. luckily i had plenty of breaking distance, because it was a serious pucker moment - had to practically pull the vinyl out my crack after that one. totally unexpected as i've never experienced this in 18 months of daily driving - i'm guessing it was the intense, uninterrupted dousing that did it. needless to say, i left even more breaking distance the rest of the trip and pumped the breaks before stopping each time.

i haven't touched my breaks since buying the car and i have no idea what kind of pads they have. they are "adequate" in the dry but probably could use a refresh. i will be watching this thread intently to see if the collective forum knowledge can shed some light on best options (without spending $$$ on a "big rotor" swap with new lines, proportioning valves, etc.)

[Mark Maras]

 I ran many brands of pads over the years. Most were cheap, some were better quality. Little to no difference in wet braking. IMO The problem of wet brakes isn't caused by pads. It is caused by old piston "o-rings" and or stuck pistons. The o-ring seals are actually a squarish configuration with the outer edge angled. This angle allows the pads to retract just a bit when the brakes are released but still contact the rotor to wipe away water. 

 Time for a caliper rebuild. Not a difficult process with one exception. I was able to blow my pistons out with air. Take care. The pistons will come out like they are shot out of a cannon. I was careless the first time and my Z sat for a few days while my hand healed. If they won't come out with air, a pneumatic grease gun is the answer. I used brake fluid and a Scotch Brite pad to clean things up.The o-ring seals are directional. Be sure the new ones are oriented correctly. 

[Chickenman]

I'll have to respectfully disagree with you on Pad material Mark. It can and does make big difference in braking, IF you are unfortunate enough to get a set of Pads that exhibit this problem. I've had it happen a few times on different cars... and these cars all had very well maintained calipers and rotors. Most of them were Autocrossed in the wet as well, and cold stopping power really shows up in that scenario.

Note that my very first sentence I stated that the braking system had to be in 100% condition, before considering a Pad compound change:

Quote

Assuming that everything else is 100% in proper working condition ( No stuck pistons, glazed or polished  rotors ):

Naturally if you have sticking pistons ( or binding calipers in a sliding design ) or any other issues as mentioned, then those issues have to be fixed first. Not disagreeing there. But some brands of pads truly suck in the rain.  I have learned to avoid those brands over the years.

Edit: The lack of brake rotor shields on Tomohawks car can also be a contributing factor. In fact a very large factor.

 

Edited February 26, 2016 by Chickenman

[Chickenman]

6 hours ago, rossiz said:

(Snip)...

i haven't touched my breaks since buying the car and i have no idea what kind of pads they have. they are "adequate" in the dry but probably could use a refresh. i will be watching this thread intently to see if the collective forum knowledge can shed some light on best options (without spending $$$ on a "big rotor" swap with new lines, proportioning valves, etc.)

It would be wise to give the brakes a complete service if they haven't been serviced in a while. All pistons must be free, sliding caliper carriers must be cleaned and lubricated, guide pins as well. Pad contact areas must be lubricated where they contact the caliper. This is often over looked when changing pads, but is an part of a proper service. Rotors should not be glazed or polished or have any unusual wear patterns or run-out. Dust/Splash  shields should be in place. Wheel bearings should must be properly adjusted and have no play. Pads must not be glazed.

Once all the above criteria is met, then a Pad compound may be required if you still have problems stopping in the wet after a long run on the Freeway.

BTW, I always brush my brakes occasionally in wet Freeway driving as well. Especially if you start getting into traffic after a long run. Nice to know the darned things will work when you REALLY need them.

 

Edited February 26, 2016 by Chickenman

[TomoHawk]

Just in case, can you get some replacement or bigger brake shields?

OTOH-  do you need a special shop to drill or slot the rotor?

[Chickenman]

I'd look at E-bay or our regular vendors for used brake shields.

Edit. There's a couple of sets on E-Bay right now:

280Z Brake shields

I absolutely would not try and slot or drill any standard rotors at a machine shop. Good way to have a rotor crack.

Those aftermarket slotted rotors are usually made out of cheap alloys and infamous for cracking and exploding on track days. They are NOT the same as drilled Porsche rotors that cost $700 + Each. Buyer beware. The aftermarket slotted rotors are much less prone to cracking, but they are not needed if your braking system is in tip top shape and you have correct pad materials.

Edited February 27, 2016 by Chickenman

[TomoHawk]

I forget for sure, but the brake shields may still be on the car. I would borrow them to make some patterns for some nice made of an alloy.  From the looks of it, you could hammer some out in a day, or weld together  some bits.

Too bad you can't just hook up a hose for cooling air (if you do track driving.)

Otherwise, I think my pads could use a change-out, and I was looking around at  what's available, so that would be the easiest thing to try- some semi-metallic pads.

Edited February 27, 2016 by TomoHawk