brakes work poorly when it is raining (96 300zx)

[doctordan]

My brakes on my 96 300zx work fine except when driving in the rain. It acts like the power assist doesn't work when it is wet - requires a lot more pedal pressure to stop. I have had it in the shop to be checked 3 times, but they tell me nothing is wrong. Any ideas?

[Q45tech]

Are the pads and rotor oem? I am guessing the pad friction changes in colder conditions or did it happen last Summer also?

[doctordan]

I am not sure whether they are OEM. The car was wrecked in 1998 with extensive front end damage but I don't think the brakes were replaced. The problem has nothing to do with temperature. Only when driving in the rain.

[Defiant]

How open are the wheels? You're probably getting the discs wet, which lubes them. Scary as all get out. You might look into slotted discs, which will help. Different pads have different wet characteristics, as well. But the brakes should behave normally once they've wiped the water off.

[doctordan]

The wheels are stock. The tires are same as came on the car new. Nothing custom or aftermarket. The machanic says the pads and rotors are fine.

[Defiant]

Yeh.... even though under your foot they feel like they're getting no grip. You might want to swap-out pads and see if that helps you. Or, find a mechanic who'll listen to what you tell him.

[180fan]

what's the thickness of the rotor at the moment? also is the splash shield still in relatively good condition?

[Q45tech]

The tires are same as came on the car new.....................HOW can that be after 11 years?

Find a Nissan SPECIALTY SHOP almost every large city has a Z car garage.

[doctordan]

They are not the same tires. They are the same brand and size as original tires.

[Q45tech]

The reason I ask is I never use tires more than 2 years due to hardening of compound.

Tires : 225/50ZR-16 all around on non turbo. Make Bridgestone and model?, tread depth, mileage and age?

[doctordan]

The tires are Michelin. The brake problem has nothing to do with the tires. I have noticed it for about two years. Not getting any better. Not getting any worse. It only occurs when driving in the rain, which I don't have to do very often. When it occurs, if I pump the brakes several times, the brakes function better until they get wet again. It only occurs if I have been driving in steady rain for several minutes. I haven't had a chance to check the shields yet, but that sounds like a likely culprit.

[babowc]

lol you're blaming water for bad braking?

go look at your tires and pads.

[doctordan]

YES I'M BLAMING WATER (RAIN). THE TIRES ARE FINE AND MY MECHANIC HAS SAID THE PADS ARE FINE THREE TIMES!

[skydragoness]

Tires obviously have poor water evacuating capabilities.

But since your'e so adamant about your tires not being the problem (which the tires are what ultimately stop the car not the brakes), have a look at your brakefluid, if it's anything but clear have it bled. Although I have to say if it was a brakefluid issue, the amount of pressure you'd have to apply would vary a lot no matter what weather it is.

As for as the rotor shields, they are doing their job. Any loss in braking/etc would happen if you drove thru a puddle or standing water and flooded the vanes of the rotors. That would cause a momentarily loss of braking ability.

Also... try going to another mechanic for a 2nd opinion. Maybe set up an appt. on a day it's going to rain. Personally I just think maybe your Michelin's are no good in the rain, but your first post is kind of vague. Try finding out the exact type of Michelin you have. It may not be cutting it for the portly Z. We have a Z32 TT in the family and it brakes on a dime (equipped w/ Bridgestone RE950--best rain tire imo) no matter the weather (except snow of course).

[ralphdig]

YES I'M BLAMING WATER (RAIN). THE TIRES ARE FINE AND MY MECHANIC HAS SAID THE PADS ARE FINE THREE TIMES!

It's perfectly normal that wet brakes decrease their efficiency.

[Defiant]

It only occurs when driving in the rain, which I don't have to do very often. When it occurs, if I pump the brakes several times, the brakes function better until they get wet again. It only occurs if I have been driving in steady rain for several minutes.

I'm still with water on the discs. Happened to me the first time I drove my 510 in the wet after putting on American Libres. Scared the peewaddin out of me. It takes about twenty feet to get the discs dry and the brakes working. You can either develop the habit of dragging them just a bit every so often to keep them closer to dry and more prepared to work as usual, or just try to add more than the usual wet-weather buffer zone. Again, slotted discs may help; D-dusters -sorry, Kleen Wheels- will help:http://www.brakedustcover.com/

[Sentientbydesign]

Yelling at people who are trying to help you is bad form first of all. I don't mean to be mean, but you don't sound like you know much about your Z.

You might have the cheapest duralasts from autozone on your Z and your mechanic will look at them and say yeah "they're fine".

My personal advice... Bleed your brakes and spring for some good fluid. Keep the fluid checked. If you have a leak anywhere, it will obviously get low. Secondly, I'd spring for some powerslot rotors with Hawk HPS pads. BREAK THEM IN PROPERLY!!! If you don't, they glaze and are worthless.

And lastly, your tires have a hell of a lot to do with your braking ability. Regardless of "feel" at the pedal, if your tires aren't sticky and good at treading water, they'll constantly let you down in rain.

I originally had Bridgestone Potenza RE930s (205/65/r15) on my I30 and they sucked. I was hydroplaning at 30mph in the rain. I now have REO40s in 225/55/r17 (yes I know my tire diameter went up, sue me) and the wider track and stickier grip make a significant difference. In the end regardless if your brakes can stop your tires from spinning, it's the friction between the road and your tires that stops your car!

[doctordan]

Forgive me if it sounded like I am yelling. It was not intended that way. Everyone seems to think my problem is my tires. I am fairly certain that is not the problem. This is the fourth set of tires I have had on the car. They have all been the same Michelin's that came from the factory. I know what it feels like to hydroplane. That is not the problem. If the brake fluid was bad, it should affect braking during other conditions besides driving in the rain. If the rotors or pads were bad, I would think my mechanic would be able to tell (maybe not). The brakes work fine except when driving in steady rain. Then it takes a lot more pedal pressure to feel any effect. If I pump the pedal several times (?dry out the pads?) the brakes feel OK. This has been going on for about two years - not getting any worse, not getting any better. I think there might be some power brake electrical problem that gets wet and looses the power assist???

[Defiant]

Everyone seems to think my problem is my tires.

Well, not everyone.

Quote » The brakes work fine except when driving in steady rain. Then it takes a lot more pedal pressure to feel any effect. If I pump the pedal several times (?dry out the pads?) the brakes feel OK. [/quote]If you hit them once for about a quarter-second to wipe them off and then re-apply, they should feel nearly normal if the problem is water on the discs.Quote » I think there might be some power brake electrical problem that gets wet and loses the power assist???[/quote]No. Not "probably not", but not a chance in the world. Power brakes are driven by engine vacuum, and have no electrical component.

[Sentientbydesign]

I think in general all of our brakes fail a little in rain. Not to any extreme, but still not as firm as in dry weather.

I'd still try changing to another pad. The hawks have been good to me, although, they eat oem rotors quite easily. I think you'd like the extra bite they provide. Say no to Duralast! lol

[revenant665]

i have recently had th esame problem on my q45, it rained here in phoenix and when i went through a big puddle my brakes started failing. figuring it was just wet pads, i was pumping, but it had no effect. 2 Days later the problem still exists, it feels as is i have no power brakes! and im getting a "stop lamp innoperative" code on my display...weird. i understand about the wet brakes sucking and the tires displacing water, but this is beyond that. any ideas?

[doctordan]

sounds like you have a completely different problem. I only had trouble while driving in the rain, not afterwards. It turns out that replacing my brake pads with OEM solved the problem. I don't know what kind I had before (they had been replaced once at my mechanic shop - not the Nissan dealer). They seem to be working fine now.